Clinical signs and results of treatment in cats with patellar luxation: 42 cases (1992-2002).

Objective: To describe clinical signs and results of treatment in cats with patellar luxation.

Design: Retrospective case series.

Animals: 42 cats in which patellar luxation had been diagnosed on the basis of results of palpation of the stifle joints.

Procedures: Degree of luxation was graded on a scale from 1 to 4, and severity of lameness was graded on a scale from 0 to 5. Radiographs of stifle joints were evaluated for signs of osteoarthritis. Long-term function was classified as poor, fair, good, or excellent.

Results: 34 cats had bilateral luxation and 8 had unilateral luxation. Only 7 (17%) cats had a history of trauma. Mean age of the cats was 3.3 years, and mean weight was 4.26 kg (9.4 lb); 26 (62%) were domestic shorthairs. Seventy-three of the 76 (95%) affected joints had medial patellar luxation. Luxation grades could be assigned to 65 joints, with grade 2 (30 joints) and 3 (22 joints) luxation being most common. Lameness grades could be assigned to 73 joints, with grade 1 lameness (27 joints) most common. Outcome was excellent for 8 of 17 joints treated without surgery and for 23 of 35 joints treated surgically. Complications attributable to surgery were reported in 8 cats.

Conclusions And Clinical Relevance: Patellar luxation should be considered as a cause of hind limb lameness in cats. Low-grade luxation can be associated with lameness of the same severity as high-grade luxation. Surgical correction of patellar luxation in cats with grade 2 or 3 lameness can result in a favorable outcome.