title: Low magnitude mechanical loading is osteogenic in children with disabling conditions.
abstract: The osteogenic potential of short durations of low-level mechanical stimuli was examined in children with disabling conditions. The mean change in tibia vTBMD was +6.3% in the intervention group compared with -11.9% in the control group. This pilot randomized controlled trial provides preliminary evidence that low-level mechanical stimuli represent a noninvasive, non-pharmacological treatment of low BMD in children with disabling conditions.
  
  
  BACKGROUND
  Recent animal studies have demonstrated the anabolic potential of low-magnitude, high-frequency mechanical stimuli to the trabecular bone of weight-bearing regions of the skeleton. The main aim of this prospective, double-blind, randomized placebo-controlled pilot trial (RCT) was to examine whether these signals could effectively increase tibial and spinal volumetric trabecular BMD (vTBMD; mg/ml) in children with disabling conditions.
  
  
  METHODS
  Twenty pre-or postpubertal disabled, ambulant, children (14 males, 6 females; mean age, 9.1 +/- 4.3 years; range, 4-19 years) were randomized to standing on active (n = 10; 0.3g, 90 Hz) or placebo (n = 10) devices for 10 minutes/day, 5 days/week for 6 months. The primary outcomes of the trial were proximal tibial and spinal (L2) vTBMD (mg/ml), measured using 3-D QCT. Posthoc analyses were performed to determine whether the treatment had an effect on diaphyseal cortical bone and muscle parameters.
  
  
  CONCLUSIONS
  Compliance was 44% (4.4 minutes per day), as determined by mean time on treatment (567.9 minutes) compared with expected time on treatment over the 6 months (1300 minutes). After 6 months, the mean change in proximal tibial vTBMD in children who stood on active devices was 6.27 mg/ml (+6.3%); in children who stood on placebo devices, vTBMD decreased by -9.45 mg/ml (-11.9%). Thus, the net benefit of treatment was +15.72 mg/ml (17.7%; p = 0.0033). In the spine, the net benefit of treatment, compared with placebo, was +6.72 mg/ml, (p = 0.14). Diaphyseal bone and muscle parameters did not show a response to treatment. The results of this pilot RCT have shown for the first time that low-magnitude, high-frequency mechanical stimuli are anabolic to trabecular bone in children, possibly by providing a surrogate for suppressed muscular activity in the disabled. Over the course of a longer treatment period, harnessing bone's sensitivity to these stimuli may provide a non-pharmacological treatment for bone fragility in children.
authors.affiliation: Clinical Radiology, Imaging Science & Biomedical Engineering, University of Manchester, Manchester, United Kingdom.
authors.forename: Kate
authors.initials: K
authors.lastname: Ward
authors.forename: Chrissie
authors.initials: C
authors.lastname: Alsop
authors.forename: Janette
authors.initials: J
authors.lastname: Caulton
authors.forename: Clinton
authors.initials: C
authors.lastname: Rubin
authors.forename: Judith
authors.initials: J
authors.lastname: Adams
authors.forename: Zulf
authors.initials: Z
authors.lastname: Mughal
mesh_terms: D015519:Bone Density; D002648:Child; D002675:Child, Preschool; D019988:Children with Disabilities; D005260:Female; D006801:Humans; D008297:Male; D010012:Osteogenesis / Q000502:physiology*; D010024:Osteoporosis / Q000453:epidemiology / Q000517:prevention & control*; D010349:Patient Compliance; D013977:Tibia / Q000502:physiology; D014732:Vibration / Q000627:therapeutic use*; D016474:Weight-Bearing / Q000502:physiology