Biomechanical study of the transitional thread pedicle screw
LIU Bin, TUN Chang-Fu, DIAO Wei-Dong, SUN Pei-Dong, BI Zhen-Yu, OU Yang-Jun
Chinese Journal of Clinical Anatomy ›› 2011, Vol. 29 ›› Issue (6) : 698-701.
Biomechanical study of the transitional thread pedicle screw
Objective To clarify the biomechanical stability of the transitional thread pedicle screw (TTPS) in spinal vertebrae. Methods For this study, 30 calf thoracolumbar vertebra（60 pedicles）, with the mean bone mineral density of (1.186±0.182）g/cm2 , were used. All the specimens were cleaned of soft tissues and separated into individual vertebrae. Each vertebra was prepared and instrumented with one of six pedicle screw. Pilot hole preparation was standardized and coaxial orientation was confirmed by direct inspection. Axial pullout was performed at 0.08mm/s displacement. The typical screw pullout load-displacement curve for the TTPS was illustrated. Results The maximum axial pullout strength of the A0, A1, A2, A3, A4 and A5 screws were (983.99±324.19) N, (1119.84±362.47)N, (1067.67±398.00)N, (900.04±255.89)N, (799.07±406.79)N, and (850.71±408.11)N, respectively. No significant difference in pullout force was noted for the six TTPS. Conclusions There are no differences of pullout strength among screw types.
Pedicle screw / Pullout experiment / Thread properties / Biomechanics
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