A randomized, double blind, placebo-controlled trial of alendronate treatment for fibrous dysplasia of bone

Context: Fibrous dysplasia (FD) is a rare skeletal disorder, resulting in deformity, fracture, functional impairment, and pain. Bisphosphonates have been advocated as a potential treatment.

Objective: To determine the efficacy of alendronate for treatment of FD.

Design: Two-year randomized, double-blind, placebo-controlled trial.

Setting: Clinical research center.

Patients: Forty subjects with polyostotic FD (24 adults, 16 children). Subjects were randomized and stratified by age.

Interventions: Study drug was administered over a 24 month period in 6 month cycles (6 months on, 6 months off). Alendronate dosing was stratified: 40 mg daily for subjects > 50 kg, 20 mg for 30-50 kg, 10 mg for 20-30 kg.

Main Outcome Measures: Primary endpoints were bone turnover markers, including serum osteocalcin, and urinary NTX-telopeptides. Secondary endpoints included areal bone mineral density (aBMD), pain, skeletal disease burden score, and functional parameters including the 9-min walk test and manual muscle testing.

Results: Clinical data was collected on 35 subjects who completed the study. There was a decline in NTX-telopeptides in the alendronate group (P = .006), but no significant difference in osteocalcin between groups. The alendronate group had an increase in areal BMD in normal bone at the lumbar spine (P =.006), and in predetermined regions of FD (P<.001). There were no significant differences in pain scores, skeletal disease burden scores, or functional parameters between the groups.

Conclusions: Alendronate treatment led to a reduction in the bone resorption marker NTX-telopeptides, and improvement in aBMD, but no significant effect on serum osteocalcin, pain, or functional parameters.