Treatment of avascular necrosis of the femoral head in small dogs with micro total hip replacement.

Objectives: To evaluate clinical outcome of small dogs with avascular necrosis (AVN) of the femoral head treated with Micro total hip replacement (THR).

Study Design: Nonrandomized, retrospective efficacy case series.

Animals: Dogs (n = 7; 7 hips) that had Micro THR.

Methods: Medical records (December 2005-March 2009) of dogs affected with AVN treated with Micro THR were reviewed. Data analysis included age, sex, breed, body weight, and body condition. All dogs were evaluated at least 6 months after Micro THR was performed on the affected AVN limb. Physical, orthopedic, and radiographic examination, owner questionnaire, thigh girth, and ground reaction force were evaluated.

Results: Seven dogs (7 Micro THR) met the inclusion criteria. Mean age at time of onset of clinical signs was 7.7 months and mean age at time of Micro THR was 9.6 months. Mean body weight was 4.2 kg. Median body condition score was 5.0 (range, 4-6). Mean cumulative functional scores from client questionnaires before (19.5; range, 11-25) and after Micro THR (8.2; range, 7-14) were significantly different (P = .004). There was no significant difference between thigh girths of the Micro THR (17.8 ± 2.6 cm; range, 14.5-21.5 cm) limbs when compared with contralateral (17.5 ± 2.9 cm; range, 14.5-22.0 cm) limbs (P = .38). Peak vertical force (P = .20), vertical impulse (P = .81), peak braking force (P = .91), braking impulse (P = .19), peak propulsion force (P = .32), and propulsion impulse (P = .19) were not significantly different in Micro THR limbs compared with contralateral limbs.

Conclusion: There was no relationship between age, sex, and breed for development of AVN in this study. Dogs that received Micro THR for the treatment of AVN had no significant differences in thigh girth and ground reaction forces when Micro THR limb was compared with the contralateral limb.