Correlation of Global Femoral Offset Changes with Abductor Strength in Total Hip Arthroplasty Patients

Abstract

Background: Many people consider total hip arthroplasty (THA) to be among the most effective orthopedic treatments. Beyond pain relief, restoration of native biomechanics—particularly limb length and femoral offset (FO)—is essential for optimizing postoperative function, abductor muscle strength, and quality of life. However, discrepancies in leg length and alterations in global femoral offset (GFO) remain frequent sources of complications, gait disturbances, and patient dissatisfaction.

Aim: To evaluate the correlation of variations in the global femoral offset with hip abductor strength and patient-reported outcomes following unilateral THA, while accounting for limb length discrepancy.

Methods: This prospective observational study included 174 patients who underwent unilateral THA at SCB Medical College and Hospital, Cuttack, between 2020 and 2023. Functional outcomes were assessed using the Oxford Hip Score (OHS) and EQ-5D at baseline, and at 1, 3, and 6 months postoperatively. Limb length discrepancy (LLD) and global femoral offset were measured radiographically. Patients were classified into shortening, restoration, and lengthening groups for LLD, and into decreased, restored, and increased FO groups. Statistical analysis was performed using SPSS v23.0.

Results: All groups showed significant improvement in OHS and EQ-5D postoperatively (p < 0.001). Patients in the lengthening group (>10 mm) reported slightly lower OHS scores and higher use of shoe lifts (p = 0.04). Reduced FO (>5 mm decrease) was associated with significantly weaker abductor strength (78%) compared to restored (90%) and increased FO groups (92%) (p < 0.001). Radiological analysis revealed that excessive limb lengthening was predominantly caused by femoral stem malposition (82%).

Conclusion: THA significantly improves function and quality of life, but suboptimal restoration of limb length and FO adversely impacts outcomes. Excessive limb lengthening compromises patient satisfaction, while decreased FO reduces abductor strength and gait efficiency.

Recommendations: Meticulous surgical planning with attention to femoral stem positioning and restoration of global FO is recommended to minimize complications. Future work should incorporate advanced imaging and navigation techniques to improve accuracy and enhance patient outcomes.

Keywords: Total hip arthroplasty; Femoral offset; Limb length discrepancy; Abductor strength; Patient-reported outcomes