Understanding Patellar Luxation in Dogs
Patellar luxation in dogs is considered a developmental orthopedic disease and is a frequent cause of disability. Medial luxation is more common than lateral; little information is published on treatment and outcomes in dogs with lateral patellar luxation (LPL). This retrospective study examined the clinical features, including complications and outcomes, of 65 dogs treated for LPL; most (76.9%) were medium or large breeds. Conformation abnormalities were present in 34 of 95 pelvic limbs, and included genu valgum (n = 28), hip dysplasia (n = 18), and long digital extensor tendon damage of stifle joints (n = 8). A range of luxation grades were present including grades I (n = 14), II (n = 41), III (n = 29), and IV (n = 11). A higher grade of luxation was associated with a younger age and genu valgum. Complications occurred in 22 of the 58 stifles managed surgically. No risk factors for complications were identified in this study. A good or excellent short-term outcome was reported in 92% of evaluated dogs.
Commentary
This study demonstrated similar complications and outcomes following treatment of LPL compared to literature on medial patellar luxation (MPL) in dogs. Important concurrent conformational abnormalities were noted in 36% of cases, although this likely underestimates the true prevalence, as routine screening of all patients was not employed. A complication rate of 38%, although similar to some historic reports of MPL, is arguably higher than the current body of larger studies1,2 and is likely related to the high rate of conformational deformity not present in the majority of MPL cases. This suggests that a careful diagnostic investigation of these patients, including radiography or computed tomography of the complete femur and tibia, is essential to fully understand the contributing factors for luxation and to optimize patient treatment and outcomes.—Jason Bleedorn, DVM, DACVS
Source
Lateral patellar luxation in dogs: A retrospective study of 65 dogs. Kalff S, Butterworth SJ, Miller A, et al. VET COMP ORTHOPAED TRAUMATOL 27:130-134, 2014.