Biomechanical Research Of Monosegment Pedicle Instrumentation In Spinal Tuberculosis

Objective Through biomechanical stability test of calf spine model and clinical research, explore feasibility of monosegment pedicle instrumentation (MSPI) and monosegment short pedicle instrumentation used in treatment for spinal tuberculosis;Method Calf spines were made into the mechanical test models of simulating resecting operation on spinal tuberculosis, being cut off the L1/2 intervertebral discs and the adjacent end plates, auto-iliac grafting and posterior being fixed with different method. Simulate spine motion in axial compression, lateral bending, flexion-extension and rotation and test range of movement(ROM) in all move directions. Calculate and compare relative range of movement(RROM). The research was mainly composed of four parts to discuss the stability of MSPI:(1) Compare the biomechanical properties of long segment pedicle instrumentation(LSPI), short segment pedicle instrumentation(SSPI), monosegment instrumentation with long pedicle screw (MILPS), monosegment instrumentation with short pedicle screw (MISPS): Posterior fix with LSPI,SSPI,MILPS,MISPS. Test ROM in all move directions;(2)Compare stability of MSPI with and without intervertebral bone graft: Separately test ROM of graft group and non-graft group in all directions and synchronously measure stress along the posterior internal fixation;(3)Analysis the effect of cross-linkage on monosegment pedicle instrumentation: Test ROM of the models without cross-linkage, with 1 and 2 cross-linkages in all directions;(4)Follow up 45 cases with monosegment pedicle instrumentation and analysis the curative effect.Result(1) Relative range of movement (RROM) of LSPI and SSPI were significantly smaller than that of MILPS and MISPS in all loading directions (P<0.05).However, range of movement(ROM) of MILPS and MISPS were smaller than that of control group(P<0.05); no statistical difference of the RROM was found between MISPS and MILPS(P>0.05);(2) The RROM of the models with bone graft was significantly lower than that of the ones without bone graft in axial compression, lateral bending and flexion-extension (P<0.05). However, no significant difference was found between them in rotation (P>0.05). In axial compression, lateral bending and flexion-extension the stress along the posterior internal fixation in group without bone graft was significantly increased than that in group with bone graft (P<0.05);(3) The RROM of fixation with 1 cross-linkage and 2 cross-linkages was significantly lower than that of fixation without cross-linkage in rotation (P<0.05), but there is no statistical difference in other directions (P>0.05). However, comparison of RROM between 1 and 2 cross-linkages was no significantly different in all directions (P>0.05);(4)The result of follow up showed that graft got well fused in monosegment fixation. There was no significant loss of correction angle;Conclusion(1)The stability of MILPS was significantly lower than that of LSPI and SSPI, but higher than that of control group. MILPS could reconstruct instant stability of spine; With iliac struting graft in anterior and mid column, MISPS can provide identical instant stability compare with MILPS in axial compression, lateral bending, flexion-extension and rotation;(2)Intervertebral bone graft could increase the load-sharing on the anterior and mid column , decrease stress along posterior internal fixation. It could increase the stability of spine in axial compression, lateral bending, flexion - extension, Otherwise, it effects little in rotation without interbody fusion;(3)With monosegment pedicle instrumentation, cross-linkage only increased torsional stability of spine. With 1 cross-linkage, the fixation will achieve the best effect to resist rotation;(4) The result of clinical research confirmed that bone-graft and fuse intervertebrae with monosegment pedicle instrumentation could reconstruct and sustain stability of spine effectively;...