Bone density and size in ambulatory children with cerebral palsy

Abstract

To examine the relation of axial and appendicular bone properties in ambulatory children with cerebral palsy (CP) to functional (Gross Motor Function Classification System [GMFCS]) level. Quantitative computed tomography measurements were compared among 37 children with CP (12 children in GMFCS level I, five in level II, 18 in level III, two in level IV; five with hemiplegia, 23 with diplegia, two with triplegia, seven with quadriplegia; mean age 9y 4mo, SD 1y 6mo; 18 males, 19 females) and 37 children in a comparison group (same age and sex distributions). Linear regression was used to evaluate differences in volumetric cancellous bone density (vBMD) and geometric properties of the L3 vertebra and tibia, adjusting for height, weight, and sex as covariates. The comparison group had larger vertebrae than the children with CP (p = 0.02) owing to smaller vertebral size in GMFCS levels III and IV, but there was no difference in vertebral vBMD (p = 0.49). In the tibia, bone volumetric density (p = 0.09) and size (p = 0.02) decreased with increasing GMFCS level. GMFCS level had a greater effect on bone size in females than in males (p<0.07). Children with CP of all levels may have less bone in their tibias, whereas spine deficits differentially affect more involved children. Because even small bone deficits may manifest as osteoporosis later in life, it is important to study bone acquisition in all children with CP.