Page 365 - Canine Lameness

19.8 Osteochondrosis Dissecans 337

injury is due to stifle luxation, as part of multiple ligamentous injury or rupture. The CaCL is rarely
injured on its own (Johnson and Olmstead 1987) but generally results from trauma such as a blow
to the proximal tibia that stresses the integrity of the CaCL. However, since isolated CaCL disrup-
tion is easily mistaken for CCLD, it is important to be aware of this differential diagnosis. Since
CaCL injury frequently does not require surgical intervention, preoperative identification is imper-
ative to establish an appropriate treatment plan.
Isolated CaCL injury can be challenging to differentiate from CCL disruption. The mainstay of
diagnosis involves physical examination and stress radiographs. To evaluate the integrity of the
CaCL, the examiner performs the caudal tibial drawer test. This test is performed in the same fash-
ion as the cranial drawer test; however, a positive test shows a tibia that translates caudally relative
to the femur (rather than cranially as with CCLD). It is important to evaluate the end-feel when
moving the tibia cranially and caudally – the intact CCL will create a hard stop (distinct end-feel)
once the maximum, cranial displacement is reached (i.e. the intact CCL is engaged). When trans-
lating the tibia caudally relative to the distal femur, a subjectively loose/sloppy end-feel (i.e. capsu-
lar end-feel) will be encountered when maximum, caudal tibial displacement is reached (i.e. where
in a normal dog the CaCL would be engaged). Unfortunately, even experienced evaluators are
unable to reliably differentiate caudal, cranial, and combined injuries of the cruciate ligament(s)
based on drawer testing (Might et al. 2013).
Stress radiographs can be used to confirm disruption of the CaCL. To perform these views, the
observer levers the tibia caudally, requiring manipulation of the proximal tibia close to the joint;
therefore, appropriate collimation is necessary. Caudal displacement of the tibia can be identified STIFLE REGION
by evaluating the position of the intercondylar eminence in relation to the femoral condyles.
Cranial displacement of the popliteal sesamoid may also be observed (Figure 19.17). Arthroscopy
or advanced imaging can be used to definitely confirm the diagnosis.

19.8 Osteochondrosis Dissecans

Osteochondrosis/osteochondritis dissecans (OCD) is a rare disease of the canine stifle and overall
the stifle joint is the least common joint to be affected by OCD (i.e. the shoulder, elbow, and tarsus
are more common joints to be affected). It typically strikes large- or giant-breed puppies including
Great Danes, Labrador Retrievers, Golden Retrievers, Newfoundlands, German Shepherds,
Mastiffs, and Wolfhounds (Denny and Gibbs 1980; Fitzpatrick et al. 2012; Kowaleski et al. 2018).
Male, rapidly growing puppies fed nutritionally inappropriate diets (e.g. excessive consumption or
over supplementation of protein or calcium) are at greatest risk; clinical signs appear between 5
and 10 months of age. Stifle OCD can be bilateral or unilateral and is most commonly seen on the
axial (medial) aspect of the lateral femoral condyle but can also be seen on the axial (lateral) aspect
of the medial femoral condyle. Stifle OCD in the juvenile dog is treated similarly to other OCD
lesions with simple removal of the flap or resurfacing techniques (Fitzpatrick et al. 2012). If OCD
is diagnosed in older animals, secondary osteoarthritis is likely to be present. Additionally, con-
comitant CCLD needs to carefully be ruled out (and treated if present). In these cases, accomplish-
ing a diagnosis can be challenging if there is only partial disruption of the CCL.
On physical exam, a mild-to-severe weight-bearing lameness can be observed unilaterally or
bilaterally. In dogs with bilateral disease, there is generally one side more severely affected than the
other. The dogs may stand with the stifles in extension, and in bilateral cases, may be shifting
weight to the thoracic limbs. Patients may show significant pain and disability from this disease
due to loss of a major weight-bearing surface of the stifle. Later in life, symptoms may be due to