Gluteus medius muscle atrophy contralateral and ipsilateral hip is related to joint osteoarthritis

In order to understand the role of the gluteus medius muscle (GM) in hip joint osteoarthritis, the objective of this study was to analyze the correlation between morphometric data of GM samples with osteoarthritis scores of ipsilateral and contralateral hips in 41 patients. GM samples obtained during unilateral hip replacement surgery were used to evaluate muscle fibers in the cross-sectional area (CSA) and other features indicative for muscle aging. Clinical symptoms were assessed by the Lequesne pain score. Hip osteoarthritis was graded by the Kellgren score and by measuring the sum joint space width (sumJSW) at three different articular locations and minimal JSW in a.p. radiographs. Varying degrees of GM muscle atrophy correlated with the pain score; pain score also correlated with radiographic signs of osteoarthritis. GM CSA was significantly correlated with all radiographic signs of the contralateral hip, but only with the sumJSW in the ipsilateral hip. It can be concluded that a weak GM may be the result of ipsilateral osteciarthitis, but may especially predispose the contralateral hip to develop osteoarthritis. This can be associated with an impaired GM capacity to avoid the shock impact in the load transfer during gait. Muscle strengthening is therefore recommended.