Regional changes in bone mineral density following spinal cord injury in children.

Objective: To document the serial changes in bone mineral density (BMD) following paediatric spinal cord injury (SCI).

Design: Retrospective case series.

Setting: Paediatric tertiary care hospital.

Patients: Eighteen children (nine males) followed in an outpatient spinal cord injury service.

Interventions: Not applicable.

Main Outcome Measure: Serial bone mineral density (BMD) measurements using dual energy X-ray absorptiometry (DXA).

Results: Mean follow-up was 5.0 +/- 3.6 years (range 0.4-12.4 years). Three children sustained minimal trauma fractures, all femoral. For the cohort, BMD Z-scores were significantly less than zero in the legs (-2.7 +/- 2.0, p < 0.001), femoral neck (-2.1 +/- 1.4, p < 0.001), total body (-0.8 +/- 1.3, p=0.02) and lumbar spine (-0.8 +/- 1.6, p=0.04), but not in the arms (-0.2 +/- 1.0, p=0.5). Lean tissue mass (LTM) Z-scores were reduced in the legs (-1.9 +/- 1.3, p < 0.001). Longitudinal data showed an initial decline in lower extremity BMD, BMC and LTM aged-matched Z-scores in the 12 months following SCI, followed by an age appropriate increase thereafter.

Conclusions: Lower extremity osteopenia and sarcopenia develop rapidly in the first 12 months following the SCI. The reduced bone strength increases the risk of low trauma fracture.