Musculoskeletal Midterm Flashcards
What are examples of group 2, semicritical, fractures?
articular fractures, physeal fxs, joint luxation
What time frame should group 2 fractures be treated?
2-5 days
What type of open fracture is when skin is penetrated from the inside out by sharp bone fragment?
type 1
What type of open fracture is when skin wound larger than 1 cm?
type 2
What type of open fracture is when bone is fragmented from high energy trauma?
type 3
What are the different subclassifications of type 3 open fractures?
a - no major reconstruction
b - reconstruction required
c - major arterial injury
What type of open fracture requires amputation?
type 4
What classification scheme is used for physeal fractures?
salter-harris scheme type 1 - just physis type 2 - physis and metaphysis type 3 - physis, epiphysis, articular type 4 - physis, meta, epi and articular type 5 - crushing injury
Term for fracture with three or more fragments whose lines interconnect.
comminuted fx
Term for fracture where 3 fragments do not interconnect
segmental fx
Term for insertion point of a tendon or ligament is fractured and distracted from rest of bone.
avulsion fx
Term for fracture line perpendicular to the long axis of the bone
transverse
Term for fracture line is at angle to the long axis of the bone
oblique
What are the 3 postoperative assessments of fracture repair?
alignment
apparatus
apposition - how pieces fit
activity - bone healing
Whats the difference between indirect bone healing and direct bone healing?
indirect - cartilage precursor
direct - no cartilage
What environment does indirect bone healing occur?
unstable mechanical environment (strain)
Does indirect bone healing increase or decrease fracture gap?
increases
What are the two types of direct bone healing?
contact - simulatneous union and remodeling
gap healing - small gaps fill with fibrous bone, haversian remodeling
How does direct bone healing look like on an xray?
fracture line increases in density, no bridging or callus
When does intramembranous bone healing occur?
strain of less than 5%, bridging of comminuted bone fragments occur, smaller callus
What does creatinine kinase measure?
myonecrosis, peaks at 6-12 hours
What does aspartate aminotransferase (AST) measure?
cell damage, not specific - skeletal, cardiac muscle, liver, RBC
Where is the place to take muscle biopsies for horses for most diseases?
semimembranosis (type 2 fibers)
What muscle should a biopsy be taken for equine motor neuron disease? (TQ)
sacrocaudalis medialis dorsalis (type 1 fibers)
What is the most common myopathy in horses?
exertional myopathies
What causes HYPP on cellular level?
failure in Na channel in muscle
What is the tx for mild HYPP?
mild exercise, feeding grain or corn syrup (insulin)
What is the Tx for severe HYPP?
calcium gluconate, IV dextrose, sodium bicarbonate
What breeds get recurrent exertional rhabdomyolysis?
thoroughbreds, standardbreds, arabians
What is the pathogenesis of RER?
defect in intracellular calcium regulation ->necrotic muscle
What are CS of RER?
tying up, pigmenturia, increased CK
How is RER treated?
prevent renal damage, correct acid-base, alleviate anxiety and muscle pain
What breeds get PSSM?
quarter horses and like-breeds
What is the pathology of PSSM?
increased muscle glycogen, enhanced insulin sensitivity
How is PSSM diagnosed?
serum CK persistently increased, submaximal exercise challenge test
How should PSSM be managed?
increase fat in diet, regular exercise
What 3 molecules are responsible for matrix breakdown in osteoarthritis?
aggrecanases, cathepsins, free O radicals
What cells produce the mediators that progress osteoarthritis?
chondrocytes, synovial cells, subchondral osteoblasts
What are the 3 differential diagnosis for aggressive bone disease?
osteosarcoma, osteomyelitis, blasto
Where are common areas of OCD in front limb?
shoulder - caudal humeral head
hock - medial trochlear ridge of talus
elbow - medial humeral condyle
What is OCD?
defect in cartilage
What are common areas of OCD in hind limb?
stifle - lateral femoral condyle
What causes metaphyseal osteopathy/hypertrophic osteodystrophy?
failure of endochondral ossification (young large breed dogs)
What is seen with metaphyseal osteopathy on radiographs?
double physis, periosteal proliferation, widened metaphyseal region
What will be seen on radiographs with panosteitis?
increased medullary opacity near nutrient foramen
What is osteochondromatosis?
benign proliferation of bone and cartilage
What age and species is osteochondromatosis seen?
older cats
What age and types of dogs do you see femoral head and neck necrosis?
small breed dogs
What are the radiographic signs of DJD?
narrowing joint space, subchondral bone lysis, osteophytes
What is the signalment for patients with masticatory muscle myosiits?
young to middle aged, german shepherds, retrievers, doberman
What antibodies are involved in masticatory muscle myositis?
type 2M fiber antibodies
What is the tx for masticatory muscle myositis?
immunosuppressive, azathioprine
What is the signalment for patients with extraoculuar myositis?
young large breed dogs
What is polymyositis?
diffuse inflammation of skeletal muscle, immune mediated
What is breed predilection for polymyositis?
large breed adult dogs - GSD
What is the treatment for extraocular myositis?
corticosteroids, will resolve
What are the CS of feline idiopathic polymyositis?
acute onset weakness, cervical ventroflexion
What is a primary cause of feline hypokalemic myopathy?
renal disease
also inherited in burmese cats
What is the pathogenesis of feline hypokalemic myopathy?
GI loss
translocation from EC to IC (alkalemia, insulin)
urinary loss (renal dz, diuretics)
insufficient intake (anorexia)
How is muscular dystrophy inherited?
x-linked recessive trait, variable expression
What breeds of dogs and cats get muscular dystrophy?
dogs - golden retriever, GSP, rottie
cats - DSH, siamese, maine coone
What are CS of muscular dystrophy?
weakness, muscle loss in first few weeks of age
What breed gets centronuclear myopathy?
labs
How is centronuclear myopathy inherited?
autosomal recessive (males and females affected)
What 2 inherited myopathies do labs get?
centronuclear myopathy, lab episodic/exercise induced collapse
What are CS of exercised induced collapse in labs?
youung adult, paresis, ataxia, recover within 30 mins
What dog breed gets fibrotic myopathy?
GSDs
What are CS of myotonia?
onset 2-6 months, muscle stiffness, neuro normal
What breed mostly gets myotonia?
mini schnauzer
What is the hallmark of osteoarthritis?
degeneration of cartilage
What are the drugs in the “disease modifying” group of anti arthritic drugs?
hyaluronic acid
PSGAGs - chondroiton sulfate/glucosamine
IRAPs - stem cells
What topical NSAID targets cox 2 for osteoarthritis?
diclofinec sodium
What is the MOA of corticosteroids?
inhibit phospholipase A
What is the MOA of NSAIDs?
inhibit Cox 1 and 2 (want to inhibit cox 2 mostly)
What is the best way to deliver corticosteroids in osteoarthritis?
intra-articularly
How do corticosteroids produce chondroprotective effects?
inhibit MMPs
What is the half life and target of hyaloronic acid?
12-24 hours
synovial lining
What are the MOAs of PSGAGs with osteoarthritis?
inhibit degradation enzymes
inhibit PGE2 synthesis
stimulate matrix synthesis
What are the side effects of PSGAGs?
potentiation of infectious arthritis
hemarthrosis
How is IRAP made? (interleukin receptor antagonist)
WBCs of patient and chromium sulfate beads makes them produce antiinflammatory cytokines
What drug binds to bone surfaces and poisons osteoclasts as they resorb bone?
bisphosphanates
What is the MOA of platelet rich plasma therapy in osteoarthritis?
lysing platelets releases anabolic growth factors, no clinical studies
What are stem cells indicated for in osteoarthritis?
intraarticular soft tissue injuries but not cartilage damage
What are CS of rickettsial disease involvment with arthritis?
polyarthritis, lymphadenopathy, thrombocytopenia
What type of infectious arthritis spreads to other joints locally?
lyme arthritis
What type of arthritis results from systemic inflammation?
reactive polyarthritis (immune complexes)
What is the most common form of polyarthritis in dogs?
idiopathic polyarthritis (immune mediated)
WHat joints are more severely affected in idiopathic polyarthritis?
distal joints (hock, carpus)
What are CS of shar pei fever?
episodes of fever, swelling around hock, young dogs
What may be seen with joint tap in hock fever in sharpeis?
amyloidosis
What disease results in subcutaneous abscesses and causes polyarthritis in cats?
L form-associated arthritis
What are the “erosive” forms of joint disease in SA?
L-form arthritis, greyhound arthritis, rheumatoid arthritis, feline chronic progressive polyarthritis
What happens in the joints with rheumatoid arthritis?
is like idiopathic polyarthritis but joints destroyed over a few weeks
What type of reduction is indicated in articular fractures?
open reduction
What type of reduction is indicated in comminuted nonreducible diaphyseal fractures of long bones?
open reduction or closed reduction (external fixator)
What type of reduction is indicated in greenstick or nondisplaced fractures of long bones below elbow and stifle?
closed reduction
Term for ability of the material to induce migration and differentiation of mesenchymal stem cells into osteoblasts via presence of transforming growth factor beta superfamily.
osteoinduction
Term for the ability of cells to survive transplantation and serve as source of osteoblasts
osteogenesis
Term for ability of the material to provide a scaffold for host bone invasion
osteoconduction
Term for the surface bonding between graft and host bone
osteointegration
Where can cancellous bone autografts be harvested on a patient?
proximal humerus, proximal tibia, ilial wing (metaphysis)
Where can cortical bone autografts be harvested on a patient?
ribs, ilial wing, distal ulna and fibula
What type of lameness may be indicated if a horse is “on a right line”?
suspect right forelimb lamness
What type of lameness is indicated if the horse is “on the right shaft”?
left hindlimb lamness
What are the factors that increase stiffness in an ESF?
increasing pin diameter (up to 25% of bone diameter pin number (2-4) pin location closer to fracture clamp 1 cm from skin connecting bar size and number
What are the 4 different types of ESFs?
Type 1a - unilateral, uniplanar
Type 1b - unilateral, biplanar
Type 2 - bilateral, uniplanar
Type 3 - bilateral, biplanar
Is loop cerclage wire or twisted cerclage better for tension?
loop
How does cerclage wire affect blood supply to long bone?
no effect if placed correctly, if loose, will disrupt periosteal blood supply
WHat is the advantage to IM pins?
very resistant to bending forces
What is the disadvantage to IM pins?
do not counteract rotational forces (smooth pin)
What is the most commonly used IM pin?
steinmann pins, trocar point
How should IM pins be placed in the tibia?
always normograde
What bone should IM pins not be placed?
radius
What fractures are good for interlocking nail IM pins?
comminuted diaphyseal fractures
What is the maximum size of an ESF pin?
no larger than 25% of bone
What is the maximum size of a bone screw?
no larger than 40% of bone
What are the differences between cortical and cancellous screws?
cortical - more threads per inch
cancellous - larger outer diameter
What is the advantage of using locking head screws?
head of screw has threads, locks into plate to provide stability
How are positional screws placed different than compression screws?
compression screw must be perpendicular to fracture line
cis cortex must have gliding hole
trans cortex must have threaded hole
What are the three types of bone plates?
compression
neutralization
bridging
What type of bone plate is best for fracture lines that are transverse or short oblique no greater than 45 degrees?
compression plate
What type of bone plate is best for reducible comminuted fractures and oblique fractures greater than 45 degrees?
neutralization plate
What type of bone plate is best for fragmented diaphyseal fractures where reduction is not possible?
bridging plate
What are characteristics of a dynamic compression plate?
oblong holes
Where must screws be placed on a DCP to get compression? neutralization?
neutralization - centrally
eccentrically - compression (loaded)
What are characteristics of bridging plate?
no holes in the middle, stronger
What is a LC-DCP plate?
bottom surface of plate is scalloped to decrease periosteal blood supply disruption
can compress in either direction
Term for horse foot is thrown outward in flight but lands inside the normal track.
paddling
Term for horse foot swings inward in flight but often lands outside normal track. Can result in interference.
winging
Term for horse feet are placed directly in front of one another, associated with base narrow/toe out conformation.
plaiting
Term for horse food striking a limb with the opposite limb.
interfering
Term for horse hitting the sole of the forefoot with toe of ipsilateral hindfoot
forging
Term for hitting the heels of the forefoot with ipsilateral hindfoot
overreaching
How long should forelimb flexion tests last? Which one is the most specific?
distal limb - 30 s
carpus - 60 s, most specific
shoulder - 60 s
Elbow - 60 s
What does a wedge test do?
exacerbates problems in the foot
What is blocked by palmar/planter digital nerve block? (medial and lateral PD nerves)
blocks heel, caudal 1/3 of foot
What does a PD block with a ring block desensitize?
whole foot
What does an abaxial sesamoid block desensitize?
foot and pastern
What is desensitized by the low palmar/planter block?
fetlock
What are the 3 main proposed hypothesis of pathogenesis of laminitis?
- blood flow alterations –> cell death
- BM breakdown by endogenous enzymes stimulated by toxin
- systemic inflammatory response leading to inflammation in lamellae
What phase of laminitis is the period between first signs of lamness to rotation or sinking?
acute
What phase of laminitis is mild lamness without mechanical failure?
subacute
What are the different types of the chronic stage of laminitis?
early chronic - first several months
chronic active - recurrence after improvement
chronic stable - stable coffin bone with improvement in hoof
What drug can be used as a free radical scavenger in laminitis cases?
dimethyl sulfoxide
What is the duration of analgesics for lameness diagnostics?
lidocaine - 1.5-3 hrs
mepivicaine - 2-3 hrs (most used, less irritating)
bupivicaine - 3-6 hrs
What are the landmarks for palmar or plantar digital nerve block?
distal pastern just proximal to collateral cartilages
What nerves are blocked by abaxial sesamoid nerve block?
medial and lateral palmar/planter nerves
What is blocked by the abaxial sesamoid nerve block?
entire digit and pastern +/- partial fetlock
What nerves are blocked by low palmar/plantar block in a horse?
medial and lateral palmer nerves, and medial and lateral palmar metacarpal nerves
What structures are blocked by low palmar block?
fetlock, pastern, digit
What nerves are blocked by high palmar block?
same nerves as low palmar block –> medial and lateral plamer nerves, and medial and lateral palmar metacarpal nerves
What nerves does the high palmar block?
entire metacarpus
What does the median, ulnar, and musculocutaneous nerve block in a horse?
mid to distal antebrachium and carpus
What structures does the peroneal and tibial nerve block in a horse?
distal crus, tarsus, and metatarsus
What nerve block blocks the fetlock joint?
metacarpophalangeal/metatarsophalangeal joint block
What 2 joints are blocked by the tibiotarsal joint block?
tibiotarsal and proximal intertarsal joints
What radiographic technique is better for determining laxity in hip dysplasia patients?
PennHIP
At what age is pubic symphysiodesis for hip dysplasia done?
12-20 weeks
What surgical procedure can be performed for hip dysplasia if patients are too old for pubic symphysiodesis?
triple pelvic osteotomy
What types of puncture wounds of the sole of the horse are most severe?
around the frog - emergency if involves synovial structure
Term for deviation of limb medially.
varus
What is the most common angular limb deformity in foals?
carpus valgus
What breeds are susceptible to periarticular laxity angular deformities?
“windswept” standardbreds and drafts
Which angular limb deformities is restricted exercise indicated?
DOCBs - delayed ossification of cuboidal bones
What surgical technique is used for growth acceleration in angular limb deformities?
periosteal elevation - releave tension on concave aspect
What surgical technique is used for growth retardation in angular limb deformities?
transphyseal bridging
What is the time frame for periosteal elevation/stripping correction in the fetlock?
less than 4 weeks
What is the time frame for periosteal stripping/elevation correction in the carpus?
less than 6 months
What type of cranial cruciate ligament rupture results from acute trauma?
failure of tibial attachment site
What is the most commonly performed surgery for cranial cruciate rupture?
lateral fabellar-tibial suture (extracapsular)
What is the difference between osteotomies and extracapsular techniques in repairing a cranial cruciate rupture?
osteotomies change biomechanics of joint (affects cranial tibial thrust)
What is an alternative to TPLO for immature patients to avoid cutting into physis?
tibial wedge ostectomy
When do acquired flexural limb deformities most commonly appear in horses?
4 weeks to 4 months of age or as yearlings
What nutritional factors are involved in acquired flexural deformities in horses?
excessive intake, abrupt change, mineral imbalance
What drug can be given IV to younger foals as part of conservative treatment of flexural limb deformities?
oxytetracycline - dramatic response but doesnt last
What is the surgical treatment for an angular limb deformity in the DIP(coffin) joint?
inferior check ligament desmotomy, DDFT tenotomy
Where are DDFT tenotomy usually performed?
level of pastern or at mid-metacarpus (more proximal is easier but can get blemish)
What is the sx tx for flexural limb deformities at the MCP joint?
superior check ligament desmotomy +/- ICL desmotomy
What is the sx tx for flexural limb deformities at the carpal joint?
ulnaris lateralis, flexor carpi ulnaris tenotomy
What should be avoided in flexor tendon laxity in foals?
no splinting or bandaging!!!!!
What are CS of ruptured common digital extensor tendon in foals?
swelling in tendon sheath at dorsolateral carpus, buckled knees
