The functional muscle-bone unit in children with cerebral palsy

Osteoporos Int. 2017 Jul;28(7):2081-2093. doi: 10.1007/s00198-017-4023-2. Epub 2017 Apr 1.

Abstract

Our results suggest that the prevalence of bone health deficits in children with CP was overestimated, when using only age- and height-adjusted bone mineral content (BMC) and areal bone mineral density (aBMD). When applying the functional muscle-bone unit diagnostic algorithm (FMBU-A), the prevalence of positive results decreased significantly. We recommend applying the FMBU-A when assessing bone health in children with CP.

Introduction: The prevalence of bone health deficits in children with cerebral palsy (CP) might be overestimated because age- and height-adjusted reference percentiles for bone mineral content (BMC) and areal bone mineral density (aBMD) assessed by dual-energy X-ray absorptiometry (DXA) do not consider reduced muscle activity. The aim of this study was to compare the prevalence of positive DXA-based indicators for bone health deficits in children with CP to the prevalence of positive findings after applying a functional muscle-bone unit diagnostic algorithm (FMBU-A) considering reduced muscle activity.

Methods: The present study was a monocentric retrospective analysis of 297 whole body DXA scans of children with CP. The prevalence of positive results of age- and height-adjusted BMC and aBMD defined as BMC and aBMD below the P3 percentile and of the FMBU-A was calculated.

Results: In children with CP, the prevalence of positive results of age-adjusted BMC were 33.3% and of aBMD 50.8%. Height-adjusted results for BMC and aBMD were positive in 16.8 and 36.0% of cases. The prevalence of positive results applying the FMBU-A regarding BMC and aBMD were significantly (p < 0.001) lower than using age- and height-adjusted BMC and aBMD (8.8 and 14.8%).

Conclusions: Our results suggest that the prevalence of bone health deficits in children with CP was overestimated, when using age- and height-adjusted BMC and aBMD. When applying the FMBU-A, the prevalence decreased significantly. We recommend applying the FMBU-A when assessing bone health in children with CP.

Keywords: Cerebral palsy; Dual-energy X-ray absorptiometry; Fracture; Muscle-bone interactions; Osteoporosis.

MeSH terms

  • Absorptiometry, Photon / methods
  • Adolescent
  • Bone Density / physiology*
  • Cerebral Palsy / complications
  • Cerebral Palsy / physiopathology*
  • Child
  • Female
  • Humans
  • Male
  • Muscle, Skeletal / physiopathology*
  • Osteoporosis / etiology
  • Osteoporosis / physiopathology
  • Retrospective Studies
  • Severity of Illness Index
  • Sex Factors
  • Young Adult