title: Rapid remineralization of the distal radius after forearm fracture in children.
abstract: BACKGROUND
  Bone mineral content (BMC) and density (BMD) have been shown to diminish after fracture and immobilization in adults. Distal radius fractures are common in children, and unlike adults, there is a low incidence of refracture. The primary aim of this study was to assess the change in radial BMC and BMD after upper extremity fracture and casting in healthy pediatric patients.
  
  
  METHODS
  Patients were recruited at the time of distal radius fractures casting. The nonfractured (non-Fx) distal radius was initially scanned by dual energy x-ray absorptiometry (baseline), and then both arms were scanned at the time of cast removal (CastOff), and 4, 8, 12, 24, and 52 weeks post CastOff.
  
  
  RESULTS
  Twenty-one patients were enrolled (13 male, 13 Caucasian; 10.4±2.5 y) with an average length of casting of 38±11 days. Eighteen patients (86%) completed all protocol requirements. At CastOff, there was no significant difference in total BMC or BMD between the Fx and non-Fx arms. From CastOff to 24 weeks, the overall change in BMC and BMD for the non-Fx arm was +4.2% and +0.2%, respectively, whereas for the Fx arm, the change was +8.3% and +3.4%, respectively. By 24 weeks, the difference in the overall change in BMD between the Fx and non-Fx arms was statistically significant (greater than instrumental error; P<0.05). However, by 52 weeks, these differences were no longer significant. The increased mineralization was unrelated to age, sex, arm dominance, or calcium intake.
  
  
  CONCLUSIONS
  These data show that there is rapid remineralization after a simple forearm fracture in children, with a transient elevation in BMD in the Fx arm after casting. This novel finding suggests that bone may be stronger around the site of fracture and could significantly change how we counsel young patients recovering from forearm fracture. Future research should focus on children immobilized for varying lengths of time and those with repeat fractures, using volumetric techniques of bone geometry and strength assessment.
  
  
  METHODS
  
  
  
  METHODS
  Therapeutic Studies-investigating the results of treatment, Level IV.
authors.affiliation: Children’s Hospital & Research Center, Oakland, HEDCO Health Science Center 5700 Martin Luther King Jr Way, Oakland, CA 94609, USA. efung@mail.cho.org
authors.forename: Ellen B
authors.initials: EB
authors.lastname: Fung
authors.forename: Marcie L
authors.initials: ML
authors.lastname: Humphrey
authors.forename: Ginny
authors.initials: G
authors.lastname: Gildengorin
authors.forename: Natalie
authors.initials: N
authors.lastname: Goldstein
authors.forename: Scott A
authors.initials: SA
authors.lastname: Hoffinger
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods*; D000293:Adolescent; D015519:Bone Density; D002370:Casts, Surgical; D002648:Child; D002675:Child, Preschool; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011446:Prospective Studies; D011885:Radius Fractures / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000601:surgery; D013997:Time Factors; D014458:Ulna Fractures / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000601:surgery