LEIPZIG, Germany — A novel orthosis created by combining computer aided design and manufacture, along with finite element simulation was shown to be effective compared with a traditional plaster TLSO designed for adolescent idiopathic scoliosis.
Julien Clin, PhD, department of mechanical engineering, École Polytechnique de Montréal, presented results at OTWorld from a study that included 15 patients with adolescent idiopathic scoliosis (AIS). Each patient wore both a standard plaster casted Boston orthosis, and the novel design or “Sim” orthosis, which was created using an optimized 3-D reconstruction of the trunk skeleton, and computer aided design and manufacturing (CAD/CAM) software to simulate the predicted scoliosis correction and model the final fabrication. Patients completed a questionnaire to compare each orthosis.
“The objective of the optimization process was to minimize the surface area of the brace while keeping the best correction possible,” Clin said. After the simulation, the orthosis efficiency can be evaluated to verify its quality before fabrication.
“You can evaluate the effect of the brace on the spine in the coronal plane and notably in terms of correction of the curve angles, but you can also assess the efficiency of the brace in the sagittal plane, to verify the brace will not reduce too much the kyphosis and the lordosis,” Clin said. “You can visualize the pressures exerted by the brace on the torso so you can verify the pressures are not too high and the brace will be comfortable enough, and that the patients are positioned properly. You can also visualize the distance from the skin to the brace, so in certain parts of the brace that don’t touch the skin, you can remove this part of the brace to create a lighter and more comfortable brace.”
Average Cobb angle before applying the orthoses was 31° for the main thoracic curve (MT) and 32° for the thoraco-lumbar/lumbar curve (TL/L). According to study results, the novel orthosis reduced Cobb angles by 42%, whereas the standard orthosis reduced the Cobb angles by 43%. The highest pressures exerted by the novel orthosis were on the thoracic and lumbar regions and at the axillary and trochanter extensions, according to study results.
Compared with the standard orthosis, the Sim orthosis was 61% thinner and had 32% less covering surface. Eleven patients said the novel brace was more comfortable, whereas four considered both orthoses to be equivalent.
Clin said this preliminary study made it difficult to draw any conclusions; however, the simulation tool proved reliable in predicting corrections and pressures. Clin said the simulation tool may be used to help orthotists design better braces, but “it won’t replace the orthotist’s experience.”
Clin said the thinner design may lead to better treatment compliance. A randomized controlled trial is under way and “the validation is being extended to other centers in Europe and North America,” he said. — by Carey Cowles
For more information:
Clin J. Advanced brace design combining CAD/CAM and biomechanical simulation for the treatment of adolescent idiopathic scoliosis. Presented at: OT World Congress; May 12-16, 2014; Leipzig, Germany.
Disclosure: Clin has no relevant financial disclosures. Project funded by the Natural Sciences and Engineering Research Council of Canada, the Canadian Institutes of Health Research, Lagarrigue, Rodin4D and Boston Brace.