A Biomechanical Study Of An Improved Spinal Deformity Correction System For Scoliosis

Objective: To evaluate the stability of the improved spinal deformity correction system,to clarify the safety and effectiveness of the improved spinal deformity correction system and to provide theoretical basis for the clinical application and popularity of the improved spinal deformity correction system by comparing the biomechanical parameters of the improved spinal deformity correction system and pedicle screw and rod system in vitro.Methods: Collect five lumbar(L)specimens from fresh frozen adult cadavers.Each specimen includes five segments(L1-L5)and the range of motion(ROM)of each specimen would be tested in three conditions including complete specimen,the condition fixed with transverse process hook and rod system and the condition fixed with pedicle screw and rod system.Through the spinal three dimensions motion system,a moment of 8 N · m was applied to the lumbar specimens to produce activity in six directions including flexion,extension,left bending,right bending,left axial rotation and right axial rotation.The ROM of segments L2/3 and L3/4 in each direction was tested.Results:(1)In the flexion direction,the ROM value of the pedicle screw group significantly reduced comparing with the complete specimen group and the transverse process hook and rod system group,while there was no significant difference on the ROM value between the complete specimen group and the transverse process hook and rod system;In the extension direction,the ROM value of the pedicle screw group was lower than the complete specimen group or transverse process hook and rod system group.In addition,the difference of the ROM value between the complete specimen group and the transverse process hook and rod system group was not significant.(2)In the bilateral bending direction,there was nostatistically significant difference in the ROM value between the transverse process hook and rod system group and pedicle screw and rod system group,and the ROM value of both internal fixation groups were lower than the complete specimen group.(3)In the left and right axial rotation direction,the ROM value of the transverse process hook and rod system group and pedicle screw and rod system group were significantly lower than those of the complete specimen group,whose difference was statistically significant;The pedicle screw and rod system group had slight advantage comparing with the transverse process hook and rod system group in controlling the activity of the axial rotation direction.Conclusion:(1)The improved transverse process hook and rod system has advantages of implanting easily and safety.(2)Comparing with the pedicle screw and rod system,the improved transverse process hook and rod system can provide similar stability of the spine on the coronal plane and horizontal plane.