title: New brace design combining CAD/CAM and biomechanical simulation for the treatment of adolescent idiopathic scoliosis.
abstract: BACKGROUND
  A numerical based brace design platform, including biomechanical simulation, Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) was developed to rationalize braces for the treatment of adolescent idiopathic scoliosis. The objective of this study was to test the feasibility of the approach and assess the effectiveness of braces issued from this platform as compared to standard brace design.
  
  
  METHODS
  The biomechanical finite element model was built using the 3D reconstruction of the trunk skeleton from bi-planar radiographs and of the torso surface from surface topography. The finite element model is linked to a CAD/CAM software (Rodin4D), allowing the iterative design and simulation of the correction provided by the brace, as well as predicting pressures exerted on the torso. The resulting brace design was then fabricated using a numerical controlled carver. A brace designed using this platform (New Brace) as well as a standard thoraco-lumbo-sacral orthosis (Standard Brace) were built for six scoliotic patients. Both brace effectiveness was assessed using radiographs and compared to the simulations.
  
  
  RESULTS
  The New Brace corrected on average the spine deformities within 5° of Cobb angle of the simulated correction and with a similar correction as compared to the Standard Brace (average correction of 16° vs. 11° (MT); P=0.1 and 13° vs. 16° (TL/L); P=0.5 for the Standard Brace and the New Brace respectively). The two braces had a similar 10° lordosing effect of the thoracic curve. The coronal balance was quite similar (7.3 vs. 6.8mm balance improvement respectively for New Brace vs. Standard Brace).
  
  
  CONCLUSIONS
  These first clinical results showed the feasibility of building computer-assisted braces, equivalent to standard orthosis. An extended study on more cases is under way to fully assess this new design paradigm, which in the long term would allow improving brace design and rationalize the conservative treatments of scoliosis.
authors.affiliation: Ecole Polytechnique de Montréal, Department of Mechanical Engineering, PO Box 6079, Station Centre-ville, Montreal (Quebec), Canada H3C 3A7.
authors.forename: Frederique
authors.initials: F
authors.lastname: Desbiens-Blais
authors.forename: Julien
authors.initials: J
authors.lastname: Clin
authors.forename: Stefan
authors.initials: S
authors.lastname: Parent
authors.forename: Hubert
authors.initials: H
authors.lastname: Labelle
authors.forename: Carl-Eric
authors.initials: CE
authors.lastname: Aubin
mesh_terms: D000293:Adolescent; D001696:Biomechanical Phenomena; D001915:Braces; D002648:Child; D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design / Q000379:methods*; D005240:Feasibility Studies; D005260:Female; D020342:Finite Element Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted; D011312:Pressure; D011859:Radiography; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000628:therapy*; D012984:Software