title: Local Epiphyseal Growth Modulation for the Early Treatment of Progressive Scoliosis: Experimental Validation Using a Porcine Model.
abstract: METHODS
  Experimental study of a localized device for the control of the vertebral growth using an immature porcine model.
  
  
  OBJECTIVE
  The aim of the study was to experimentally evaluate a localized device acting on the epiphyseal growth plates without bridging the intervertebral disc of immature hybrid pigs over 3 months of growth.
  
  
  BACKGROUND
  Based on current published literature, fusionless devices offer promising scoliosis treatment alternatives to conventional spinal instrumentation and fusion in the growing spine. Current compression-based devices achieve growth modulation while also compressing the intervertebral discs, increasing the risk of long-term disc degeneration.
  
  
  METHODS
  An intravertebral staple acting on both the superior and inferior growth plates was inserted locally over T7-T9 of seven healthy immature pigs. Four age-matched animals served as controls. Radiographs were acquired monthly to assess induced spinal curvature and vertebral wedging (inverse model). Global (spinal) and local (vertebral, discal) geometric changes were evaluated over 3-months follow-up. Final left/right vertebral height differences were also quantified.
  
  
  RESULTS
  The only postoperative complication observed was one pig that had a persistent deep infection and was excluded from the study. No significant changes in spinal alignment were reported in control animals. Final induced Cobb angle was 25.0° ± 4.2° measured over T7-T9, with no observable sagittal profile modification. Highest vertebral wedging occurred at T9 with 18.2° ± 2.7°. Cumulative vertebral wedging over T7-T9 accounted for 45.4°, demonstrating evidence of reversed disc wedge phenomenon. Vertebral height was 3.9 ± 1.0 mm shorter on the instrumented side suggesting full growth restraint. Local and regional induced deformities significantly differed from their control counterparts (P < 0.001).
  
  
  CONCLUSIONS
  In this animal model, the local epiphyseal device achieved significant localized growth modulation over as little as three instrumented levels, with explicit vertebral wedging exclusive of the intervertebral disc. By increasing the number of instrumented levels, one may achieve higher curvature control potentially providing a unique local correction method to correct spinal deformity without affecting the intervertebral disc.
  
  
  METHODS
  5.
authors: Department of Mechanical Engineering, Polytechnique Montreal.|Research Center, Sainte-Justine University Hospital Center.
authors: Bahe
authors: B
authors: Hachem
authors: Department of Mechanical Engineering, Polytechnique Montreal.|Research Center, Sainte-Justine University Hospital Center.|Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada.
authors: Carl-Eric
authors: CE
authors: Aubin
authors: Research Center, Sainte-Justine University Hospital Center.|Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada.
authors: Stefan
authors: S
authors: Parent
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena / Q000502:physiology; D004195:Disease Models, Animal; D018450:Disease Progression; D004838:Epiphyses / Q000601:surgery*; D005260:Female; D007403:Intervertebral Disc / Q000601:surgery*; D012600:Scoliosis / Q000601:surgery*; D013552:Swine; D013904:Thoracic Vertebrae / Q000601:surgery*