Recovery of Muscle Activity of the Gluteus Medius and Gait Function after Total Hip Arthroplasty in the Early Postoperative Stage

Abstract

[Purpose] The purpose of this study was to clarify the recovery of hip abductor muscles strength, muscle activity of the gluteus medius during locomotion and gait function after total hip arthroplasty (THA) in the early postoperative stage. [Subjects and Methods] The subjects were seven women who were end stage hip OA patients (mean age 70.6 ± 8.2 years) and had received anterior-lateral approach THA. Hip abductor muscle strength was measured by a musculator. Muscle activity of the gulteus medius was recorded at maximum voluntary contraction (MVC) and during locomotion by surface electromyography. [Results] Hip abductor muscle strength showed significantly lower values in postoperatively, 3-4 weeks, than preoperatively (p<0.05), but showed the same value after 5 weeks. The values of the gluteus medius %MVC was not changed significantly at any postoperative stage compared to the preoperative stage. The value of gait speed improved significantly 5 weeks after THA compared to the preoperative stage. [Conclusion] We suggest that gait function of elderly THA patients may be improved in the early postoperative stage but qualitative disability of the gluteus medius muscle remains.