Musculoskeletal Flashcards
What are the fibrillar collagens?
Major 1,2,3
Minior 5,11,24,27
major component of macromolecular collagen fibrils
What are fibril-associated collagens with interrupted tuple helices (FACIT)?
9,12,16,19,20,21,22
do not assume fibrillar structure
assocted with fibrilla
important roles in 3D organization and interaction fo fibrillar collagens
Basmentmembrane collagens?
4, 7, 15, 18
Filamentous collagen
6
What is the structure of collagen?
triple helix made of 3 separate polypeptide molecules (alpha chains)
homotypic (same 3 chains) = 2, 3
heteroypic = 5
Describe collagen biosynthesis
transcription of gene and translation mRNA = pre-proalpha chains (pre-pro-collagen)
proline hydroxylation (rate limiting step)
O-linked glycoslation reactions
triple helicies stablized by disulfide bonds
folding = molecular chaperones, cis-trans isomerization (prolylpeptidyl isomerase) = triple helical procollagen
globular teloprptide somains cleaved metalloproteinases = trocollagen
fibrillogenesis (trocollagen +ECM) = fibrils = fascicles = macroscopic fibers
Descrine the structure of a proteoglycan.
Glucosaminoglycan = heparin sulfate, keratan sulfate, D-glucosamine
Galatosaminoglycans = chondroitin sulfate, dermatuan sulfate, D-galactosamine
Hyaluronic acid = nonsulfonated glucosaminoglycan, repeating unitsD-glucuronic acid and D-glucosamine
Diagram of the basic structure of an aggregating proteoglycan. Proteoglycan monomers consist of a core protein with numerous covalently linked glycosaminoglycans. Keratan sulfate and chondroitin sulfate, the most common glycosaminoglycans in articular cartilage, are depicted. In a typical aggregating proteoglycan, hundreds of proteoglycan monomers may associate with a single hyaluronic acid backbone. This association is noncovalent and is stabilized by link proteins. The positions of the globular domains (G1, G2, and G3) of the core protein relative to the glycosaminoglycan binding region are shown. G1 contains a hyaluronan binding domain, and G3 contains domains that bind a variety of extracellular matrix components. The function of G2 is unknown
What are matrix metalloproteinases
Zinc dependent endoprptidases that cleave ECM protieins (collagenaes, gelatinases, stromolysins)
What is elastin?
protein biopolymer = monomeric component is protein tropoelastin (65-70kDa)
formation requires fibrillin microfibrils and fibronectin as scaffold for tropoelastin
elastic deformation or strain of approx 70% restin length, maximum extension of 220% before loss of strength
How does the modulus of elasticity compare between type 1 collagen and elastin?
300-600 kPa elastin compated with 10^6 kPa for type collagen
Sturcture of bone - cortical.
Haversian units
Volkman’s canal
What makes up periosteal ECM?
Type 1 collagen, proteoglycans and elastin
What orchestrates osteoclastic recruitment?
monocyte colony stimulating factor (M-CSF) and receptor activator of NFkB ligand (RANKL)
expressed by osteoblasts, decreases expression of osteoprotegerin (blocks RANKL and prevents differentiation of osteclast precusors)
What is sclerostin?
Released from osteocytes - exerts inhibitory effects on proliferation and biosynthetic activity of osetoblasts
What is another name for a resorption pit?
Howship’s lacuna
What is the mineral composition of bone?
70% mineral, resists compressive force
calcium hydrocyl-apatite
What is the organic matrix of bone composed of?
90% collagen (primarily type 1, also 5 and 3)
What law describes bones ability to remodel in response to mechanical load?
Wolff’s Law 1892
What is the make up of articular cartilage?
70% water
Dry weight = 50% collagen (85-90% type 2- provides tensile stiffnes and strength)
- 35% proteoglycan
- 10% gylcoprotien
minerals and lipis
- 2-10% chondrocytes
Other components: firoenectins, type 11 (stablizes lateral gowth fibrils), Aggrecan (240kDa, major proteglycgan, 90% carbohydrate), leuine rich proteoglycans (chondroitin/dermatan sulfate- decorin, biglycan and keratin sulfate - fibromodulin) modulate fibrillogensis
What are the zones of cartilage?
1: superfical/tangential zone - fibrils tangential (tension)
2: transitional zone - fibrils parallel and branching (shear and compression)
3. radiate zone - fibrils perpendicular (compression)
tidemark
- calcified cartilage zone
conc proteoglycan increase with depth from surface
collagen fibrils more concentrated at surface
How much does osmotic pressure contribute to compresive stiffness of cartilage?
50%
GAGs account for 75% of the osmotic pressure of PGs
What kind of collagen makes up fibrocartilage?
Type 1
Small amounts of proteoglycans
makes up annulus fibrosus, menisci and parapartellar isetions of quadriceps mm.
What are types of tendons?
Aponeuroses
Positional tendons - DDFT
Energy storing tendongs = calcaneal tendon - greater elastic fiber component
Stress-strain relationship of tendons.
intial pahse - straighten fibrils
linear elastic region
rapid loaging = fibrillar elongation and stress relaxation and creep = interfibrillar shear
yeild point
larger diameter = greater stiffness
small diameter - greater surface area and viscoelastic properites
healed collagen fibrils remain smaller and more uniform = inferior properties
Name parts of muscle
Z-band
A-band = conjoined myosin fibers
I-band = centerd on z disc and actin fibers
Describe muscle contraction
Action potential → acetylcholine released → binds sarcolemma and depolarizes causing Ca release from sarcoplasmic reticulum
→ confrom change in tropmyosin exposes myosin site on actin → globular head myosin filament engages with ATP → shorten sarcomere
What is the ECM of muscles?
Epimysium: fasicles assembed to mm. bellies
Perimysium: Fibers into fasicles
Endomysium: myofibers into fibers (satellite cells = myoblastic progenitor cells)
basement membrane basis of ECM in each layer: Composed of nerves, vessels, lymphatics, Type 1 collagen, proteglycans, fibroblasts
ECM <10% skeletal m
ECM provides structure for force transfer and elastic recoil
What are the 2 types of muscle fibers?
Type 1 = slow twitch = mitochondria rich, sustained low velocity, low force (oxidative metabolism) = improved aerobic capcity, stimulated by prolonged low levels force
Type 2 = fast twitch = few mitochondria, rich in myofibrils, transient high velocity and force = high intesity conditioning = hypertrophy type 2, synthesis myofibril proteins, enlarment and increase contractile capabilites
Define viscoelastic and anisotropic.
Visoelastic = strength depends on the rate the bone loaded (bone stronger when rapidly loaded)
Anisotropic = mechanical properties depend on the direction of loading
Define stress and strain
Stress = N/m^2 = newton/ meter squared
Stain = local deformation = L1-L2 / L1
Illustration of stress (A) and strain (B). A, Force (F) is applied to a block, producing stress (σ). When the surface area is decreased by one half, the stress is doubled (2σ) for the same amount of force. B, The mathematical definition of strain is the change in length divided by the original length
Define strength and stiffness
Strength = load material can withstand before failure
Stiffness = rate at which material deforms with load
Describe stress strain curve.
Illustration of a stress/strain curve produced when a material is loaded. The slope of the ascending linear portion of the curve is the stiffness of the material. Point Y is the yield point of the material. Point U is the ultimate strength of the material. Toughness is defined as the area under the curve (red shading)
How does cortical bone compare to cancellous bone in porosity and stres/strain curves?
Porosity (volume open space to bone): cortical 5-10%, cancellous 75-95%
Cortical bone short plastic phase, cancellous bone long plastic phase
Cortical bone higher stiffness and strength
Total energy absorbed can be greater for cancellous due to prolonged plastic phase
Note the prolonged plateau in cancellous loading representing the collapse of trabeculae.
Describe bending forces:
moment
pure bending
cantileve ending
3 point bending
4 point bending
Cantilever = break at fixation point
3-point = break at middle force (where bending point present)
4 point = constant loads between middle points
moment = tendency of a force to twist or rotate an object, expressed in units of torque
Illustration of bending moment diagrams for various loading conditions. A, Pure bending when opposite torques are applied to each end of a beam. B, Cantilever bending with an applied load at the end of a beam. C, Three-point bending with two equal loads applied at each end and a third load applied between them. D, Four-point bending with two equal loads applied at each end and two additional loads applied between them
Describe the fracture associated with the following forces.
Compressive = oblique fracture
tensile and bending = transverse
bending with compression = butterfly fragment
torsional = spiral
Primary gap healing
Primary gap healing. A, The gap is initially filled with transversely oriented lamellar bone. B, A cutting cone moves across the lamellar bone, producing osteoid that is mineralized to form longitudinally oriented lamellar bone. This process is known as longitudinal Haversian remodeling
Occurs when gap <1mm, Strain <2%
- Lamellar bone forms in gap early = Deposited within days, No cartilage intermediary, Transverse orientation, Little stability
- 3rd week of healing = Longitudinal remodeling = Osteons (with osteoprogenitor cells) cross gap, Longitudinally oriented osteons placed (still weak)
- By 8 weeks = secondary remodelling = Similar to contact healing cascade
Primary healing - no gap
A, Because of direct contact with bone ends, lamellar bone is not formed transversely. Cutting cones cross the fracture line directly and form new longitudinally oriented lamellar bone. B, Mature osteons cross the original fracture site, connecting the segments and providing strength to completely repaired bone
Secondary bone healing
Plt-rich hematoma formation
- Release of TNF-α, IL-1, IL-6
- MSC release from soft tissues, periosteum, bone marrow
- BMPs induce proliferation and differentiation of MSCs
- Granulation tissue replaces hematoma
- Angiogenesis (VEGF, angiopoietin)
- Hard callus (woven bone) forms by intramembranous ossification from cambium layer of periosteum
- Fracture gap bridges by soft callus
- Endochondral ossification replaces soft callus with bone
- Remodelling: hard callus replaces with lamellar bone
What are types of bone healing?
Endrochondral ossification (cartilagenous precusor)
Intramembranous (direct differentiation of mesenchymal cells to ostoblasts) - how flat bones formed, compaction of trabeculae to cortical bone
Direct (no evidence of callus)
Indirect aka secondary bone healing
List the strains associted with bone healing for various tissues
Granulation / hematoma up to 100% - 40 degrees
Fibrous tissue 20%
Cartilage 15%
Fibrocartilage 10% - 5 degrees
Woven bone < 10%
lammelar Bone <2% - 0.5 degrees
How does distraction osteogensis work?
regnerate bone via intramembranous ossification
- fibrous interzone (central radiolucent zone) = once distraction stops the zone mineralizes
During distraction osteogenesis, osteoid is laid down in parallel columns that extend from osteotomy surfaces centrally. Lamellar bone develops within these columns if the fracture is sufficiently stable
What is the user agreement for open fractures? And what is the Gustil-Anderson scheme?
60% agreement
Type 1: Open fracture with wound <1cm, soft tissues mild/mod contused, usually inside out
Type 2: wound >1cm w/o extensive soft tissue damage, flaps or alvusions, usually from outside
Type 3: extensive soft tissue damage
3a = adequate soft tissue coverage despite extensive trauma
3b = extensive soft tissue loss, periosteal stripping, bone expsoure, usually massive contamination
3c = associated with arterial injury requiring repair
What is the orthopedic trauma associated scheme for open fractures?
Each given subscore of 1, 2, or 3 for mild, mod or severe
S-skin defect
M- muscle injury
A- arterial injury
B - bone injury
C- contamination
SMABC = M-CABS
What are risk factors for infection for open fractures?
Lack abx
resistent organisms
too much time from injurgy to starting abx
extensive soft tissue trauma
positive port-debridement/irrigatation culture
What is the infection rate for open fractures and what common organisms?
human: within 3 hours = 4.7% vs 7.4% for +4 hours
Type 1 and 2 fractures: ~6% with fluoroquinolone or cephalsporin/gentamycin = rec. 1st/2nd gen cephalporin
Type 3: 7.7% with ceph/genta vs. 31% with cipro = rec. ceph + fluoro
Common = staph, strep, kleb, pseudomonas, clostridium, enterobacter, e. coli
abx beads = decreased from 12% to 3.7%
Does early surgical debridment effect sucess?
Human studies no difference, old dogma = debride within 6 hr
What are the advantages of negative pressure wound healing?
Decreased interstitial edema
Increased blood flow
Accelerate formaiton of granulation tissue
increased bacterial clearence
promotes wound contraction
secure skin graft
Which bone graft is safe for an open wound?
Cancellous is safe
Cortical = risk for infection/sequestum formation
What are the delayed/non-union rates for open fractures?
Type 1 = 0-5%
Type 2 = 1-14%
Type 3 = 2-37%
Physeal cartilage healing. A, Salter-Harris Type I physeal fracture occurs through the hypertrophied zone of cartilage. B, If reduced accurately, these physeal fractures heal by continued formation of cartilage. C, If the fracture involves the reserve zone or if the germinal cells are damaged, healing occurs by endochondral ossification
What is the tensile strength of wire?
related to cross-sectional area
π x r^2
How do single, double and twist orthopedic wire conformations compare?
Peak load = twist knot superior
Tension lower twist (70N vs 165N single loop) but similar load to losening (268N vs 259N loop)
double loop more tension (391N) and higher load to losening (661N)
Resting tension drops <30N after collapse of only 1%
What are the principles of circlage wire?
at least 2 wires
space 1/2 bone diameter apart
shaft completely rebuilt
What sizes do K wire come in?
0.035mm 0.045mm 0.062mm
How do you determine stiffness and strength of a pin?
Area moment of inertia = r ^4
Stiffness also influenced by the length of the pin (shorter = stiffer)
How much of the medullary diameter should be filled by a Steinmann pin?
70% when pin is used as only intramedullary device
What is the advantage of scre-cone pegs in interlocking nails?
self locking and self centering
What are advantages of the traditional interlocking nail?
Placed neutral axis of bone = direct axial compression
Large AMI = more resistence to bending
- nail AMI = r^4 vs plate AMI = thickness ^3 (aka 8mm nail AMI 6.8x 3.5mm DCP plate)
Locking mechanism = stability in torsion and compression
What are flaws of the traditional interlocking nail?
Weakest when bending parallel to the long axis of the screw
- screw holes concentrate stress, small hole = stronger nail (3.5mm to 2.7mm in 6mm nail = 52x increase in nail fatigue life)
Plate rod may be biomechanically superior (ILN more slack in bending and torsion - upto 33 degrees)
Rotational instability = nonhealing rate of 14% for 2nd gen ILN
How can you increase stability of a ILN?
Bolts not scews
Placement of IM pin with ILN
Excessive angling of screws
Use of bolts attached to ESF
How does Angle stable ILN compare to traditional ILN?
ASLIN elminates all slack in bending (both planes) and torsion
- ASLIN smaller maximal deformation, 50% deformation in ILN due to slack
— ASLIN stable directly after sx
- ASLIN decreases interfragmentary motion
Titanium ILN increased stiffness, strength in torsion, compression and bending
Lower lameness scores at 8w
Clinical union at 8-10w vs. 12-18w (stiffer/stronger under torsion = calus matured faster)
What are the 2 modes the ILN can be placed in?
Dynamic mode = need axial loading bc only secured to 1 fragment
- minmal resistence to rotation, locking prevents migration, associated with prolonged healing and the need for removal of locking device but potential for increased micromotion and healing
Stable mode - can be destabilized at 6-10w
Non-Reaming of the canal associated with less infection, fat metabolism and histological more rapid healing.
Angle stable vs normal ILN appearence
Examples of interlocking nail systems. Regular interlocking nail attached to extension piece and aiming device; drill bit is placed through the sleeves into the most distal nail hole. The guide sleeve closest to the top of the attachment guide contains a trocar, which is used to create a path through soft tissues and to score the bone, so that the drill bit purchases the bone at the appropriate site (A). Interlocking screw and bolt (B). Screw-cone peg (C). Angle-stable interlocking nail with screw-cone pegs (D–E)
How do you pick a nail for an ILN?
Should not exceed 70-90% of isthmus
3.5-4.7mm nails for cats/sm. dogs
6mm 15-30Kg
8-10mm for large or giant breeds
What is the general technique for ILN?
Blunt tips
Normograde placement - entry hole, extension piece to nail
Controlled impacted with mallet (more secure than twisting)
Etch marks assess depth
2 Locking devices in prox and distal = 1-2 bone diameters from fracture and in metaphyseal region
Locking device not sucessfully placed through distal hole in 28%
How should the ILN be placed in the humerus?
Normograde: lateral junct. crest of greater tubercle and the greater tubercle
Seated proximal to supratrochlear foramen (or retrograde)
Prox locking device should be distal to level of greater tubercle
What is the sucess and complication rate fo the ILN?
83-96% success, 95% heal w good function by 3m (median 6w vs 8w)
Complication = 4-23%
- Pulmonary embolism (2 dogs)
- bending/breaking drill bit, nail, screw or bolt
- fracture of bone through hole, fx prox or distal to nail
- osteomylitis
- nerve damage (radial or sciatic)
_ quads contracture, psuedoartho]\rosis, granuloma at tip, windshield wiper effect, pain, infection, seroma, instbility, delayed/non-union
Screws with different thread type and arrangement and design have different uses and indications. All screws in this figure are 3.5 mm in outer diameter. The cortical screw (A) has a thread pitch and depth designed for dense, hard bone. Cancellous screws (B–C) have greater thread pitch and depth to optimize purchase in trabecular bone. These screws are available in a fully or partially threaded design. The partial thread creates a lag effect when the screw is placed. The shaft screw (D) is a partially threaded screw; the diameter of the shaft is the same as the diameter of the threads. This design modification results in a stronger screw and improves contact between the screw and the bone in the near cortex. The thread design is cortical in nature. The cannulated screw (E) has a hole through its length. It is often used after closed reduction or when exposure of the fragments is difficult. A Kirschner wire is used to maintain reduction. The screw is placed over the Kirschner wire, thus ensuring accurate placement. The self-tapping screw (F) has a cutting flute in the tip that allows insertion without a tap to cut the thread pattern into the bone. It must be advanced so that the cutting flute passes completely through the far cortex to achieve holding power similar to a tapped screw
When is it difficult to place a lag screw?
if fx line is <1.5x the diameter of the bone
Configuration of screws, demonstrating differences between cortical and cancellous screws. Root diameter is also commonly referred to as core diameter
Pull out strength determined by outer diameter and strength of material it is placed in
Bending strength = core diameter
Types of material plates are made out of?
316L stainless steel
steel (reconstruction plates may be softer)
Titanium plates: theoretical advantage with respect to failure, not as stiff or strong as stainless steel
What are the advantages of LC-DCP vs. DCP?
- Even stress distribution - AMI less between screws, can bend over the whole plate
- Periosteal damage less
- Holes allow screw angulation more (80 degress longituindally, 14 degrees side to side
- Bidirectional compression
- Strength compared to DCP – similar, maybe sl. weaker, no significant difference
Comparison of the inner (core or root) and outer diameters of cannulated, shaft, cortical, and cancellous, screws
Examples of eight-hole dynamic compression plates from the Association for the Study of Internal Fixation system: 2.0 (A); 2.7 (B); 3.5 standard (C); 3.5 broad (D) (this plate has the same dimensions as the 4.5 narrow, but the screw holes are smaller); 4.5 narrow (E); 4.5 broad (F). The screw holes are staggered to improve the holding strength and to distribute the holes within the bone farther from each other.
How do reconstruction plates compare to DCP?
Softer steel
Weaker than DCP
V notched = contour in 3 directions
Sizes: 2.0,2.7,3.5 (no 4.5)
Examples of specialized plates. The cuttable plate (A) is pictured in the 2.0 size; a size suitable for 1.5 mm screws is also available. The semitubular plate (B) is thinner than the dynamic compression plate and is rarely used on load-bearing bones. The lengthening plate (C) has a central solid section that can be used to span a defect. The reconstruction plate (D) is pictured in the 3.5 size; a size suitable for 2.7 mm screws is also available. Reconstruction plates are V notched and are made from softer metal to enable contouring to irregularly shaped bone
Pull-out of standard screws and locking head screws. A, Fixation with cortex screws. B, With conventional plating, if axial load exceeds the frictional force between the plate and the bone, plate loosening occurs, and screws are subject to an axial pull-out force and to sequential screw loosening. C, Fixation with locking head screws. D–E, Failure of the locking system requires concurrent axial pull-out of all implants or compressive failure of the bone surrounding the screws. The force or load required to cause failure of the bone or of all screws greatly exceeds that required to cause failure in a sequential fashion
What is plate-span ratio and what is plate screw density?
Importance of the plate-span ratio and plate-screw density in bridge plating technique. The schematic drawing shows mechanically sound fixation of a multifragmentary diaphyseal fracture in the lower leg. The ratio between the length of the plate and the length of the fracture is known as the plate-span ratio. In this case, the ratio is high enough, that is, approximately 3, indicating that the plate is three times longer than the overall fracture area. The plate-screw density is shown for all three bone segments. The proximal main fragment has a plate-screw density of 0.5 (three out of six holes occupied); the segment over the fracture has a density of 0 (none of the four holes occupied); and the distal main fragment has a density of 0.75 (three out of four holes occupied). The higher plate-screw density in the distal main fragment has to be accepted, because for anatomic reasons, there is no way of reducing it. The overall plate-screw density for the construct in this example is 0.43 (six screws in a 14-hole plate).
What are indications for use of a locking plate?
Poor bone quality
Comminuted metaphyseal or diaphyseal fx
Periprothetic fx
Complex periarticular fx
What are common locking systems?
LCP (synthes, locking compression plate)
String of pearls (standard cortical screw)
Advanced locking plate system (ALPS, Kyon)
Fixin (traumavet Italy)
What factors are associated with implant failure and how is biological osteosynthesis statistically better than ORIF?
extensive soft tissue dissection, disruption of the fracture hematoma, multifocal periosteal necrosis secondary to plate compression, and iatrogenic trauma associated with interfragmentary implants such as lag screws and cerclage wires. In this study (human), the best predictor of success was the use of longer bridging plates with fewer plate and interfragmentary screws.
Biological osteosynthesis, time to union decreased from 20 to 13 weeks, nonunion rates decreased from ≈10% to ≈4%, and revision surgery rates decreased from 43% to 13%. Overall, the success rate increased from 62% to 87%, despite a drastic decrease in the use of bone grafts, from 30% to 4%.
What is elastic plate osteosynthesis?
Immature animals <5-6m
Due to weak bone, failure of bone-screw interface with pullout complication of stiffer implants
long thin plate that span entire bone with few screws, increased working distance
Clinical union 2w, union by 4w in all cases
Immediate and 4-week postoperative radiographs of a comminuted diaphyseal fracture treated using a locking compression bone plate applied in bridging mode. Note that in the absence of anatomic reconstruction, no load sharing occurs between the bone and the plate, which now sustains all forces at the fracture gap. The plate is secured onto the bone using two to three screws at each end. This results in increased compliance of the construct and decreases the risk of fatigue failure. Indirect reduction and percutaneous plate fixation were performed to preserve the fracture site and optimize bone healing potential. These principles serve as the basis of biological osteosynthesis and are applied to promote early formation of callus and rapid clinical union as observed by 4 weeks postoperatively in this case
In a plate rod construct, how much of the medulary cavity should be filled and how does stiffness change as filling increased?
Recommend 35-45%
For each 10% increase, strain reduced by 20%
Overal stiffness increased 6% for 30%, 40% for 40% and 78% for 50% (too ridgid)
How does brdiging differ from butress plating?
anatomic location (metaphysis, trans-cortical defects for bridging)
relative compliance (increased bridging?)
limited reliance on plate screws near the fx site
elimination of interfragmentary implants
limited use of bone grafts
MIPO
longer plates (high plate bridigng ratio), fewer screws (low plate screw density), low plate span ratio (plate to fracture length ratio)
Examples of commercially available clamps designed for use with linear external skeletal fixation systems. A, Kirschner-Ehmer clamp; single and double clamps (IMEX Veterinary Inc., Longview, TX). B, SK clamp; single and double (IMEX Veterinary Inc.). C, Securos external skeletal fixator clamp (Securos, Sturbridge, MA). D, Titan external skeletal clamp (Securos). Black arrow, position for transfixation pin; white arrow, position for connecting bar
How does adding a unilateral plate agumentation steel connecting plate or 2nd steel connecting bar add to the stiffness of a type 1a fixator?
Steel plate = 4.5x increase axial stiffnes and med/lat bending, 2x increased cr/cd bending and stiffness
Double steel connecting bar = 80% stiffer in axial and 170% stiffer in med/lat beneing compared to external plate.
= stiffness of IIb or 50% IIa
Which is more important, bar diameter or pin number?
larger diameter bar to increase stiffness negated when 2 or more full pins used
What factos improve stiffness type 1 fixators?
stonger frame
hybrid design
Tie-ins
threaded pins
At what point will pin number not increase stiffness?
>4 per segment
What size pins should be used and at what spacing for ESF?
no greater than 20-30% bone diameter = stress riser
Evenly spaced, no closer than 3x pin diameter or 1/2 bone diameter from joint/fracture
What can be done to decrease bone resorption around the pins?
reduce pin-bone interface stress
smooth pins at 70 degrees to long axis
position bar closer to the bone = stiffer construct
Pin stiffness porportinal to the pin length^3 (shorter is stiffer)
No chuck (wobbles), power drill <150rpm
60 degree pin offset = 4-5x stiffness in 1a (acylics)
What are the advantages of circular ESF?
1- increased stiffness in bending/shear and decreased stiffness in axial compression
- small fragmenrs 1-1.5cm
- adjustable after placement
What are the 15 principles of ESF application?
- Aseptic technique
- Proper locaiton for pin insertion
- Select most suitable ESF
- Auxillary fixation when indicated
- Maintain stabilization and reduction when applying frame
- Insert pins without damaging soft tissues
- proper pin insertion technique
- Engage both corticies
- insert smooth pins and neg. profile pins at 70 degree angle
- Insert all pins in same plane when using bar
- Even distribution - optimize mechanical stability
- 3-4 pins in each fragment
- Optimal size implants
- Optimal distance between clamps and skin
- Cancellous graft in sig cortical defects
How does the use of ESF effect surgery time and healing time for comminuted tibia fractures?
Decreased surgery time 45%
Decreased healing time 27%
What is the incidence of mal/non-union in small breed dogs treated with exernal coaptation for radial fractures?
83%
What is this?
Robinson sling
Other wierd slings = schroeder thomas
What are the guidelines for external coaptation?
Reduction = at least 50% contact of cotical fracture fragments
Proper alignment
Neural standing angle
immobilize joints above and below
What are grades of sprains?
Grade 1 = overstretch ligament
Grade 2 = partial tear
Grade 3 = complete tear
What are types of orthoses?
Non-ridgid, semi-ridgid, Rigid
Static vs. Dynamic
Stifle braces: prophylactic, rehabilitative, funcitonal
Contracture/assist type braces
What are the types of non-unions?
Viable = mechanical issue (motion, fracture gap), biologically OK
- Hypertrophic
- Moderately hypertrophic
- Oligotrophic - some biologic failure as well (loose implant at fracture- prevent bone proliferation and vascularization.
Non-viable = biologically inactive
- Dystrophic - compromised vasculature/non-viable bone 1 or both sides
- Necrotic - infected dead bone = sequestrum
- Defect - gap too large and filled with non-bone (fibrous or muscle)
- Atrophic- result of above types, host removes bone but doesn’t replace
What are less conventional methods to deal with delayed/non-unions?
Extracorporeal shock wave - hypertrophic but not atrophic
Pulse electromagnetic field
Low intensity pulsed US
What is the mean value for the mLDHA?
mechanical lateral distal humeral angle = 83.7 +/- 2.9 degress
What is the definition of an elbow straight rad?
1) No appearance of medial or lateral surfaces of the anconeal process
2) The distance from the medial epicondyle to the med cortex olecranon is 45% of the transcondylar distance
What are the normal angles of the proximal and distal radius?
aMPRA = 83
aLDRA= 86
aCdPRA = 85
aCdDRA = 22
Procurvatum = 27
How do you calculate procurvatum?
procurvatum = (90-aCdPRA) + (90-aCdDRA) + theta
What are the landmarks used to measure joint angles and antomic axis for the radius?
proximal radial joint orientation line (frontal plane) = proximolateral edge of the radial head and the medial portion of the coronoid process OR distal aspect of the humeral condyle
distal radial joint orientation line = lateral-most aspect of the articular surface and the medial aspect of the articular face, ignoring the styloid process.
anatomic axis is drawn by connecting three points with a best-fit line that bisects the radius at levels within the metaphyses and mid-diaphysis. (aMPRA) and (aLDRA)
How do you measure anatomic and mechanical axis of the femur?
distal joint orientation line = distal-most aspect of the lateral and medial femoral condyles
proximal joint orientation line = center of the femoral head to the dorsal-most aspect of the greater trochanter of the femur.
anatomic axis = line that connects points selected 33% and 50% below the proximal aspect of the femoral neck in the middle of the femur (normal distal femoral varus) (aLDFA), (aLPFA)
mechanical axis = line that runs from the center of the femoral head to the center of the distal femoral joint orientation line. (mLDFA), (mLPFA) i
How do you define angle of inclinaiton?
Femoral angle of inclincation = angle formed by the proximal anatomic axis and a line that bisects the femoral head/neck
coxa vera = decreased AOI
coxa valga = increased AOI
Normal angle of inclination = 134
What is angle of anteversion?
anteversion angle of femoral head and neck = angle between the neck and frontal plane of the caudal aspect of the condyles
Normal = 27-31
In 4 studies, axial range = 16-30.8, oblique planer analysis = 31.3, CT 19.6
What are the normal anatomic and mechanical axis of the femur?
Labs, Golden, GSD, Rotties
aLDFA = 97, 97, 94, 98
aLPFA = 103, 98, 101, 96
mLDFA = 100, 100, 97, 100
MLPFA = 100, 95, 97, 93
How do you measure the anatomic axis of the tibia?
the frontal plane, prox orientation line = distal points of the subchondral bone concavities of the medial and lateral tibial condyles
distal point angle = most proximal points of the subchondral bone of the two arciform grooves of the cochlear tibiae
mechanical axis = point in the center of the proximal-most aspect of the intercondylar fossa of the femur and at the most distal point of the subchondral bone of the distal intermediate tibial ridge (mMPTA, mMDTA)
Saggital proximal tibial joint orientation line = cr. and cd. aspects medial tibial condyle
Distal tibial joint orientation line = distal aspect of the distal intermediate ridge of the tibia cranially, and the caudodistal aspect of the cochlea tibia caudally.
mechanical axis = midpoint between the apices of the two tibial intercondylar eminences and the center of the circle created by the talus. (mCdPTA, and mCrDTA)
What are normal mechanical tibial angles?
mMPTA = 93
mMDTA = 96
mCdPTA=64
mCrDTA = 82
Important pointes when determining Center of Rotation Angulation (CORA)
Torsion > 15 degrees = >5 degree miscalculation in frontal deformation
Each CORA had a location, plane and magnitude
What are opening and closing CORA?
CORA on convex = opening
CORA on concave = closing
A distal antebrachial deformity with resulting intersection of anatomic axes (red). Bisection of the mediolateral angles formed by the intersecting axes results in determination of the transverse bisecting line (tBL), which is an infinite line of centers of rotation of angulation (CORAs); the CORAs are named opening (light blue) if on the convex side of the neutral CORA, and closing (dark blue) if on the concave side. Basing the angulation correction axis on an opening or a closing CORA results in an opening or closing wedge ostectomy, respectively
How to measure CORA
Canine antebrachium with distal uniapical deformity as determined by the intersection of proximal and distal anatomic axes (red) as determined from joint orientation lines (green). The magnitude of the center of rotation of angulation (CORA) is calculated as the angular difference between the axes (α). The location of the CORA is measured from a nearby anatomic landmark, such as the radiocarpal joint.
If angulation is apparent in both orthogonal planes, then an oblique plane deformity is present. It is necessary to determine the plane of the deformity. This can be done by using a graphical interpretation of oblique plane analysis, as discussed in the next section.
What is Paley’s nomenclature for angular limb deformities?
of CORAs = Uniapical, biapical multiapical
If biapical = partially compensate (valgus and varas) or noncompensated (2 of the same)
Translation deformitiy
Oblique plane deformities
hondrodystrophic dog might be classified as having a biapical, partially compensated radial deformity with a proximal varus and distal valgus and concurrent procurvatum and external torsion. Similarly, a giant-breed dog with a grade IV medial patellar luxation may have a uniapical distal femoral varus deformity with external torsion.
What are Paley’s rules of osteotomies?
Paley’s rules of osteotomies. A, Rule 1: If the osteotomy (black line) and the angulation correction axis (ACA) (yellow circle) pass through any of the centers of rotation of angulation (CORAs) along the transverse bisecting line (tBL) (dotted line), then the bone is appropriately realigned through angulation. B, Rule 2: If the osteotomy is completed at a level different from the CORA, but the ACA is based on a CORA, appropriate realignment of the bone occurs through angulation and translation. C, Rule 3: If the osteotomy and the ACA occur at a level different from the CORA, then co-linearity of the segments does not occur, and iatrogenic translation results.
Correcting a uniapical oblique deformity with a hinged circular external skeletal fixator. Schematic shows the relationship between the motor and the angulation correction axis (ACA) and the center of rotation of angulation (CORA) plane (blue arrow), as determined by the graphical method of oblique plane determination. Note that the ACA is perpendicular to the CORA plane.
What are the advantages and disadvantages of a radial osteotomy for ALD?
Advt = maintatins bone length, only 1 cut, maintains apposition, resists shearing loads
Dis = can only be performed on uniplaner deformities
What are the advantages of the dome blade forALD?
advantages of a dome osteotomy include all of those associated with cylindrical osteotomies along with the versatility to correct deformities in three planes. Thus, torsion angulation deformities can potentially be corrected with the completion of a single cut. Limitations arise, however, with application to bones that are nonuniform in cross-section, such as the canine radius, which is ovoid and thus possesses diameters that differ in the orthogonal planes. This occurs because the dome osteotomy blade must be size-matched with the bone in the widest dimension (in the case of the radius in the frontal plane), which results in size-mismatching in the sagittal plane and large decreases in postcorrectional apposition and correctional accuracy.10 Still, the potential usefulness of the saw blade in correcting oblique plane torsional angulation deformities in bones with circular cross-sections, such as the canine femur, is intriguing.
What is reactive hyperemia?
Area of bone surrounding ischemic bone that has increased osteoclastic activity
What is thought to be the location and general pathogensis of hematogenous osteomylitis?
Metaphyseal region
imcomplete basement membraneof capillaries in the region
downregulation fo Tcell immunity and cytokines
Most common bacteria in osteomyelitis?
Staph 60%, mostly intermedius
What are the 4 stages of biofilm formation?
- reverisble attachement
- irreversible attachment
- growth and differentiaton
- Disseminaiton
What are the 3 main components of biofilm?
Microbe
microbe induced glycocalyx
host-bacteria surface
What are 3 possible mechanisms for biofilm antimicrobial resistence?
- Molecular filter
- Slow growth/reproduction of bacteria
- Changing the microenviroment - loweing pH, increasing PCO2, decreasing P)2, and hydration levels neg. affect antimicrobials
What are growth factors potentially involved with bone growth
BMP 2,4,7
TFG beta
Insulin GF/GH
platelet dervied GF
fibroblast GF
What are the 4 stratagies of bone graft in enhancing healing?
Osteogensis - supply and support bone forming cells: autogenous cancellous bone graft, bone marrow
Osteoconduction - scaffhold
Osteoinduction - induces bone formation where no bone would form: chemoattraction/migration, induce proliferation of stem cells
- demineralized bone matrix: decalcifcaiton without inactivation cytokines (BMP, TNF, etc.) and organic matrix
Osteopromotion - enhances regenerating bone - platelet rich plasma
Why is autogenous cancellous bone graft gold standard?
Osteoblasts (osteogensis)
cytokines/GF (osteoinduction)
scaffold (osteoconductoin)
blood clot - IGF, PDGF, TGFbeta (osteopromotion)
What are locations for autogenous bone graft?
Proximal humerus - large amount
Wing of illium - no prob if fx
Proxmed tibia
Subtrochanteric portion femur
Fermoral condyles
Cdventral Mandibule/rib
Biofilm containing bacteria on a metal implant. The biofilm or (slime) is made up of the implant passivation layer, host extracellular macromolecules (fibrinogen, fibronectin, collagen), and bacterial extracellular glycocalyx (polysaccharide). Staphylococci are bonded on the implant, and this inhibits phagocytosis. Failure of antibiotics to cure prosthesis-related infection is due to the diminished antimicrobial effect on bacteria in the biofilm environment
Normal osseous circulation to a growing tubular bone. Nutrient arteries (1) pierce the diaphyseal cortex and divide into descending and ascending (2) branches. These latter vessels continue to divide, becoming fine channels (3) as they approach the end of the bone. They are joined by metaphyseal vessels (4) and, in the region of the physis, form a series of end-arterial loops (5). The venous sinuses extend from the metaphyseal region toward the diaphysis, uniting with other venous structures (6) and eventually piercing the cortex as a large venous channel (7). At the ends of the bone, nutrient arteries of the epiphysis (8) branch into finer structures, passing into the subchondral region. At this site, arterial loops (9) are again evident, some of which pierce the subchondral bone plate before turning to enter the venous sinusoid and venous channels of the epiphysis (10). At the bony surface, cortical capillaries (11) form connections with overlying periosteal plexuses (12). Note that in the growing child, distinct epiphyseal and metaphyseal arteries can be distinguished on either side of the cartilaginous growth plate. Anastomoses between these vessels either do not occur or are infrequent.
Hematogenous osteomyelitis occurs most commonly in the metaphyseal region. In this illustration, increased pressure in the medullary cavity eventually results in extension of inflammatory exudate through the Haversian systems of the cortex and beneath the periosteum. The elevated periosteum will lay down a sleeve of new bone (the involucrum) around the infected bone segment. This reaction is likely to be prominent in young animals and tends to be less prominent in mature animals
What size are morselized cortical bone used for allografting?
125-1180 microns
Describe DBM (Demineralized bone matrix)
20-35% calcium reduced to 3% - favorably influences bone healing
Osetoinductive - acid resistnet BMPs and other GFs
Can be mixed with other sustances including bone chips (=osteoconduction)
Time to destablization of arthrodesis was same for dogs treated with DBM, autograft or both
Where are mesenchymal stem cells most abundant?
periosteum
bone marrow
fat
Difference in cell behavior depening on source
What are strategies to get mesynchaml stem cellls?
1) Culture epanded autogenous - isolated from BM by density gradient centrifugation
2) Culture expanded allgenic - potentially can cause T-cell mediated cell rejection, but not seen in the clinical setting and healing similar to autogenous MSC
3) Selective MSC retention - large bone marrow aspirate passed over demineralized cortical fibers and mineralized cancellous bone chips as an allomatrix
- femoral defect - 33% allomatrix alone, 50% BM, 100% selective retention
What makes a bio-ceramic good for stem cell ingrowth?
chemistry/sintering = different avilable levels of stiffness, hardness and brittleness
Interconnective porosity = allows vasular ingrowth = if low O2, cells become fibroblastic, chondroblastic or adiopoblastic
pores 300-500 microns
What are various types of synthetic materials used for bone graft substitues?
Ceramics
Calcium phosphate ceramics - hydroxapatite, others
Coralline bone graft - Ca carbonate→Ca hydroxapatite, 200-500 microns
Tricalcium phosphate - Ca:Phos 1:5, hydroapatite 1.67:1= more soluable, granules do not provide support
Biphasic calcium phosphate = combo of Tricalcium and hydroxyapatite
Nanocrystalline calcium phosphate - hardens with endothermic rx
calcium sulfate aka plaster of paris - rapid absorption, not suitable for sturctural support
Which BMP cause MSC → osteoprogenitor cells and which cause osteoprogenitor → osteoblastic cells?
MSCs → osteoprogenitor = BMP 2,6,9
osteoprogentior to osteoblastic = BMP 2,4,7,9
Only 2 and 7 commerically available
What percent of scapular fx have concurrent injuries?
56-70%
What are 2 classification schemes that have been described for scapular fx?
Classified as I (fx body/spine/acromion), II neck, III glenod fx
OR
Stable extra-articular, unstable extra-articular, intra-articular (sx rec for last 2)
What recommendations have been made regarding plating of the scapular body?
Recommend inverted tubular plates as “best fit”
Recommend plating dorsal fractures caudally and ventral fractures cranially - do to thickness of bone
Locking plates may be benefical but not evaluated
Screw angles at 45 degress to spine
double vs single plate = double stronger but not stiffer, equally properties with cyclic loading
Scapular anatomy
Proper positioning for a craniocaudal radiographic view of the scapula. The patient is rotated 30 degrees away from midline
Photograph of positioning a patient for a distoproximal (axial) radiographic view of the scapula. The spine of the scapula is perpendicular to the table. B, Radiographic image made from the positioning in A
How much scapula can be removed with good function?
60% = excellent outcome
total - fair outcome in 1 case
Transverse computed tomography (CT) section of the midbody of the scapula. The right arrow indicates the recommended angle of screw placement at the base of the scapular spine (see text for comment regarding placement of the plate along the cranial or caudal aspect of the scapular spine). Note also the thicker bone available at the caudal aspect of the scapular body (left arrow)
Caudocranial radiograph of an overriding scapular body fracture. Surgery is indicated because of the impact on joint function. Interfragmentary wire (B) and scapular body plate fixation (C) for scapular body fracture. Note that the location of the interfragmentary wires requires greater overall exposure than plate fixation. The wires are placed in the thicker cranial and caudal aspects of the scapular fossae. The plate is placed along the thicker bone at the base of the scapular spine
Fracture or osteotomy of the acromion is stabilized using Kirschner wires with a figure-of-eight tension band (A), interfragmentary wires (B), or single interfragmentary wire in small dogs and cats (C)
Which direction is the neck displaced with a scapular neck fx and how can you tell the suprascapular n is damaged?
Distal neck displaces medially
Atrophy of the supra and infraspinatus
What are methods to repair a scapular neck fracture?
Cross pin fixation (visualize supraglenoid tubercle and caudal aspect of glenoid
Divergent pin fixation (through supraglenoid)
Plate (T or L plate)
Place in Velpeau post op
What are additional methods to gain exposure to the neck of the scapula?
osteotomy of the greater tubercle of the humerus
tenotomy of the infraspinatus and/or teres minor muscles.
A recent study described a muscle separation approach to the scapular neck, which avoids the need for acromial osteotomy. After dissection through the deep brachial fascia and cranial retraction of the omotransversarius muscle, the fascial plane between the supraspinatus muscle, the acromial head of the deltoideus muscle, and the infraspinatus muscle is dissected. The supraspinatus muscle is retracted cranially, while the infraspinatus muscle and the acromial head of the deltoideus muscle are retracted caudally
What is the percentage of articular fractures and what are the 2 most common types?
28% are articular
58% cranial glenoid
23% T or Y fx
How is an avlusion fracture of the supraglenoid tubercle treated?
Tubercle = accessory center of ossifcation, fuses at 5m
Osteotomy of greater tubercle or myotomy of supraspinatus m.
Lag screw +k wire OR tension band OR excise fragment
If excision = tenodesis of biceps brachii
How do you perform a supraspinatus myotomy?
Approach in which a longitudinal myotomy of the supraspinatus muscle precludes the need for an osteotomy. The myotomy begins at the level of the midbelly of the supraspinatus muscle and continues distally to the level of its humeral insertion.
How to repair glenoid fx?
In picture should have been a lag screw rather than a pin
approach may include osteotomies of the greater tubercle or acromion, as well as tenotomy of the tendon of insertion of the infraspinatus or teres minor muscles, or any combination of osteotomy and tenotomy. With T or Y fractures, the articular surface should be reduced anatomically first, using a screw in lag fashion (Figure 50-9). The screw is typically directed in a craniocaudal direction. The neck is then reduced and stabilized to the scapular body as described earlier. Fractures of the medial or lateral labrum of the glenoid are less common, and in small breeds, inadequate bone may be available for adequate implant purchase (Figure 50-10). In larger dogs, if adequate bone is available, one or two lateral-to-medial directed screws may be placed in lag fashion
What are options for highly comminuted articular fx?
Excision of the glenoid
OR
scapulohumeral arthrodesis
What is this?
Ununited accessory ossificaiton center of the caudal glenoid
Often bilateral
Treat with arthroscopic removal if causing pain
How do you fix this?
Scapular luxation is typically stabilized using 20 or 22 gauge cerclage wire that is passed around the fifth, sixth, or seventh rib and through holes drilled near the caudodorsal border of the scapula in the area of the origin of the teres major muscle.13 Additionally, the insertion of the serratus ventralis muscle on the scapula may be reconstructed through drill holes at the craniodorsal angle of the scapula
Movement of the upper arm
2/3 glenohumeral joint
1/3 scapulothoracic synarcosis
When do the glenoid and humeral physes fuse?
glenohumeral = 6m
proximal humeral = 1yr
What composes the rotator cuff?
Medially = subscapuaris, coracobrachialis
Laterally = supraspinatous, infraspinatous and teres minor
What is the normal flexion/extension for the shoulder joint in the dog/cat?
dogs 57-165 degrees
cats 32-164 degrees
What are the stabilizers of the shoulder joint?
Passive = limited joint volume, adhesion/cohesion mechanism, concavity compression, capsuloligamentous restraints
Active: supraspinatous, infraspination, teres minor, subscapularis, biceps brachii, long head triceps, deltodieous and teres major
Describe how the shoulder is a moderately congruent joint
The glenoid provides relatively little coverage of the humeral head, and the joint, based on topographic distribution of cartilage thickness, is classified as being moderately congruent. The cartilaginous glenoid lip (labrum glenoidale or labrum) surrounds the glenoid on all sides, is wider on the lateral side, and extends the surface area of the glenoid by 25% to 30%. The labrum is triangular in cross-section and is highly vascularized, except along the free margin.75 Both articular surfaces are covered in hyaline cartilage of moderate thickness (approximately 1 millimeter thick in 20 to 25 kg dogs), as is typical of moderately congruent joints
Describe the ligaments of the shoulder
Type 1, 2, and 3 mechanoreceptors present in the collateral ligaments of the shoulder allow the ligaments to serve not only as passive restraints but as sensory structures that actively contribute to joint stability.51 Type 1 (Ruffini) receptors are most common and are more densely concentrated at the cranial aspect of the scapular side of the ligament
What is the most common locaiton of OCD in the shoulder?
Caudal central or caudal medial aspect of humeral head
27-68% bilateral
Usually large breed dogs
What occurs in 10% of OCD shoulder cases?
nonmineralized cartilage flaps trapped within the biceps tendon shealth - why US or MR or contrast may be useful
What are the 2 appraoches to the shoulder joint that can be used to treat OCD?
craniolateral (Hohn)
Caudal (Gahring)
The caudal approach requires a surgical assistant to provide tissue retraction for adequate viewing of the osteochondritis dissecans flap but results in less loss of shoulder range of motion and increased weight bearing (as evidenced by increased peak vertical forces when compared with the lateral approach), at least within the first month after surgery. The lateral approach offers increased exposure of the caudal humeral head.
What is this?
Glenoid dysplasia with med luxation
Treat with excision arthroplasty (glenoid +/- humeral head) or arthrodesis
How is a glenoid excision arthroplasty performed?
A lateral approach111 to the shoulder is recommended, and the glenoid is excised by making a distolateral-to-proximomedial osteotomy of the scapular neck with an osteotome or, preferably, a sagittal saw (Figure 51-4). The suprascapular nerve should be identified and protected while the osteotomy is performed
No evidence to support humeral head excision
How do you perform a shoulder arthrodesis?
In small dogs, arthrodesis can be performed by placing a large transarticular screw or diverging Kirschner wires (with or without tension band wire); this method is not recommended in medium- or large-breed dogs, and clinical outcomes are generally better when plates and screws are used for all sizes of dogs and cats. Arthrodesis of the shoulder using bone plate and screws is performed through a craniolateral approach. The insertion of the trapezius muscle and the origin of the omotransversarius muscle are elevated from the cranial edge of the scapular spine as needed. The incision is continued distally along the cranial border of the acromial head of the deltoideus muscle. If greater exposure is required, an osteotomy of the acromion can be performed and the acromial head of the deltoideus muscle retracted caudally. The omobrachial vein (and cephalic vein, if necessary) is divided and the incision follows the lateral aspect of the brachiocephalicus muscle to its insertion. The insertion of the superficial pectoral muscle is incised and the muscle elevated and retracted cranially. An osteotomy of the greater tubercle allows elevation and retraction of the supraspinatus, or, alternatively, the insertion of the supraspinatus muscle on the greater tubercle is incised and elevated as needed to allow placement of a bone plate and screws along the cranial aspect of the humerus. The elevation of the supraspinatus muscle is continued proximally through the entire supraspinous fossa until the muscle can be retracted cranially. The suprascapular nerve should be identified, carefully retracted, and protected at all times. If necessary, the insertional tendon of the infraspinatus muscle is transected and the muscle retracted caudally. This approach exposes the entire craniolateral aspect of the scapula and the cranial aspect of the humerus. The lateral collateral ligament is transected and the joint capsule incised to allow luxation of the humeral head from the glenoid fossa. A motorized burr is used to remove the articular cartilage from the surfaces of the humeral head and the glenoid fossa.
What is this?
Mediolateral radiograph of the shoulder of a dog affected by multiple epiphyseal dysplasia. Observe the severely misshapen and irregular humeral head
Radiographically evident by 8w, usually severe lameness by 5-8 months
euthanasia
bone changes similar to congential hypothyroidism
What is the joint angle for arthrodesis of the shoulder?
105-110 degrees
What is chondrocalcinosis?
Disease in plateu humeral head greyhounds and femoral head GSD
White spots on cartilage = hydrosyapatite (pseudogout)
Incidental finding??
What are the 3 palpation tests for Biceps tendinopathy?
Biceps tendon test
Drawer test
Biceps retraction test
What are radiographic and other modalities to test for biceps tendonopathy?
Radiographs = flexed crainodistal-cranioproximal skyline veiw, allows surpraspinatus vs. biceps
Contrast arthrography - may be more sensitve than US
US: Sonolucent line around the tendon; an enlarged, hypoechoic tendon with fiber pattern disruption; irregular or proliferative synovium; and, in chronic cases, irregularities in the surface of the bicipital groove - not all cases have US changes
MRI: in one study all biceps tendopathy had concurrent joint problems
Arthroscopy
What is this?
Skyline radiographic view of the cranial aspect of a dog shoulder demonstrating a small mineralization within the tendon of the supraspinatus muscle (arrow). The tendon of origin of the biceps brachii muscle lies medial to the greater tubercle, within the intertubercular groove.
What are methods to Tx biceps tendopathy?
1-2 injections of methylpred (10-40mg) or trimacinolone (5mg) intra-articluar with 4-6 weeks cage rest
Tenodesis - open or arthroscopy, attach to prox. humerus
Tenotomy - open or arthroscopy
Drawing of a biceps tenodesis performed with the use of a cannulated screw and washer. B, Mediolateral radiograph of a biceps tenodesis performed with the use of a cannulated screw and washer in a dog
What other disease that effect the biceps tendon besides biceps tenopathy?
medial displacement with rupture transverse humeral ligament: Varying degrees of atrophy of the deltoideus, infraspinatus, and supraspinatus muscles, pain with range of motion, and a “popping” sound with range of motion. variable duration and severity of lameness. Varying degrees of atrophy of the deltoideus, infraspinatus, and supraspinatus muscles, pain with range of motion, and a “popping” sound with range of motion have been reported
rupture of the tendon
rupture of the tendon sheath
dystrophic mineralization
Supraspinatus tendiopathy
with or without calcification
Rotties, labs
Supraspinatus contraction: trauma or VonWillenbrand or end-stage supraspinatus tendinopathy
Pain>biceps tendopathy
Tx: rest and NSAID, extracorporeal shock therapy
Sx excision of calcified tissue within tendon/muscle
Axial T2-weighted magnetic resonance image of the proximal portion of the right humerus of a dog. Observe the partial medial displacement of the tendon of origin of the biceps brachii muscle (solid arrow) from the intertubercular groove by the increased mass of the tendon of insertion of the supraspinatus muscle
The enlarged tendon of the supraspinatus muscle may also impinge on the adjacent tendon of the biceps brachii muscle, and excision of diseased tissue may decompress the tendon of origin of the biceps brachii muscle.47 Impingement on the tendon of origin of the biceps brachii muscle may be positional and may be best evaluated when the joint is extended
What are possible causes of shoulder joint instability?
- loss of concavity compression - abnormally small or flat glenoid, torn or avulsed glenohumeral ligaments, fracture of the lesser tubercle, or a decrease in the depth of the concavity as a result of injury or chronic repetitive wear
- disruption of glenohumeral balance (uncentered net joint reaction force)- dynamic muscle imbalance, abnormal angulation of the glenoid as it interdigitates with the humeral head, and disruption of the capsuloligamentous restraints
How do you dx shoulder joint instability?
Most commonly middle aged, large breed aiwth chronci lameness
Positive biceps and shoulder drawer
Abduction angle (normal 30, abnormal 50) - measured btwn scapula spine and humerus, must stabilize scapular spine
Rads (varus and valgus stressed) - DJD in absence of OCD strongly inficative of instability
MRI
Arthroscopy - cartilage erosion caudal region of head aand medial ridge of glenoid
US NOT useful for medial
What are treatments for subluxation of the shoulder?
Transposition of the biceps tendon or supraspinatus - both result in abnormal biomech and OA
Augmentation of the exsisting medial collateral - anchor large monofilament suture at the origins and insertions of the cranial and caudal bands of the medial glenohumeral ligament in a V-shaped manner
inbrication of tendon of the subscapularis - craniomedial approach and was imbricated with two to five horizontal mattress sutures of polydioxanone suture (PDS)
Radiofrequency induced thermal modificaiton (RITM) - Only arthroscopic tx- thermal energy is applied to the joint capsule, shrinking the collagen bundles
Excision arthroplasty or arthrodesis
Bilateral rotator cuff injury and repair in a canine model. A: The superior two-thirds of the infraspinatus tendon was sharply detached from its insertion at the greater tuberosity, and a 1.5 x 2-cm portion of the underlying joint capsule was excised. B: The infraspinatus tendon was immediately repaired back to its insertion on the humerus with use of two transosseous sutures. C: In one shoulder from each dog, a 12-mm-wide x 34-mm-long poly-L-lactide scaffold was affixed over the tendon repair. The scaffold was attached first to the tendon medially with use of three number-0 FiberWire modified Mason-Allen sutures. The device was then laid down over the repair and was tensioned by advancing the lateral edge approximately 2 mm laterally for the osseous attachment. Fixation to the humerus was achieved with use of a low-carbon stainless-steel cortical screw with a polyetheretherketone spiked washer
woven poly-L-lactide device
What is a modified Campbell prosthetic suture ?
modified Campbell prosthetic suture (heavy suture passed through transverse holes in the humeral head and scapular neck to create or augment glenohumeral ligaments
What mm. are suseptible to strain?
Biceps , Tendon, pectorals, serrutus ventralis, rhomboideus, ex.carpi radialis, flexor carpi ulnaris
In human beings, muscles at risk of strain include those that cross two or more joints (subject to stretch at more than one joint), those that have the ability to limit range of motion across a joint by their intrinsic tightness, those that function in an eccentric manner, and those that have a relatively high percentage of type 2 (fast-twitch) muscle fibers
What is this?
Mediolateral positive-contrast arthrogram demonstrating numerous intra-articular radiolucent filling defects associated with synovial chondrometaplasia
What are less common diseases of shoulder?
Infraspinatus/supraspinatus mm. contracture
Villonodular synovitis
Synovial chondrometaplasia
Infraspinatus burasl ossification
Mineralization = Ectopic or heterotopic ossification of soft tissues (metastaic calicificaiton, dysrophic), Fibroplasia ossificans progressive like syndrome, soft tissue meralizaiton (progressive, multifocal nonprogressive disorder - excision of mineralization may make worse)
What is the difference between the dog and cat humerus?
In the cat: Supracondylar foramen – proximal to the medial epicondyle
¤Supratrochelar foramen absent
¤Closed with bone, while dogs have membrane
¨Median n. and branch of the brachial a. pass through the supracondylar foramen
Intertubercular groove: biceps brachii tendon
From the deltoid tuberoisty, the humeral crest spirals distally toward the lateral epicondyle (cranial border of the brachialis m. courses along the crest)
Humeral condyle:
- medial: trochlea (articulates with ulna)
- Lateral: capitulum (articulates with radial head)
Intertubercular groove: biceps brachii tendon
Tricipital line – origin lateral head of the triceps brachii m.)
•cranial to this line, the bone is more cancellous with a relativley thin cortx, cuadal the bone is thicker (more cortical bone)
Deltoid tuberoisty (proximal and middle 1/3 humerus) insertion deltoideus
S shape more pronoced in dogs than cats
Closure of growth plates in the humerus: dog and cat
Describe cr. lateral approach to the shoulder
Physeal fracture of the greater tubercle. B, Repair of fracture of the greater tubercle with two pins and a tension band wire. C, Physeal fracture of the greater tubercle and humeral head with separation of the greater tubercle and humeral head fragments. D, Repair of the greater tubercle with Kirschner wires and tension band fixation; repair of the humeral head with a lag screw and Kirschner wire. E, Isolated physeal fracture of the humeral head. F, Repair with a lag screw and Kirschner wire; the Kirschner wire prevents rotatio
Physeal fracture of the proximal humerus with the greater tubercle and humeral head fragments remaining together. B, Repair with two Kirschner wires and a tension band wire. C, Repair with two Kirschner wires. D, Repair with a lag screw
approach to the craniolateral aspect of the humerus, combined with the approach to the proximal humerus, will expose the proximal three quarters of the humerus.69 The triceps brachii muscle is reflected caudally, and the biceps brachii, pectoral, and brachiocephalicus muscles are retracted cranially. The radial nerve with the brachialis muscle can be reflected cranially or caudally according to the position of the fracture
medial approach to the humerus involves cutting the pectoral muscle origins proximally, reflecting the biceps brachii muscle caudally and the brachiocephalicus muscle cranially. If exposure needs to be continued in a more distal direction, the biceps brachii muscle can be reflected cranially. Great care must be taken to identify the median and ulnar nerves and the brachial vessels when a medial approach is taken
What size pin and what methods of pin placement are recommend in the humerus?
Pin with plate 35-50% diameter of diaphysis
Pin can be directed in 4 ways (all directed): proximal retrograde, distal retrograde, proximal normograde (cr-lat greater tubercle to trochela) or distal normograde
20% of pins placed in a non-directed proximal retrograde penetrated shoulder joint
Drawbacks of interlocking nail for humerus fractures?
Not ideal for humerus - Tapering shape
- Distal fractures, only room for 1 locking device
- Poor screw holding power in proximal humerus
¨Described (20, 21, 61) for Mid-diaphyseal fractures
- 2 locking devices, 1 bone diameter from the fracture
- If 1 locking device proximally, place distal to tricipital line
- Young dogs
- Too larger to place through medial epicondylar cres
What is the tension side of the humerus?
Convex crainolateral surface = proximal tension aka place plates cranial and lat for proximal fractures
Caudomedial surface - distal tension aka place plates medially for distal fx
Plates not usually placed caudally except in medial epicondyle region where plates can be placed caudallyor medially/both
What are methods to repair a supracondylar fracture of the humerus?
Intramedullary pins – 2 pins places in crossed or rush fashion
•Better for rapidly healing hones and simple fractures
Best results when medial and lateral plates applied
- Caudomedial placement allows for greatest purchase, while avoiding the olecranon
- Medial placement used if extending proximally
- Can place 2 medial plate (caudal and cranial medial) if small distal fragment
Monocortical screws and locking plates – decreased risk screw placed in the joint
ESF as described for diaphyseal fractures
What are the most common salter-harris fractures of the distal and prox humerus?
Prox = type 1 or 2
Distal = type 4, type 1 rare
Why do cats have a low incidence of humeral condylar fx?
The lat and med epicondyles stronger and wider
olecranon fossa absent
What percent of dogs have a lateral condylar fracture when the condyle is fractured?
41% of the humeral fracture
34-67% lateral aspect
- 9-11% medial aspect
- 9-35% intracondylar (T-Y fractures)
Why does closure of the distal humeral growth plate not have a sig impact on humeral growth?
Only 20% of humeral growth from distal - normal closure at 5-8m (fracture usually at 4m)
mild insig. humeral overgrowth
no decrease in length even when plates cross the physis
What are factors that increase the risk of failure of a lateral condylar fx reconstruction?
¨Increase surgery time associated with increased risk complications
¤Every 30 minutes odds complications increased by 2
¨Fracture gap associated with increased risk fracture failure
¤Increased shear on screw, larger bone hole = screw loosening
¨Transcondylar screw angle
¨IOHC
Lack of corrleation between reduction and outcome
What were the findings of Perry et al. VetSurg 2015 related to humeral condylar fx?
132 fractures
- 61 stabilized with a transcondylar screw and supracondylar K wire
- 13 transcondylar screw and supracondylar screw
- 61 transcondylar screw and plate
Complications more common with K-wire (28%) than plate or screw (11%)
Cases with complications more likely to have a poor outcome
Overall 41% had complications, 18% of cases had major complications and required a second surgery
•
Complications: Implant loosening (14), implant failure (14), infection (19), seroma (6), malunion (1), diaphyseal fracture (1), lysis around implants (2)
What is the approach for a T-Y fracture of the humeral condyle?
AKA: Intercondyler, dicondylar, bicondylar fracture
¨Approach:
Osteotomy of the tuber olecrani
- Complications with repair osteotomy in 37% cases
Tenotomy of the biceps brachii
Separate lateral and medial approaches
How do you repair a T-Y fracture?
With osteotomy or tenotomy: Transcondylar screw
Condyle attached to diaphysis via: Bone plate, Lag screws, Steinman pins, K-wires
Bilateral Approach: order determined by fracture
- Repair the medial aspect (bone plate)
- Reposition and stabilize lateral portion of the condyle with lag screw and plate
- Accuracy assessed indirectly
- Inaccurate repair of the medial condyle (usually varus) key reason for poor fracture reduction
What breeds are associated with incomplete ossificaiton of the humeral condyle?
Spaniels (aka cocker and springer) most common
Others: Labs, pointer, GSD, Rotties, Yorkies, German Wachtels, Tibetan Mastiff
What percent of IOHC have current elbow problems?
23-35%
What special radiographic view is recommend for IOHC?
15 degree oblique CrMed to CdLat
How do you treat IOHC?
Conservatie = high rate fx, 43% with partial radiolucent and 8% with complete radiolucent
Prophylatic repair = standard later condylar fx +transcondylar bone tunnels, concellous bone graft, recommend lat plate.
If fracture more guarded px than trauamtic fx = 23% nonunion
What is the normal ROM of the elbow joint?
130 degrees ROM
Flexion 36
Extension 165
Supination 17-50
Pronation 31-70
What are the stablizers of the elbow joint?
Anconeal process - pronation
Supination = LCL (primary), anconeal process (secondary), MCL (third)
MCL weaker than LCL, both split into cr an cd crura distal
Joint capsule
Annular lig
What is the Campbell test?
Flex carpus and elbow to 90 degrees = rotate antebrachium to test stability
Pronation: dog normal 30, transect MCL (60-100); cat normal 50, no MCL (99)
Supination: dog normal 46, transect LCL (70-140), cat normal 130, no LCL (167)
How do you diagnose traumatic luxation?
antebrachium abducted and externally rotated
lateral epicondyle less distinct
Rads
Transcondylar screw placement
What are open methods of reduction of an elbow luxation?
Reconstuction of lig. +/-augmentation (locking loop)
Ligament replacement with syntehtic materials = transverse bone tunnels or screws/washers or lag screw through avulsed piece
If bilateral lig rupture: Transcondylar tunnel and biaxial suture repair
After treating need joint immobilzation
What are the benefits of early mobility and the drawbacks of prolonged immobolization (>3weeks)?
Pros: decreased adhesions btwn periarticular structures, Stim GAGs and HA, Stim more orderly collegen deposition/normal cross-linkage, improved joint nutrition and clearence of hematoma
Cons: decreased synovial fluid production, decreased cartilage stiffness and thickness, DJD, loss of muscle mass and bone/mineral content
How do you make a flexible ESF for post-elbow luxations?
2 centrally threaded pins through dital humerus and olecranon
allow 140 degree extension
removed 3-4 weeks post-op
Flexible external skeletal fixation after reduction of a traumatic luxation. A, The pins are connected with connecting bars immediately after surgery. B, Once swelling is reduced, the connecting bars are replaced by tight rubber bands, to allow limited flexion of the elbow joint
Px: 47-89% good with closed reduction, 37% residual instability
What are the types of congenital luxation elbow?
I: Lat of cd-lat dislocation of the radial head with ulna in normal position, med-large breed, mild deformity, loss of function
II: Disruption humeroulnar articulation with lat rotation and subluxaiton or luxaiton of the ulna, sometimes with dislocation of radial head - most common, small breed, severe disability
III: Luxation of radius and ulna - no breed, general laxity (polyarthrodysplasia), multiple congenital skeletal deformites
What radiographic findings are associated with cdlat luxation of the radial head?
Convex articular fovea or radial head
hypoplasia prox radial diaphysis/epiphysis
Lateral andular deformity of the proximal radial diaphysis
Angular deformity of the distal humerus (trochela further distal)
Medial deviation and distorion of olecranon
Cr. curvature prox ulna
Secondary OA
What are sugical options for caudolateral luxation of radial head?
Open reduction/stabilization - lateral approach to prox radius, oblique osteotomy/ostectomy distal to radial physis,
Radial head ostectomy: poor outcome
modified Bell-Tawse procedure: (1) dissection of the soft tissues surrounding the radial head and humeral condyle through a lateral approach radial, (2) wedge ostectomy and counterclockwise rotation of the proximal radius, followed by plate fixation to align load transmission along the axis of the radius, (3) reconstruction of the annular ligament with a muscular fascial strip obtained from the extensor carpi ulnaris muscle (modified Bell-Tawse procedure), and (4) temporary (20 days) humeroradial fixation with a transarticular Kirschner wire.
Arthrodesis: no pain but marked gait abnormality
Total elbow contralidicated
What are treatment options for Lateral roation of the ulna?
If <4m closed reduction and transarticular pin or modiefied ESF
If>4-5m open reduction, then:
medial imbrication,
transposition of the olecranon medially and distally,
ulnar osteotomy and radioulnar synostosis,
trochlea and trochlear notch reconstruction,
external fixation, and transarticular pins.
If the trochlea and trochlear notch are fairly congruent, lateral release, medial imbrication, and distomedial olecranon transposition/modified external fixation may be sufficient to maintain reduction
What is the signalment of UAP?
BMD and mastiffs, others GSD Golden, lab, newfie, rottie, St. Bernard
20-35% bilateral
Males 2:1 over females
FCP in 13%, RU incongrence 50%
No separte ossification in sm dogs, large dog between 14-20w
When can the radiographic diagnosis of UAP be made?
After 22-24 weeks
What is the treatment of UAP?
-
Excision (caudolateral approach, midbelly incision)
- 90% owner satsified, normal flexion 58%, normal extension 85%, 50% free of lameness -
Reattachment AP (dogs <24w with normal notch, lag screw or K-wires)
- 3. Ulnar osteotomy +/- reattachement (elbow incongurity)
- 3-6cm distal to radial head, obliquel starting prox cd/lat at 40-50 degrees
- or IM pin
- variable portion should union of AP 20-70%, improvement 80-90%
What is the signalment and incidence of concurrent disease with medical compartment disease?
Young, large - giant breed dogs (OCD 5-8m, MCD 13m)
male 2:1
Smaller chondrodystrophic disease
Bilateral 25-80%
Incidence of multiple components of ED: 0-60%
Several lesions in 42% GSD, incongruity and MCD most common (34%), incongurity diagnosed in 16% (most common singular condition?)
Coronoid is 1 of 6 centers of ossification of the elbow, when does it fuse?
20-22 weeks
What are the 3 forms of elbow incongruity?
- HU incongurity - insufficient growth ulnar notch
- RU incongurence and HU conflict
- short radius, redistribute forces to MCP, step of 0.5 normal , increased to 1.4mm in MCP
- Found in 14% (CT) and 22% (arthroscopy) of dogs with MCP
- Absence of staic doesn’t mean no dynamic, temorpary or localized (Bardet 1997, Gemmill 2005) - Rotational incongurity - transmission of shear forces from the BB/B muscle to MCP = conversion of supinaiton to shear forces along the radial incisure (Therory behind BURP)
OR for MCD and OC in various breeds
List the scoring system for MCD on arthroscopic exam of the elbow.
MCD type 1: Fragment on the medial margin of the medial coronoid process
Type 2: Erosion /fragment of the lateral rim of the MCP
Type 3: Free fragment (in situ, nondisplaced or minimally displaced and attached)
Type 4: Fissure (cannot be freed by probing alone)
Type 5: Multiple fragments
Type 6: Osteophyte on MCP
Type 7: Joint mouse (displaced fragment, fractured osteophyte)
Name the 0-5 Outerbridge classificaiton scheme
When is pain usually elicted with elbow manipulation and MCD?
Flexion and suppination
What percent of MCD have bilateral disease
37-50%
What is the radiographs sens and spec. for MCD?
100% spec, 23% sens, 57% accurate
What are the most common radiographic findings with MCD?
Subtrochlear sclerosis - 87%
Osteophytosis of AP - 70%
Osteophytosis lateral condyle - 56%
Osteophytosis radial head - 37%
What radiograph improves the sens for MCD to 80%?
DMPLO 35 degrees
What is the sens and spec for diagnosis of RU incongurence?
Sens 78%, Spec 86%
1.5-4mm step required for 90% sens
>2mm 94-100% sens
What is the recommended pressure for arthroscopy?
70mmHg
How do you perform a medial arthrotomy to remove the fragments?
Avoid median n.
Flexor carpi radialis and pronator teres separated
Can be combined with osteotomy fo medial epicondyl or tenotomy of pronator teres
What is OAT (osteochondral autogenous transfer)?
Post removal of OCD flap
- donor cores harvest from non-weight bearing regions of the stifle
- core 1mm wider that recipient site and 2-3 mm deeper
Benefits: Accurate reconstruction, subchondral and articular contour, resufacing with hyaline cartilage, barrier between subchondral bone and synovial fluid
Cons: Regional differences in cartilage thickness, lack of evidence of benefit, donor site morbidiity
Suboptimal results in 33 elbows with OCD (MCD in 31), suboptimal results
What is BURP?
Biciptial ulnar release procedure for rotational incongruity
medial to joint so flexion = supination and shear along radial incisure
Tenotomy distal insert BB/B ( ridge caudal to MCP)
Recommended for cartilage malacia or fissures along radial incisiure, poss. adjunct to fragment excision in dogs with no incongurence and mild changes
Weak evidence, traumatic rupture in Greyhounds = hyperextension, + biceps test, circumduction
What are the treatments for RU incongruence?
Proximal ulnar ostectomy +/- pin
Medial coronoidectomy
BURP
Radius lengthening not recommended
What are treatment options for elbows with moderate to severe DJD?
multimodal medical management
sliding humeral osteotomy (shift weight laterally) usually combined with arthroscopic treatment of medial coronoid lesions
(medial opening wedge of humerus 10 degres - goal to shift wt laterally - 30% fracture fixation failure)
arthrodesis
elbow replacement.
What are the 3 zones of contact in the elbow?
1) caudomedial aspect of the radial head
2) the medial aspect of the distal articular surface of the trochlear notch, extending to the radial incisure of the coronoid process
3) the craniolateral surface of the proximal trochlear notch
How much does a sliding humeral osteotomy decrease the force on the ulna?
4mm 25%
8mm 28%
Improvement in lameness in 50-100%, 66% of cases
Complicaiton rate 19% - major complications more common post medial epicondylar osteotomy (abandoned approach)
What are the various total elbow replacements available?
Synopsis of past and current linked (A) and unlinked, semi-constrained total elbow replacement (TER) systems (B–E). From left to right: Chancrin, Lewis (third generation), Cook, Iowa State (Conzemius fourth generation), and TATE (Acker/Van Der Muelen). Chancrin’s prosthesis (A) was a pure linked, hinged system. The current Lewis prosthesis (B) is a hybrid three-component system in which the humeral component and a radial ultra-high-molecular-weight-polyethylene (UHMWPE) button (allowing pro-supination) are cemented, and a radioulnar (RU) shelf is screwed to the ulna. This system is still in limited use today. Cook’s prosthesis (C) used a hybrid cemented/screwed design. This system has been abandoned because of severe complications. The current Iowa State (Conzemius) prosthesis differs slightly from the one depicted here (fully cemented [D]). It now uses a hybrid design, allowing bone ingrowth at the level of the lateral and medial condylar surfaces. Finally, the TATE (Acker) prosthesis was designed as a resurfacing cementless cartridge unit
Describe the IOWA State TER?
Composite fixation (cemented and porous) system
cobalt chrome humeral stemmed component and a 120 degree arc ultra-high-molecular-weight-polyethylene (UHMWPE) radioulnar component.
The articular surfaces of both components are symmetric with respect to the sagittal plane and therefore do not differ between right and left implants.
The humeral stem can be used in both left and right elbows, whereas right and left radioulnar components feature side-specific peg locations.
The humeral stem and radioulnar posts are cemented in the corresponding medullary cavities for primary implant fixation.
The lateral and medial aspects of the humeral stem feature a porous surface for subsequent osteointegration and long-term fixation.
The humeral and radioulnar components are implanted individually in sequence
Describe the TATE elbow
TATE Elbow system uses a cementless resurfacing design consisting of a cobalt chrome humeral component and a 175-degree arc ultra-high-molecular-weight-polyethylene radioulnar component featuring a cobalt chrome metal backing. Both humeral component and radioulnar metal backing feature two mediolateral posts for primary fixation and a porous surface for long-term stability via bone ingrowth. The TATE Elbow system was designed to use a minimally invasive approach via osteotomy of the medial humeral epicondyle. During implantation, both components are linked by a set plate and are inserted simultaneously as a “cartridge implant.”
Photographs of the newest total elbow replacement prosthesis designed by Conzemius’ group (A and B). This new design is a highly constrained, metal-on-metal, hybrid fixation system. While the humeral stem is cemented, stability of the radioulnar (RU) component relies on a dual fixation mechanism. Primary fixation is provided by an ulnar screw through the RU median ridge, while long-term stability relies on osteointegration of the radial peg. Humeral and RU components are highly congruent. The humeral component features a prominent medial section, a deepened median trochlea, and a smaller capitulum. Schematic of a second generation TATE cartridge (C). This new design features hollow humeral and radioulnar posts, hydroxyapatite coating, and a modified articular profile. Front view of a TATE cartridge (E, left) and side view of the radioulnar component (E, right) illustrating the modification of the cranial and caudal aspects of the RU polyethylene profile (red areas) between first and second generations. The median RU ridge was flattened in the second generation TATE to reduce prosthetic constraint. Immediate (D) and 12 month (F) postoperative mediolateral radiographs after implantation of a second generation TATE. This patient had received a first generation TATE on the contralateral elbow 21 months earlier (see Figure 54-4). Note the absence of radiolucent line at the bone-implant interfaces.
Radius/Ulna anatomy
Ligaments of radius/ulna
Interosseus lig
annular lig - radius incisures med/lat on ulna
oblique lig
med/lat collateral lig - cr/cd crura
radioulnar lig - joint capsule conflent with interosseois membranes
What are the Mean Joint Orientation Angles for the Canine Radial Anatomic Axes?
What percentage of growth occurs at the radial and ulnar physes?
100% distal ulnar physis - closure at 220-250d (7-8m)
30-50% prox radial physis
What are methods of radial elongation?
Dynamic elongation - transverse osteotomy with pins and elastic material
Controled elongation
- Stader apparatus - ESF with threaded connecting bar
- Circular ESF - increase in upto 50% of length
Acute distraction (mature animal)
- transverse osteotomy with bone graft
- sagittal sliding (stairstep) osteotomy with lag screws
Methods ulnar elongation?
Dynamic - proximal ulnar ostectomy +/- IM pin
- ostectomy >ostetomy
- do not score radius = synostosis
Distal ulnar oestectomy or removal of physis
- in vitro did not allow adequate movement of ulna, some clinical sucesses reported
sagittal sliding osteotomy of the ulna
What are 3 methods to help prevent premature closure of ostectomy gap?
gap >1.5 bone diameter
removal of perosteum
fat graft
What is Hueter-Volkmann law (also known as Delpech’s law)?
Hueter-Volkmann law (also known as Delpech’s law), which states that physeal growth is slowed by excessive compression and is accelerated by distraction
What percent of cylindrical/radial osteotomies for ALD in the radius with an obliquely planed defromitey allowed accurate correction?
44%
Correction of a congenital radial head luxation in a juvenile patient with a semi-closed technique and a circular external skeletal fixator. A, Illustration depicting the laterally positioned radial head in the frontal plane. B, Placement of the transarticular circular external skeletal fixator. A ring (a) is placed at the level of the distal humerus to allow proximal distraction of the humerus (1). Rings (b, c) are placed at the level of the proximal ulna and the mid-diaphysis of the ulna, making sure to not engage the radius with the wires. An additional ring (d) is placed at the level of the distal ulna and radius, with wires engaging both bones. An olive wire is placed from lateral to medial through the radial head and is tensioned medially (2) after completion of an osteotomy or ostectomy at the level of the center of rotation of angulation (CORA). Note that no other wires are able to be placed in the radius proximal to the CORA to allow it to pivot at the CORA. C, After the radial head is reduced by tensioning the olive wire over 7-10 days (2), the humerus is lowered (3), and the transarticular portion of the ring is removed
Reduction and fixation of a proximal radial physeal fracture (Salter-Harris type I) with cross pins.
Cranial lateral approach to radius
Reduction and fixation of a distal radial physeal fracture (Salter-Harris type I) with cross pins in the radial and ulnar styloid processes
What is the tension surface of the radius?
tension
llustration demonstrating the placement of a partial ring extension on the top of a circular external skeletal fixator montage to allow opposing olive wires to engage the olecranon at a single level, in such a fashion as to resist bone translation along the parallel wires
What is the most common articular fx of the radius?
Radial styloid fx (avulsion injury with medial collateral ligament)
Radial styloid process fractures repaired with two pins and a figure of eight tension band (left) or with the placement of two bone screws in lag fashion if the fragment is large enough
What is the prognosis and complications assoicated with R/U fx in toy breeds?
70-85% return to function with bone plate
Complications: 54%: skin irriaiton, cold conduction, synostosis, angulation osteopenia, plate failure screw loosening
Reducible articular fractures of the ulna at the level of the mid-trochlea repaired with a bone plate and screws positioned caudally (left) or along the lateral cortex
What is the classificaiton scheme of Monteggia fx?
I: Cr luxation of radial head, Cr-prox angulation of the ulnar fx
II: Caudal luxaiton of the radius, Cd angulaiton of the ulnar fx
III: lateral luxaiton of radius
IV: fx of prox radius and ulnar diaphysis, cr. luxation radial head
Picture is a type I
Most distal ulnar fractures are associated with radial fractures; with repair of the radius, stabilization of the ulna is not necessary. However, in large dogs, or in situations where bilateral forelimb injuries are present, additional support may be required, thus prompting fixation of the distal ulna fracture. This can be accomplished with application of a bone plate to the lateral surface of the ulna, if the dog is large enough. A less invasive, but also less stable, alternative is the placement of an intramedullary pin or Kirschner wire in the ulna in normograde fashion from distal to proximal
Attachment of lateral collateral lig
Name the ligaments of the dorsal surface of the metacarpus?
radioulnar ligament (articular disc)
dorsal radiocarpal ligament
short ulnar collatearl ligament
short radial collateral ligament
short lig.
What are the ligaments of the palmar surface of the carpus?
Short radial collateral lig
palmar radiocarpal lig
palmar ulnocarpal lig
accessorometacarpal lig - accessory carpal to MC IV&V
Intercapral ligaments
Flexor retinaculum - accessory to radial styloid
Palmar fibrocartilage - all proximal and number CB (except accessory) and MC3-5
Superficial ligaments of the left carpus, palmar aspect
Where are the metaphyses of the metacarpal bones and when is ossification done by?
MC1 proximal epiphysis
MC2-5 distal
Ossification done by 5-6m
What are the differences between dogs and cats related to ligaments of the carpus/metacarpals/digits?
Cats: absence of straight medial collateral lig of the carpus = feline antebrachiocarpal luxation with only partial disruption of MCL
Dogs: Lack dorsal elastic lig attachement to the head of the middle phalanx - may allow cats to hold prey
What is the antebrachiocarpal joint angle at stance and and the peak antebrachial joint angle?
Stance =
18 degrees mos of stance
-12.4 at start to 26 degrees at 75% stance
10 degree +/-12
Peak antebrachiocarpal joint angle = 47.3 degrees at 50.9% stance
Peak metacarpophalangeal joint angle = 19.2 +/- 6.1 (at 62.6% stance)
How do the ligments of the carpus tend to fail and what is their elastic modulus (greatest to weakest)?
58.3% failed by mid lig tear, 22.9% avulson fx, 18.8% bone-lig interface
Highest elastic modulus: accessorometacarpal ligs >palmar radiocrpal and ulnocarpal ligs > medial and lateral collateral ligs
Ligaments of forepaw, lateral aspec
What breeds are associated with radial carpal bone fractures?
Boxers, English Springer Spaniels, Setters, Pointers
Males predisposed
Usually active
What are the configurations of radial carpal bone fractures?
dorsal slab
midbody saggittal (dorsoproxlat to palmardistmed)
Comminuted T shaped
May result from incompete fusion of the 3 centers of ossificaiton of the radial carpal bone
Traumatic in right carpal of Greyhounds: most common oblique midbody fx and chip/avulsion at attachement of palmar carpometacarpal lig or oblique part short radial collateral
How do you repair a radiocarpal fx?
lag screw: palmaromedial aspect in dorsolat direction
K-wire
excision of fragments
Approaches: dorsal (dorsal slab), palmaromedial (midbody RC fx), combination to increase exposure
Accessory carpal bone fracture classification.
5 types:
I: (67%) avulsion fx dital margin articular surface at attachemnt of lig from AC to ulnar carpal
- Ia: palmarolateral
- Ib: palmaromedial
II: (13%) prox margin of articular surface AC at the origin of the lig from AC to distal radius
III: (3%): avulsion at the distal surface at the caudal end of the AC
IV: (12%): Avulsion tendon insertion flexor carpi ulnaris at caudoproximal surface AC
V: (3%): comminuted fx
What treatment is recommended for accessory carpal bone fx?
Type V: non-surgical
Palmarolateral approach
Fragment removal or interal fixation (1.5 or 2mm lag or positional screw)
Preserve accessormetacarpal lig and the accessoroulnar carpal lig
What are the guidelines for metacarpal fracture repair?
> or = 2 meta fx same limb
involve both wt bearing bones
articular
displaced >50%
base of meta II or V
large breed or atheltic dog
Where do stress or fatigue fx occur in Greyhounds?
MC V left and MC II right
What are the 3 types of metacarpal fx in Greyhounds?
I: endosteal and cortical thickening - rest/NSAID 3m
II: minimally displaced hairline - external coaptation 6-8w
III: complete fx with dispalcement - surgical
Px good I and 2, guarded 3
70% return to training
What are the treatment options for metacarpal/tarsal fx?
medial approach MC 2, Lateral MC 5, rest dorsal
Avulsion fx meta 2 or 5 = lag screw or pin/tension band
Amputation
IM k wires (normograde)
Dowel pinning
bone plates
ESF
What is this?
Sesamoid disease
Greyhound, Rotties, Labs, Austrailian Cattle Dogs
Usually 2 and 7 (fewer vascular foramina)
lameness, pain, joint effusion, reduced flexion
Rest for 4-8 weeks
Surgery to remove frag or sesmoid (palmar appraoch)
What are the most common joint locations for the carpus to luxate?
Antebrachiocarpal = 10-31%
Middle = 22-50%
Carpometacarpal = 40 -47%
Conservative management usually not sucessful = arthrodesis
Where do shearing injuries most commonly occur?
27% thoracic limb
69% medial surface
What are the indications for carpal arthrodesis?
effects antebrachiocarpal joint
the other effected joints cause damage to teh accessory lig, palmar fibrocarilage and the palmar ligs.
Complete luxation of any carpal bone or joint (subluxation more common)
What approach to carpal arthrodesis is biomechanically superior but rarely performed due to difficulty?
Palmar
What are the most common approaches for carpal arthrodesis?
Medial
Dorsal (most common) - Distal 1/3 radius through length of MC3
- extensor carpi radialis m. tendon to MC2 and 3 severed and other extensors retracted laterally
What are plating options for pancarpal arthrodesis?
DCP or LC-DCP
hybrid DCP
Single of double stepped hybrid arthrodesis plate
- more normal relationship btwn radius, carpal bones and MC, smaller MC screw, maintain 10-12 degree without bending plate
Castless plate
- engages both MC3 and MC4 at 8 degree, available 4 lengths, stiffer and greater load to failure than hybrid with or without cross pins
What is the complication rate for carpal arthrodesis?
7-50%
ESF = 35%
What is the max width that screws should be in the metacarpal bone?
do not exceed 40% bone diameter
plates should span >50% of the metacapal 3 length
What are the average bone bridging times for arthrodesis of the varius MC joints?
9-12 weeks intercarpal and carpometacarpal
17-30 weeks radiocarpal
What is the ideal angle for a pancarpal arthrodesis?
ideal angle = 10-12 degrees
true range = 10-47 degrees, metacarphal phalangeal joint range = -3 to 19 degrees
How do satisfactory results compare for partial carpal and pancarpal arthrodesis?
50% satisfactory for partial carpal
75% satisfactory for pancarpal
How do you performed a partial carpal arthrodesis?
T-plate secured to radiocarpal bone (distal to not interfere with joint)
Can also use cross pins
Which metacarpal phalangeal joints more commonly effected with OA?
MC 4 and 5
excessive periosteal rxn with OA in the area up to 33% bone
How is carpal laxity syndrome in puppies treated?
65% recover in 2 weeks with appropriate diet and controlled exercise on good surface
- due to under/over suppelmentation in diet and concrete surfaces with little exercise
- usualy 5-27w old, 2:1 male predilection
- no evidence of coaptation
What is distribution of cause of masses in the digits (mal/benign/inflammation) and what are the most common neoplasms?
61% malignant
20% benign
19% pyogranulomatous inflammation
SCC (38%), melanoma (32%), MCT (11%), PNST (7%), and <5% others
With SCC 66% from subungal epithelium (poorer survial) = 1 and 2yr survival 76%, 43%
- lung mets more common with melanoma (32%) than others (SCC 13%)
What digits and breed are commonly affected by paw pad corns?
Greyhounds (male>female)
90% thoracic digital pads 3&4 (40% had additional foot deformities)
mechanical = >50% return in 2m in Greyhounds, do not return in other species with excision and 1 layer closure
Stepped hybrid plates used for carpal arthrodesis. A, Single-step plate. B, Double-step plate.
What is the tension surface of the ilium?
Ventral
Options for plating the ilium?
Lateral
Ventral
Dorsal - allows longer plate and screws (cats)
- Long oblique can also be repair with 2-3 lag screws
ome ilial fractures are caudal to the body of the ilium, located directly adjacent to or extending dorsal to the acetabulum. This location requires a more dorsal plate position. A straight plate may be contoured with a simple twist to facilitate extension of the plate dorsal to the acetabulum. A, This is the dorsal view. B, Cranial and lateral view showing the dorsal position of the plate. C, End- on view of the twist contour needed for placement of a straight plate as used for the caudal ilial fracture
everal procedures can help in reduction of acetabular fractures. A, Kern bone-holding forceps applied to the ischiatic tuberosity or ischiatic table through a limited approach provide excellent control of the caudal acetabular fragment. A bone hook may assist in elevating the caudal fragment from its medially displaced location. B–C, Reduction can be maintained and compression of the articular surface achieved with point reduction forceps. Care is taken to avoid overcompression, which may alter articular shape and congruity. Care is taken to prevent crushing the sciatic nerve during retraction and reduction
note Bone hook
ixation of acetabular fractures. A, Oblique fracture types may be repairable with lag screws alone. Large dogs may need lag screws and a bone plate. B, Repair of a central transverse fracture with an acetabular plate. C, Small fragments of comminuted acetabular fractures are first held in reduction with Kirschner wires or small lag screws, and are reconstructed one at a time. D, After reconstruction of small fragments of a comminuted acetabular fracture, a bone plate is applied and must span the fracture, which requires a longer plate and careful plate contouring
As an alternative to plate fixation, pin, screw, wire, and polymethylmethacrylate composite fixation may be used for acetabular fracture repair. A, Fragments are held reduced with Kirschner wires and/or lag screws. One screw and washer is placed cranial and caudal to the fracture on the dorsal tension surface of the acetabulum. Figure-of-eight orthopedic wire connects the cranial and caudal screws. B, Polymethylmethacrylate is applied over the screw and wire fixation, creating the composite fixation
Doesn’t require perfect contour to maintain reduction
What was the outcome in 34 dogs with peripheral n. injury?
41% associated with SI luxation - 81% good funcitonal outcome
91% LS trunk damage assoicated with cr-med displacement of ilial fx
What are methods of SI luxation repair?
Lag screw fixation (1-2 screws) - <60% 38% loosen, >60% 7-8.4% loosen, >79% none loosend, loosend fixation results in only sl loss recution with little effect on pelvic canal diameter (lat or ventral), (open or minimally invasive)
trans-illiosacral rod- method uses fluoroscopy for placement
single long transsacral screw is placed to capture both ilial wings, with lag effect on one side and positional effect on the opposite side (ventral)
transilial pinning
pin and tension band
What percent of ilial body fractures unilateral?
77% unilateral SI
85% have concurrent injuries that disable both limbs
Fixation of sacroiliac luxation. A, Cranial view of the pelvis showing one lag screw deeply seated in the sacral body, at approximately 60% of sacral width. A second shorter screw is placed dorsal and cranial to the first, but must be short to avoid the spinal canal. B and C, Lateral views of the pelvis show the relationship between sacral screw position and the wing of the ilium. + marks the spot for the glide hole in the ilium and the thread hole in the sacrum. Craniocaudally in the ilial wing, the hole site is at the center of the caudal half. Proximodistally, the hole site is in the proximal one third of the ilial width. D, Lateral view of the sacral wing illustrating the location of the area for screw placement, as denoted by the clear area. This area is slightly larger than 1 cm × 1 cm in the average large dog. The cross-hatched area represents sites in which if placed here, screw depth would be short because of inadequate bone thickness or the presence of the spinal canal. The notch (a) and C-shaped cartilage (b) are used as visual landmarks in locating the site for screw placement. E, The first lag screw is inserted through the glide hole of the ilium and is directed by site into the thread hole previously drilled into the sacral body. A second short screw is located just cranial and dorsal to the first, and must stop short of the spinal canal. F, Dorsal view shows the positions of two lag screws. As an alternative, or if additional fixation is needed for stabilization, a transilial bolt, passing through the ilial wings and dorsal to the seventh lumbar vertebrae, may be used
Where should the holes be drilled in the dog and cat for an SI luxation?
Cat: distance of the drill hole in the cat from the cranial margin of the sacral wing is 51% of sacral wing length, just cranial to the C-shaped cartilage.8 The distance from the dorsal margin of the sacral wing is 47% of sacral wing height.8 The sacral wing notch is not useful for screw placement location in the cat
Dog: drawing an imaginary line between the dorsocranial and ventral aspects of the sacral wing. A hole is drilled just caudal to this line, approximately 40% from the ventral point on the sacral wing. Sacral wing notch (see Figure 57-17, D). is present in mature dogs and may be palpated along the cranial edge of the sacral wing. The notch is located exactly cranial to the sacral body in dogs
What are abaxial and axial sacral fx and what are the types?
Abaxial = lateral to sacral foramen (includes spinous process)
Axial = medial to sacral foramina and ventral to spinous processes
Type:
I: alar
II: foraminal
III: transvers
IV: avulsion
V: comminuted
What was the outcome in 32 dogs with sacral fx?
69% neuro deficits
43% hindlimb defeicits
28-34% - perineal, anal tone, urinary tract
28% tail denervation
axial more likely to have defeicits
Ischial body fractures are reduced with bone forceps, and fixation is achieved with a small contoured bone plate, taking care to preserve the sciatic nerve (Figure 57-21, A). Another fixation method using pin and tension band wire has been described.29 Avulsion fractures of the ischial tuberosity are seen and may be repaired with lag screws (Figure 57-21, B) or with pin and wire fixation
Ventral approach = hemicirclage
What kind of joint is the coxofemoral joint?
Diarthroidaidal articulation
What are the secondary stabilizers in the hip?
- Acetabular labrum - fibrocartilagenous band that extends from the DAR, ventrally extend across the acetabular notch as the transverse acetabular lig
- joint fluid
- periarticular mm (deep, middle, superfical gluteals, iliopsoas, quadratus fermoris, gemelli, internal and external obtrurator)
What are the reluxation rates of closed hip reductions that were performed after 5 days of luxation?
15-71%
Where are screws placed for a prosthetic capsule technique for hip luxation?
Left: 10 and 1, right 10 and 2)
sm-med = 2.7mm
large = 3.5=4.0mm
hole from cr to cd through neck of femur
suture in figure of 8
limb in abduction and sl. internal rotation
What are the sucess rates of various open reduction techniques for the hip?
General sucess rate = 85%
Capsulorrhaphy: 83-90%
Prosthetic capsule technique = 66-100%, 18% mild and 18% severe lameness
Transposition of the greater trochanter = 84%
Transarticular pinning = 80% success, unsatsifactory in 40% dogs >20kg
Toggle rod stabliazation = 85%, 88% toe touching at dc, 11% reluxation
Other techniques: Fascia lata loop stabilzation (1cm wide, passed over acetabulum and through hole in hip/femur), extra-articular iliofemoral suture placement (ilium hole -ventral, cr-cd femur, cd-crd under gluteal m (no comp or relux), transposition of sacrotuberous lig, Femoral head and neck excision arthoplasty, triple pelvic osteotomy, total hip arthroplasty.
How do you stablize a ventral hip luxation?
Dorsal approach
Reduce hip
ventral acetabular lig can be sutured
autogenous iliac crest shelf graft to augment acetabular rim
What long term outcomes were noted after a varitey of repairs for hip luxation?
62% not lame
20% severely lame
32% crepitus
48% pain
92% normal range of motion
OA progression in 55-62%, more pronouced in heavier dogs
Delayed Tx did not worsen prognosis
Radiographic view of a dog’s femur demonstrating a direct method of measuring the angle of femoral neck torsion on an axial fluoroscopic projection. Line A is drawn through the axis of the femoral neck, bisecting the femoral head. Line B is drawn parallel to the caudal surface of the distal femoral condyles. The angle formed by the intersection of these lines represents the angle of femoral torsion or anteversion.
What angle of reduction are good candidates for TPO?
<30 degrees angle of reduction with ortalani
some recommend using a 20 degree plate only
up to 10 months old
How do values of peak vertical force change with TPO?
Increase by 8 w post-op
normalize by 28w post-op
What can be done if instability still exsists after TPO plate is placed?
Greater rotation
Capsulorrhapy
Lembert imbrication
What percentage of dogs have cranial screw loosening for TPO?
62%
Limited by:
- cancellous scres in cranial seg
- use of longer screws that purchase sacrum??
- strict activity restrict
- Ventral plate stablization
How can you prevent pelvic narrowing with TPO?
Remove most lateral portion of pubis
pre-angle TPO plates
Measurement of the Ortolani angles of reduction (left) and subluxation (right). The angles of reduction and subluxation of the hip joint, respectively, represent the maximal and minimal angles needed to provide stability for acetabular rotation
Location and orientation of pelvic osteotomies according to the procedure described by Slocum.122,123 The cranial ramus of the pubis is removed first (bottom inset), then an ischial osteotomy is performed (top inset); finally, a transverse ilial osteotomy is made immediately caudal to the caudal dorsal iliac crest (center) with the osteotomy oriented perpendicular to the long axis of the pelvis (dotted line)
Muscle interpositions are no longer recommended clinically on a routine basis. If revision osteotomy is contemplated because of unacceptable bone-on-bone contact or extensive limb atrophy, what can be done?
use of antibiotic prophylaxis
creation of a muscle flap base 1.5 times the width of the ostectomy surface
use of the caudal pass of the biceps femoris muscle flap
suturing of the muscle flap under minimal tension
suturing of the flap to the middle gluteal and vastus lateralis muscles
careful identification and protection of the ischiatic nerve (damage reported in 3 dogs post biceps muscle transposition)
Cranial view of the canine femur demonstrating two levels of osteotomy for canine total hip arthroplasty: a, region of isthmus; b, axis of femur; c, midcervical cut; d, lesser trochanter cut
What are the benefits of vaccum mixing and pressurization?
Vaccum mixing: Reduces cement porosity, increases fatigue strength evauates funes from OR
Pressurization: forces cement into irregularites - increases max stregth of bone/cement interface
What are the advantages and disadvantages of cementless THR vs cemented?
Advantages:
- longer potential implant life
- decreased risk of post-op infection
- better implant stability
Disadvantages:
- Greater risk of femoral fx during reaming
- more critical for precise acetabular and femoral reaming to allow good fit
What are major types of total hip systems?
Biomatrix - cemented cup, press-fit stem
Zurich (Kyon) - screw in acetabular component, less subsidence, higher complication rate than BFX (17%)
HELICA - screw in femoral prosthesis that doesn’t extend into diaphysis of femur, screw in acetabular cup.
How are total hip implants placed?
slightly closed (5-10 degrees)
retroverted (10-20 degrees)
What are complications associated with THR? (cemented and cementless)
Cemented (12-13% overall): luxation (4-5%), aseptic loosening (2-3%), Infection (1-2%), pulmonary embolism (upto 82% but death uncommon), femoral fx, sciatic neuroparaxia, medullary bone infarction, neoplasia, acetabular cup displacement.
Cementless: Luxation, fissure fx, acetabular cup displacement, aseptic loosening, subsidence of stem, lucency at acetabular cup-bone inferace, bone infarction, lameness
What is the frequency of femoral fx during surgery?
3%
risk factors: osteopathy iatrogenic bone fissures
How does infection compare to aspectic loosening?
Both more common in cemented
Similar appearence initialy
Later infection = more periosteal reaction, increased bone lysis, sclerosis, formaiton of bone cloacae, drainaing tracts
What is associated with increased ventral luxation for THR?
Short neck and Bernies
What is acceptable subsidence and how can it be avoided?
2-5mm not significant, >5mm significant
- undersized stems greater subsidence than large stems in nwutral position or undersized stems in varus
- >85% canal fill less likely to subside
Prevent: appropriate sized implant, removal of most of cancellous bone in prox femur
If pistoning causing lameness = fresh ream and placment of cement (or remove entirely)
Canine total hip replacement centralizer mold (A) and resulting polymethylmethacrylate centralizer (B) (BioMedtrix, Allendale, NJ)
How is coxofemoral denervation performed and what is the outcome?
Scrape periosteum from ventral border orgin of rectur femoris to dorsal midline acetabulum.
- Equivocal = some relief but variable and prob not permanant
- improved visual analog score and precieved pain but GRF no improvement
- Poss protective effect on opposite limb - decreased peak vertical force and impluse
What are treatments for CHD that have fallen out of favor?
Intertrocahnteric osteotomy
Pectineus myectomy
Shelf arthroplasty
Dorsal acetabular rim arthroplasty
Ventrodorsal radiographs of a dog with coxa valga and bilateral hip joint subluxation before (A) and after (B) intertrochanteric osteotomy. Coxa valga is accentuated by external rotation of the femur (noted by prominence of the lesser trochanter) in (A). Note how the hip subluxation is resolved in the postoperative view
How does the prox femur prevent tension and compression?
Tension: lineal transversa (ossesous ridge from head to greater trochanter), femoral neck
Compression: greater trocanter and femoral head
What inserts on the greater trocanter?
internal and external obturator mm. and gemelli
How does growth occur from the proximal femur?
Single physis for 2-3m, then divide into capital physis and trochanteric physis
- Capital physis = 25% longitudal growth, forms femoral neck
- Trocanteric physis = no growth, shifts that mm. laterally
- Closure of both physes begins at 6m, complete by 9-12m dogs, 7-10m cats
What is the vascular supply to the proximal femur?
Extraosseous: lateral and medial circumflex femoral, caudal and cr. gluteal, iliolumbar
Intracapsular: extraossous anastomse to form vascualr ring
Intraosseous
A. of the lig of the femoral head (epiphyseal blood in cat, not dog)
What % growth occurs from the distal femoral physis?
75%
What is the vascular supply to the diaphysis?
medial circumflex femoral a. (nutrient formen)
Nutrient a. (asending and desending medullary a)
metaphyseal a. anastomose with medullary
Periosteal a. - enter along facies aspera (important puppies, no adults)
Where do the gastrocnemius m. originate?
Caudal supracondylar tuberosites
Where does the superficial digital flexor m. arise from?
lateral supracondylar tuberosity
When does the distal physis of the femur close and what is the blood supply?
same as proximal (starts 6m, closes 9-12m dogs, 4m, 7-9m cats)
Distal metaphysis: branches of saphenous and descending genicular aa. off femoral a.
What is the fracture classification for the femur?
- Alpha numeric based on location, degree comminutation and severity, prognosis): femur = 3, position within femur (1-3 prox-distal), morphology (A= single fx, B= butterfly, C= comminuted), severity and px (1-3, least to most severe)
- Proximal femur= intracapsular or extracapsular (intracapsular = epiphyseal, physeal, subcapital, transcervical), (extracap = basiler neck, intertrochanteric, subtrochanteric)
- Metaphyseal = supracondylar
- epiphyseal = physeal (cats SH type1, dogs SH type 2), condylar (unicondylar or bicondylar)
When/where do most proximal femur fx occur?
- 91% in animals <12m
- 70% capital physis
How do you treat a epiphyseal fx?
prosthetic joint capsule or iliotrochanteric band (augmentation techniques)
How can pins be placed to repair physeal fx?
Retrograde (more accurate, but have to dissect fx site) or normograde (if thorugh articular surface need to transect lig = instability)
Rec placing 2 parallel pins - # pins not associated with OA develop, 1-2 pins = strength to normal, 3 pins increases strength by 30%)
Centrally placed pins advanced 75-80% contralateral epiphysis or width pubic bone, eccentric = 65%
upto 70% resportion of femoral occurs following ORIF, minimally invasive decreses chance of resorption or segmental collapse
What is the signalment and associated histopath for capital physeal dysplasia?
Cats>dogs
Young, overweight, castrated male cats (poss. associated with early castration
Histo: viable bone with irregular clusters of chonfrocytes in EC matrix and necrotic cartilage
Lag screw fixatoin with antirotational K wire
What is the tension surface of the femur?
lateral cortex
How can you reduce sciatic n. injury when placing an IM pin in the femur?
Adduction
stay in cr lateral fossa
max extension
What is the complication rate for stack pinning?
50%
pin migration
loss of reduction
implant failure
sciatic neuropraxia
neurotmesis
What is dynamic ILN placement in the femur?
bolts on only one side
What is the success of rate of the ILN in the femur?
83-96%
old version = 12% instability and need supplemental implants
What are complications associated with ESF?
Pin tract inflammation 60-80% dogs, 22% cats
implant failure
fracture
Quadriceps contracture 33% dogs, 7% cats
non-union
What kind of disruptions in femoral length can dogs compensate for?
loss 20% femoral length
rotaional/valgu/varus malalignment worse
What percent of dogs and cats expirence sciatic injury from retrograde pinning?
23% cats
14% dogs
What is the angle for cross pins and rush pins for distal femoral physeal fx?
Cross pin = 30-45 degrees
Rush = 15-20
What % of distal physeal femoral fx have premature closure?
83%
Craniocaudal radiograph of the proximal femur illustrating the trabecular network of the femoral head and neck. This network is oriented to resist both tensile (A) and compressive (B) forces generated during activity. Note the orientation of the trabecular lines of the linea transversa extending from the greater trochanter to the femoral head. This presumably helps counter bending moments generated by eccentric loading of the femoral head
adiographic and gross images illustrating the angles of inclination and anteversion. Inclination, defined as the angle between the femoral neck and the anatomic axis of the femur in the frontal plane, is estimated from ventrodorsal and/or craniocaudal horizontal beam radiographs. Anteversion is defined as the angle between the femoral neck axis and the tangent to the femoral condyles. This is best illustrated using a proximal-to-distal projection of the femur; however, clinically, this projection is difficult to obtain without advanced imaging (CT). Lateral radiographs are traditionally used to estimate this angle
Radiographic appearances of the distal femur from a nonchondrodystrophic dog and a chondrodystrophic dog. In nonchondrodystrophic dogs, the distal metaphysis progressively widens from proximal to distal, which creates a smooth transition between the diaphysis and epiphysis. In contrast, the transition between the metaphysis and the epiphysis of chondrodystrophic dogs occurs at an acute angle (red line) and is associated with an isthmus proximal to the trochlea (arrowheads). This conformation is thought to predispose these breeds to supracondylar and condylar fractures
Radiographic appearance of the proximal femur of a nonchondrodystrophic dog and a chondrodystrophic dog. Note the altered contour of the femoral head, the shortened neck, and the more proximally located greater trochanter with respect to the femoral head (red X) in a chondrodystrophic dog compared with a nonchondrodystrophic dog.
Illustration of the blood supply over the cranial (radiograph) and caudal (dry bone specimen) surfaces of the proximal femur. The complex vascular network of the proximal femur includes the lateral (a) and medial circumflex (b) femoral arteries, the caudal gluteal artery (c), the extracapsular vascular ring (d), the ascending intracapsular arteries (e), the intraosseous arcuate network (f), the ligament of the femoral head (g), and the nutrient artery (h)
Classification of proximal femoral fractures with respect to their intracapsular (a through d) or extracapsular (e through g) locations. Intracapsular fractures include epiphyseal (a), physeal (b), subcapital (c), and transcervical (d). Extracapsular fractures include basic cervical (e), intertrochanteric (f), and subtrochanteric (g)
Classification of distal femoral fractures with respect to their anatomic location. These include supracondylar (a), physeal (b), and condylar (c and d) fractures. Condylar fractures are further classified as unicondylar (c) or bicondylar (d).
Radiographs showing different femoral neck fracture planes. Cervical fractures with steeper angles are associated with greater risk of postoperative instability than those with shallower angles
Craniolateral approach to the shoulder. A, Make an incision in the skin and subcutaneous tissue from just proximal to the acromion process to the proximal humerus. B, Incise the deep fascia along the cranial margin of the acromial portion of the deltoideus muscle and retract the muscle caudally. C, Isolate the infraspinatus tendon, place a stay suture in its proximal portion, and incise the tendon. D, Incise the joint capsule midway between the glenoid rim and the humeral head. Craniolateral approach to the shoulder. E, Internally rotate the humerus until the head subluxates and remove the cartilage flap. F, Curette the edges of the bony defect to ensure removal of all affected cartilage
Caudal approach to the shoulder. A, Make an incision in the skin, subcutaneous tissue, and deep fascia that extends from the midscapular spine to the midhumeral diaphysis. B, Incise the intermuscular septum between the caudal border of the scapular portion of the deltoideus muscle and the long head of the triceps muscle. C, Elevate and retract the teres minor muscle cranially, exposing the axillary nerve and joint capsule. D, Place a Penrose drain around the nerve and gently retract it caudally. E, Incise the joint capsule 5 mm from and parallel to the glenoid rim to expose the humeral head
Surgical stabilization of a medial shoulder luxation. A, Perform a craniomedial approach with biceps tendon transposition. Incise the skin and subcutaneous tissue over the greater tubercle and continue the incision medially to the midhumeral diaphysis. B, Incise the fascia along the lateral border of the brachiocephalicus muscle. C, Incise the insertions of the superficial and deep pectoral muscles from the humerus and retract them medially. Retract the supraspinatus muscle laterally. D, Transect the tendon of the coracobrachialis muscle to expose the subscapularis muscle tendon. Incise the tendon of the suprascapularis muscle. E, Incise the joint capsule to inspect the joint. F, To transpose the biceps tendon, incise the transverse humeral ligament. Make a small incision in the joint capsule under the biceps tendon to free it and move the tendon medially. Secure it to the humerus with a bone screw and spiked washer
To surgically stabilize a lateral shoulder luxation, perform a cranial approach with biceps tendon transposition. A, Expose the joint. B, Perform an osteotomy of the greater tubercle, including the supraspinatus muscle insertion. C, Incise the joint capsule and the transverse humeral ligament over the biceps tendon. D, Free the biceps tendon, and move it laterally across the osteotomy site. Hold the tendon in place, and reduce and stabilize the osteotomy with Kirschner wires and a tension band wire or lag screw
To expose the medial aspect of the elbow joint by means of transection of the pronator teres muscle, make a skin incision on the medial surface of the joint, starting at the medial epicondylar crest and extending distally over the medial epicondyle. B, Gently retract the median nerve and brachial artery and vein cranially. C, Transect the pronator teres tendon and make an incision parallel to the humeral condyle through the joint capsule and collateral ligament to expose the FCP. D, Remove the fragment
To expose the medial aspect of the elbow joint using a muscle-splitting approach, identify the demarcation between the flexor carpi radialis and the superficial digital muscles and separate and retract them. Expose the joint capsule and incise it parallel to the muscle-splitting incision to expose the coronoid process
For closed reduction of a laterally luxated elbow (B), flex the elbow and inwardly rotate the antebrachium to hook the anconeal process into the olecranon fossa. C, Then extend the elbow slightly and abduct and outwardly rotate the antebrachium while placing pressure on the radial head
To stabilize the elbow, replace collateral ligaments by using two screws and a figure-eight wire. C and D, To secure an avulsed fragment, use a lag screw with a spiked Teflon washer
Arthrodesis of the elbow. A, Make two osteotomies and remove a portion of the proximal ulna. Temporarily stabilize the elbow in the correct position with a pin placed through the ulna and into the humerus. B, Contour a plate to fit onto the caudal surface of the humerus and the caudal surface of the ulna. Place at least three screws in the humerus and three in the ulna. Use additional screws as lag screws to gain compression across the arthrodesis site
Radial lengthening of the radius using a transverse osteotomy
Cemented canine THR implants. B, Cementless canine THR implants
What complication is this?
Radiograph of aseptic loosening of a cemented THR
Coxofemoral joint stabilization by placement of a prosthetic capsule. Note the strategic placement of bone screws in the dorsolateral acetabulum. Suture material is passed from the screws through a predrilled tunnel in the dorsal femoral neck and tightened. The presence of suture in this position prevents craniodorsal reluxation. The same procedure may be performed using suture anchors
Intercondylar tubercles
cr/cd intercondyloid area - CrCL (cd-med lateral condyle & cd-lat intercondylar fossa, fibers spiral axially 90 degrees) and cr/cd meniscal ligs
Lateral area of politeal notch = CdCL (lat surface medial femoral condyle)
cr/cd meniscotibial ligs for MM and LM
intermeniscal lig
meniscofemoral lig
popliteal tendon
coronary lig (MM to MCL)
medial collateral lig - fused to MM and joint capsule
lat collateral lig - separated to LM dt popliteal tendion, loose attach to joint
Diagramatic representation of the collagen fiber orientations within the outer two thirds of the meniscus. The distribution of the type I collagen fibers is predominantly circumferential. Radial fibers are less numerous and act as a “tie” holding together the circumferential fibers. The illustration shows that a vertical longitudinal tear may develop along the circumferential fibers
Collagen fibrils - 3 layers
Collagen bundles on surface randomly oriented
Outter 2/3 = circumfrential, immermost budles in radial
Proximal aspect of the menisci showing the approximate extent of the three vascular zones of the meniscus. The red-red zone is characterized by greater vascularity and extends for 15% to 25% in the periphery of the meniscus. The rest of the meniscus is mostly avascular and is divided into the axial “white-white” zone and an intermediate zone called red-white, with only a small amount of vessels reaching this latter zone
Perimensical capillary plexus - medial and lateral genicular aa.
what is the normal ROM stifle?
140 degrees
How are valgus and varas constrained by the stifle?
Extension: MCL limits valgus, LCL and CrCL limit varus
Flexion: all limit valgus, LCA and CCLs limit varus
What percentage of load to the menisci bear across the joint?
40-70%
How does removal of the caudal horn of the medial meniscus affect forces on the joint? And what is the effect of serial menisectomies?
cut caudal meniscaotibial lig = 140% increase in peak contact pressure, 50% decrease in contact area
30% radial width = minial effect (aka partial)
75% radial width and hemimensectomy = sig change in contact mechanics
To be functional, meniscus needs >25% radial width
Partial menisectomy did not change contact pressure noted under torn meniscus
The peak vertical force on the normal hindlimb was 70% of the static body weight of the dog. Following cranial cruciate ligament transection, the peak vertical force was 25% of body weight at 2 weeks, 32% at 6 weeks, and 37% at 12 weeks
Figure 62-11 The Slocum active force model of the stifle joint. According to this model (A), the joint reaction force during weight bearing (magenta arrow) is approximately parallel to the longitudinal axis of the tibia, and can be resolved into a cranially directed shear force (cranially directed yellow arrow) and a joint compressive force (proximally directed yellow arrow, perpendicular to the tibial plateau). Tibial plateau leveling (B) results in a joint reactive force (magenta arrow) that is perpendicular to the tibial plateau. Thus it can only be resolved into a joint compressive force (yellow arrow); cranial tibial thrust is eliminated
The Tepic model of the stifle joint. According to this model (A), the joint reaction force (magenta arrow) is approximately parallel to the patellar ligament, and can be resolved into a cranially directed shear force (cranially directed yellow arrow) and a joint compressive force (proximally directed yellow arrow). Advancing the tibial tuberosity (B) such that the patellar ligament is perpendicular to the tibial plateau neutralizes the cranial tibial thrust force
Avulsion of the tibial attachment of the cranial cruciate ligament (A). Small fragments can be stabilized with stainless steel wire (B) placed through the ligament, around the fragment(s) and through two bone tunnels that exit on the medial cortex, where the wire is twisted. Large fragments can be stabilized with diverging Kirschner wires (C) or a bone screw placed in lag fashion
Alternatively can TX avulsion with epiphysiodesis - screw in cranial part of epiphysis - caudal continues to go and decreased TPA
In 22 dogs: reduction in TPA of 4-24 degrees
Eccentric screw = valgus
What is the sens and spec of US and MRI for dx meniscal tears?
Ultrasonographic examination of the canine menisci has been reported, and its sensitivity and specificity compared with arthroscopy for the diagnosis of meniscal pathology was 90.0% and 92.9%, respectively
high field MRI appears to be a very reliable method for diagnosing meniscal tears preoperatively, with reported sensitivity of 100% and specificity of 94% in a small number of case (low field not, 60% sens and 90% spec)
What is the incidence of mensical tears in relation to CCL disease?
reported incidence varies from 33.2% to 77%
Radial tears of the lateral meniscus have been reported with an incidence of 77%
Findings of a study with a 1000 dogs with CCL disease?
insufficiency, 33.2% of dogs presented with a meniscal tear diagnosed at the time of the first surgery. The sex distribution was 39.7% neutered males, 32.2% neutered females, 13.7% intact males, and 13.4% intact females
What is the incidence of postliminary and latent (aka missed) meniscal tears?
The incidence of postoperative (including both postliminary and latent) meniscal injury has been reported for several surgical techniques; it ranges between 2.8% and 17.4%
What percent of dogs with meniscal tears have a mensical click?
27%
Exacerbation of lameness in cranial cruciate ligament–deficient dogs was 52% sensitive in identifying moderate to severe meniscal injury
How much does probing increase the liklihood of dx a meniscal tear?
probing enhanced the sensitivity and specificity of all diagnostic methods. An accurate diagnosis obtained by arthrotomy or arthroscopy was 2.1 to 2.6 or 8.0 times more likely, respectively, when probing was performed compared with observation alone.
What are types of meniscal tears?
Proximodistal view of a right tibial plateau with illustrations of the classification of meniscal tears. A, intact; B, vertical longitudinal tear; C, bucket handle tear (oblique); D, flap tear; E, radial tears; F, horizontal tear; G, complex tear; H, degenerative tears
What is the best approach to evaluate stifles with cruciate deficient stifles vs. cruciate intact?
a craniomedial arthrotomy was most sensitive in cranial cruciate ligament–deficient stifle joints, whereas caudomedial arthrotomy was most sensitive and had the highest sensitivity and specificity in stable, cranial cruciate ligament–intact stifle joints
Mid-body meniscal release performed with an inside-to-outside technique (A) or with an outside-to-inside technique (
place blade caudal to the medial collateral lig and aim towards tuber of gerdi (30 degree angle)
What is another name for the vest over pants suture pattern?
modiefied Mayo pattern
Why is Nylon leader line superior to other types of Nylon line?
recovers resting tension to a greater degree
higher failure load and greater stiffness = elongates less under a given load than nylon fishing line
biologically inert, has low bacterial adherence and is minimally affected by steam or ethylene oxide sterilization
Why are nylon crimps better than square knots?
metallic crimp tube - lower loop elongation, higher load at failure, greater stiffness, and greater initial loop tension compared with nylon leader line secured with a square knot
What is the estimated load applied to LFS?
estimated load applied to the suture is 120 to 600 N
What are the quasi isometric points?
F2 - caudal edge lateral femoral condyle immediately adjacent to distal pole of fabella
T3 - caual wll extensor groove
What is the complication for LFS?
In 363 dogs, 17.4%, 7.2% required a second surgery
Factors associated with complications: high body weight and young age
3.9% infection rate - lower rates associatd with suture material other than staples, and post-op oral antibiotics
incisional complications 8.8%
implant related 2.8%
1.9% post liminary meniscal tear rate
What angle is recommend for performing a cranial closing wedge osteotomy?
TPA + 5 degrees
TPA +7.5 degrees = caudal tibial subluxation
–Complications more likely to require surgical revision (11.9% vs. TPLO 4.5%)
What is the average TPA and what is the intra/inter observer variability?
•Mean mCaPTA (blue angle a)
–63.8+/-3.7 lab (TPA 26.2)
–63+/-3.9 non-lab (TPA 27)
–Intraobserver variability +/- 3.4 degrees
–Interobserver variability =/- 4.8 degrees
•Another study +/- 6 degrees due to DJD
What is the complication rate with TPLO?
- Complication rate: 18.8-28%
- Tibial fracture, intra-articular screw placement, hemorrhage, broken drill bit, fibular fracture, intra-articular jig placement, screw in the osteotomy site, retained surgical sponge, broken holding pin and broken screw
- Inflammation, bandage issues, seroma, dehiscence, incisional drainage, incisional infection, hematoma, edema and bruising
- Patellar ligament thickening, periosteal reaction, osteomyelitis, postliminary meniscal tear, implant loosening, patellar fracture, septic arthritis, ring sequestrum and luxation of the tendon long digital extensor
What are the risks and complication rate associated with TPLO?
•Bilateral single stage TPLO higher risk complications
–20-40% complication rate (unless you are Fitzpatrick)
–8.5-9.6 fold increase tibial tuberosity fracture
•Rockback (remodeling of the subchondral plate of the medial tibial plateau)
–1.5 +/-2.2 degrees (range +/-3 to 9)
–Less change occurs with locking plates
•Infection rate ~ 6%, but much higher in some
–Multiple studies have found post antibiotics to be protective
–Weight, anesthesia time, locking construct have been loosely associated
What are indications for performing a TPLO and cranial closing wedge ostectomy?
•Indications:
–Rotation greater than 34 degrees with a 24 blade (12mm)
–Rotation past insertion of patellar lig.
–Severe tibial valgus/varus/torsion
–Patella alta
•Surgery:
–TPLO cut scored, then wedge scored
–TPLO cut completed and pins placed
–Wedge completed, tension band/s, plate/s
–Bone graft from wedge
What are the 2 methods for TTA planning?
- Stifle 135 degrees with no cr. tibial translation
- Use transparency or digital software to pick plate
•Can use PTATPA or common tangent method PTACT (preferred)
What are systems for TTA?
Kyon - U of I system
Securos - uses screws
Rita Leibinger: RAPID - Similar to TTA-2 by Kyon
Synthes
Others: OssAbility, Vetisco, Everost - Absorbable cage
What is the TTA complication rate?
•Complication rate: 20-59%
–12.3-38% major
- Meniscal tears, infection, medial patellar luxation, tibial fractures and implant failure
- Major meniscal tears, unknown if postliminary (meniscal release) or latent
–11.3-14% requiring reoperation
•Similar complications TPLO + medial patellar luxation, long digital extensor transection and issues with gap healing
What are case selection criteria for TTA?
•Patellar ligament insertion/tibial crest
–Longer crest with higher insertion may be advantageous
- Smaller = lesser buttress support, less area for force distribution aka possible fracture
- TPA
–~30 degree (possibly less) cut off due to cage size
–Hyperextension
- Cannot correct ALD
- Good for concurrent MPL
What is a triple tibial ostetomy?
- Similar to TTA in concept
- Partial frontal plan osteotomy with distal cortex intact
- Wedge angle = 2/3 or 0.6x angle between patellar ligament and a line perpendicular to the TP (CA) + 7.3
–Or TPA -5 degrees use if above formula <0
–Or TPA -12 degrees if small correction needed PTA close to 90 degrees
•Proposed advantages:
–Minimal change to articulating surface
–Small osteotomy gap
–No loss limb length
–“Low technical difficulty’
•Complication rate 23-36%
–Tibial tuberosity fracture, infection, postliminary tears
•Intra-op tibial tuberosity fracture occurred in 23%
Overall similar complications as TTA and TPLO combined
Comparison of long-term outcomes associated with 3 surgical techniques of cranial cruciate ligament disease in dogs. Vet Surg 2013
- > 1yr outcomes TPLO (65), TightRope (79) and TTA (18)
- TTA greater rates of complications and meniscal tears than TR or TPLO, TPLO had greater than TR
- Similar percent function at 1 year
–More TPLO and TR cases reached full function than TTA
•Conclusions: TPLO and TR better than TTA but each had high long-term success. TR highest safety to efficacy ratio
Risk factors for developing patellar ligament thickening post TPLO?
included a cranially positioned osteotomy, a partially intact cranial cruciate ligament in conjunction with a cranially positioned osteotomy, and postoperative tibial tuberosity fracture.
What are structural changes to the joint/bones that occur with MPL?
1, Coxa vara. 2, Distal femoral varus and genu varum. 3, Shallow trochlear groove with poorly developed or absent medial ridge. 4, Hypoplastic medial femoral condyle. 5, Medial displacement (torsion) of the tibial tuberosity associated with internal rotation of the tibia at the stifle joint. 6, Proximal tibial varus. 7, Internal torsion of the foot, despite external torsion of the distal tibia.
What is the frequency of medial vs. lateral patellar luxation?
frequency and distribution of medial and lateral patellar luxation in 124 dogs, 82% of cases were found to be developmental. In small-breed dogs, luxation was medial in 98% of cases, and in only 2% it was lateral; the female-to-male ratio was 1.5 : 1.153 In another retrospective study of 134 dogs, medial patellar luxation was found in 127 dogs (95%), and lateral luxation was identified in 7 dogs (5%).7 Bilateral medial patellar luxation is common, occurring in 50%29 to 65% of cases
What is Q angle in relation to MPL?
Deviation of the direction of force of the quadriceps femoris muscle can be calculated and is referred to as the Q-angle.185 Utilizing MRI, the Q-angle was measured in dogs with medial patellar luxation referencing the origin of the rectus femoris muscle, the deepest point of the trochlear groove, and the attachment of the patellar ligament on the tibial tuberosity.185 The average Q-angle of normal dogs was 10.5 degrees; it was 12.2 degrees in dogs with grade I medial patellar luxation, 24.3 degrees in dogs with grade II medial patellar luxation, 36.6 degrees in dogs with grade III medial patellar luxation, and 19.3 degrees in dogs with cranial cruciate ligament rupture
What is the rate of concurrent rupture of the cranial cruciate ligament with MPL? i
oncurrent rupture of the cranial cruciate ligament is present in 15% to 20% of the stifle joints of middle-aged and older dogs with chronic medial patellar luxation
What are the methods of deepening the trochlear groove?
Trochlear sulcoplasty (abrasion trochleoplasty) - periosteal graft ( fill with fibrocartilage in 4w vs 40w)
chondroplasty
trochlear wedge
block recession
Why is the block superior to the wedge for a trochlear recession?
increased proximal patellar depth
increased patellar articular contact with the recessed proximal trochlea
recession of a larger percentage of the trochlear surface area
greater resistance to patellar luxation in an extended position as compared with trochlear wedge recession
What is the underlying abnormality suspected to be associated with MPL?
coxa vara (a decreased angle of inclination of the femoral neck) and a diminished anteversion angle (relative retroversion) are the underlying skeletal abnormalities
What is the prevalence of medial patellar luxation in medium-size dog breeds?
the prevalence of medial patellar luxation in medium-size dog breeds was 81%, in large breeds it was 83%, and in giant-breed dogs it was 67%,
What L:P ration is associated with patella alta?
large-breed dogs with an L:P ratio greater than 1.97 were considered to have patella alta
What is another name for anteversion angle?
The femoral torsion angle (anteversion angle)
What are methods to repair a combination MPL and CCL?
If no tibial torsion is present:
TTT and LFS
TPLO with internal torsional correction combined with a de-rotational proximal tibial osteotomy
TTTA
lateral translation of the tibial tuberosity segment following TPLO/CCWO (in this case, a cranial closing wedge or a simple osteotomy at the exit of the tibial plateau leveling osteotomy caudally can be used to isolate the tibial tuberosity segment) (see Figure 62-47, A–D)373;
tibial closing wedge osteotomy and TTT
What are these?
Verbrugge bone clamp
How can fractures of the patella be classified?
Fractures of the patella can be classified into
nondisplaced or minimally displaced
apical, basilar, or body fractures
displaced transverse body fractures
comminuted fractures
Where are OCD lesions most commonly in the stifle?
the lesion is most commonly located on the axial (medial) aspect of the lateral femoral condyle (96% of cases).251 In some cases, the lesion may be located on the axial (lateral) aspect of the medial femoral condyle (4%)
Patellar fracture repair. Nondisplaced fissure fractures, or minimally displaced fractures can be reduced with an orthopedic wire placed circumferentially around the patella; the wire is tightened (twisted) to achieve reduction and compression. Further stability can be achieved by placing a second wire as a tension band from the tendon of insertion of the quadriceps muscle from proximal to the patella to distal to it (A). First placing a bent hypodermic needle in the desired location, and then inserting the wire through it can facilitate passage of wire through the tissue. Displaced transverse fracture of the patella (B) can be stabilized by a pin and tension band wire technique. A drill hole is made in a retrograde fashion from distal to proximal into the basilar fragment (C). The fracture is reduced, held in compression with pointed reduction forceps, and the drill hole is advanced from proximal to distal into the apical fragment (D). A Kirschner wire is placed in a normograde fashion from proximal to distal (E). The tension band wire is placed around the Kirschner wire and tightened (F). An additional tension band wire can be placed to augment the reconstruction (G). Multifragmentary patellar fractures can be reconstructed and stabilized with any combination of a Kirschner wire(s), tension band wire(s) and a wire placed circumferentially around the patella (H).
Rupture of the patellar ligament. The distracted ends of the patellar ligament (A) can be apposed by placing a tension band wire from a drill hole placed transversely across the patella, or into the insertion of the quadriceps tendon proximal to the patella to a drill hole placed in the tibial tuberosity (B–C). The wire is tightened to appose ligament ends, and a locking loop suture(s) is used to appose the ligament ends. The locking loop sutures can be augmented with additional simple interrupted or mattress sutures
tifle joint arthrodesis with bone plate fixation. Planning of the ostectomies (A). Kirschner wires 1 and 2 are placed perpendicular to the femoral and tibial shafts (dotted lines) respectively. In this case, the joint angle chosen is 140 degrees; the complementary angle is 40 degrees. Dividing this by two yields 20 degrees, thus pins 3 and 4 are placed at an angle of 20 degrees to pins 1 and 2, such that they are parallel to the planned femoral and tibial ostectomies, respectively. The tibial crest osteotomy has been completed, the tibial articular ostectomy has been completed parallel to pin 4, and the sagittal saw is placed parallel to pin 3 in preparation for the femoral ostectomy (B). The joint is temporarily stabilized by crossed pins (C). Prior to and during pin placement, ensure that Kirschner wires 1–4 are maintained in the sagittal plane to avoid tibial rotation at the stifle joint. In addition, Kirschner wires 3 and 4 should be parallel to optimize apposition of the femur and tibia at the ostectomies. Kirschner wires 1–4 are removed once the cross pins are placed, and the proper alignment and apposition of the femur and tibia are confirmed. A portion of the tibial crest is ostectomized to allow ample bone plate contact, and a compression plate is contoured and applied to the cranial surface of the femur and tibia (D). Two bone screws are applied in compression on each side of the stifle joint, and two plate screws are placed in lag fashion across the stifle joint.
What is the angle of arthodesis of the stifle?
proper angle (135 to 140 degrees for dogs, and 120 to 125 degrees for cats)
Describe the physes of the tibia (4)?
The tibia has four separate epiphyses: proximal epiphysis (40% growth), tibial tuberosity epiphysis, distal epiphysis (60% grpwth), and medial malleolar epiphysis
between 6 and 8 months in large-breed dogs), the proximal epiphysis fuses to the tibial tuberosity epiphysis (apophysis
apophyseal growth plate normally closes relatively late in the development of the dog (>12 months in large-breed dogs
piphysis of the medial malleolus fuses to the distal tibial epiphysis very early in development (4 to 5 months in large-breed dogs
What is the blood supply to the tibia?
nutrient artery and the periosteal vessels derived from the cranial tibial artery. The nutrient foramen is located in the caudolateral edge of the proximal one third of the diaphysis. Within the medullary canal, the nutrient artery divides into proximal and distal branches that anastomose with the metaphyseal arteries at each end.
The fibular head is supplied by a branch of the cranial tibial artery, and the fibular body is supplied by the nutrient artery derived from the peroneal artery.
Where is the tibia commoly fractured?
Proximal, diaphyseal, and distal fractures accounted for approximately 1%, 83%, and 18% of fractures in two studies by Boone (multiple locations involved in some fractures), and for 7%, 72%, and 20% of fractures in a study by Unger
A pin with a slightly smaller-than-normal diameter should be chosen, typically about 50% of the diameter of the medullary canal at the tibial isthmus
Methods to repair tibia fractures?
What is the % of bone filling for a IM rod with plate in the tibia?
The pin selected should fill approximately 30% to 40% of the diameter of the medullary canal
Malleolar fractures. A–B, Lateral malleolar fracture of the fibula with tibiotarsal luxation (4-year-old castrated male Maine Coon Cat); C, pin and tension band wire fixation; and D, screw fixation
tarsocrural (talocrural)
talcalcenal
talocalcaneaocentral
calcaneoquartal
centrodistal
tarsometatarsal
sustentaculumm tali - medial side
tuber calcanei
What is a hinge joint?
Ginglymus
What are the ligaments of the Tarsus?
Thickended tarsal fascia = tendon sheath flexor helicus longus, saphenous, plantar n.
Medial tibial collateral (3)= long part (med malleous-1st tarsal: taut extension), tibiocentral (taut extension), tibiotalar (taut flexion, most substanial)
Lateral collateral ligment (fibular)(3) = long lateral (taut extension), c_alcaneofibular short_ (taut extension), talofibular short (taut flexion)
Plantar (3) = middle plantar (calcan - 4th tarsal - MT4/5), medial plantar (sustentaculum tali - tarsoMT joint), lateral plantar (cd calcaneus - long collateral -MT5)
(Long lig taut extension, underlined most improtant to fix)
Tarsal lig
What is the blood supply to the tarsus?
Cr tibial - dorsal pedal a. - dorsal MT aa. (lateral and dorsal)
plantar br. saphenous a. (medial and plantar)
venous med and lat saphenous
What is the innveration to the tibia?
Tibial n. (sciatic)
- medial plantar
- lateral plantar
Common peroneal n (sciatic)
- superficial peroneal
- deep peroneal
Saphenous (br femoral) = cutaneous innervation to dorsomedial tarsus/metarsus
What is the range of motion and normal standing angle of the tarsus?
ROM: dog 39-164 degrees, cat 22-167
angle: dog 135-145, cat 115-125
What tarsal fx are common in Greyhounds?
calcaneal fx (right tarsus)
central tarsal bone (often concurrent, right tarsus) - 79% all injuries in tarsus (allows collapse and hyperextension of join)
3rd tarsal bone - dorsal slab fx, 20% incidence when looking at tarsal fx types in greyhound
What are the types of central bone fx (5)
I: nondisplaced doral slab
II: displaced dorsal slab
III: large displaced medial (rarest)
IV: medial slab with dorsal slab (most common)
V: comminuted fx
75% are IV or V
Ideally lag screws for I-IV. Extension splint/external coaptation for types 1-II, V (minimal chance race again, but good fxn)
Where are screws placed to reconstruct medial and lateral collateral lig of the tarsus?
Medially (talus) = body and head
Lateally (calcaneous) = coracoid process and distal calcaneous
What joints are associated with plantar intertarsal luxation or subluxation?
Hyperextension of the calceneoquartal and talocalcaneocentral joints (aka prox. intertarsal joint)
What breed is associated with plantar intertarsal sub/luxation and how do you treat it?
Shetland sheepdogs and collies
Arthrodesis of calcaneoquartal joint
= transfixation pin an tension band, compression screw from calcaeus to 4th tarsal, lateral plate,
35 cases with lag screw +/- tension band = 2 fail by screw breakage
What are options for arthrodesis of the tarsometatarsal joint?
Pin and tension band
transfixation pin
multiple pins
lateral bone plate
Transarticular ESF without removal of cartilage = ankylosis
What are the parts of the Achielles tendon?
pair gastrocnemius
superfical DFT
common tendon = semitendinosus, gracilis and biceps femoris
How do you treat a ruptured Achielles tendon?
Locking loop or 3 loop pulley
immoblize tarsus - calcaneotibial screw (3/38 broke), transarticular ESF, cast/splint
Dental radiographs of a cat with separation of the mandibular symphysis. A, Before treatment. B, After circumferential wiring: note that two mobile incisor teeth were also extracted.
Final dissection of the right pelvic limb. 1, Adductor longus muscle; 2, quadrates femoris muscle; 3, external obturator muscle; 4, internal obturator muscle; 5, gemelli muscle; 6, superficial gluteal muscle; 7, middle gluteal muscle; 8, deep gluteal muscle; 9, articularis coxae muscle; 10, partially severed origin of the rectus femoris muscle; 11, tensor fasciae latae muscle; 12, biceps femoris muscle; 13, semitendinosus muscle; 14, semimembranosus muscle; 15, adductor muscle; 16, abductor cruris caudalis muscle; 17, vastus lateralis muscle; 18, sartorius muscle (cranial belly); 19, sartorius muscle (caudal belly); 20, sciatic nerve; 21, acetabulum; 22, head of the femur; 23, superficial circumflex iliac artery.
Final dissection of the right pelvic limb. 1, Adductor longus muscle; 2, quadrates femoris muscle; 3, external obturator muscle; 4, internal obturator muscle; 5, gemelli muscle; 6, superficial gluteal muscle; 7, middle gluteal muscle; 8, deep gluteal muscle; 9, articularis coxae muscle; 10, partially severed origin of the rectus femoris muscle; 11, tensor fasciae latae muscle; 12, biceps femoris muscle; 13, semitendinosus muscle; 14, semimembranosus muscle; 15, adductor muscle; 16, abductor cruris caudalis muscle; 17, vastus lateralis muscle; 18, sartorius muscle (cranial belly); 19, sartorius muscle (caudal belly); 20, sciatic nerve; 21, acetabulum; 22, head of the femur; 23, superficial circumflex iliac artery.
Labially mounted dental radiograph showing the left mandibular third and fourth premolars (teeth 307 and 308) and portions of the left mandibular second premolar and first molar (teeth 306 and 309). Moderate periodontitis is evidenced by loss of alveolar bone interdentally between teeth 306 and 307 and teeth 307 and 308, and also in the furcation region of tooth 308. AM, Alveolar margin; D, dentin; E, enamel; F, furcation; LD, lamina dura; PC, pulp cavity; PL, periodontal ligament.
Dental radiographs of the lower jaw of an 8-month-old dog. A, Before treatment: note fracture of the left mandibular body between the first premolar and the third premolar in the area of a missing second premolar (arrow). B, Interdental wiring and intraoral splinting: note that a modified Stout multiple-loop technique was used, with the wire twisted over the missing left mandibular second premolar. C, 5-week reexamination confirming fracture healing; splint and wire were removed, and root canal therapy of the endodontically affected left mandibular canine tooth (note slightly increased root canal width) was performed (not shown)
Clinical photograph of case in Figure 65-20, following interdental wiring and intraoral splinting. Note that the bis-acryl composite splint was applied primarily on the lingual surfaces of the mandibular teeth to allow closure of the mouth.
Occlusal alignment and stabilization of caudal mandibular fractures or chronic temporomandibular joint displacement may be achieved with bis-acryl composite bridges between the maxillary and mandibular canines (or other teeth)
Note that the tooth roots occupy a large portion of the mandible. Normal relationships of the maxillary and mandibular dental arcades are illustrated.
Bones of the skull, lateral aspect.
Bones of the skull, dorsal aspect.
Bones of the skull, ventral aspect
Left and right mandibles, dorsal lateral aspect
Bones of the skull, hyoid apparatus, and laryngeal cartilages, lateral aspect
Drawing of the intact mandible demonstrating normal lines of stress (red arrows) through the body of the mandible with muscular contraction and any external force applied to the rostral portion of the jaw (biting, chewing [small arrows]). B, Bending forces are the primary forces acting on the mandible during functional stress; with a fracture at this level, there is distraction along the alveolar surface of the bone; the point at C shows that the ventral portion of the bone is the only area where compressive stresses exist—if there is contact. (D, Digastricus muscle; M, masseter muscle; P, pterygoideus muscle; T, temporalis muscle.)
Cranial (A–B) and lateral (C) views of the canine skull, which is transilluminated to reveal the buttressing. The lines drawn indicate the horizontal (A) and vertical (B) buttresses of the maxillofacial region of the canine skull (compare with Figure 67-4). The three maxillofacial buttresses can be described as a combination of these horizontal and vertical buttresses (C). The nasomaxillary (medial) buttress is seen rostrally, the zygomaticomaxillary (lateral) buttress is seen caudally, and the pterygomaxillary (caudal) buttress is shown with the dashed line
Caudal = lacrimal, palatine and pterygoid bones
Can reconstruct facial frame with 2/3 butresses (rostal/medial and lateral)…if butresses not compromised does not need to be fixed
To facilitate appropriate tightening of the intraosseous wire, angled drill holes (obtuse angles [open arrows]) are placed in the bone such that after wire passage, all wire/bone contact is present with obtuse angulation, thus enabling the wire to slide easily (small arrows) during the early wire tightening process (large arrow, tension applied to the twist). B, If, for example, the drill holes are placed transversely through the bone, obtuse angles are present only at the wire/bone contact areas on the side where tension is applied (open arrows); on the opposite side of the bone, these bone/contact areas result in an acute angle of the wire as it passes through the drill hole (curved arrows). Despite appropriate tension applied to the twist, the wire cannot slide (at curved arrows), and this results in an inadequately tightened wire. C, Even in the case of appropriately angled drill holes, as the wire is tightened (as the twist moves toward the bone surface), wire/bone contact results in an acute angle of the wire (curved arrows), and the wire ceases to slide at this level; however, the obtuse angle at the wire/bone contact on the opposite bone surface (straight arrows) allowed this side to be appropriately tightened, as the wire will continue to slide more easily. D, This wire can be tightened further by levering an instrument (a periosteal elevator is shown) directly under the wire twist; this technique ensures a tight wire opposite the twist (large arrow) as it continues to slide easily with the obtusely angled corners. The twist then can be secured by taking up the remaining slack adjacent to the twist.
An intraosseous wire can adequately secure two opposing bone fragments as a rigid suture (and also compress the fragments together [arrows]). B, With an oblique fracture line or a curved section of bone, or when the cortex is thin, overriding of the bone fragments (arrows) often occurs. C, To prevent such malreduction, a Kirschner wire can be placed across the fracture site (as a “skewer-pin”) to prevent overriding, and a figure of eight wire is placed over the ends of the skewer-pin (compare with Figure 67-13, A–B). D, Alternatively, a Kirschner wire may be used as an external “splint,” where its position on the outer surface of the bone serves as an anchor to multiple wires fastened to each comminuted bone fragment (compare with Figure 67-13, C–D).
Artist’s rendition of the mandible and the relative size of the teeth to the bone. Miniplates can be contoured to match the alveolar bone surface and applied immediately adjacent to the gingival margin (as a tension band plate); the screws are directed so as to be placed in between, thus avoiding, the tooth roots. A second miniplate (or standard plate) is placed along the aboral (ventral) bone margin as a stabilization plate. The figure demonstrates appropriate plate position on the mandible and the ramus (in the latter, the tension band plate is located along the coronoid crest, and the stabilization plate is placed along the condyloid crest toward the condylar process).
What are features of a SYnthese maxillofacial system (mini plate)?
Titanium
low profile (.7-1mm thick) 1x4.8, 1.3 x 5 (mini), 1.5 x 6.5 (intermediate) for 2.0mm (large) system
Low elasticity, high deformability
deformatino occurs in connecting bridge not screw holes
Sizes: 1, 1.3, 1.5, 2, 2.4, 3, 4
2.0mm screw with 1.4 or 1.5mm core
Screw instertion upto a 20 degree angle from the plate
Drill holes usually are made of the same diameter of the screw core to obtain a more secure fit between the screw-bone interface (as opposed to standard plate fixation, where screw holes generally are 0.1 mm larger than the screw core diameter).
Simplified schematic of proposed cytokine-mediated interactions in osteoarthritis. Chondrocytes respond to proinflammatory cytokines such as interleukin (IL)-1 and tumor necrosis factor (TNF)-α produced by activated macrophages and fibroblast-like synovial cells. In addition, chondrocytes produce these cytokines themselves to act in an autocrine/paracrine fashion. Activation of matrix metalloproteinases (MMPs) and aggrecanases leads to degradation of extracellular matrix components such as type II collagen and aggrecan. Neo-epitopes generated by such proteolytic activity are thought to lead to further proinflammatory cytokine production by synovial cells and chondrocytes. TIMPs, Tissue inhibitors of metalloproteinases; NO, nitric oxide.
Typical Total and Differential Cell Counts for Canine Synovial Fluid in Normal Joints and Joints With Osteoarthritis, Rheumatoid Arthritis, Nonerosive Immune-Mediated Polyarthritis (IMPA), and Infective Arthritis
What percent IMPA have fever of unknown origin?
20%
What are the types of immune mediated polyarthritis?
Nonerosive IMPA
- Idiopathic immune-mediated polyarthritis groups I to IV
- Polyarthritis-polymyositis syndrome
- Systemic lupus erythematosus and systemic lupus erythematosus-related disorders
- Drug-induced immune-mediated polyarthritis
- Breed-associated immune-mediated polyarthritis
Erosive IMPA:
- Rheumatoid
- Other: PA in Greyhounds (young dogs), feline chronic progressive PA (periosteal proliferation)
What are the 4 types of idiopathic IMPA?
Type 1: 50% dx of exclusion (stiff, pyrexic, lymphadenopathy, neutrophilic lekocytosis) = chemotherapeutic immunosupression (pred) cure in 56%, 15% die, 31% relapse.
Type 2: 25%: associated with infection remote from joint. May or maynot resovle with infection treatment
Type 3: GI disease (15%)
Type 4: neoplasia
What tumors have been associated with ype IV IMPA?
seminoma
mammary, renal, tonsillar carcinoma
sertoli cell tumor
leiomyoma
What drugs are associated with drug induced IMPA?
Sulfonamides
penicillins
erythromycins
lincomycin
cephalosporin
Onset 7-21 days post starting. PMNS without toxic changes in synovial fluid. Improve 1-3 days afer withdrawl
Large breed dogs and dobies
What symptoms are associated with SLE related IMPA (besides standard IMPA like problems)?
skin, mucocutaneous ulceration
serositis (pleuritis)
immine complex glomerulonepropathy
Anemia (hemolytic), thrombocyopenia, leukopenia
menigitis
polymyositis
KCS, retinopathy, Uveitits
What are breed associated IMPAs?
Chinese Shar Pei (familial amyloidosis- shar pei fever, poor px renal failure)
Japanese Akita - adolescnece, aseptic menigitis
What is rheumatoid factor?
Collective term for antibodies (IgM and IgA) with specificty for Fc receptor of IgG
How do you dx rhematoid arthritis?
Classical rheumatoid arthritis is diagnosed when seven criteria are satisfied, and definite rheumatoid arthritis when five are satisfied. With criteria 1 through 5, the joint signs should be present for at least 6 weeks. In addition, two of criteria 7, 8, and 10 should be satisfied; these three criteria have been considered probably the most specific for canine rheumatoid arthritis
What is the criteria for feline chronic progressive PA?
Erosive PA
Periostal new bone
Negative for RF
Enthesopathies
Disease hocks and carpus
Usually neg. RF and ANA, but positve for syncytial forming cirus (FeSV) and FeLV
What bacteria in cats and dogs are associated with infective arthritis?
Dogs: staph (auerus and intermedius) and beta hemolytic strep
Cats: Pasturella mutocida and bacteroides
Risk factors = previous surgery and exisiting joint disease
Other forms infective arthritis = Borrelia (Lyme), Bacterial L forms, mycoplasma arthritis, Protozoal, fungal, rickettsial, mycobacterial
Growth plate of a 17-week-old dog. EP, Epiphysis; EPC, epiphyseal cartilage; HZ, hypertrophic zone; MP, metaphysis; MZ, mineralization zone; PZ, proliferative zone; RZ, resting zone. Bar represents 100 µm.
Endrocondral Ossification = growth plate
1= superficial/tangential
2= transitiional
3= radiate
tide mark
4= calcified
