Department of Orthopaedic Surgery, Sports Medicine and Rehabilitation, Wright State University, Boonshoft School of Medicine, Dayton, OH, USA.
J Shoulder Elbow Surg. 2010 Jun;19(4):495-501. doi: 10.1016/j.jse.2009.11.003. Epub 2010 Mar 1.
Locking plates have emerged as the implant of choice for stabilization of proximal humeral fractures. The biomechanical properties of a locked plating system using smooth pegs vs threaded screws for fixation of the humeral head were compared to test the hypothesis that there would be no biomechanical difference between pegs and threaded screws.
Sixteen pairs of fresh frozen cadaveric humeri were randomized to have a surgical neck gap osteotomy stabilized with a locked plate using threaded screws (n=8) or smooth pegs (n=8). The intact contralateral humerus served as a control. Each specimen was tested with simultaneous cyclic axial compression (40 Nm) and torsion (both +/-2 Nm and +/-5 Nm) for 6000 cycles. All specimens were loaded to failure. Interfragmentary motion and load-displacement curves were analyzed to identify differences between the groups. Our data were then compared to previously published forces across the glenohumeral joint to provide evidence based recommendations for postoperative use of the shoulder.
There was a statistically significant difference between test specimens and their paired control (P < .001) in cyclic testing and load to failure. Differences between the smooth pegs and threaded screws were not statistically significant.
There is no biomechanical difference between locked smooth pegs and locked threaded screws for proximal fragment fixation in an unstable 2-part proximal humeral fracture model.
Our study contributes to the published evidence evaluating forces across the glenohumeral joint and suggests that early use of the affected extremity for simple activities of daily living may be safe. Use of the arm for assisted ambulation requiring a crutch, cane, walker, or wheelchair should be determined on a case-by-case basis.
对于稳定肱骨近端骨折，锁定钢板已成为首选的植入物。本研究旨在比较使用光滑钉和螺纹螺钉固定肱骨头的锁定接骨板系统的生物力学特性，以验证光滑钉和螺纹螺钉之间不存在生物力学差异的假设。
将 16 对新鲜冷冻的尸体肱骨随机分为两组，分别使用螺纹螺钉（n=8）或光滑钉（n=8）固定锁定钢板以稳定外科颈间隙骨折。对侧完整肱骨作为对照。每个标本均进行同步轴向循环压缩（40 Nm）和扭转（正、负 2 Nm 和正、负 5 Nm）测试，共 6000 个循环。所有标本均加载至失效。分析断端间活动度和载荷-位移曲线，以确定组间差异。将我们的数据与先前发表的盂肱关节力进行比较，为术后肩部使用提供循证建议。
在循环测试和失效载荷方面，实验组与配对对照组之间存在显著差异（P <.001）。光滑钉与螺纹螺钉之间的差异无统计学意义。
在不稳定的 2 部分肱骨近端骨折模型中，对于不稳定的近端骨折，锁定的光滑钉和锁定的螺纹螺钉在固定近端骨折块方面没有生物力学差异。
本研究为评估盂肱关节力的已发表证据做出了贡献，并表明早期在简单的日常活动中使用受累肢体可能是安全的。对于需要拐杖、手杖、助行器或轮椅辅助步行的活动，应根据具体情况确定使用手臂。
