Influence of the femoral head size on early postoperative gait restoration after total hip arthroplasty.

BACKGROUND We investigated the effects of using large-diameter femoral heads in total hip prostheses on early postoperative gait restoration in patients undergoing total hip arthroplasty (THA). METHODS We collected data for 19 primary THAs using 28-mm metal-on-polyethylene heads (conventional group) and for 12 THAs (BHR group) using metal-on-metal femoral heads with an average size of 45 mm (range, 40 - 49 mm). All patients had unilateral femoral head avascular necrosis. All patients underwent Harris Hip Scores evaluation and gait analysis with the IDEEA device at the same 3 time points which were before surgery and then at 1 month and again at 3 months after surgery, and the parameters measured were walking speed, stride length (SL), single limb support (SLS), cycle duration (CD), and swing power (SP). Harris Hip Scores and gait analysis parameters for both groups were compared. RESULTS Intraclass comparison indicated that Harris Hip Scores, speed scores, and gait parameter measures in both groups improved significantly with the passage of time; Interclass comparison showed no significance between Harris(1m postop) - Harris(preop) and Harris(3m postop) - Harris(preop) in both groups. The speed in the BHR group at 1 month and at 3 months after surgery was significantly higher than that of conventional group. At 1 month after surgery, each mean for SL(normal) - SL(affected), (SLS(normal) - SLS(affected))/CD, and SP(normal) - SP(affected) in the BHR group was significantly lower than that for the conventional group. At 3 months after surgery, the differences between means for both groups for SL(normal) - SL(affected), (SLS(normal) - SLS(affected))/CD, and SP(normal) - SP(affected) were not significant, but the mean of SP(normal) - SP(affected) in the BHR group was significantly lower than that in the conventional group. CONCLUSIONS Our data suggest that large-diameter femoral heads in THA provide better early gait restoration than conventional-size femoral heads.