Orthopedics Flashcards
Name the four zones of the physis from the epiphysis to the metaphysis
RPH-PO
Reserve zone
Zone of proliferation
Zone of hypertrophy
Zone of provisional ossification
Zone of the physis where most fractures occur
Hypertrophic Zone
Tendons that contribute to the Achilles tendon
Gastrocnemius (major component), superficial digital flexor + common tendon (gracilis, semitendinosis and biceps femoris)
What is the classification system utilized for external skeletal fixators? describe
Type Ia: (Unilateral, uniplanar), composed of a single bar and clamps through which pins are introduced.
Type Ib: (unilateral, biplanar), composed of two bars located on the same side (i.e. frontal plane) with pins penetrating the bone from two different sides (i.e. craniolateral and craniomedial angles)
Type II (bilateral, uniplanar), composed of two bars on opposite sides of the limb. Further subdivided into “maximal” (all full pins) and “minimal” (full and half pins)
Type III (bilateral, biplanar), typically composed of three or more bars with pins protruding into the limb from three or more different planes.
Major factors contributing to fracture nonunions (3)
• Instability: Typically caused by poor technical judgement and/or execution on the part of the surgeon. Examples include the use of external coaptation in distal radial fractures, IM pins without added constraints against rotational and axial forces, ExFix with insufficient stiffness and loose cerclage wire.
• Poor biological environment: fracture location (small muscle envelope), extensiveness of soft tissue damage (high energy trauma) and surgical trauma may affect blood supply and prolong the debridement phase delaying healing.
• Nutrition: Adequate supply of protein, calcium, vitamin C and D are essential for bone healing and must derive from a well-balanced diet. Supplements are rarely indicated except for malnourished patents.
What are the types of a viable fracture nonunions?
• Vascular nonunion: characterized by cartilage and fibrous tissue formation within the fracture line. Radiographically characterized by a lucent line through the fracture observed on sequential radiographs.
• Hypertrophic nonunion: similar to vascular, but characterized by the presence of a prominent non-bridging callus.
Three properties of cancellus bone graft and their basic physiology
• Osteogenic property: synthesis of new bone from donor cells, which include MSC’s, osteoblasts and osteocytes.
• Osteoinductive property: MSC’s from donor site are recruited to produce chondroblasts and osteoblasts which produce new bone through endosteal ossification. The process is mediated by growth factors such as bone morphogenic proteins (BMP) ad platelet-derived growth factor (PDGF).
• Osteoconductive property: implanted scaffold passively allows ingrowth of host capillaries , perivascular tissue and MSC’s.
Describe the three phases of acceptance of a free skin graft
• Imbibition – (first 24-48 hours) thin film of fibrin and plasma separate the graft from recipient site, providing oxygenation and nutrition (although poorly). After 48 hours a fine vascular network begins to form withing the fibrin layer.
• Inosculation – (day 2 to 3 ) capillary buds interface with the deep surface of the dermis and provide more robust oxygenation and nutrition.
• Revascularization – (day 3 to 5 ) new blood vessels either directly invade the graft or anastomose with to open dermal vascular channels, establishing a permanent vascular supply.
Describe the aetiopathogenesis of Renal Secondary Hyperparathyroidism. What and where lesions are typically found?
The condition is known as Renal Secondary Hyperparathyroidism, characterized by elevated parathormone levels (PTH) secondary to Chronic Renal Disease. PTH is naturally degraded and excreted by the kidneys, and its production is limited by calcitriol (negative feedback inhibition). Calcitriol, the active form of vitamin D, is produced by renal tubular cells. The relative deficiency of Calcitriol induced by renal disease leads to persistently high PTH, which increases calcium resorption from bone and leads to osteopenia.
Bones of the skull and mandible are most commonly affected. Severe demineralization leads to softening to the point that the jaw is bendable (“rubber jaw”). Facial deformity, swelling and pain typically develop.
Most common sign of juvenile hip dysplasia
exercise intolerance
Name the five overlapping stages of secondary bone healing
- Inflammation
- Intramembranous ossification
- Soft Callus Formation (chondrogenesis)
- Hard Callus formation (endochondral ossification)
- Bone remodeling
Describe the sequence of events that take place during the Inflammatory phase of secondary bone healing, from the moment of fracture until the beginning of intramembranous ossification (second phase). State the end product of this phase.
- Inflammation: Loss of vascular integrity leads to hemorrhage and reduction of local oxygen tension. Primary hemostasis occurs and platelets release cytokines and growth factors, recruiting macrophages, neutrophils and other inflammatory cells. Fibroblast and platelet growth factors activate progenitor mesenchymal cells within periosteum, muscle and soft tissues. These progenitor cells will differentiate into osteoprogenitor cells, modulate inflammation and provide anabolic factors to encourage bone healing. Secondary hemostasis produces a hematoma composed of fibrin matrix, which provide further degranulating platelets and serves as a scaffold for mesenchymal cell infiltration as well as macrophages, endothelial cells and fibroblasts. The end result of this phase is the production of a provisional cell, growth factor and matrix-rich scaffold along the cortex, medullary cavity and periosteum into adjacent soft tissues. This scaffold is eventually remodeled into granulation tissue to form a reparative granuloma, termed external callus.
Describe the events that take place during the second stage of secondary bone healing (intramembranous ossification). State the end product of this phase.
- Intramembranous ossification: Mimics the process of skeletal development. Progenitor cells from the overlaying periosteum proliferate and differentiate into osteoblasts to start new bone production adjacent to the fracture gap, between the periosteum and cortex (no cartilaginous intermediate). This leads to the formation of an early hard callus, but is insufficient to bridge and stabilize the fracture.
Describe the events that take place during the third stage of secondary bone healing (soft callus formation/chondrogenesis).
- Soft Callus Formation (chondrogenesis): Starts as soon as a robust bed of granulation tissue is formed across the fracture gap (external callus). Granulation tissue transitions to fibrovascular tissue and finally to fibrocartilage containing collagens type I and III over several weeks. The matrix is initially avascular as resembles the proliferative zone of the physis. The persistent tissue hypoxia, presence of growth factors and cell-matrix interaction cause stem cell population to differentiate into chondrocytes. These chondrocytes produce extracellular matrix rich in collagen Type II, aggrecan and other cartilage-specific proteins. The resulting callus is termed “soft callus” and bridges the fracture gap. This callus is fragile, however, and remains insufficient to decrease strain to a level that permits osteoblast survival.
Name the four bone envelopes?
periosteal, endocortical, trabecular and intracortical
Discuss the fifth phase of secondary bone healing, explaining the role of bone multicellular units (BMU) as it pertains to the production of this phase’s final product (name and explain it).
- Bone remodeling: This final phase of bone healing lasts months to years. The abnormally large and misshapen woven bone produced during ostechondral ossification is weaker than primary bone, and therefore gradually replaced by lamellar bone. Resorption occurs withing each of the four bone envelopes (periosteal, endocortical, trabecular and intracortical). Osteoclasts and osteoblasts work together as Bone Multicellular Units (BMU) is a continuous process of activation, resorption, reversal, formation and quiescence. The end result of the formation of Osteon, a structure composed of concentric layers of bone enclosed by a cement line with a central Harversian canal.
Explain the Wolff’s Law and how it relates to mechanotransduction.
Bone remodeling is strongly influenced by Wolff’s Law, which states that bone in a healthy animal will adapt to the loads under which it is placed. This occurs through the process of mechanotransduction. Bone generates a small electrical potential when it deforms, with an electropositive environment on the concave surface (compression) and electronegative environment on the convex side (tension). Electropositivity is associated with an increase in osteoclastic activity, whereas electronegativity induces osteoblastic activity. This justifies the fact the cortical bone under compression (concave surface) typically appears osteopenic on radiographs, while bone under tension (convex side) appears sclerotic.
Define area moment of inertia
A structural property that describes a structure or material’s ability to resist deformation
How is implant compliance calculated (give formula)? Which factor can be changed with the highest degree of influence on the overall compliance of the contract? How does this apply to a juvenile bone fracture?
Compliance = L3 / I x E
L= functional length (distance between the two innermost screws), multiplied to the third power
I= Area Moment of Inertia (a material or structure’s ability to resist deformation)
E= Elastic modulus of the plate material (inherent to the type of material used in the making of the implant)
Changing the distance between screws (functional length) affects compliance the most, and is typically under the surgeon’s control.
In young patients the physes are still developing and continuously elongating. They are composed of an anastomosed network of medullary vasculature and robust periosteal blood supply with periosteum membrane that acts as an external split. The cortices remain thin and exhibit low stiffness and strength, although have high ductility compared to adult bone. Implants typically fail at the screw-bone interface because the implant is to step in comparison to the juvenile bone. This leads to high stress at the screw-bone interface and eventually implant failure. The use of more pliable constructs, term “elastic osteosynthesis”, has been proposed as a means to distribute stress along the entire plate, limiting stress at the screw-bone interface and minimizing the chance of implant failure.
Define “elastic osteosynthesis” and how it applies to juvenile bone fractures
The use of more pliable constructs, term “elastic osteosynthesis”, has been proposed as a means to distribute stress along the entire plate, limiting stress at the screw-bone interface and minimizing the chance of implant failure.
Define interfragmentary strain and how it determines the kinds of tissues that can be supported within a fracture gap
• Interfragmentary strain: The formation of various tissue types during bone healing is directly dependent on the degree of interfragmentary strain. Strain is defined as the effect of loading on a fracture gap. Practically it is calculated by dividing the resulting length of the gap after loading by the original length. Smaller fracture gaps experience greater strain (concentrate strain) than large gaps. Granulation tissue can withstand almost 100% deformation, and is therefore the tissue found it to be formed within fracture gaps undergoing significant strain. As strain is reduced, tissues region collagen can develop and form a soft callus. Specifically, fibrocartilage is capable of accommodating 10 to 15% deformation. Osteoblasts and osteocytes can only survive in a very low strange environment, and bone can only tolerate 2% deformation.
Give three possible approaches to a distal humeral intercondylar fracture (T-Y fracture) And discuss the pros and cons of each
“A variety of surgical approaches can be used to gain access for accurate fracture reduction of the articular surface. A surgical approach by osteotomy of the tuber olecrani72,81 provides good exposure,2,6,21,106 but complications with repair of the olecranon osteotomy can occur in up to 37% of cases.2,6,39,76 Alternatively, tenotomy of the tendon of the triceps brachii muscle can be performed23,100; this may be advantageous in immature animals because it avoids damage to and possible premature closure of the proximal ulnar growth plate. Intracondylar fractures can also be approached via separate lateral and medial approaches.64 Combined medial and lateral approaches enable exposure of the whole distal part of the humeral diaphysis for fractures with supracondylar comminution. The combined approach avoids risk of damage to the proximal ulnar growth plate in immature dogs.”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
Classification scheme for Medial Patella Luxation, expected anatomical abnormalities and clinical signs
Grade 1: the patella can be manually luxated during stifle extension but tends to spontaneously reduce itself. Typically asymptomatic incidental finding.
Grade 2: Spontaneous luxation occurs with clinical signs ranging from non-painful “skipping” lameness to mild discomfort. Mild deformities typically exist, consisting of internal tibial rotation and abduction of the hock.
Grade 3: The patella is permanently luxated by can be manually reduced. More severe bony deformities are usually present, including marked internal tibial rotation, distal femur varus and a shallow troclear groove. The patient usually stands with a “crouched” posture due to internal rotation of the stifle.
Grade 4: The patella is luxated and cannot be manually reduced. Similar anatomical abnormalities as for Grade 3, but more severe. The tibia is internally rotated between 60 and 90 degrees relative to the sagittal plane. Severe mobility impairment present, similar to grade 3 but more severe.
Pelvic fractures: how many sites are typically fractured? In order a frequency, where are the fractures most commonly located?
 “Of 556 cases of pelvic fractures in dogs and cats, 76% of cases had fractures at three or more sites. The pubis was the most frequently fractured bone, followed, in order of frequency, by the ischium, sacroiliac joint, ilium, acetabulum, and pubic symphysis.”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
How are acetabular fracture‘s classified according to location of involvement of the articular surface? Fractures affecting which areas demand anatomical reconstruction?
“Fractures of the acetabulum are classified as cranial, central, or caudal according to the location of involvement of the articular surface. The cranial and central portions of the acetabulum are the weight-bearing areas, and fractures of these areas should be anatomically reduced and rigidly fixed for optimal function. Caudal fractures are less demanding but may result in degenerative joint disease with conservative treatment.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Approximately what percentage of pelvic fractures will have bilateral iliac body fractures, acetabular fractures or acetabular fracture’s coupled with contralateral iliac body fracture?
“approximately one-fourth of pelvic fractures involve bilateral iliac body fractures, bilateral acetabular fractures, or acetabular fractures coupled with a contralateral iliac body fracture. ”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
What are the three zones of contact in the elbow?
- Caudomedial aspect of the radial head
- Distomedial aspect of the articular surface of the trochlear notch, extending into the radial incisure
- Craniolateral surface of the proximal portion of the trochlear notch
What are the main contraindication for PAUL, CUE and Sliding humeral osteotomy?
OA affecting the lateral compartment for the elbow
Describe a Monteggia fracture
When fracture of the proximal part of the ulna is associated with a radial head luxation, it is referred to as a Monteggia fracture.”
Excerpt From
Veterinary Surgery: Small Animal Expert Consult
Spencer A. Johnston VMD, DACVS & Karen M. Tobias DVM, MS, DACVS
https://books.apple.com/us/book/veterinary-surgery-small-animal-expert-consult/id1250368401
This material may be protected by copyright.
Describe how to perform the Barden test
“With the patient in lateral recumbence, place the thumb and index finger of the upper hand on the greater trochanter. Gently grasp the flexed stifle joint with the lower hand with the thumb on the lateral aspect and the remaining fingers extended on the distal aspect of the femur. Press laterally with the fingers of the lower hand to lever the femoral head out of the acetabulum. Alternately, press down on the greater trochanter to reduce the femoral head back into the acetabulum. A normal hip joint should have little to no subluxation. Juvenile hip dysplasia may result in up to two centimeters of lateral subluxation.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
What are the 4 planning steps in the selection of an appropriate fracture repair?
“The process of selecting an appropriate method of fracture repair includes the following steps:
(1) patient assessment,
(2) fracture assessment,
(3) fracture assessment scoring, and
(4) selection of the fracture repair method.
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
What is the difference between Mechanical and Biological Fracture Assessment as it pertains to fracture scoring?
“Mechanical assessment estimates the strength of implant necessary. Biological assessment estimates the length of time implants must be functional (i.e., time to bone union). ”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Fracture Scoring: Define High, Moderate and Low score fractures. Give examples of type of repairs that can be employed for each case
Low Scores (1 to 3): Generally, these are nonreducible fractures in older animals in which healing will be affected by other extenuating circumstances. Implants must bridge these fractures and therefore must have sufficient strength to prevent permanent bending or breakage for more than 6 weeks. Suggested implants (or combinations of implants) with sufficient strength and stiffness to function at the lower end of the fracture assessment scale are lengthening bone plates (see p. 1022), locking bone plates, bone plate–intramedullary (IM) pin combinations (“plate-rod”) (see p. 1022), interlocking nails (see p. 1011), or type III external fixators (see p. 998). These patients are not candidates for casts, IM pin, and cerclage wire fixation. Bone grafting should be considered in patients with low fracture assessment scores.
Moderate Scores (4 to 7): Overlapping biological and mechanical factors affect healing and implant selection when the fracture assessment score moves toward midscale. For example, in an older dog with a transverse fracture, the implant and bone share the load after surgery, and the implant will be subjected to less stress, but healing may be delayed. Alternatively, in an immature dog with a nonreducible fracture, the biological assessment may indicate early callus formation, despite “the implant being subjected to high initial loads as it functions to bridge the fracture. In both situations, less implant strength and endurance are required than in patients with low assessment scores because of either immediate load sharing or early callus formation. Suggested implants include bone plates, type II external skeletal fixators, IM pin–external skeletal fixator combinations, and interlocking nails. Bone grafting may be considered in patients with moderate fracture assessment scores.
High Scores (8 to 10): When the fracture assessment score is high, mechanical assessment indicates minimal implant stress because of load sharing, and biological assessment indicates enhanced healing potential. Immediate load sharing between the bone-implant construct and rapid bone union are expected. Suggested implants include type I external skeletal fixators, IM pin–cerclage wires, and external coaptation. Bone grafting is rarely indicated in patients with high fracture assessment scores.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Define “positive” and “negative” radio-ulnar incongruence
‘Positive” and “negative” refer to the ulna.
“Positive” radio-ulnar incongruence = ulna too long
“Negative” radio-ulnar incongruence = ulna too short
Describe the caudal approach to the ulna as utilized to repair a Monteggia fracture
“For a caudal approach to the proximal ulna, make an incision through skin and subcutaneous tissue over the caudoproximal ulna. (B) Elevate the flexor carpi ulnaris and the deep digital flexor muscles to expose the bone surface. (C) Reflect the origin of the flexor carpi ulnaris muscle to expose the trochlear notch.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Describe the technique for proximal ulnar osteotomy, including recommended angles
“In the proximal third of the ulna, perform an oblique osteotomy; the angle of the osteotomy should be caudoproximal to craniodistal (Fig. 34.45A) and craniolateral to caudomedial (Fig. 34.45B). Reappose the periosteum with 3-0 absorbable suture in a simple continuous pattern. Close the deep fascia in a simple continuous pattern with absorbable suture. Apply a bandage for 3 to 5 days to aid in patient comfort.”
23 deg on lateral plane and 30 deg on caudal plane (in relation to anatomical axis of the ulna)
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Describe the technique for distal segmental ulnar ostectomy
“Make a 3-cm longitudinal incision over the lateral aspect of the distal third of the ulna, ending at the distal ulnar physis. Dissect between the tendon of the lateral digital extensor muscle and the tendon of the ulnaris lateralis muscle to expose the diaphysis of the ulna. Incise and elevate the periosteum, and isolate the ulna with Hohmann retractors. Remove a 5-mm-length section of the ulna with an osteotome, rongeur, or bone saw. Reappose the periosteum with 3-0 absorbable suture in a simple continuous pattern. Close the deep fascia in a simple continuous pattern with absorbable suture. Apply a soft bandage for 3 to 5 days to aid in patient comfort. Various locations for the distal ulnar osteotomy have been used. Elevation of the interosseous ligament off the ulna aids in distal migration of the ulna; however, it may lead to significant hemorrhage.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Describe the postoperative care for a patient immediately afterward and for the first 8 to 12 weeks after ulnar osteotomy
“Immediate postoperative radiographs should be made. The limb may be bandaged after surgery for up to 1 week to provide soft tissue support, and the animal should be confined for 4 to 8 weeks. Repeat radiographs are recommended 6 weeks after surgery. Physical rehabilitation may be beneficial in management of osteoarthritis and in improving the range of motion (see Table 34.7). After surgery, cryotherapy, passive range of motion, and controlled leash walks are the primary methods of physical rehabilitation.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Surgical treatment of elbow MCD is meant to decrease pain and inflammation by decreasing stimulation of exposed subchondral bone. How can this be accomplished (categories of surgical treatment)
“Surgical treatments of MCD are intended to decrease pain and joint inflammation by decreasing stimulation of nerve endings located in the subchondral bone. This may be accomplished by removal of the coronoid (subtotal coronoidectomy), decreasing transarticular loads (sliding humeral osteotomy [SHO], radial osteotomy, ulnar osteotomy), or replacing the bearing surface (total elbow replacement).”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Breed most commonly affected by idiopathic or immune-mediated carpal joint collapse
“Shetland sheepdogs, are overrepresented for idiopathic or immune-mediated collapse of the carpal joints.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Describe the 3 categories of carpal hyperextension injuries
Category I injuries are subluxations or luxations of the antebrachial carpal joint.
Category II injuries include subluxation of the middle carpal and carpometacarpal joints and are associated with disruption of the accessory carpal ligaments, palmar fibrocartilage, and palmar ligaments of the middle carpal and carpometacarpal joints. Dorsal displacement of the free end of the accessory carpal and ulnar carpal bones occurs.
Category III injuries are disruptions of the accessory carpal ligaments, carpometacarpal ligaments, and palmar fibrocartilage. However, in these injuries subluxation of the carpometacarpal joint occurs without disruption and displacement of the accessory carpal and ulnar carpal bones.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
What are the two most common causes for progressive collapse of the carpal joints?
“Differential diagnoses for progressive collapse of the carpal joints include any form of polyarthritis or joint collapse due to chronic steroid administration.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Discuss the anatomy of the carpus. Include names of bones, articulations, anatomical divisions (joints) and important ligaments. Discuss the importance of the accessory carpal bone.
“The carpus consists of seven bones arranged in two rows. The radiocarpal and ulnar carpal bones make up the proximal row, and the first, second, third, and fourth carpal bones make up the distal row. The accessory carpal bone lies caudally and articulates with the ulnar carpal bone. The radiocarpal and ulnar carpal bones articulate with the radius and styloid process of the ulna to form the antebrachial carpal joint. The middle carpal joint, formed by articulation of the proximal and distal rows of carpal bones, has the greatest movement—accounting for 10% to 15% of carpal motion. Very little motion occurs in the carpometacarpal and intercarpal joints. Palmar support is from the flexor retinaculum proximally and palmar fibrocartilage distally. Multiple small ligaments cross the intercarpal articulations between carpal bones to provide additional collateral and palmar support. Two accessory ligaments originate from the free end of the accessory carpal bone and insert onto the palmar surface of the fourth and fifth metacarpal bones. The caudal position of the free end of the accessory carpal bone, in conjunction with the accessory carpal ligaments, acts as a moment arm to balance the vertical force produced when the paw strikes the ground.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
List three possible options for the stabilization of a stifle with a CAUDAL cruciate ligament rupture
“Joints with caudal cruciate ligament injury are treated with resection of the remnants of the ligament and stabilized by one of several extracapsular reconstruction techniques: suture stabilization, redirection of the medial collateral ligament, or popliteal tendon tenodesis. Suture stabilization consists of imbrication of the caudomedial joint capsule and placement of a medial or lateral stabilizing suture. Redirection repair uses existing autogenous tissue, such as the medial collateral ligament.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Describe the function of the stifle collateral ligaments and their status (tension/relaxation) during the different phases of the gait
“The medial and lateral collateral ligaments function in concert to limit varus-valgus motion of the stifle joint. This is most important when the stifle joint is extended and both the medial and lateral collateral ligaments are taut. As the stifle joint flexes, the medial collateral ligament remains tight, but the lateral collateral ligament relaxes to allow internal tibial rotation. This motion permits the foot to turn inward beneath the body during ambulation. As the stifle joint extends, the lateral collateral ligament becomes taut once again to assist in external rotation of the tibia. This motion aligns the foot into proper position for weight bearing.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
In what position should the stifle be held when evaluating the integrity of the medial and lateral collateral ligaments?
“Be sure to hold the stifle joint in extension when assessing the medial and lateral restraints.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Describe how you would repair a midsubstance medial collateral ligament rupture
“If the ligament injury is an intrasubstance tear, perform primary repair by suturing the ligament ends; use a locking-loop suture pattern with small, nonabsorbable suture (see p. 1283). Supplement the primary repair with screws or bone anchors and figure-eight support (Fig. 34.134C). After repair of the collateral ligament, carefully reconstruct the meniscocapsular ligaments and joint capsule using interrupted sutures of small, nonabsorbable suture material (polypropylene or nylon).”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Describe the possible relationship between hit luxation/FHO and patellar luxation
“Careful examination of the hip joint is essential because some patients with patellar luxation also have avascular necrosis of the femoral head (see p. 1255) or hip dysplasia (see p. 1209). Shortening of the limb because of hip luxation (see p. 1220) or FHO (see p. 1213) will cause laxity of the quadriceps mechanism, enabling luxation of the patella in some cases. This usually resolves with treatment of the hip luxation and with time after FHO.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
When is surgical correction of a patellar luxation indicated?
“Surgery is advised in symptomatic immature or young adult patients because intermittent patellar luxation may prematurely wear the articular cartilage of the patella.73–75 Surgery is indicated at any age in patients showing lameness and is strongly advised in those with active growth plates because skeletal deformity may worsen rapidly. The surgical techniques used in actively growing animals should not adversely affect skeletal growth. Owners of dogs with bilateral grade IV patellar luxations should be warned of the likely need for multiple surgeries and probable continued lameness even after successful surgery because of the severity of the underlying long bone abnormalities.74”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
What is the primary causative abnormality of patellar luxation? Why does it matter from a surgical point of view?
“It is important to understand that the primary abnormality is biomechanical, whereby the patella within the straight quadriceps mechanism fails to align with the trochlear groove. Surgeries that involve only deepening of the trochlear groove, capsule and fascial release, and imbrication are more prone to failure, as the patella and trochlear groove have not been permanently realigned.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Where is Stifle OCD most commonly observed?
“With OCD of the stifle, a piece of cartilage and subchondral bone is usually observed that involves the medial surface of the lateral femoral condyle (most frequently affected) or the medial femoral condyle. The condition is often bilateral.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Typical signalment for patients affected by Legg-Perthes disease
“Legg-Perthes disease is diagnosed in young, small-breed dogs (i.e., <10 kg). The peak incidence of onset is 6 to 7 months with a range of 3 to 13 months, and males and females are equally affected. This condition occurs bilaterally in 10% to 20% of affected animals.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Legg-Perthes disease results in collapse of the femoral epiphysis due to interruption of blood flow. Explain the pathophysiology of this process
“The vascular supply to the femoral head in young animals with open proximal femoral physes is derived solely from epiphyseal vessels; metaphyseal vessels do not cross the physis to contribute to femoral head vascularity. Epiphyseal vessels course extraosseously along the surface of the femoral neck, cross the growth plate, and penetrate bone to supply nourishment to the femoral epiphysis. Synovitis or sustained abnormal limb position may increase intraarticular pressure enough to collapse the fragile veins and inhibit blood flow. An autosomal recessive gene has been proposed as a genetic cause for the development of aseptic necrosis of the femoral head. After cell death occurs, the reparative processes begin. The bone substance is weakened mechanically during the revascularization period, and normal physiologic weight-bearing forces may cause collapse and fragmentation of the femoral epiphysis. When this happens, incongruence of the femoral epiphysis and acetabulum results in DJD. Fragmentation (fractures) of the femoral epiphysis and osteoarthrosis cause pain and resulting lameness.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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When should the capital femoral physis close? From which physis does the femur derive most of its growth?
“The capital physis functions to provide femoral neck length until the animal is approximately 8 months of age. The distal physis functions to provide most of the femoral length.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Typical signalment for a patient dog or a cat) with a femoral capital physeal fracture?
“Most affected animals are younger than 10 months. Young male dogs are more likely to sustain trauma resulting in femoral physeal fracture, probably because of their tendency to roam. Young heavy male cats that have been neutered before 6 months of age are also at risk.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Describe the surgical treatment of femoral capital physeal fractures (repair type, implants)
“Surgical treatment of physeal fractures consists of anatomic reduction and stabilization with K-wires or small pins that are smooth so as to not interfere with any residual physeal function. These fractures heal rapidly, and smooth implants are generally sufficient. In animals that are close to maturity, threaded implants may be used to increase the stability of the fixation. Anatomic reduction is critical for optimal outcome with capital physeal fractures. Mechanically, prevention of movement of the reduced capital physeal and distal physeal fractures is assisted by the shape of the fractured physeal surfaces. If separated, the physis of the greater trochanter must also be anatomically reduced and stabilized with a tension band to counteract the distractive forces of the gluteal muscles.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What are the main differences on the approach to treatment of patellar fractures between dogs and cats?
“Conservative management is indicated in cats if minimal displacement of the patellar segments occurs. Conservative management (i.e., rest or passive physical therapy) is not indicated in dogs if a transverse or comminuted fracture has separated the proximal and distal poles of the patella. Fibrous union may occur, but the stability afforded is insufficient to allow normal activity. Small fragments near the proximal or distal pole may be managed conservatively if they do not interfere with motion of the patellofemoral joint.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What is the prognosis and complication rate for feline patellar fractures treated surgically?
“Feline patellar fractures treated with pin and tension band fixation have a high complication rate, with greater than 85% of cases resulting in additional fracture and fragment displacement. Transverse proximal tibial fractures may occur in cats with chronic nonunion of transverse patellar fractures.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What is the prognosis for surgically-treated patellar fractures in dogs
“Return to athletic function in dogs depends on adequate healing and reduction of the articular surface. Radiographic evidence of degenerative joint disease will usually develop. Functional prognosis is good to excellent if postoperative instructions are followed closely and if the integrity of the patellofemoral joint is maintained. ”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What is the prognosis for patellar fractures managed conservatively in cats?
“Most cats with patellar fractures progress to a fibrous or functional nonunion, with many cats exhibiting intermittent lameness. Osteoarthritis and peripatellar ossification are commonly seen in cases given long-term follow-up.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What are two of the most common chronic muscle strains observed in dogs? (Although both are relatively rare)
“Chronic muscle strains (e.g., bicipital tenosynovitis, iliopsoas muscle injury) occasionally occur in dogs.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What are the definitions of muscle “contusion” and “strain”?
A contusion is a bruise of the muscle with varying degrees of hemorrhage and fiber disruption.
A strain is a longitudinal stretching or tearing of muscle fibers or groups of fibers.
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Lameness exacerbated by exercise. Hyperextension of one digit. Where is the lesion?
“Dogs with chronic tendon lacerations have lameness exacerbated by exercise. Those with isolated deep digital flexor tendon lacerations have characteristic hyperextension of one digit.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Describe the appropriate surgical repair of a muscle laceration
“Thoroughly debride the wound edges to fresh, bleeding muscle (Fig. 35.3). Debride carefully to prevent excess removal of tissue, which makes apposition of the severed ends difficult. Place interrupted sutures in the outer muscle sheath around the circumference of the muscle. Support the appositional sutures with heavy stent sutures placed in a cruciate pattern.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What suture material (material properties) would you look for when selecting Sutures for the repair of a muscle laceration versus a tendon laceration?
“Nonabsorbable or absorbable suture material may be used to repair muscle, provided the material maintains its mechanical strength for 3 to 4 weeks. Nonabsorbable suture material is recommended for tendon repair. Swaged-on needles are helpful in limiting tissue trauma during suturing.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What is the recommended postop activity restriction after the repair of a muscle laceration?
“After muscle repair, the limb should be immobilized for 5 days, followed by 4 to 6 weeks of protected activity. ”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What is the recommended activity/load restriction after the surgical repair of a major Tendon?
“After tendon repair, the limb should be immobilized for 3 weeks with the use of rigid external coaptation, protective orthotics, or external fixation with the joint positioned to release stress on the repaired tendon (see p. 981). When the splint is removed, the limb should be semirigidly immobilized for an additional 3 weeks with a heavy padded bandage or a half cast (i.e., one side of a split cast applied cranially or caudally to the limb). ”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Breed affected by bilateral idiopathic Achilles tendon degeneration
“Doberman pinschers may have idiopathic bilateral common calcanean tendon degeneration.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Describe the medical management for complete and for partial common calcaneal tendon ruptures. What is the success rate?
Trick question :)
“Surgical repair of completely ruptured tendons is indicated; medical management is not. External coaptation may be tried with partial rupture, but results are usually unsatisfactory.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Describe the surgical repair of acute and chronic Achilles tendon ruptures
“Make an incision over the site of injury on the caudolateral surface of the limb. If the injury is acute, identify the three tendons composing the Achilles complex, and suture each tendon separately with an interrupted far-near, near-far pattern (see Fig. 35.4) using nonabsorbable, small-diameter (3-0 to 4-0, depending on the size of the animal) monofilament suture. If the injury is chronic and identification of individual tendon units is not possible; continue surgical dissection to expose the circumference of the thickened fibrous band. Then sequentially remove sections of scar tissue from the center of the mass. Remove enough tissue so that tension is present in the Achilles complex when the stifle joint is in a normal standing position and the tarsus is slightly extended. Be careful to avoid removing too much of the proliferative fibrous tissue. If excess fibrous tissue is excised, apposition of the cut ends will be difficult. Suture the cut ends with a three-loop pulley pattern (see Fig. 35.4).”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
What diagnostic and therapeutic option is recommended for all cases of presumed supraspinatus or biceptal tenosynovitis? Why?
“Disease of the biceps and the supraspinatus may occur together, and thickening of the supraspinatus may displace the biceps tendon, resulting in inflammation and pain.2 In the most severe cases, other diseases of the shoulder (e.g., instability, osteoarthritis) may also be identified; thus shoulder arthroscopy should be performed in dogs with suspected supraspinatus tendinopathy. Radiographic mineralization is a common incidental finding and is not associated with clinical lameness; therefore accurate determination of the cause of the lameness is critical.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What is the most common ultrasound finding in patients with supraspinatus tendinopathy?
“The most common ultrasound finding in dogs with supraspinatus tendinopathy is enlargement of the tendon of insertion”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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You are presented with a middle-age large breed dog with a history of recurring exercise induced forelimb lameness. On radiographs observe mineralization of the supraspinatus muscle tendon insertion. You suspect supraspinatus tenosynovitis. List 4 other possible differential diagnosis.
“Mineralization of the supraspinatus tendon must be differentiated from other shoulder diseases, including biceps tendinopathies. Differential diagnoses include biceps tenosynovitis, osteochondritis dissecans, shoulder instability, and shoulder osteoarthritis.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Describe the medical management of supraspinatus or bicipital tenosynovitis. What are the risks of corticosteroid injections? What are their injectable therapies can be considered? Physical Therapy options? Benefits?
“Medical management of supraspinatus mineralization is often attempted first. Glucocorticoid injections combined with rest are often attempted and may provide temporary relief. Injection of glucocorticoids into the tendon may cause tendon degeneration; therefore multiple injections are not recommended. The use of PRP in the treatment of supraspinatus tendinopathy is currently being investigated (see Chapter 31).”
“Physical rehabilitation for mineralization includes cryotherapy and passive range of motion. Therapeutic ultrasound may aid in eliminating mineral deposits in the muscle (see Chapter 11).”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Describe the surgical treatment of supraspinatus/biceps tendinopathy (combined arthroscopic/craniomedial approach)
“Arthroscopy of the shoulder joint is the most efficient means of thoroughly evaluating the joint including the biceps tendon. Surgical treatment involves removal of the mineral from the tendon of insertion of the supraspinatus, resection of diseased tendon, and multiple longitudinal tenotomy. Longitudinal tenotomy may decrease intratendinous pressure, increase vascularization of the critical zone, and induce healing, thus improving or reversing degeneration.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What MRI and MSK U/S do you expect to find in patients with infraspinatus contracture?
“Ultrasonography helps evaluate stabilizers of the scapulohumeral joint. The normal infraspinatus tendon should show a typical arrangement of parallel, echogenic striae against a hypoechoic background on ultrasound. Acute injury may demonstrate fiber pattern disruption with edema and hemorrhage. Chronic muscle contracture varies in appearance depending on the severity and the stage of the disease. Fibrosis of the muscle is visible as increased echogenicity of the tendon. MRI of infraspinatus contracture demonstrates heterogeneous signal intensity within the muscle and at the musculotendinous junction, with minimal extension into the tendon.3”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Describe the craniolateral approach to the shoulder joint, including infraspinatus tenotomy
“Make an incision in the skin and subcutaneous tissue from just proximal to the acromion process to the proximal humerus (Fig. 34.19A). Curve the incision over the joint along the palpable cranial margin of the deltoid muscle’s acromial head. Incise the deep fascia along the cranial margin of the acromial portion of the deltoid muscle, and retract the muscle caudally (Fig. 34.19B). Isolate the infraspinatus tendon, and place a stay suture in its proximal portion. Incise the tendon 5 mm from its insertion on the humerus and retract it caudally (Fig. 34.19C). Incise the joint capsule midway between the glenoid rim and the humeral head (Fig. 34.19D). Internally rotate the humerus until the head subluxates, exposing the caudal surface of the humeral head (Fig. 34.19E). Remove the cartilage flap from the humeral head and curette the edges of the bony defect to ensure removal of all affected cartilage (Fig. 34.19F). Flush all parts of the joint thoroughly to remove any cartilage debris or joint mice. Close the joint capsule with 3-0 absorbable suture in a simple interrupted pattern. Reappose the infraspinatus tendon with an absorbable suture in a Bunnell or locking-loop pattern (see p. 1283). Close the muscular fascia, subcutaneous tissue, and skin separately.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Describe the pathophysiology of quadriceps muscle contracture, including typical causes/associations and late consequences to the stifle joint
“Quadriceps muscle contracture usually occurs after distal femoral fracture in young dogs; however, congenital contracture of the quadriceps muscle has been reported. Inadequate fracture stabilization, excessive tissue trauma during surgery, or prolonged limb immobilization with the stifle in extension may singly or in combination contribute to quadriceps contracture. It is often associated with Salter-Harris type I or II fracture in puppies (see p. 984). Quadriceps contracture may occur after splinting in extension for as little as 5 to 7 days. The disease is likely a result of the combination of muscle trauma, rapid bone callus formation, and limb immobilization. Joint stiffness develops because of fibrous adhesions between the quadriceps and the fracture callus. With time, adhesions form between the joint capsule and the distal femur, limiting limb use and causing the quadriceps muscle to atrophy. In later stages, the disease also causes bone atrophy, atrophy of cartilage in the stifle, intraarticular fibrosis, and eventual ankylosis of the stifle joint. The cause of congenital quadriceps contracture and the reason why contracture occurs most commonly in young dogs are unknown.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What is the recommended immediate post-op care in puppies with femoral fractures to prevent quadriceps contracture?
“Prevention of quadriceps contracture should begin within 24 hours of surgery for distal femoral fracture in puppies (see Chapter 11). Therapy should include passive range of motion several times a day, cryotherapy, and massage for edema reduction. Tissue mobilization techniques help prevent fibrosis. Exercises to encourage weight bearing should begin approximately 3 days postoperatively and may include slow leash walking, treadmill walking, and aquatic therapy (see Table 32.7).”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Describe the surgical treatment of quadriceps muscle contracture
“Treatment of quadriceps contracture is aimed at restoring limb function. Release of fibrous thickening and adhesions between joint capsule and femur and between quadriceps muscle and femur is necessary. If a functional range of motion is not achieved after adhesion release, lengthening of the quadriceps muscle-tendon unit is required. Lengthening may be accomplished by a Z-plasty or by release of the origin of each muscle. Recurrence of contracture with resultant loss of stifle joint motion occurs if preventive rehabilitation measures are not taken after surgery. An effective method of maintaining a functional range of stifle motion is to apply a transarticular fixator postoperatively to maintain passive flexion of the stifle joint, while allowing active or passive extension.4 Alternatively, if sufficient flexion is obtained at surgery, a 90/90 bandage can be used.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Describe the postoperative care of a patient following surgical treatment of quadriceps muscle contracture
“After application of a transarticular fixator for quadriceps muscle contracture, pin-to-skin interfaces must be cleaned daily (see p. 1002). Passive flexion and extension of the stifle joint and tarsus should begin as soon as the patient allows limb manipulation (see Table 32.7). Joint movement should be repeated 20 to 30 times and at least three times daily; increased frequency of manipulation improves rehabilitation. The external fixator should be maintained for 3 to 5 weeks. Physical rehabilitation should be continued for an additional 5 weeks after it is removed. If a 90/90 flexion bandage is applied, it should be maintained for 3 weeks. After bandage removal, passive flexion and extension of the joint should be performed as described previously.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Prognosis for quadriceps muscle contracture, even with surgical treatment
“The prognosis after surgery for quadriceps muscle contracture is guarded and depends on the degree of degenerative joint changes present and on whether a functional range of motion is obtained at surgery.4 The prognosis is fair for functional limb use, but contracture may recur following surgery. A normal range of motion is seldom achieved, and most animals are able to flex the stifle only 45 to 90 degrees.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What physical exam findings do you expect to observe (gait and exam) in a patient with gracillis and semitendinosus fibrotic myopathy
“Dogs with gracilis or semitendinosus myopathy have a shortened stride, rapid elastic medial rotation of the paw, external rotation of the hock, and internal rotation of the stifle during the mid- to late-swing phase of the stride (“circumduction gait”) (Fig. 35.11 and Video 35.5). The lameness is more pronounced at a trot. Affected muscles are palpable as a distinct taut band differentiated by the location of origin. Some dogs are in pain on muscle palpation. Most dogs exhibit a nonpainful lameness. Abduction of the hip and extension of the stifle and hock may be limited.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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What is the prognosis for surgically-treated gracilis/semitendinosus fibrous myopathy
“The prognosis for gracilis or semitendinosus myopathy is guarded, with recurrence of fibrosis and restriction of gait occurring within 4 months in most dogs. Intensive, long-term physical rehabilitation following surgical intervention may improve the prognosis.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Pathoanatomy and relevant clinical features of Superficial Digital Flexor Displacement (SDFD). Breed most commonly affected
“The superficial digital flexor tendon is the most superficial part of the Achilles tendon and inserts distally on the toes. Tearing of the retinaculum that keeps the tendon over the tuber calcanei allows the tendon to displace medially or laterally. Lateral displacement is more common than medial displacement.7 Dysplasia of the tuber calcanei leading to a shallow groove may contribute to tendon displacement.”
“Shelties may be overrepresented for SDFD”
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Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
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Describe the etiopathogenesis of panosteitis
“Panosteitis is an idiopathic entity causing endosteal and periosteal new bone formation. Osseous compartment syndrome due to a protein-rich, high-calorie diet has been proposed as a potential cause. Excessive protein may cause intraosseous edema and secondary increased medullary pressure and ischemia. Although some periosteal new bone is often evident, the predominant change is endosteal bone formation as the marrow is invaded by bone trabeculae. The marrow remains highly cellular with varying degrees of fibrosis, and no evidence of chronic inflammation, acute infection, or malignancy is noted.”
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Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Short and long term prognosis for panosteitis
“The disease is self-limiting, and most animals eventually have normal function of affected limbs without evidence of pain. However, the disease may continue to affect different limbs, causing pain and lameness until the dog reaches maturity. Clinical signs rarely persist after maturity.
Advise owners that panosteitis may recur, but that it usually resolves by the time the dog is 2 years of age.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Typical radiographic findings in a patient with panosteitis, including timeline from onset of clinical signs. Is there a more sensitive diagnostic than radiographs for this condition?
“Radiographic signs of panosteitis are progressive. Radiographs of affected limbs are often normal during early stages, and clinical signs may precede radiographic abnormalities by up to 10 days. If clinical signs are consistent with panosteitis but radiographs are normal, radiographs should be repeated in 7 to 10 days. Nuclear scintigraphy is a more sensitive diagnostic test of panosteitis than radiography. The earliest radiographic signs include widening of the nutrient foramen and blurring and accentuation of trabecular patterns (which are often difficult to identify, except in retrospect); these are followed by the appearance of radiopaque, patchy, or mottled bone within medullary canals (Fig. 36.1). Eventually, remodeling of medullary canals occurs, and cortical thickening may remain as the only residual finding.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Proposed pathophysiology and possible causes of HOD
“The cause of HOD is unknown. Proposed causative factors include vitamin C deficiency, oversupplementation of dietary calcium, and infectious organisms. A link to canine distemper virus has been postulated but is not supported by epidemiologic studies. Experimentally, vaccination protocols have been associated with the development of HOD in Weimaraner puppies; however, no specific vaccine has been identified. The pathogenesis is obscure, but an apparent disturbance of metaphyseal blood supply leads to changes in the physis and adjacent metaphyseal bone, causing delayed ossification of the physeal hypertrophic zone. The acute phase lasts approximately 7 to 10 days. Affected animals show signs ranging from mild lameness to anorexia, pyrexia, lethargy, severe lameness, refusal to rise, and generalized weight loss. Clinical signs may wax and wane.NoteAffected animals may be very ill, requiring intense supportive care.”
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Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Typical signalment of patients with HOD
“This disease affects young, rapidly growing, large-breed dogs, and males are affected more often than females. Clinical signs are usually first noted at 3 to 4 months of age; however, they may occur as early as 2 months. Relapses may occur as late as 8 months of age. The highest incidence is in the fall. Weimaraners may be at increased risk.”
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Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Typical PE findings in patients with HOD
“Findings on physical examination range from mild lameness to severe lameness affecting all four limbs. More severely affected animals are often unable to stand or walk. Long bone metaphyses are swollen, warm, and painful on palpation. Swelling is often present in all four limbs; however, forelimb swelling may be more obvious, especially in distal radial metaphyses. Severely affected dogs may be depressed, anorexic, and pyrexic (body temperature of up to 106°F [41°C]).”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
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Radiographic findings of early and late HOD
“Radiographs of affected long bones reveal an irregular radiolucent zone in the metaphysis, parallel and proximal to the physis. This gives the appearance of a double physeal line. Metaphyseal flaring with increased bone opacity occurs because of periosteal proliferation in later stages of the disease. This reaction subsides with time but may leave a permanently widened metaphysis (Fig. 36.2).”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
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Prognosis for HOD
“Most animals recover fully within 7 to 10 days of the onset of clinical signs; however, multiple relapses may occur. Occasionally, severe debilitation or multiple, severe relapses cause owners to request that affected animals be euthanized. Interference with normal physeal development may cause permanent deformity of long bones.
Warn owners that multiple relapses may occur and that deformity of the long bones may occur.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Pathophysiology, typical age and presentation pf dogs affected by craniomandibular osteopathy
“Proliferation of new, coarse, trabecular bone occurs adjacent to the mandibular rami, occipital bones, and tympanic bullae in affected animals. This new bone formation causes irregular enlargement of mandibles and tympanic bullae. Existing lamellar bone is resorbed by osteoclasis and is replaced with new bone that expands beyond the periosteal borders. Osteoclastic destruction of the original lamellar bone is accompanied by invasion of inflammatory cells (i.e., neutrophils, lymphocytes, and plasma cells). Normal bone marrow is lost as it is replaced with a vascular fibrous stroma. This proliferative stage of disease occurs when the dog is approximately 5 to 7 months old and is accompanied by intermittent fever, discomfort when eating, and pain when the mouth is forced open. Owners should be warned that multiple relapses may occur; however, bone proliferation decreases as dogs reach maturity and physes close.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Calvarian hyperostosis syndrome is similar to craniomandibular hyperostotic syndrome, but observed in what breed?
“Calvarial hyperostosis syndrome has typically been considered to be a disease of bullmastiffs.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Craniomandibular osteopathy typically affects WHWT, Cairn Terriers and Scottish terriers between 3 and 8 months of age. What are the typical PE and radiographic findings ?
“Physical Examination Findings
Affected dogs have bilaterally enlarged mandibles and tympanic bullae. In severe cases, fusion of these structures may occur, preventing the jaws from being fully opened. Pain on opening of the mouth and intermittent fever (body temperature reading of up to 104°F [40°C] for 3–4 days) may be observed.
Diagnostic Imaging
Skull radiographs typically reveal increased irregular bone density of the caudal mandibles; in many dogs the tympanic bullae also appear denser (Fig. 36.4). Whereas approximately one-third of dogs have lesions confined to the mandibles, some animals also have lesions of the base of the skull and/or have a thickened calvarium. As dogs reach maturity, the edges of the new bone become smooth and affected areas shrink.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Prognosis for craniomandibular osteopathy
“The prognosis is guarded until the extent of bone production is known (i.e., at maturity). Excessive bone production, leading to fusion of mandibular and tympanic bullae, can restrict mandibular motion sufficiently to prevent dogs from eating. These animals are often euthanized.”
Excerpt From
Small Animal Surgery E-Book
Theresa Welch Fossum DVM, MS, PhD, Dipl ACVS
https://books.apple.com/us/book/small-animal-surgery-e-book/id1367916984
This material may be protected by copyright.
Define the Viscoelastic property of bone
The viscoelastic property of bone states that the strength of bone depends on the rate upon which it is loaded. For example, bone is stronger when it is loaded rapidly versus slowly (ie, the more rapidly bone is loaded, the more inflexible it becomes). This property is advantageous because most injuries are inflicted by impact with high loading rate forces. Therefore, fewer fractures actually occur because the more rapidly bone is stressed, the stiffer it becomes. However, once any bone reaches a failure point of loading, it will fracture.1
Define the Viscoelastic property of bone
The viscoelastic property of bone states that the strength of bone depends on the rate upon which it is loaded. For example, bone is stronger when it is loaded rapidly versus slowly (ie, the more rapidly bone is loaded, the more inflexible it becomes). This property is advantageous because most injuries are inflicted by impact with high loading rate forces. Therefore, fewer fractures actually occur because the more rapidly bone is stressed, the stiffer it becomes. However, once any bone reaches a failure point of loading, it will fracture.1
Define the anisotropic nature of bone
The anisotropic nature of bone suggests that bone strength is dependent on the direction in which it is loaded. For example, bone is stronger when loaded longitudinally versus transversely, which explains why bone is more likely to fracture with sudden high impact placed transversely upon the bone.
What is the mechanism of action of hyaluronic acid administered intra-articularly?
Hyaluronic acid binds to CD44 receptors on chondrocytes inducing cellular proliferation and extracellular matrix production, stimulates synoviocytes causing an endogenous hyaluronan synthesis, inhibits inflammatory mediators, and exerts an anti-apoptotic effect on chondrocytes. Results of several studies using intra-articular HA in dogs have demonstrated decrease in pain, lameness, and cartilage degradation.
Reported post-op meniscal tear rate following TPLO
0.7 to 13% (Berg MS; Peirone B; VCOT 5/2012)
Legg-Calve-Perthes disease
• Etiology
• Typical signalment
• Inheritable? Pattern of genetic transmission
• Reported in cats?
• A painful hip condition caused by interruption of blood supply to the proximal femoral epiphysis, producing bone necrosis and collapse of the articular cartilage and eventually hip osteoarthritis. The problem is unilateral in about 80% of cases.
• Small-breed dogs
• Mean age of onset of clinical signs is 7 months, with a range of 3-11 months.
• This disease has not been reported in cats.
• Autosomal recessive trait in West Highland white and Manchester terriers, miniature poodles
• Other commonly affected breeds include Yorkshire, Lakeland, and cairn terriers; miniature pinschers; toy poodles; Australian shepherds; Chihuahuas; dachshunds; Lhasa apsos; pugs.
Discuss the cause and pathophysiology of Legg-Calve-Perthes disease
• Cause and pathogenesis are unknown.
• The primary lesion appears to be ischemic injury causing necrosis of the bone of the femoral capital epiphysis.
• Dead bone trabeculae collapse, forming hollow spaces that cause loss of support to overlying articular cartilage. Trabeculae that form in their place are abnormally thin and unable to support normal loads.
• Subsequent weight bearing causes collapse of the femoral head and deformation of the cartilage, leading to development of osteoarthritis.
You are presented with a 10 month-old pug with a history of progressive left hind limb lameness. These are his radiographs. What is your diagnosis?
Legg-Calve-Perthes disease
What is the estimated percentage of Legg-Calve-Perthes disease cases that respond favorably to medical Vs surgical therapy
• Lameness resolves in > 80% of cases after FHNE or THR.
• Lameness resolves in < 25% of cases with medical treatment alone.
What condition can easily be confused with Legg-Calve-Perthes disease on radiographs but has a completely different etiology?
Femoral capital physeal fracture
Define Cartilaginous Exostosis in dogs and cats. Include affected areas/tissues, etiology, therapy and prognosis
Multiple cartilaginous exostoses is a proliferative disease of young dogs and cats characterized by multiple ossified protuberances arising from metaphyseal cortical surfaces of the long bones, vertebrae, and ribs. The exact etiology is unknown, but hereditary (in dogs) and viral (in cats) causes are suspected. Animals may be asymptomatic, and diagnosis is confirmed by palpation and radiography. Surgical excision of the masses is recommended if clinical signs such as lameness or pain develop.
Panosteitis
• Etiology
•Predisposed breed and signalment
• Pathophysiology
• Clinical signs and pattern
• Therapy
• Prognosis
• Predisposing factors
Panosteitis is a spontaneous, self-limiting disease of young, rapidly growing large and giant dogs that primarily affects the diaphyses and metaphyses of long bone. The exact etiology is unknown, although genetics (in German Shepherds), stress, infection, and metabolic or autoimmune causes have been suspected. The pathophysiology of the disease is characterized by intramedullary fat necrosis, excessive osteoid production, and vascular congestion. Endosteal and periosteal bone reactions occur.
Clinical signs are acute and cyclical and involve single or multiple bone(s) in dogs 6–16 months old. Animals are lame, febrile, inappetent, and have palpable long bone pain. Radiography reveals increased multifocal intramedullary densities and irregular endosteal surfaces along long bones. Therapy is aimed at relieving pain and discomfort; oral NSAIDs and opioids can be used during periods of illness. Excessive dietary supplementation in young, growing dogs should be avoided.
Retained Ulnar Cartilage Cores
• Definition
• Etiology
• Clinical signs
• Potential consequences
• Treatment
• Prognosis
Retained ulnar cartilage cores is a developmental disorder of the distal ulnar physis in young, large, and giant dogs characterized by abnormal endochondral ossification. As a result, progressive physeal calcification ceases, and forelimb bone growth is restrained. The exact etiology is unknown, although dietary causes are suspected.
Clinical signs include lameness and angular limb deformities. Radiography reveals a radiolucent cartilage core in the center of the distal ulnar physis. Treatments include cessation of dietary supplements and osteotomy or ostectomies of the bone to reduce limb deformation. Prognosis is based on severity of the condition.
Scottish Fold Osteodystrophy
• Definition
• Clinical presentation
• Treatment
• Prognosis
This heritable condition of Scottish Fold cats is characterized by skeletal deformations of the vertebrae, metacarpal and metatarsal bones, and phalanges secondary to abnormal endochondral ossification. Affected cats are lame, and affected bones are deformed and swollen. Treatment is by removal of exostoses. Prognosis is guarded.
According to Sanchez et al; what canine breed is particularly predisposed to Humeral Condylar fractures?
• How many time is this breed predisposes to HCF as compared to other breeds?
• What fixation method was associated with the lowest complication rate?
French Bulldogs
6.5 times as predisposed
Epicondylar plate fixation
Sanchez Villamil, C, Phillips, ASJ, Pegram, CL, O’Neill, DG, Meeson, RL. Impact of breed on canine humeral condylar fracture configuration, surgical management, and outcome. Veterinary Surgery. 2020; 49: 639– 647. https://doi.org/10.1111/vsu.13432
According to Ober et al; what was the difference in the effect of TPLO versus TTA on the degree of passive cranial tibial translation at 150, 135 and 120deg of flexion? To what phases of the gait do these angles correspond? 
At a stifle angle of 150 , the foot is reported to strike the ground32,33; however, this angle may be closer to midstance in certain dog breeds. At this joint angle, there was no differ- ence in the craniocaudal stability conferred to the stifle by either of the 2 techniques. However, less cranial tibial transla- tion was detected after TPLO than after TTA when the stifle was tested at 135. At this angle, the stifle has completed its flexion phase, which is roughly in the middle of the stance phase.32,33 The same decrease in cranial tibial translation was measured in the TPLO group at a joint angle of 120; how- ever, at this angle of stifle flexion, the hind limb is in a non- weight bearing position.
Ober, CA, Factor, G, Meiner, Y, Segev, G, Shipov, A, Milgram, J. Influence of tibial plateau leveling osteotomy and tibial tuberosity advancement on passive laxity of the cranial cruciate deficient stifle in dogs. Veterinary Surgery. 2019; 48: 401– 407. https://doi.org/10.1111/vsu.13177
Concerning tension, what is the state of each of the bands that compose the cranial cruciate ligaments during flexion and extension?
The ligament is located intra-articularly and is composed of the craniomedial band, which is taut throughout flexion and extension, and the caudolateral band, which is taut only during extension.
- Spencer DD, Daye RM. A prospective, randomized, double‐blinded, placebo‐controlled clinical study on postoperative antibiotherapy in 150 arthroscopy‐assisted tibial plateau leveling osteotomies in dogs. Veterinary Surgery. 2018;47(8). doi:10.1111/vsu.12958
What were the conclusions of this study regarding the impact of post-operative antibiotic therapy on the incidence of SSI?
What phenotype feature was directly and proportionally associated with an increased risk of SSI? What was the numeric association?
- Although the wide CL may be consistent with a type II error, a 7-day course of cefpodoxime after arthroscopy-assisted TPLO did not influence postoperative SSI in the population tested here.
- The only association between the factors tested in this study and SSI involved the body weight (kg), with each 1 unit increase in kilogram weight increasing the odds of developing an SSI by 4.7%.
What is the reported infection rate for TPLO? What is the time range when most infections are diagnosed?
Tibial plateau leveling osteotomy (TPLO) remains among the most common surgical treatments for CCLR in dogs7,8 in spite of a surgical site infection (SSI) rate of 3%-13%.
* The majority of SSI occur within 6 weeks of surgery.
- Spencer DD, Daye RM. A prospective, randomized, double‐blinded, placebo‐controlled clinical study on postoperative antibiotherapy in 150 arthroscopy‐assisted tibial plateau leveling osteotomies in dogs. Veterinary Surgery. 2018;47(8). doi:10.1111/vsu.12958
What is the reported incidence of hip dysplasia among dogs in the USA
20-30%
What is the expected lifetime rate of revision after a healed (uncomplicated) THR?
< 5%
What are the three most common complications associated with the prolonged casting of tibial fractures in juvenile canine patients (less than 6 months)? What is roughly the maximum amount of time these fractures should be casted (if at all)?
Medial Patellar Luxation
Hip dysplasia
Quadriceps muscle contraction
Ideally, do not exceed 10 to 14 days
For puppies under 6 months of age, what is the rule of thumb to estimate the number of weeks a fracture will take to heal?
The age in months roughly equals the number of weeks the fracture will take to heal (i.e. a two-month-old puppy will take two weeks to heal)
What are the two limb positional goals of the Ehmer sling? How can this be more easily achieved?
Hip abduction and internal rotation
Add the abduction Roll (Palmer)
What structures must be preserved during the treatment of a distal humeral fracture in a cat? These structures are located within a foramen – can you name it?
The median nerve, and the brachial artery are located within the supracondylar foramen in a cat. These structures can be inadvertently damaged during attempts to reduce and fix distal humerus fractures. Some authors have recommended that a focal osteotomy be performed through the medial branch of the condyle to allow exteriorization and gentle retraction of these structures outside of the foramen during fracture reduction
Excerpt:
“In cats, to avoid lesions of the median nerve and brachial artery during reduction and fixation maneuvers, an ostectomy of the medial branch of the supracondylar foramen was per- formed with a high-speed burr or a rongeur. The neurovas- cular bundle was then gently freed from the foramen and allowed to rest unconstrained next to the medial epicondyle”
Guiot, LP, Guillou, RP, Déjardin, LM. Minimally invasive percutaneous medial plate-rod osteosynthesis for treatment of humeral shaft fractures in dog and cats: Surgical technique and prospective evaluation. Veterinary Surgery. 2019; 48: O41– O51. https://doi.org/10.1111/vsu.13134
When using a plate and rod construct (PRC), what is the recommended size of the intramedullary rod in relation to the medullary cavity?
40%
Hulse D, Ferry K, Fawcett A. Effect of intramedullary pin size on reducing
bone plate strain. Vet Comp Orthop Traumatol. 2000;13:185-190
Define Plate Span Ratio (PSR) and how it applies to the concept of biological osteosynthesis
PSR is defined as the quotient plate length divided by the fracture length.
A larger PSR, which characterizes the bridging function of the plate, is recommended for biological osteosynthesis because it reduces interference between plate and fracture site, thus potentially promoting bone healing.
Guiot, LP, Guillou, RP, Déjardin, LM. Minimally invasive percutaneous medial plate-rod osteosynthesis for treatment of humeral shaft fractures in dog and cats: Surgical technique and prospective evaluation. Veterinary Surgery. 2019; 48: O41– O51. https://doi.org/10.1111/vsu.13134
Define Plate Screw Density (PSD)
Plate screw density is the quotient formed by the number of screws inserted and number of the plate holes (From Gautier E, Sommer C: Injury 34(Suppl 2), 2003).
What is the reported rate of patellar reluxation with and without realignment of the quadriceps mechanism? 
8% with realignment
48% without realignment
M. Newman et al.: tibial tuberosity, transposition advancement (VCOT 2014)
According to AO, what are the three types and subtypes of open fractures?
Open:
Type 1 – small laceration, clean
Type 2 – larger laceration, more soft tissue damage
Type 3 A – large laceration, high energy, able to be closed
Type 3 B – extensive soft tissue loss, bone exposure, periosteal stripping
Type 3 C – arterial supply to limb severely damaged – amputation in veterinary medicine
According to AO, define:
Transverse fracture
Short oblique fracture
Long oblique fracture
Long spiral fracture
transverse (<30°)
short oblique (30-60°)
long oblique (>60°)
long spiral
Define fracture comminution according to AO (three types)
Comminuted (more than 2 fragments):
• mild (e.g., single butterfly fragment)
• marked (or highly)- multiple butterfly fragments
• segmental (cylindrical bone fragment)
What are the six possible anatomical locations of fractures according to AO?
• epiphyseal
• physeal
• metaphysis
• diaphysis
• apophysis-traction epiphysis
• articular
Describe the Salter-Harris physeal fracture classification system
Salter-Harris Classification
• Type I- through the plane of the physis
• Type II-through the growth plate extending into metaphysis (most common)
• Type III- through the growth plate extending into epiphysis (articular)
• Type IV- through the metaphysis, across the growth plate, through the epiphysis (articular)
• Type V- compression fracture of physis (germinal layer) results in premature closure (symmetric or asymmetric
AO descriptive fracture classification
What are the eight questions which must be answered?
• Extent (complete, greenstick, fissure)
• Soft tissue injury (open vs. closed)
• Type (simple vs. comminuted)
• Where (anatomical location in the bone)
• How (cause of fracture)
• Which bone
• Displacement
• Reducible Vs. non-reducible
Define “Optimal Customary Strain”
Optimal Customary Strain – bone cells sense their mechanical environment and either make or remove bone to maintain an optimal amount of bone (Wolff’s Law). Stress protection (shielding) results from the application of a large, stiff implant on a small bone. There may be also a vascular component to this phenomenon due to the physical obstruction of blood vessels to provide blood supply to the fracture.
What are the four forces acting upon a bone?
• Compression
• Bending
• Rotation
• Tension
- shearing is sometimes included, but is more of a motion than a force.
What is the rough composition of 316 stainless steel? What properties are attributable to each of the different components?
Grade 316 stainless steel is composed of approximately 16% chromium, 10% nickel, and 2% molybdenum. High concentrations of chromium and nickel offer increased chemical resistance over other medical grade steels, while molybdenum helps to bolster corrosion resistance.
Melting point of 316 SS and titanium Vs. lead
316 SS: 2500 F
Titanium: 3000F
Lead: 600F
What are the three factors that influence the bending strength of an implant?
Type of material
Area moment of inertia (AMI)
Working length
What forces can bone plates resist best? What force can be more or less resisted by altering plate position? What can be done to improve resistance to this force?
Plates – resist compression & rotation well. Bending strength – load sharing vs bridging;
If concerns about being strong enough to resist bending forces, add an IM pin (Plate-Rod) – improves bending strength (greater AMI-based construct stiffness)
Two types of primary bone healing
Contact healing
Gap healing
Under what biomechanical conditions can gap bone healing occur?
• Absolute stability (Interfragmentary strain <2%)
• Gap <= 10 um
Name the 7 phases of secondary bone healing
1) Blood clot
2) Inflammation
3) Granulation (soft callus)
4) Fibrous callus
5) Fibrocartilage
6) Woven bone
7) Lamelar bone / osteon
What is the estimated “ideal” strain condition for secondary bone healing?
20-40%
List 5 of the factors that play a role in contributing or controlling interfragmentary strain.
• Weight of the animal
• Physical activity
• Fixation method
• Implant size
• Implant material
• Implant application
• Fracture configuration
Among all factors influencing fracture stability, which has the greatest role in deciding between absolute and relative stability?
Fracture configuration
What is the maximum screw diameter as a percentage of bone diameter recommended by AO?
40%
Define “position screw”, including a potential application
Position screws hold fragments in place to prevent them from collapsing into the medullary canal. There is no interfragmentary compression. In very young patients the epiphyseal or metaphysical bone may be too soft to accommodate a glide hole. In this case compression may be achieved using a reduction forceps, and the fragment stabilized using a position screw.
Give two possible definitions of a long-oblique fracture
• More than twice the diameter of the bone
• >60 deg
What is the effect of cerclage on bone blood supply?
Minimal. Blood supply is centripetal, not longitudinal.
Roughly what tensions can be generated by a twist knot, single-loop and double loop cerclage knots?
• Twist knot: 70-100 N
• Single loop knot: 150-200 N
• Double loop knot: 300-500 N
What is the maximum screw angulation for DCP and LC-DCP plates?
DCP: 7deg transverse and 25 deg longitudinal
LC-DCP: 7 deg transverse and 40 deg longitudinal
What are the three main ways bone plates can be applied?
Neutralization
Compression
Bridging
List two of the main disadvantages associated with bone plates applied in neutralization mode
1) The implants take almost the entire load of weight bearing, and are predisposed to failure.
2) The application tends to require large approaches, potentially compromising local blood supply.
To which surface of long bones are bone plates typically applied?
The tension surface
What is the purpose of “prestressing” a bone plate prior to compression plating?
Prestressing, or “over-contouring” is done with the intention of maintaining trans-cortex contact after compression. If this is not done a “gap” tends to develop in the trans-cortex, changing the application from compression to bridging. The small gap tends to lead to high interfragmentary strain and premature implant failure.
How many loaded screws can be placed per fracture for compression? What must be done if more than one is applied?
Up to 2 loaded screws can be applied per fragment for compression. The first screw must be loosened slightly to allow the bone to shift during the application of the second.
How much compression can be obtained from a 3.5/4.5mm screw in a DCP or LC-DCP plate? How about from a 2.7mm screw?
3.5/4.5mm - 1mm
2.7mm - 0.8 mm
What three principles must you observe when applying a bone plate in bridging mode?
• how much bone should the plate span above and below the bone defect?
• what is the recommended screw to hole ratio?
• how many holes should be left empty over the bone defect?
• the plate should span at least three times the length of the fractured segment above and below the fracture
• the screw-to-hole ratio should be less than 0.5
• at least 2–3 screw holes should be left empty over the bone defect
Bridging implants should be applied in a “less rigid fixation mode“ in order to increase construct compliance. What is the rationale for this approach?
A slightly compliant construct allows micromotion at the fracture site, which stimulates early callus formation, and secondary bone healing
What are your options to increase construct stiffness if you think that a plate applied in bridging mode is too compliant?
Use larger implants.
Use locking implants.
Shorten the working length of the plate
Apply additional implants such as IM rods
When used in combination with a cerclage wire, what size intramedullary pin is recommended as a percentage of the medullary canal?
70%
How is the area moment of inertia of a intramedullary pin calculated?
Diameter (mm) to the fourth power
What are the guidelines for the placement of cerclage wire to long bones?
Cerclage wires should be placed at least 5 mm from the fracture edge and 1 cm apart, or 1/2 of the bone diameter from the fracture edge and at least 1/2 of a bone diameter apart. Two or more wires should be used.
When applying an IM pin to the tibia, what is the preferred direction and insertion point?
Normograde, starting proximomedially between the patellar ligament and the medial collateral ligament.
How do you estimate the length and diameter of an intramedullary pin to be applied to a humeral fracture?
For guidance, a line can be placed from greater tubercle to the distal aspect of the medial epicondyle on radiographs and the diameter of the humerus is measured at 80% of the length of this line. An IM pin with a diameter that is approximately 36-45% of the humeral diameter at this level can be used.
Why can’t IM pins or Interlocking nails be used in the radius?
Lack of apophyseal portal
Percentage of dogs with concomitant patella luxation and CrCLR
13-23%
What are the four reported factors that influence the Patellar reluxation rate following surgery?
- Performing a trochleoplasty (Arthurs & Langley-Hobbs2006, Cashmore et al.2014, Perry et al. 2017)
- Performing a TTT (Arthurs & Langley- Hobbs2006),
- Performing release of the cranial belly of the Sartorius muscle (Cashmore et al.2014)
- Lower grade of luxation (Wangdee et al.2013)
What are the four reported factors that influence the Patellar reluxation rate following surgery?
- Performing a trochleoplasty (Arthurs & Langley-Hobbs2006, Cashmore et al.2014, Perry et al. 2017)
- Performing a TTT (Arthurs & Langley- Hobbs2006),
- Performing release of the cranial belly of the Sartorius muscle (Cashmore et al.2014)
- Lower grade of luxation (Wangdee et al.2013)
What muscle attaches to the linea aspera? What is the importance of this anatomical structure? 
Adductor muscle
Important landmark to the lateral approach to the femur
Name for possible complications of a simple radial/ulnar fracture repair in a three month old large breed dog
Infection
Implant failure
Delayed/nonunion
Angular limb deformity
In regards to quadriceps muscle contracture, what degree of reduction is preferred and why?
Over reduction is recommended to reduce the chance of quadriceps muscle contracture (tiedown).
When would you expect the physis of the tibial tuberosity to close?
8 - 11 months , but up to 22 months in some large breeds
How long should the Tarsus be immobilized following the surgical repair of a gastrocnemius/common tendon rupture? Why?
5 to 9 weeks
Tendon healing progresses slowly for the first four weeks, and is followed by 6 to 8 weeks of rapid healing, tendinous organization, and a bony ingrowth.
Achilles tendon injury classification according to Meutstege (1991) - Describe Type I
Achilles tendon injury classification according to Meutstege (1991)
Type 1 - complete disruption of the entire tendon usually as the result of trauma. The outcome is maximal flexion of the hock when the stifle is extended. The separated tendon ends are palpable through the skin. In some cases a skin laceration may be evident, indicative of external trauma.
Type 2 - variable degree of increased hock flexion with stifle extension and are the result of only partial disruption of the tendon.
Type 2a - incomplete separation between the gastrocnemius muscle and the tendon.
Type 2b - total disruption of the tendon, but the paratenon is still intact.
Type 2c - tendons of the gastrocnemius muscle and the semitendinosus, biceps femoris and gracilis muscles are torn from the attachment to the tuber calcanei, leaving the superficial flexor tendon component in tact. Results in a characteristic hyperflexion of the toes during weight bearing.
Type 3: Represent an earlier stage of type 2c. The distal end of the gastrocnemius tendon is thickened, as is the fibular tarsal bone. These changes may represent small tears in the tendon and enthesitis. Radiographically there maybe evidence of soft tissue swelling, with calcification or bone fragmentation and changes to the size and shape of the tuber calcanei. Type 2c and type 3 injuries are recognised commonly in Dobermans.
Achilles tendon injury classification according to Meutstege (1991) - Describe Type 2a, 2b an 2c
Type 2 - variable degree of increased hock flexion with stifle extension and are the result of only partial disruption of the tendon.
Type 2a - incomplete separation between the gastrocnemius muscle and the tendon.
Type 2b - total disruption of the tendon, but the paratenon is still intact.
Type 2c - tendons of the gastrocnemius muscle and the semitendinosus, biceps femoris and gracilis muscles are torn from the attachment to the tuber calcanei, leaving the superficial flexor tendon component in tact. Results in a characteristic hyperflexion of the toes during weight bearing.
Achilles tendon injury classification according to Meutstege (1991) - Describe Type 3
Type 3: Represent an earlier stage of type 2c. The distal end of the gastrocnemius tendon is thickened, as is the fibular tarsal bone. These changes may represent small tears in the tendon and enthesitis. Radiographically there maybe evidence of soft tissue swelling, with calcification or bone fragmentation and changes to the size and shape of the tuber calcanei. Type 2c and type 3 injuries are recognised commonly in Dobermans.
Young cat presented with retained deciduous teeth and stifle pain. Name the condition.
Feline knees and teeth syndrome
Name five criteria that should be considered to determine if a fractured pelvis can be treated conservatively
1) degree of displacement
2) presence of acetabular fractures
3) continuity of the pelvic ring
4) rectal/urinary bladder integrity
5) presence of open fractures
Name six sites where you can harvest a cancellous bone graft in the dog
1) Humerus
2) Sternum
3) Ribs
4) Greater trochanter
5) Ilium
6) medial aspect of the proximal tibia
Define creeping substitution
The process of bone remodeling by osteoclastic resorption and the creation of new vascular channels within osteoplastic bone formation, resulting in new Haversian systems. This is the method by which strong cortical bone is formed from grafted material.
Name three benefits that a cancellous bone graft can bring to a fracture
1) Osteogenesis: production of new Bohn from direct transfer of viable osteoblasts/osteocytes
2) Osteoconduction: Scaffold for ingrowth of new host bone.
3) Osteoinduction: Stimulation of revascularization and recruitment of osteoclasts and osteoblasts.
What is the osteocyte jumping distance (OJD)
Direct gap healing can occur up to 1 mm. After that the osteocyte can’t “jump“ across the fracture, gap, therefore, secondary bone healing will occur.
Describe the three types of congenital elbow luxation in dogs
Type I: Caudolateral luxation of the radial head
Type II: Lateral rotation and luxation of the ulna
Type III: Humeroulnar and humeroradial luxation
At what age does the medial cartilage plate of the humeral appear, disappear, and completely ossify?
Appears at 14-21 days
Disappeares at 70-80 days
Ossifies at 32 weeks (7.5 months)
What is the likelihood of fracture of the humeral condyle in a case of IOHC treated conservatively?
1 in 5 chance of fracture within 18 months of diagnosis of IOHC without surgical management
Marcellin-Little DJ: Incomplete ossification of the humeral condyle in dogs, in Bonagura JD (ed): Kirk’s Current Veterinary Therapy XIII. Philadelphia, PA, Saunders, 1999, pp 1000–1004
Contrast the Wolff’s Law to the Hueter-Volkmann Law
Wolff ’s law describes adaptations of the bone induced by increased mechanical load leading to increased bone density.
The Hueter-Volkmann law describes growth principles around joints and joint deformation in which there are alterations in longitudinal growth rates in response to tensile and compressive loads. Increasing compressive load slows epiphyseal growth while increasing tensile forces accelerates growth.
