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19.4 Cranial Cruciate igament Disease 321

may feel soft or water balloon-like, and over time as the disease progresses, swelling can be detected
laterally and attains a harder thickening representative of joint capsule thickening.
Over time, a knob of thickened tissue can be felt on the proximal medial aspect of the medial
tibial joint line, termed “medial buttress,” which represents a buildup of scar tissue to counteract
excessive internal tibial rotation with CCL deficiency. A challenge to the novice examiner is detec-
tion of CCL disease when present bilaterally, as the joint effusion and medial buttress can be fairly
symmetrical.
Pain or resistance to stifle ROM is a hallmark sign of the painful inflammation accompanying
CCL disease. Early on in the disease, pain on stifle hyperextension may be elicited, even when insta-
bility tests are negative. This is because the CCL counteracts hyperextension of the joint. Stifle
hyperextension needs to be tested without hyperextension of other joints (e.g. hip/tarsus) and
should therefore be performed with the hip and tarsus in a standing angle. The examiner can reach
in between the back legs to place one hand cranially to the stifle while using the other hand to
hyperextend the joint (Figure 19.6). As osteoarthritis and instability progress, the joint capsule
thickening and joint effusion can make full stifle flexion physically impossible and quite
uncomfortable.
In particular, patients with medial meniscal tears may have marked pain on flexion and in some
cases, upon internal rotation of the stifle, in fact dogs with pain specifically of stifle flexion are 4.3
times more likely to have medial meniscal disease (Dillon et al. 2014). Meniscal tears most fre-
quently involve the caudal aspect of the medial meniscus with various types of tears having been
described (Kowaleski et al. 2018). Cranially displaced vertical (“bucket handle”) or flap meniscal STIFLE REGION
tears may make full stifle extension physically impossible. An additional finding on physical exam
that supports the presence of a meniscal tear is a “meniscal click” – the popping or clunking sound
emanating from torn or displaced meniscal tissue as the femur subluxates over the caudal medial
meniscal horn, snapping into a subluxated position (Video 19.2). The sound can also emanate from
a vertical longitudinal or flap meniscal tear as it displaces and reduces through ROM. When pre-
sent, a meniscal click has been reported to be 75–96% specific for actual meniscal damage
(McCready and Ness 2016). When combined with observation of pain on stifle flexion, the diagnos-
tic accuracy (i.e. correctly identifying the presence or absence of a disease) of detecting a meniscal
click is around 75% (Dillon et al. 2014; Neal et al. 2015). In other words, lack of a meniscal click
does not mean that meniscal injury is not present, and surgical examination, ultrasound, CT, or
MRI are necessary to definitively diagnose meniscal pathology. However, when a meniscal click
and pain on stifle flexion are observed, there is high likelihood that meniscal damage is present.
Performing ROM while placing the stifle in a stressed position (i.e. flexing the joint while perform-
ing tibial compression) can make it easier to detect a meniscal click in some patients. This test has
been described as the “modified tibial compression test” and was associated with a sensitivity of up
to 63% and specificity of up to 77% for detection of meniscal tears (Valen et al. 2017).

Video 19.2

Anatomy of meniscal tears.

Once osteoarthritis has developed, an additional noise that may be encountered during stifle
ROM is crepitus. Caused by the rubbing of the joint capsule on periarticular osteophytes, crepitus