Choice Fusion Therapy of Pumc IId2 Adolescent Idiopathic Scoliosis a Finite Element Analysis of Optimal Fusion Segment

BACKGROUND: At present, experimental animal models of primate idiopathic scoliosis with erect feet have not been established. With rapid development of computer and imaging, we can use computer software to simulate models of human idiopathic scoliosis, and do relevant biomechanical analysis and provide instructions for clinical surgery operation. OBJECTIVE: To research the best surgical fusion level for the adolescent idiopathic scoliosis (AIS) of PUMC Ⅱd2 with the finite element model (FEM). DESIGN, TIME AND SETTING: The comparison observation was performed at the Department of Orthopedics, Beijing Union Hospital from May 2007 to May 2008. PARTICIPANTS: One female patient with PUMC Ⅱd2 scoliosis (double curve malformation) was included. METHODS: FEM (T5-S) of PUMC Ⅱd2 idiopathic scoliosis was used to simulate upper thoracic curve, lower lumbar curve and double curve fusion manners. Hollow lateral curvature pedicle of vertebral arch received 50, 100, 150 N load. Displacement of T5 and T11 on upper sagittal plane (displacement of Z axis positive value on upper sagittal plane, displacement of negative value on lower sagittal plane) and their difference value were compared. T5 displacement represented outcomes of double curve orthopaedics. T11 displacement represented outcomes of lower lumbar curve orthopaedics. Their difference value (T5-T11) represented outcomes of upper thoracic curve orthopaedics. MAIN OUTCOME MEASURES: Different fusion segments and displacement of T5 and T11 under different orthopedic forces were measured. RESULTS: In PUMCⅡd2 lateral curvature, T5 displacement on Z axis: fusion displacement of double curves was greater compared with upper curve alone or lower curve alone (P＜0.01). Difference of T5-T11 displacement: double curves orthopaedics＞upper thoracic curve orthopaedics alone＞lower lumbar curve orthopaedics alone (P＜0.01). Displacement of T11 on Z axis: double curves orthopaedics＞lower lumbar curve orthopaedics alone＞upper thoracic curve orthopaedics alone (P＜0.01). CONCLUSION: Fusing two curves would get the best effect on the AIS of PUMCⅡd2 compared with upper curve alone or lower curve fusion alone. Effects of 3 kinds of load on correction of upper thoracic curve: double curve orthopaedics＞upper thoracic curve orthopaedics alone＞lower lumbar curve orthopaedics alone. Effect of 3 kinds of load on correction of lower lumbar curve orthopaedics alone: double curve orthopaedics＞lower lumbar curve orthopaedics alone＞upper thoracic curve orthopaedics alone. Three-dimensional finite element analysis is an effective method to analyze biomechanics of scoliosis deformity correction and provides a virtual non-invasive verification manner, and can optimize surgery scheme.