The effect of zoledronic acid on attenuation of bone loss at the hip and knee following acute traumatic spinal cord injury: a randomized-controlled study.

STUDY

DESIGN

Randomized double blind, placebo-controlled trial.

OBJECTIVES

To examine the effect of early intravenous zoledronic acid (ZA) on bone markers and areal bone mineral density (aBMD) in persons with acute ASIA Impairment Scale (AIS) A traumatic spinal cord injury (SCI).

SETTING

Two inpatient rehabilitation units.

METHODS

Thirteen men, 2 women, aged 19-65, C4-T10 AIS A SCI, received 5 mg intravenous ZA vs. placebo 12-21 days post injury. Markers of bone formation (procollagen N-1 terminal propeptide [P1NP]), bone resorption (serum C-telopeptide [CTX]), and aBMD by dual-energy X-ray absorptiometry (DXA) for hip (femur-proximal, intertrochanteric, neck), and knee (distal femur, proximal tibia) were obtained at baseline, 2 weeks post infusion (P1NP, CTX only), 4 and 12 months post injury.

RESULTS

P1NP remained unchanged, while CTX decreased in ZA but increased in controls at 2 weeks (mean difference = -97%, p < 0.01), 4 months (mean difference = -54%, p < 0.05), but not 12 months (mean difference = 3%, p = 0.23). Changes in aBMD at the hip favored ZA at 4 months (mean difference 10.3-14.1%, p < 0.01) and 12 months (mean difference 10.8-13.1%, p < 0.02). At 4 months, changes in aBMD favored ZA at the distal femur (mean difference 6.0%, 95% CI: 0.7-11.2, p < 0.03) but not proximal tibia (mean difference 8.3%, 95% CI: -6.9 to 23.6, p < 0.23). Both groups declined in aBMD at 12 months, with no between group differences.

CONCLUSION

ZA administered ≤21 days of complete traumatic SCI maintains aBMD at the hip and distal femur at 4 months post injury. This effect is partially maintained at 12 months.