title: Factors affecting bone mineral mass loss after lower-limb fractures in a pediatric population.
abstract: BACKGROUND
  The purpose of this study was to assess the effects of the durations of cast immobilization and non-weight-bearing periods, and decreases in vigorous physical activity (VPA) on bone mineral parameters in a pediatric population treated for a lower-limb fracture.
  
  
  METHODS
  Fifty children and teenagers who had undergone a cast-mediated immobilization for a leg or ankle fracture were prospectively recruited. The durations of cast immobilization and non-weight-bearing periods were recorded for each participant. Dual-energy x-ray absorptiometry scans were performed at the time of fracture treatment (baseline) and at cast removal. Physical activity during cast immobilization was assessed using accelerometers.
  
  
  RESULTS
  A strong negative correlation was found between the total duration of cast immobilization and decreases in both calcaneal bone mineral density (BMD) (r=-0.497) and total lower-limb bone mineral content (BMC) (r=-0.405). A strong negative correlation was also noted between the durations of the non-weight-bearing periods and alterations in calcaneal BMD (r=-0.420). No apparent correlations were found between lower BMD and BMC and decreased VPA.
  
  
  CONCLUSIONS
  Bone mineral loss was correlated to the total duration of cast immobilization for all measurement sites on the affected leg, whereas it was only correlated to the durations of non-weight-bearing periods for calcaneal BMD and total lower-limb BMC. However, no correlations were noted between bone mineral loss and decreased VPA.
authors.affiliation: *Service of Pediatric Orthopedics, Department of Child and Adolescent, University of Geneva Hospitals †Department of Internal Medicine, La Tour Hospital and University of Geneva, Geneva, Switzerland.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Ceroni
authors.forename: Xavier
authors.initials: X
authors.lastname: Martin
authors.forename: Omar
authors.initials: O
authors.lastname: Kherad
authors.forename: Davide
authors.initials: D
authors.lastname: Salvo
authors.forename: Victor
authors.initials: V
authors.lastname: Dubois-Ferrière
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000293:Adolescent; D018488:Bone Demineralization, Pathologic / Q000175:diagnosis / Q000209:etiology / Q000517:prevention & control; D015519:Bone Density; D002370:Casts, Surgical; D002648:Child; D002675:Child, Preschool; D005260:Female; D005592:Fracture Fixation / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods; D050723:Fractures, Bone / Q000175:diagnosis / Q000628:therapy*; D006801:Humans; D007867:Leg Bones / Q000293:injuries / Q000473:pathology; D008137:Longitudinal Studies; D008297:Male; D009043:Motor Activity / Q000502:physiology; D013557:Switzerland; D013997:Time Factors; D016474:Weight-Bearing