Fatty involution of the gluteus medius muscles: a late-onset girdle myopathy?

Involvement of the gluteus medius muscle has been reported in girdle myopathies or facioscapulohumeral myopathies. Camptocormia, or Bent spine syndrome, characterized by involuntary forward flexion of the trunk in the standing position, may be secondary to a late-onset myopathy essentially involving the spinal erector muscles. In this article, we report the observations of patients with severe deficiency of the gluteus medius, suggesting a late-onset myopathy.

Computed tomography and magnetic resonance imaging (MRI) were performed in 17 patients, with a mean age 76 years, 3 men and 14 women, presenting a Trendelenburg limp related to fatty infiltration of the gluteus medius muscles. Eight of these patients also had camptocormia.

Computed tomographic scan and MRI appearance differed from that of age-matched controls and suggested myopathy. MRI excluded an inflammatory disorder or disinsertion of the gluteus medius muscle. Biopsies of gluteus medius and paravertebral muscles showed marked septal fibrosis and adiposis, whereas control biopsies were normal. Creatine phosphokinase was moderately increased in two thirds of patients.

Involvement of the gluteus medius muscles, like involvement of the paravertebral muscles with which it is frequently associated, may be a form of late-onset girdle myopathy.