Issue release date: 12.11.2024
Part I. Evaluation of Pedcile Screw Pullout Strength
2Spine Research Laboratory, The Cleveland Clinic Foundation, Cleveland, OH, USA
3Department of Neurosurgery, School of Medicine, İnönü University, Malatya,Turkey
4Department of Neurosurgery, School of Medicine, Ege University, İzmir,Turkey OBJECTIVE: To determine the pullout strength of a Turkish-made pedicle screw (Tıpsan Posterior Instrumentation System, Tıpsan Tıbbi Aletler, İzmir, Turkey) compared to another well-known system (VSP System, DePuy AcroMed, Raynham, MA, USA).
METHODS: A series of pedicle screw axial pullout tests were performed in 14-week-old calf vertebrae. A sample size of 8 for both screw types was used to quantify pullout performance determined by peak load and stiffness.
RESULTS: The mean peak loads were 1892 ± 554 N for Tıpsan and 1959 ± 594 N for VSP screws. The difference was statistically insignificant (p>0.05). The mean stiffness values were also similar for the two screw types: 1063 ± 192 N for Tıpsan and 1126 ± 155.8 N for VSP screws (p>0.05). The mean insertional torque of the Tıpsan screw (3.89 ± 0.66 Nm) was significantly greater than those of VSP screws (2.68 ± 0.57 Nm) (p=0.0016).
CONCLUSION: Tıpsan screws provided sufficient pullout strength when compared to another well-known system as demonstrated by the similar peak load and stiffness results. The authors therefore consider the Tıpsan screw to be equal to its imported counterpart for use in a pedicle fixation system.
Keywords : Biomechanics, bone screws, lumbar vertebrae, testing, torque