Patellofemoral Pain Syndrome in Incomplete or Low-Grade Medial Patellar Luxation in French Bulldogs

Introduction: Repetitive medial luxation of the patella can induce lesions of the cartilage surface of both the patella and the medial femoral condyle. French bulldogs are commonly presented for low-grade or incomplete patellar luxation. In these cases, patellofemoral friction is a constant clinical finding, and it is sometimes difficult to determine if the lameness is attributable to a mechanical abnormality (patellar luxation) or pain (friction leading to cartilage erosion).

Materials and Methods: Eighteen consecutive stifle joints of 11 French bulldogs operated for incomplete or complete patellar luxation were included in this study.

Results: Four stifles presented incomplete patellar luxation. The patella can move medially until the top of the trochlear ridge without going to the other side of the ridge. Patellar luxation was classified in grade 1 in seven dogs, and in grade 2 in seven dogs. In all cases, patellofemoral friction was evident on clinical examination and was accompanied by discomfort or pain. Well delimitated cartilage lesions of the articular surface of the patella and medial trochlear ridge were seen during surgery in all cases. Persistent friction after surgery was still present in 33% of the stifles without any reluxation.

Discussion/Conclusion: Articular cartilage erosion on the patella following patellar luxation has already been studied. Our results showed a higher prevalence of articular cartilage lesions in French bulldogs with incomplete or low-grade patellar luxation which may represent a breed predisposition to this feature. Incomplete patellar luxation encountered in dogs, particularly in French bulldogs, may represent a similar pathology as human patellofemoral syndrome.

Acknowledgment: None.