Reduced bone density of the hip in elderly patients with Parkinson's disease.

Parkinson's disease (PD) is a major cause of falls and reduced mobility in elderly people. Fractures often occur as a result of these falls but there have been no studies of bone mineral density (BMD) in PD. We have prospectively studied 29 elderly women (mean age 77 years) and 26 elderly men (mean age 74 years) with PD over 2 years and compared them with similar numbers of age- and sex-matched controls. Bone mineral density was measured by dual X-ray absorptiometry. Women were more likely to sustain fractures (38% compared with 8% of men). Mean BMD of the lumbar spine was similar in the 55 combined PD patients compared with combined controls. However, the total hip BMD was 10% lower (p = 0.014) and the neck of femur BMD 12% lower (p < 0.004) in the 51 PD patients compared with controls. The relatively lower hip BMD in elderly PD men and women combined with their abnormal gait and tendency to fall backwards or to the side may explain their excess risk of hip fractures, particularly in women. The neuromuscular deficit in PD may differentially reduce hip BMD relative to other sites and may thus be amenable to measures designed to improve mechanical loading in the lower limbs in the early stages of PD.