Comparison of Hip Abductor Muscle Composition and Its Age-Related Alterations Between Female Patients with Unilateral and Bilateral Osteoarthritis of the Hip

Objectives: This study aimed to compare hip abductor muscle composition and its age-related alterations between female patients with unilateral and bilateral osteoarthritis (OA) of the hip. Methods: This study enrolled 57 and 43 female patients with unilateral and bilateral advanced OA, respectively. Muscle composition of the glutei medius and minimus and the upper portion of the gluteus maximus was evaluated by computed tomography for planning unilateral total hip arthroplasty. The cross-sectional area ratio of the individual composition to the total muscle was calculated. Correlation coefficients were calculated to determine associations between age and muscle composition variables. Results: Comparison of hip abductor muscle composition between the affected and the contralateral sides in unilateral OA patients showed increased fatty infiltration in the muscles around the affected joint. Comparison of the composition around bilateral OA between the joint scheduled for operation and the contralateral joint demonstrated enhanced fatty infiltration in the glutei medius and minimus but no increase in the gluteus maximus around the operation-scheduled joint. Comparison of muscle composition between unilateral and bilateral OA demonstrated similar fatty infiltration around the operation-scheduled joint whereas there was increased fatty infiltration around the contralateral joint of bilateral OA. Significant association was found between age and hip abductor muscle composition around both sides of unilateral OA. However, there was no association between age and hip abductor muscle composition around both sides of bilateral OA. Conclusions: There were significant differences in hip abductor muscle composition and its age-related alterations between female patients with unilateral and bilateral OA.