Esenkaya Irfan, Denizhan Yurdaer, Kaygusuz Mehmet Akif, Yetmez Mehmet, Keleştemur Mehmet Halidun
Department of Orthopedics and Traumatology (Ortopedi ve Travmatoloji Anabilim Dali), Medicine Faculty of Inönü University, Malatya, Turkey.
Acta Orthop Traumatol Turc. 2006;40(1):72-81.
We investigated the possible effects of three pedicular screws on axial pull-out strength in pedicular revision surgery.
Two study groups were formed from calf lumbar vertebrae. Initially, Alici pedicular screws with an outer diameter of 6.5 mm were applied (with or without tapping) to all the pedicles. All the pedicles were subjected to axial pull-out testing to induce pedicular insufficiency. Then, Alici pedicular screws with an outer diameter of 7 mm were applied to the left pedicles. The right pedicles in the two study groups were assigned to receive two different types of pedicular screws with an expandable (enlargeable) end, respectively. Axial pull-out testing was repeated in both groups and the results were compared with the initial pull-out strength values.
In the first group, 65% and 64% of the initial pull-out strengths were obtained with 7-mm Alici pedicular screws and with expandable pedicular screws, for the left and right pedicles, respectively. The corresponding pull-out strengths in the other study group were 70% and 68.5% of the initial values, respectively. Tapping of the screw hole entrance resulted in a mean decrease of 13% in the pull-out strength compared to screw applications without tapping.
Pedicular screw revisions using a 0.5 mm greater screw in diameter did not provide adequate screw-bone inter-face strength and pedicle filling. Similarly, expandable pedicular screws did not contribute to screw stability.
我们研究了三种椎弓根螺钉在椎弓根翻修手术中对轴向拔出强度的可能影响。
从小牛腰椎椎体组建两个研究组。最初，将外径6.5 mm的Alici椎弓根螺钉（有或无攻丝）应用于所有椎弓根。对所有椎弓根进行轴向拔出测试以诱发椎弓根功能不全。然后，将外径7 mm的Alici椎弓根螺钉应用于左侧椎弓根。两个研究组中的右侧椎弓根分别被指定接受两种不同类型的带有可扩张（可扩大）末端的椎弓根螺钉。两组均重复进行轴向拔出测试，并将结果与初始拔出强度值进行比较。
在第一组中，左侧和右侧椎弓根使用7 mm Alici椎弓根螺钉和可扩张椎弓根螺钉分别获得了初始拔出强度的65%和64%。另一研究组中的相应拔出强度分别为初始值的70%和68.5%。与未攻丝的螺钉应用相比，螺钉孔入口攻丝导致拔出强度平均降低13%。
使用直径大0.5 mm的椎弓根螺钉进行椎弓根翻修未提供足够的螺钉-骨界面强度和椎弓根填充。同样，可扩张椎弓根螺钉对螺钉稳定性没有帮助。
