Biomechanical Evaluation And Clinical Application Of Pedicle Screw Augmentation In Osteoporosis

Objective 1.To investigate the effectiveness of thread design in enhancing the effect of screw fixation through in vitro experiments.2.To investigate the feasibility of increasing the internal fixation strength of cement-augmented pedicle screw(CPS)by increasing pressure.3.To investigate the clinical effect of CPS for the treatment of multiple spinal diseases with osteoporosis.Methods 1.12 of the osteoporosis modules prepared were randomly divided into 2 groups:group A and group B,inserting single-threaded pedicle screw(SPS)and single and dual-threaded pedicle screw(SDPS)separately.Mechanical tester was used to test the pull-out strength of screws.The biomechanical results of 2 groups were compared.2.12 of the osteoporosis modules prepared were randomly divided into 2 groups:group C and group D,inserting single and dual-threaded cement-augmented pedicle screw(SDCPS).The two groups were injected with bone cement at different pressures.Mechanical tester was used to test the pull-out strength of screws.The biomechanical results of 2 groups were compared.3.Retrospectively review the patients undergoing spinal surgery in our department from May 2013 to August 2016.The cases were divided into group A and B according to whether cement-augmented pedicle screw(CPS)were used.The basic data of patients,surgical indicators,clinical outcomes before and after surgery,and radiological parameters were recorded and compared between groups.Results 1.The maximum axial pull-out strength of group A and group B is 39.2±6.2 N and 38.1±6.3 N respectively,without statistical difference(P>0.05).Compared to SPS,SDPS can not significantly increase the intensity of internal fixation.2.The maximum axial pull-out strength of group C and group D is 261.8±15.7 N and 305.5±9.0 N respectively,with statistical difference(P<0.05).Compared with low-pressure injection,high-pressure injection of bone cement significantly improved the internal fixation strength of screws.3D-CT scan of the specimen shows better dispersion of cement in osteoporotic models with high pressure.3.There was no statistical difference in age,gender,and preoperative bone mineral density between the two groups.The average operation time in group B was longer than group A.There was no statistical difference in other surgical indicators.In terms of clinical results and radiological parameters,the long-term results of group B were better than group A.Conclusion 1.The single-double thread design of pedicle screws can not improve the pull-out strength of the screws in vitro biomechanical experiments.2.High-pressure injection of bone cement for CPS can effectively increase the pull-out strength of screws and improve the dispersion of cement,providing a new idea for improving the effect of pedicle screw fixation.3.The use of CPS for the treatment of multiple spinal degenerative diseases with osteoporosis is safe and effective,and can achieve satisfactory long-term results.