Trendelenburg gait after total hip arthroplasty due to reduced muscle contraction of the hip abductors and extensors.

Background: Despite experiencing pain relief and improved activities of daily living after total hip arthroplasty (THA) for osteoarthritis of the hip, a Trendelenburg gait may be observed in some patients. The concentric and eccentric contraction patterns of hip muscles in a Trendelenburg gait are not well understood. Methods: This study included 89 patients (28 males and 61 females, mean age 66.5 ± 8.4 years, mean postoperative period 1.3 ± 0.4 years) after unilateral THA without functional impairment on the contralateral side. Gait analysis utilized a three-dimensional motion capture system to assess pelvis and hip angles, hip moment, and hip power. A Trendelenburg gait was defined as positive when nonoperative pelvic descent occurred at 30 % of the gait cycle, equivalent to mid-stance. Patients were classified into Trendelenburg gait-positive and -negative groups for statistical analysis. Unpaired Results: A Trendelenburg gait was observed in 24 patients (27 %). Multiple regression analysis indicated that abduction (p < 0.01) and extension (p = 0.03) of hip joint power were significant determining of a Trendelenburg gait. Patients with a Trendelenburg gait exhibited reduced eccentric contraction of the hip abductor muscles and decreased concentric contraction of hip extensor muscles during early to mid-stance of their gait. Conclusion: Centrifugal contraction of hip abductor muscles and diminished eccentric contractility of hip extensor muscles appear crucial for hip stabilization mechanisms during gait after THA.