垂直的
斜格
骨合成
固定装置
医学
固定(群体遗传学)
口腔正畸科
悬臂梁
复合材料
材料科学
机械工程
几何学
人口
哲学
语言学
数学
环境卫生
工程类
作者
Robert Waldrop,W. G. Wood,Brian P. Cunningham,Ryan McLemore,A. C. McLaren
标识
DOI:10.1097/bot.0000000000000642
摘要
The technique of placing an oblique screw in the terminal hole of a plate to increase screw pullout strength is widely taught in the operating room. The origin of this technique is unclear; however, it may have been used simply as a means to identify radiographs and misinterpreted to have some biomechanical benefit. The objective of this study was to measure the structural effect of oblique terminal screw placement (OTSP) during plate osteosynthesis. Foam blocks and limited contact dynamic compression plates and screws were used along with a custom fixture device. The terminal screw was placed in either an oblique (30-degree angle outward) or perpendicular fashion. A load was applied perpendicular to the plate in cantilever bending until failure. The oblique screw construct was significantly weaker than the perpendicular screw construct (399N vs. 465N, P < 0.001), independent of the block of material used. Post hoc analysis showed that the screw angle (P < 0.001) was a significant determinant of the load required to cause screw pullout. OTSP led to a decrease in pullout strength compared with a perpendicular screw in a deformable foam medium similar in density to osteoporotic bone. In patients with poor bone quality, OTSP may create a suboptimal fracture fixation construct.
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