title: Porcine spine finite element model: a complementary tool to experimental scoliosis fusionless instrumentation.
abstract: Developing fusionless devices to treat pediatric scoliosis necessitates lengthy and expensive animal trials. The objective was to develop and validate a porcine spine numerical model as an alternative platform to assess fusionless devices.
  
  
  
  A parametric finite element model (FEM) of an osseoligamentous porcine spine and rib cage, including the epiphyseal growth plates, was developed. A follower-type load replicated physiological and gravitational loads. Vertebral growth and its modulation were programmed based on the Hueter-Volkmann principle, stipulating growth reduction/promotion due to increased compressive/tensile stresses. Scoliosis induction via a posterior tether and 5-level rib tethering, was simulated over 10 weeks along with its subsequent correction via a contralateral anterior custom tether (20 weeks). Scoliosis induction was also simulated using two experimentally tested compression-based fusionless implants (hemi- and rigid staples) over 12- and 8-weeks growth, respectively. Resulting simulated Cobb and sagittal angles, apical vertebral wedging, and left/right height alterations were compared to reported studies.
  
  
  
  Simulated induced Cobb and vertebral wedging were 48.4° and 7.6° and corrected to 21° and 5.4°, respectively, with the contralateral anterior tether. Apical rotation (15.6°) was corrected to 7.4°. With the hemi- and rigid staples, Cobb angle was 11.2° and 11.8°, respectively, with 3.7° and 2.0° vertebral wedging. Sagittal plane was within the published range. Convex/concave-side vertebral height difference was 3.1 mm with the induction posterior tether and reduced to 2.3 with the contralateral anterior tether, with 1.4 and 0.8 for the hemi- and rigid staples.
  
  
  
  The FEM represented growth-restraining effects and growth modulation with Cobb and vertebral wedging within 0.6° and 1.9° of experimental animal results, while it was within 5° for the two simulated staples. Ultimately, the model would serve as a time- and cost-effective tool to assess the biomechanics and long-term effect of compression-based fusionless devices prior to animal trials, assisting the transfer towards treating scoliosis in the growing spine.
authors.affiliation: Department of Mechanical Engineering, Canada Research Chair in Orthopedic Engineering' and NSERC-Medtronic Industrial Research Chair in Spine Biomechanics, Polytechnique Montreal, Station "Centre-ville", P.O. Box 6079, Montreal, Quebec, H3C 3A7, Canada.|Research Center, Sainte-Justine University Hospital Center, Montreal, Canada.
authors.forename: Bahe
authors.initials: B
authors.lastname: Hachem
authors.affiliation: Department of Mechanical Engineering, Canada Research Chair in Orthopedic Engineering' and NSERC-Medtronic Industrial Research Chair in Spine Biomechanics, Polytechnique Montreal, Station "Centre-ville", P.O. Box 6079, Montreal, Quebec, H3C 3A7, Canada. carl-eric.aubin@polymtl.ca.|Research Center, Sainte-Justine University Hospital Center, Montreal, Canada. carl-eric.aubin@polymtl.ca.|Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada. carl-eric.aubin@polymtl.ca.
authors.forename: Carl-Eric
authors.initials: CE
authors.lastname: Aubin
authors.affiliation: Research Center, Sainte-Justine University Hospital Center, Montreal, Canada.|Department of Surgery, Faculty of Medicine, Université de Montréal, Montreal, Canada.
authors.forename: Stefan
authors.initials: S
authors.lastname: Parent
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D020342:Finite Element Analysis; D008953:Models, Anatomic; D019637:Orthopedic Procedures / Q000295:instrumentation / Q000379:methods; D012600:Scoliosis / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D013131:Spine / Q000254:growth & development / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D013552:Swine
keywords: Experimental scoliosis; Finite element model; Fusionless implant; Growth modulation; Scoliosis