The effect of instrument segments on the correction rate of lumbar scoliosis，a finite element analysis

English Keywords:Spine scoliosis  Biomechanics  Finite element analysis.

English Abstract:

  【Abstract】 Objective：To simulate the correction surgery of lumbar scoliosis by finite element analysis and investigate the effect of instrument segments on the correction rate of lumbar scoliosis．Method：A detailed three-dimensional finite element scoliotic model of L1-L5 with a Cobb angle of 40°on sagittal plane was established by using Simpleware software．Six types（group A-Ｆ）of pedicle screw instrumentations on concave side were designed on the model（of these，uniscrew placement in each vertebral body of group A-E，while biscrew placement in each vertebral body of group F）．The spinal stress and strain field during with respect to anti-rotation and the rebound in the process of correction were meassured by using software ANSYS and ADAMS software．Result：The scoliostic angle after correction was 30°，23°，25°，22°，29°and ２１°respectively for group A to E．The maximum torque was 3.1N·m，3.3N·m，4.6N·m，3.4N·m，4.2N·m and 3.3N·m，the maximum pull out force was 418N，383N，437N，395N，420N and 380N.Conclusion：Under definite circumstances，decreasing non-arc vertebrae screws can yield good correction at least in finite element model.