The effect of hip offset reconstruction on gait biomechanics following total hip arthroplasty for 12 months.

BACKGROUND

Variations in femoral offset have been shown to affect postoperative gait biomechanics, but their specific impact and temporal progression remain unclear. This study examined the effect of femoral offset on gait biomechanics within 12 months following total hip arthroplasty.

METHODS

This prospective study compared 120 patients with diagnosed hip osteoarthritis who underwent primary total hip arthroplasty, categorized into three groups based on the reconstructed three-dimensional model's 3 dimensions femoral offset differences before and after total hip arthroplasty: large femoral offset (>5 mm), small femoral offset (<5 mm), or normal femoral offset (+5 to -5 mm). Gait biomechanics were assessed using three-dimensional instrumented gait analysis. Group differences in hip kinematics were analyzed using statistical parametric mapping.

FINDINGS: Step length exhibited a significant group effect, as it was significantly greater in the larger femoral offset group than in the small femoral offset group (P = 0.026). The small femoral offset group exhibited significantly greater hip extension between 62 and 68% (P = 0.048) of the gait cycle compared to the normal group after 10 days. The large femoral offset group demonstrated significantly greater hip flexion between 67 and 94% (P < 0.001) of the gait cycle than the small femoral offset group after 3 months.

INTERPRETATION: Reduced femoral offset reconstruction may adversely influence step length and early postoperative gait kinematics. These findings suggest that under-restoration of femoral offset may impair early postoperative gait recovery, highlighting the importance of appropriate femoral offset restoration during THA.