Design and biomechanical study of bone cement injectable canulated pedicle screw / 中华创伤杂志

ABSTRACT

ObjectiveTo investigate the design and mechanical properties of bone cement injectable canulated pedicle screw (CICPS) so as to provide a safe and effective internal fixation for osteoporotic spinal disorder.Methods ( 1 ) Bone cement injection test was performed in vitro,and within osteoporotic cancellous bone models and osteoporotic vertebrae respectively.The distribution of bone cement and screw-bone interface were observed by X-ray films and CT.(2) Ten CICPSs already injected with bone cement and ten conventional pedicle screws were respectively examined by shear strength test.(3) CICPS in the cancellous bone models was augmented with 2-3 ml of bone cement.Then,the maximum axial pull-out strength of the CICPS was measured and were compared with that of conventional screws.ResultsBone cement overflowed from each side hole of the CICPS and distributed only around the front of screws in an even and extensive way.Also,no bone cement leakage was founded.The mean shear load of CICPS and conventional screws was ( 10 600.8 ± 360.1 ) N and ( 15 458.1 ± 31 1.4) N respectively ( P ＜0.05 ).The mean maximum axial force at pull-out was ( 209.3 ± 13.3 ) N for the CICPS and ( 27.0 ± 5.0) N for the conventional screws ( P ＜ 0.05 ).Conclusions By dispersing bone cement uniformly,CICPS reduces the risk of cement leakage and significantly improves the pullout strength of screws in osteoporotic vertebrae.CICPS with good efficacy and safety provides theoretic basis for its clinical application.