CCLR is first diagnosed by palpation (examination and manipulation by hand – see image above). In a dog with a complete rupture, the clinician will be able to feel the instability present – so called “cranial drawer forward” sign. In dogs with a stretched or partially torn CCL there may be no instability present but a firm swelling on the inside of the knee may be evident and pain may be elicited on manipulation of the knee joint.
Radiographs (X-rays) of the joint will usually show early osteoarthritis with an increased volume of fluid (effusion). The actual CCL does not show on X-rays because it is soft tissue. The changes seen on Xrays are therefore not specific and other disease processes need to be considered. However, X-rays will rule out certain conditions such as fractures within the knee, infection and cancer. Aspiration and analysis of joint fluid can rule out other conditions such as infection or inflammatory diseases.
CCLR may be diagnosed by arthroscopy (small camera inserted into joint) before surgical treatment of the ligament rupture. Arthroscopy may also be used to “clean out the joint” and treat meniscal injuries with a smaller incision than would be necessary with traditional surgery. However, sole arthroscopic treatments of CCLR are not in widespread use mainly because they are technically challenging to perform and because of concerns about effectiveness. Currently, therefore, the treatment of CCLR in dogs differs dramatically from that in people.