Page 366 - Canine Lameness

338 19 Stifle Region

secondary osteoarthritis. Moderate to marked joint effusion without joint instability is a key fea-
ture of OCD yet does not allow differentiation from partial CCLD. OCD may also occur in combi-
nation with CCLD, particularly if OCD lesions are mild and not detected until later in life.
Standard orthogonal radiographs of the stifle joint are a reasonable first-line of diagnostics.
However, identification of OCD of the stifle joint can be difficult since the femoral condyles nor-
mally display varying degrees of flattening radiographically. Therefore, advanced imaging may be
preferable if the index of suspicion is high based on the patient’s signalment and exam finding.
Radiographic abnormalities range from subtle subchondral bone sclerosis, flattening of the con-
dyles to easily visible cartilage flaps (Figure 19.18). Oblique views of the femoral condyles can help
further visualize potential lesions. CT is more sensitive than radiography at detecting the location,
size, and extent of OCD lesions. It is also more sensitive in detection of small osteochondrosis
lesions or small displaced mineralized free bodies. Ultrasound has also been used to detect OCD

(A) (C) (E) (G)

STIFLE REGION

(B) (D) (F) (H)

Figure 19.18 Examples of surgically confirmed stifle OCD in four patients. Patient I (A, B) adult patient
with lateral femoral OCD lesion (white arrows) that was also diagnosed with partial CCLD at the time of
surgery. Flattening and irregularity of the (black arrow) lateral condyle on the craniocaudal view indicate
OCD; however, the lesion is not detectable on the lateral view and the diagnosis may therefore be missed/
confused with isolated CCLD. Patient II (C, D) OCD-lesion of the lateral femoral condyle in a juvenile patient
that is visible as a (black arrow) flap on the lateral view and lucency in the condyle on the craniocaudal
view. Patient III (E, F) juvenile patient with an OCD lesion of the medial femoral condyle, the fragment (black
arrow) was found to be a displaced OCD fragment at the time of surgery. Note that neither view clearly
establishes the diagnosis of OCD. Patient IV (G, H) adult patient with CCLD and chronic OCD of the lateral
femoral condyle. Note the more severe osteoarthritis and the (black arrow) flap visible on the lateral view.
However, the craniocaudal view does not show clear evidence of OCD.