Schoenfeld Andrew, Vrabec Gregory, Battula Suneel, Salvator Ann, Njus Glen
Harvard Medical School/Brigham and Women's Hospital, Boston, MA 02215, USA.
Am J Orthop (Belle Mead NJ). 2008 Sep;37(9):466-9.
The cortical self-tapping screw (STS) has replaced the non-STS as an aid in fracture fixation. In a recent biomechanical investigation, Berkowitz and colleagues found that STS pullout strength increased with insertion depth up to 1 mm past the far cortex only. In the present study, we wanted to apply a standardized protocol of assessing pullout strength to STSs of different compositions and manufacturers while eliminating the sample-size and block-variance issues that affected the previous investigation. Ninety STSs were randomly divided into 5 groups, each representing a different insertion depth. Peak force was determined with trials ending in screw pullout or failure. A statistically significant difference in pullout strength was identified with insertion depths up to 1 mm past the far cortex. No block variance was detected. These results support the recommendation that STSs be inserted only 1 mm past the far cortex in healthy cortical bone.
皮质自攻螺钉（STS）已取代非STS用于骨折固定。在最近的一项生物力学研究中，伯克维茨及其同事发现，只有当插入深度超过远侧皮质1毫米时，STS的拔出强度才会随着插入深度的增加而增加。在本研究中，我们希望应用一种标准化方案来评估不同成分和制造商的STS的拔出强度，同时消除影响先前研究的样本量和块方差问题。90枚STS被随机分为5组，每组代表不同的插入深度。通过以螺钉拔出或失效结束的试验来确定峰值力。在插入深度超过远侧皮质1毫米时，拔出强度存在统计学上的显著差异。未检测到块方差。这些结果支持以下建议：在健康的皮质骨中，STS仅应插入超过远侧皮质1毫米。
