Background Incidence of a fracture, particularly in the hip joint, is high in Parkinson's disease (PD), owing to the immobilisation-induced bone resorption and vitamin D deficiency with reduced bone mineral density (BMD). The authors previously demonstrated the lowered incidence of hip fractures in PD by daily administration of risedronate and vitamin D.

Methods This randomised, double-blind, placebo-controlled study was conducted to determine the efficacy of 17.5 mg once-weekly risedronate in the prevention of hip fracture in women with PD. Patients were randomly assigned to 17.5 mg risedronate once a week (n=136) or a placebo (n=136) combined with daily 1000 IU of ergocalciferol. Incidence of hip fractures was compared between the two groups during the 2-year follow-up.

Results Hip fractures occurred in 15 patients in the placebo group and 3 patients in the risedronate group. The RR for hip fractures in the risedronate group as compared with the placebo group was 0.20 (95% CI 0.06 to 0.66). In the risedronate group, serum calcium levels decreased during the follow-up, while the levels in the placebo group increased. BMD increased by 3.4% in the risedronate group and decreased by 3.2% in the placebo group (p<0.01).

Conclusions Treatment with once-weekly risedronate and ergocalciferol prevents hip fractures in older women with PD.