Zoledronic Acid Treatment After Acute Spinal Cord Injury: Results of a Randomized, Placebo-Controlled Pilot Trial

Objective To determine the effect of intravenous zoledronic acid 5 mg on the extent and course of bone loss after spinal cord injury (SCI). Design Double-blind, randomized, placebo-controlled parallel-group trial. Setting Acute in-patient, tertiary-care rehabilitation hospital. Participants Convenience sample of 17 in-patients with SCI <12 weeks before randomization; American Spinal Injury Association Impairment scale A, B, or C and medically stable. Twelve patients were evaluated at the primary endpoint at 6 months. Methods Patients meeting study criteria were randomly assigned to zoledronic acid 5 mg or matching placebo. Dual x-ray absorptiometry scan and serum for bone markers (type 1 procollagen amino-terminal propeptide, bone-specific alkaline phosphatase, collagen type 1 cross-linked C-telopeptide) were obtained at baseline and after 3 months, 6 months, and the every 6 months for up to 2 years. Main Outcome Measures The primary endpoint was change in bone mineral density (BMD) at the total hip after 6 months; secondary endpoints were changes in BMD at other skeletal sites and changes in levels of serum bone markers. Results The group treated with zoledronic acid had a smaller decrease in BMD at 6 months at the total hip than the placebo group (right: −2.2 ± 3.4% versus −8.6 ± 3.5%, respectively, P = .03; left: −3.7 ± 1.0% versus −12.3 ± 6.9%, P = .03). Differences in BMD at the femoral neck were similar (right: −5.1 ± 6.5% versus −20.0 ± 6.4%, P = .01; left: −1.1 ± 3.5% versus −11.1 ± 7.4%, P = .02) with larger bone loss and smaller between group differences at the knee. Zoledronic acid resulted in a decrease in serum levels of both formation and resorption markers. Conclusions Zoledronic acid is effective at mitigating bone loss after SCI. Duration of efficacy and activity at different skeletal sites may differ from that observed in able-bodied individuals and needs further study.