Evaluation of functional outcome after BFX total hip replacement using a pressure sensitive walkway.

Objective: To evaluate stance phase limb use after cementless (BFX) total hip replacement (THR) in dogs and to relate postoperative radiographic variables to static bodyweight distribution after surgery.

Study Design: Prospective clinical study.

Animals: Dogs (n=35) that had THR.

Methods: THR was performed using the BFX THR technique. Postoperative pain management regimens were similar for all dogs. Standing bodyweight distribution (%BW(distrib)) was measured using a pressure sensitive walkway and radiographs made before surgery and at 3, 6, and 12 months after surgery. Repeated measures models (with backwards-stepping to obtain the final model) were used for statistical analysis.

Results: Temporally, %BW(distrib) to the operated limb increased (P<.0001; normal by 3 months) and decreased to the unoperated limb (P=.0001) and also increased to the pelvic limbs and decreased to the thoracic limbs. %BW(distrib) to the unoperated limb was significantly less than the operated limb at 3, 6, and 12 months after surgery. Postoperative canal fill and femur flare were significantly negatively correlated with change in %BW(distrib) (estimate=-0.24, P=.0413).

Conclusion: BFX THR results in normal %BW(distrib) to the operated limb by 3 months after surgery. A greater fill of the proximal femur may be associated with a suboptimal outcome.

Clinical Relevance: BFX THR normalizes standing bodyweight distribution dogs with hip osteoarthritis. Objective evaluation of THR outcome and radiographic features may reveal factors that could be improved through changes in prosthesis design or surgical technique.