Establishment and validation of 3-dimensional finite element model of Lenke 1 BN idiopathic scoliosis

Abstract

Objective To set up and validate three-dimensional finite element model (FEM) of Lenke 1 BN idiopathic scoliosis based on CT images, for building ideal digitization platform for further biomechanical study. Methods An 18-year-old female Lenke 1 BN idiopathic scoliosis patient was selected as volunteer for current study. CT transverse scanning in supine position was done from T1 to caudal end in 1mm layer interval. All CT images were imported into Mimics 10.01 to form qualified AIS three-dimensional geometric model after geometry clean, including all thoraco-lumbar-sacral vertebrae and thoracic cage, which was further delivered to Hypher Mesh 7.0 to build 3d finite element AIS model by mesh partition and quality control. A variety of material parameters were given to different mesh according to references. Validation verification was done by left and right Bending test and erect-supine test. Results 1 )A complete three-dimensional finite element model of Lenke 1 BN idiopathic scoliosis was built successfully, in consist of 341 228 nodes,1 409 929 tetrahedron elements, 163 132 shell elements, 715 cable elements and 149 rod elements. 2)The convex bending Cobb's angles of PT, MT and L curve on X-ray films and finite element simulation were 14°,26° ,8° and 15° ,24°,6° respectively. The error of finite element simulation was 8.3%. 3)Erect Cobb's angles of PT, MT and L were 37°, 50°, 24° and 33°, 51°, 24° on X-ray films and by finite element simulation.Supine Cobb's angles of PT, MT and L were 29°, 43°, 22° and 27°, 42°, 22° on X-ray films and by finite element simulation. The average error of finite element simulation was 3.9%. Conclusion Lenke 1 BN idiopathic scoliosis FEM is intact, reliable and effective for further biomechanical simulation study. Key words: Scoliosis; Finite element analysis; Biomechanics