Department of Orthopedic Surgery, College of Medicine, Soonchunhyang University Gumi Hospital, Gumi, Republic of Korea.
Convergence Material Research Center, Innovative Technology Research Division, Gumi Electronics & Information Technology Research Institute (GERI), Gumi, Republic of Korea.
Medicine (Baltimore). 2022 Jul 29;101(30):e29319. doi: 10.1097/MD.0000000000029319.
The risk of displaced and comminuted midshaft clavicle fractures is increased in high-energy traumas such as sport injuries and traffic accidents. Open reduction and plate fixation have been widely used for midshaft clavicle fractures. Among various plates for clavicle shaft fractures, superior locking compression plates (LCPs) have been mostly used. In plate fixation, nonunion caused by implant failure is the most difficult complication. The most common reasons for metal plate failure are excessive stress and stress concentration caused by cantilever bending. These causes were easily addressed using a locking screw cap (LSC).
The clavicle 3-dimensional image was made from a computed tomography scan, and the clavicle midshaft fracture model was generated with a 10-mm interval. The fracture model was fixed with a superior LCP, and finite element analysis was conducted between the presence (with LSC model) and absence (without LSC model) of an LSC on the site of the fracture. The stresses of screw holes in models with and without LSCs were measured under 3 forces: 100 N cantilever bending force, 100 N axial compression force, and 1 N·m axial torsion force. After the finite element analysis, a validation test was conducted on the cantilever bending force known as the greatest force applied to superior locking plates.
The mean greatest stress under the cantilever bending force was significantly greater than other loading forces. The highest stress site was the screw hole edge on the fracture site in both models under the cantilever bending and axial compression forces. Under the axial torsional force, the maximum stress point was the lateral first screw hole edge. The ultimate plate stress of the with LSC model is completely lower than that of the without LSC model. According to the validation test, the stiffness, ultimate load, and yield load of the with LSC model were higher than those of the without LSC model.
Therefore, inserting an LSC into an empty screw hole in the fracture area reduces the maximum stress on an LCP and improves biomechanical stability.
在诸如运动损伤和交通事故等高能创伤中，移位和粉碎性锁骨中段骨折的风险增加。切开复位和钢板固定已广泛用于锁骨中段骨折。在各种锁骨骨干钢板中，最常使用的是上锁定加压钢板（LCP）。在钢板固定中，由于植入物失败导致的不愈合是最困难的并发症。金属板失败的最常见原因是由于悬臂弯曲引起的过度应力和应力集中。这些问题很容易通过锁定螺钉帽（LSC）来解决。
从计算机断层扫描中制作锁骨三维图像，并以 10mm 的间隔生成锁骨中段骨折模型。用 superior LCP 固定骨折模型，并在骨折部位有无 LSC（有无 LSC 模型）的情况下进行有限元分析。在有和没有 LSC 的模型中，测量螺钉孔在 3 种力下的应力：100N 悬臂弯曲力、100N 轴向压缩力和 1N·m 轴向扭转力。在有限元分析之后，对已知是施加在上锁钢板上的最大力的悬臂弯曲力进行了验证试验。
在悬臂弯曲力下，平均最大应力明显大于其他加载力。在悬臂弯曲和轴向压缩力下，两个模型中最高的应力部位是骨折部位的螺钉孔边缘。在轴向扭转力下，最大应力点是外侧第一个螺钉孔边缘。带 LSC 模型的最终板应力完全低于不带 LSC 模型的板应力。根据验证试验，带 LSC 模型的刚度、极限载荷和屈服载荷均高于不带 LSC 模型。
因此，在骨折区域的空螺钉孔中插入 LSC 可以降低 LCP 的最大应力并提高生物力学稳定性。
