Effectiveness of braces designed using computer-aided design and manufacturing (CAD/CAM) and finite element simulation compared to CAD/CAM only for the conservative treatment of adolescent idiopathic scoliosis: a prospective randomized controlled trial.

PURPOSE: Clinical assessment of immediate in-brace effect of braces designed using CAD/CAM and FEM vs. only CAD/CAM for conservative treatment of AIS, using a randomized blinded and controlled study design. METHODS: Forty AIS patients were prospectively recruited and randomized into two groups. For 19 patients (control group), the brace was designed using a scan of patient's torso and a conventional CAD/CAM approach (CtrlBrace). For the 21 other patients (test group), the brace was additionally designed using finite element modeling (FEM) and 3D reconstructions of spine, rib cage and pelvis (NewBrace). The NewBrace design was simulated and iteratively optimized to maximize the correction and minimize the contact surface and material. RESULTS: Both groups had comparable age, sex, weight, height, curve type and severity. Scoliosis Research Society standardized criteria for bracing were followed. Average Cobb angle prior to bracing was 27° and 28° for main thoracic (MT) and lumbar (L) curves, respectively, for the control group, while it was 33° and 28° for the test group. CtrlBraces reduced MT and L curves by 8° (29 %) and 10° (40 %), respectively, compared to 14° (43 %) and 13° (46 %) for NewBraces, which were simulated with a difference inferior to 5°. NewBraces were 50 % thinner and had 20 % less covering surface than CtrlBraces. CONCLUSION: Braces designed with CAD/CAM and 3D FEM simulation were more efficient and lighter than standard CAD/CAM TLSO's at first immediate in-brace evaluation. These results suggest that long-term effect of bracing in AIS may be improved using this new platform for brace fabrication. TRIAL REGISTRATION: NCT02285621.

Preoperative planning simulator for spinal deformity surgeries.

STUDY DESIGN: Proof of concept of a spine surgery simulator (S3) for the assessment of scoliosis instrumentation configuration strategies. OBJECTIVE: To develop and assess a surgeon-friendly spine surgery simulator that predicts the correction of a scoliotic spine as a function of the patient characteristics and instrumentation variables. SUMMARY OF BACKGROUND DATA: There is currently no clinical tool sufficiently user-friendly, reliable and refined for the preoperative planning and prediction of correction using different instrumentation configurations. METHODS: A kinetic model using flexible mechanisms has been developed to represent patient-specific spine geometry and flexibility, and to simulate individual substeps of correction with an instrumentation system. The surgeon-friendly simulator interface allows interactive specification of the instrumentation components, surgical correction maneuvers and display of simulation results. RESULTS: The simulations of spinal instrumentation procedures of 10 scoliotic cases agreed well with postoperative results and the expected behavior of the instrumented spine (average Cobb angle differences of 3.5 degrees to 4.6 degrees in the frontal plane and of 3.6 degrees to 4.7 degrees in the sagittal plane). Forces generated at the implant-vertebra link were mostly below reported pull-out values, with more important values at the extremities of the instrumentation. CONCLUSION: The spine surgery simulator S3 has proven its technical feasibility and clinical relevance to assist in the preoperative planning of instrumentation strategies for the correction of scoliotic deformities.