Low bone mass in patients with motor disability: Prevalence and risk factors in 59 Finnish children

Abstract

Aim: Children with motor disabilities are at increased risk of compromised bone health. This study evaluated prevalence and risk factors of low bone mass and fractures in these children. Method: This cross-sectional cohort study evaluated bone health in 59 children (38 males, 21 females; median age 10y 11mo) with motor disability (Gross Motor Function Classification System levels II-V). Bone mineral density (BMD) in the lumbar spine was measured with dual-energy X-ray absorptiometry; BMD values were corrected for bone size (bone mineral apparent density [BMAD]) and skeletal maturity, and compared with normative data. Spinal radiographs were obtained to assess vertebral morphology. Blood biochemistry included vitamin D concentration and other parameters of calcium homeostasis. Results: Ten children (17%) had sustained in total 14 peripheral fractures; lower-limb fractures predominated. Compression fractures were present in 25%. The median spinal BMAD z-score was -1.0 (range -5.0 to 2.0); it was -0.6 in those without fractures and -1.7 in those with fractures (p=0.004). Vitamin D insufficiency was present in 59% of participants (serum 25-hydroxyvitamin D <50nmol/l) and hypercalciuria in 27%. Low BMAD z-score and hypercalciuria were independent predictors for fractures. Interpretation: Children with motor disability are at high risk of peripheral and vertebral fractures and low BMD. Evaluation of bone health and prevention of osteoporosis should be included in the follow-up. © The Authors. Journal compilation © Mac Keith Press 2009.