| 【Background】Adolescent idiopathic scoliosis (AIS) was a3-dimensional deformity of the spineand the causes were unknown. AIS was defined as a curve of at least10°, which wasmeasured on a standing radiograph using the Cobb technique. AIS had a negativeimpact on adolescents, if it wasn’t found and treated timely, the curve can beprogressive. AIS may have impact on patients’ body appearance, cardio-pulmonaryfunction and psychological health, which gave great burden to family and society.Bracing therapy was the only effective conservative treatment. There were manyproblems about bracing therapy, including bad comfort, no3-dimensional orthopedicand individualization and so on. Our research group had accomplished the theoreticalstudy and the design of appearance, and the air sac brace was proposed innovatively,which can improve the comfort of brace. The conventional brace treated patientsmainly focused on the coronal plane and had limited effect on the saggital plane. Iteven leaded to flat deformity if patients wear brace for a long time. Piet et al reportedthat forced lordosis on the thoracolumbar junction could correct coronal planedeformity in adolescents idiopathic scoliosis, while it had effect on the saggital plane.These results may have profound consequences on bracing therapy of scoliosis, butthe relative study was few.Finite element method made use of image to perform digital simulation, withwhich we can established the scoliosis mode and simulated the treatment of brace.The relative report confined on the coronal and the study on the saggital was very few.【Objectives】Computer techniques were used to establish three dimensional finite elementmodels, based on the patient’s CT image. After parameters optimization andvalidation, the finite element model was used to simulate brace treatment by forcingon the model respectively on the coronal plane, saggital plane and both planes. The change of relative parameters was recorded, exploring the optimum scheme of brace.【Methods】1. Establishment of the3-dimensional finite element model of AISA14-year-old female AIS patient was choosed as volunteer for the study. CTscanning was performed from C7to caudal end of spine. The CT images wereimported into software of Mimics10.0to establish a3-dimensional model aftergeometry clean. Then the geometry model was imported into software ANSYS11.0tobuild3-dimensional double curve AIS model. The parameters were optimized andverified. Choose divided spine to apply load to compare with related results ofbiomechanics empirical study．2. Simulation of individual type of three dimensional orthopedic and treatmenteffect.Based on the scoliosis FEM, the FEM of the individual brace was simulated andthe geometry of spine, thorax, pelvic and trunk appearance were composited together,in order to establish the realistic model. The force was applied on the coronal plane,saggital plane and both plane respectively. The relative parameters were recorded.【Results】1. The3-dimensional finite element model of AIS was established successfully,containing C7, all thoraco-lumber-sacral spine, thorax, clavicle, scapula and ligament.The model included4mesh types and15kinds of material parameters, whichcontained658503physical elements，32251shell elements，517link elements. Theestablished model of the spine showed good geometric similarity withanterior-posterior and bending X-ray. The divided segments were applied force,compared with biomechanics empirical study, the motion of the model was in therange of research.2. The brace finite element model was successfully accomplished. The force wasapplied on the coronal plane, saggital plane and both plane respectively. Thecorrective rate of thoracic curve was66%、37%、52%, while the corrective rate oflumber curve was65%、34%、53%. The latter two groups obtained better apex rotation correction and better saggital balance.【Conclusions】Based on the patients CT images, the3-dimensional finite element model ofdouble curve was established, which had similar geometry with the X-ray and wasqualified for the further brace biomechanical study.The parameters of the finite element model were optimized and verified, so themodel can reflex the realistic spine biomechanical character.The force applied on the saggital plane of brace was proposed firstly, combinedwith the force of coronal plane. Fine coronal curve and the apex rotation correctiverate were obtained, with the better saggital alignment. |
PDF Full Text Request