Ch 15 Stifle Flashcards
What is this measuring?
tibial plateau angle
Stifle (neutral position) and hock (flexed) parallel to the table;
1st line: intercondylar eminence/tubercles to centre of talus
2nd line: 90’ to this line
3rd line (to create the angle): cranial to caudal tibial plateau
Non-ossification of the (medial/lateral) fabella can be an occasional finding in the (cat/dog).
medial, cat
Where does the long digital extensor tendon originate?
Extensor fossa, lateral femoral condyle
The extensor fossa is located?
Lateral femoral condyle
The extensor fossa is the origin of the __________________
long digital extensor tendon
The patella is within which tendon?
quadriceps femoris; insertion is in the trochlear groove.
Which sesamoid is more proximal - popliteal or fabellae?
fabellae - they are within the gastrocnemius muscle
What are the 4 sesamoids of the stifle and where are they located, from proximal to distal (approximately), and what is their medial/lateral location?
patella, central
fabellae, lateral and medial
popliteal, lateral
Patellar fractures in cats has which typical signalment?
Young cats, no other breed/sex predisposition
What is the etiology of spontaneous patellar fractures in cats?
unknown, potentially osteogenesis imperfecta, considering concurrent pathologies (deciduous teeth, other fractures) are common
https://www.vettimes.co.uk/article/patellar-fractures-in-cats/
PADS / spontaneous patellar fractures in cats, can be bilateral - what is the average time between fracture of first and second patella?
about 6 months
https://www.vettimes.co.uk/article/patellar-fractures-in-cats/
Which other fractures can occurs with the syndrome of patellar fractures (PADS)?
https://www.vettimes.co.uk/article/patellar-fractures-in-cats/
” Furthermore, a significant proportion of cases go on to develop spontaneous fractures of other bones, the most common being proximal tibia, lateral humeral condyle, and ischium/acetabulum”
PADS / spontaneous transverse patellar fracture in a cat
Spontaneous patellar fractures in cats are usually where and which orientation?
Largely transverse and in the proximal-mid portion
https://www.vettimes.co.uk/article/patellar-fractures-in-cats/#f002
spontaneous tibial (2a) and acetabular (2b) fractures of cats with a history of patellar fractures.
https://www.vettimes.co.uk/article/patellar-fractures-in-cats/#f002
Chronic patellar fracture. Chronic fractures may occasionally be found as an incidental finding.
https://www.vettimes.co.uk/article/patellar-fractures-in-cats/#f002
Why do you need to differentiate bi/multi-partite fabellae from fabellar fractures?
Because fractures (of the lateral fabellae) may be associated with avulsion of the (lateral head of the) gastrocnemius
Which fabellae is more commonly bi/multipartite?
medial
Which breeds are predisposed to bi-partite/fragmented fabellae?
Poodles
Fox terriers
Which fabellae is smaller in cats - medial or lateral?
medial
tibial tuberosity avulsion is usually seen in ___________ (signalment)
young dogs, <8-10mo
Greyhounds and terriers appear to be predisposed (Gower et al, 2008)
5m crossbreed dog
tibial tuberosity avulsion fracture (arrowed) with associated mineralized fragments (arrowhead)
Image: the dog’s other leg showing Salter–Harris type II fracture of the proximal tibial physis (arrowed) and a fractured fibula (arrowhead)
5m crossbreed dog
Salter–Harris type II fracture of the proximal tibial physis (arrowed) and a fractured fibula (arrowhead)
Image: the dog’s other leg showing tibial tuberosity avulsion fracture (arrowed) with associated mineralized fragments (arrowhead)
10-month-old Domestic
Shorthair cat with a distal femoral physeal fracture (Salter–Harris type II)
3-year-old male cross-bred dog
avulsion of the long digital extensor tendon, showing an enlarged extensor fossa radiolucent defect (arrowed) and an associated mineralized fragment (arrowhead). This dog had a concurrent CCLR.
3-year-old male cross-bred dog; What type of injury is this?
avulsion of the long digital extensor tendon, showing an enlarged extensor fossa radiolucent defect (arrowed) and an associated mineralized fragment (arrowhead). This dog had a concurrent CCLR.
Where does the LDE originate?
Extensor fossa, lateral femoral condyle
It then runs down the muscular /extensor groove on the craniolateral tibia, and inserts on the distal phalanx of digits two through five.
What are the 2 components of the gastrocnemius muscle?
Medial and lateral heads, which contain the fabellae/sesamoids in the tendon of origin.
Which clinical signs and physical changes (e.g. stance, swelling) are possible with gastrocnemius avulsion?
Lameness, caudal stifle swelling, occasionally a plantigrade stance
Which radiographic signs are possible with gastrocnemius avulsion?
(think displacement or fracture)
- fabella may be distally displaced
- fabella may be fractured
- soft tissue swelling of the caudal fascial planes
5-year-old German Pointer
gastrocnemius tendon avulsion, showing marked caudodistal displacement of one fabella (black arrow) with the other fabella in its normal position (white arrow)
Acquired patellar luxation can be associated with _______________ in the cat.
hip luxation
6-year-old Domestic Shorthair cat
severe ligamentous disruption - collateral and cruciate ligament injuries
CCL disease
Top: acute
Bottom: chronic
Where are these enthesophytes, specifically?
the trochlear ridhes, at the insertion of the joint capsule
2-year-old Labrador Retriever
avulsion of the CCL, showing a mild joint effusion and a mineralized intra-articular fragment
what is more common - avulsion of the origin or the insertion, of the CCL?
insertion
What percentage of dogs (Sumner et al, 2010) with a CCLR have a full-thickness caudal cruciate ligament tear associated with marked synovitis?
25%
Collateral ligament rupture usually happens in conjunction with another ligamentous injury - true or false?
True, it is rare for it to happen on its own, it usually happens in conjunction with cruciate ligament rupture.
3y crossbreed dog
lateral collateral ligament tear, showing marked opening of the lateral joint space (arrowed).
How do you diagnose patellar ligament rupture in radiographs? what other modality can be used readily?
The patella maintains the same (too proximal) position in flexed and extended lateral stifle projections.
US can also diagnose this, and assess stages of healing.
What percentage of cases have concurrent meniscal tears at the time of CCLR?
25-50%
What percentage of CCLR cases have late meniscal injury/tears?
15%
Which meniscus is commonly injured?
Medial
Lateral meniscal tears are uncommon.
5y crossbreed dog
patellar ligament rupture
Image: US showing disruption of the fibers (hypoechoic area) and thickening at rupture site
Post-op radiograph, patella is more distal now.
US has poor sensitivity for meniscal tear diagnosis - true or false?
False; experienced operators with Hi-Hz (7.5-15 Hz) probes report 90% sensitivity
Quadriceps contracture is a temporary condition - T or F?
False - it is a serious complication of inadequately managed femoral fractures, resulting in permanent stifle and hock extension and subsequent femoral and tibial osteopenia.
What percentage of patellar luxations are medial?
80-90%; most of them anyway - usually toy/small breeds, but also med/large e.g. Labs
Which other changes can be present with congenital MPL?
- lateral deviation/bowing of the distal femur
- medial deviation/bowing of the tibia (image)
- coxa vara
What is juvenile gonitis?
Presents as idiopathic stifle effusion in med/large breeds e.g. Boxer, Rottie, and can be associated with CCLR (uni/bilateral).
Meniscal calcification is more common in which species?
Not dogs - usually CATS, rodents, rabbits.
Can be idiopathic, or 2nd to trauma (CCLR) or OA.
Genu valgum results in the distal limb deviating _______________ly.
lateral
Genu valgum can result in __________ patellar luxation.
lateral
The stifle (distal femur) is an uncommon location for OCD in dogs - T or F?
True, it is uncommon, but can affect both the lateral and medial femoral condyles and has been reported in the cat.
What is the most common location on the distal femur for OCD?
medial aspect of the lateral condyle
Septic arthritis can occur secondary to OA - true or false?
True
What is the most common fungal osteomyelitis in Europe?
Aspergillus
Which neoplasia has a predilection for the stifle?
Synovial / histiocytic sarcoma
Osteosarcoma
The stifle is a predilection site for changes secondary to hypervitaminosis A - T or F?
True; periarticular new bone
3y DSH
synovial osteochondromatosis, showing multiple intra- and periarticular smooth mineralized opacities (arrowheads) located in the synovium
