Neuropediatrics 2006; 37 - MP41
DOI: 10.1055/s-2006-943638

BONE DENSITY INTERPRETATION IN CHILDREN WITH CEREBRAL PALSY

C Campbell 1, L Ward 1, P Humphreys 1, J McLean 1, M Matzinger 1, L Lawton 1
  • 1Children's Hospital of Western Ontario, London, ON, Canada

Objectives: Children with CP encounter a number of orthopedic complications as a result of abnormalities in motor function. One of the most significant complications is fragility fractures occurring in up to 23% of children. Despite a growing literature on how to best interpret bone densitometry in children little research has determined how best to use dual x-ray absorptiometry (DEXA) in children with CP to predict fragility fracture and other bone complications. This study outlines the use of the mechanostat theory of bone physiology to classify and interpret bone complications in this population.

Methods: Single-centre, cross sectional study of 53 subjects with CP age 2–15 years of age. Subjects underwent a baseline interview, examination and evaluation of bone complications including DEXA bone densitometry. DEXA measurements of bone mineral content (BMC) and lean body mass (LBM) were used to determine if subjects had normal bone strength, primary, secondary, or mixed osteopenia.

Results: The subjects (51% females) had a mean age of 9 years. Severity of CP ranged across all GMFCS levels and all types of CP were represented in the sample. Normal bone parameters were seen in 24 children, with 11 children classified as primary osteopenia, 5 with secondary osteopenia and 3 with a mixed pattern. Three children had fragility fractures and using this classification the fractures were accurately allocated to the osteopenic groups. In each group there was one child with a fracture. Using z scores for BMC as an outcome variable only one CP specific factor, the GMFCS, was an important predictor variable. The use of anti-convulsants, the type of CP, family history and calcium and vitamin D intake did not contribute to the model. Other orthopaedic complications, and measures of pain or quality of life appear to be unrelated to low BMC.

Conclusion: The mechanostat theory of bone density interpretation is a more physiologic way to interpret DEXA measurements. In a sample of children with CP fragility fractures are accurately classified using this technique.