Tosun Bilgehan, Snmazçelik Tamer, Buluç Levent, Cürgül Ismail, Sarlak Ahmet Yilmaz
Department of Orthopaedics and Traumatology, School of Medicine, Kocaeli University, Turkey.
Spine (Phila Pa 1976). 2008 Sep 1;33(19):E667-72. doi: 10.1097/BRS.0b013e31817c4f9c.
The axial pullout strength of pedicle screws that were at different temperatures when inserted was compared in calf vertebrae.
To determine if insertional temperature of the screw itself affects pullout strength.
Fixation stability of pedicle screws depend on several factors. The development of alternate insertion techniques and screw designs were used to improve the stability. Polymethylmethacrylate and calcium sulfate augmentation have been shown to be viable options for improving fixation; but have the potential disadvantages.
Three cadaveric thoracic calf spines were instrumented between T1-T10 bilaterally with one type of pedicle screws stored at different insertional temperatures. The axial pullout tests were performed at cross head speed of 5 mm/min. Pullout loads and displacement were recorded at 1/20 seconds intervals until failure occurred.
The highest pullout force was obtained with the screws inserted at 4 degrees C. These screws had a 19% increase in pullout strength compared with the screws inserted at 24 degrees C. The highest force/torque proportion was gained in the same group as 0.30 kn/Nm.
The technique showed increased pullout force with the screws inserted at 4 degrees C. Using pedicle screws stored at 4 degrees C before instrumentation, seems reasonable in an attempt to obtain a better bone-screw interface.
比较在小牛椎骨中插入时处于不同温度的椎弓根螺钉的轴向拔出强度。
确定螺钉本身的插入温度是否会影响拔出强度。
椎弓根螺钉的固定稳定性取决于几个因素。替代插入技术和螺钉设计的发展被用于提高稳定性。聚甲基丙烯酸甲酯和硫酸钙增强已被证明是提高固定效果的可行选择，但也有潜在的缺点。
在3具尸体小牛胸段脊柱的T1-T10双侧植入一种在不同插入温度下保存的椎弓根螺钉。轴向拔出试验以5毫米/分钟的十字头速度进行。每隔1/20秒记录拔出载荷和位移，直至发生破坏。
在4℃插入的螺钉获得了最高的拔出力。与在24℃插入的螺钉相比，这些螺钉的拔出强度提高了19%。在同一组中获得了最高的力/扭矩比例，为0.30千牛/牛米。
该技术显示在4℃插入螺钉时拔出力增加。在植入前使用保存在4℃的椎弓根螺钉，似乎是获得更好的骨-螺钉界面的合理尝试。
