Muscle strength is significantly associated with hip bone mineral density in women with Parkinson's disease: a cross-sectional study.

OBJECTIVE To study the influence of physical impairments on hip bone mineral density in women with Parkinson's disease. DESIGN Cross-sectional study. SUBJECTS/PATIENTS Thirty-four women with Parkinson's disease and 30 age-matched healthy controls. METHODS Patients with Parkinson's disease underwent a hip scan using dual-energy X-ray absorptiometry and total hip bone mineral density values were obtained. Motor Examination III of the Unified Parkinson Disease Rating Scale was used to assess leg tremor, leg agility, leg rigidity and postural stability. In addition, all subjects were evaluated for walking speed, walking endurance, and leg muscle strength. RESULTS Based on the hip bone mineral density values, 12 patients with Parkinson's disease (35%) had osteopaenia and another 3 patients (9%) had osteoporosis. Patients with Parkinson's disease had significantly lower walking velocity (p = 0.002), walking endurance (p < 0.001) and leg muscle strength (p = 0.047) than controls. Multiple regression revealed that leg muscle strength alone accounted for 8.8-10.6% of the variance in hip bone mineral density among patients with Parkinson's disease, after controlling for body mass index, post-menopausal years, Hoehn and Yahr stage, and postural stability (p < 0.05). CONCLUSION Hip bone mineral density is independently associated with leg muscle strength in women with Parkinson's disease.