BACKGROUND Compared to other types of surgeries, minimally invasive surgeries (MISs) of humeral shaft fractures are associated with less radial nerve injury, less soft tissue injury and higher union rate. However, malrotation often occurs in MISs when closed reduction methods are used. This study aims to define specific palpable landmarks to help surgeons determine the correct torsional angle and reduce the incidence of malrotation. METHODS Twenty-eight normal humeral computed tomography scans were retrieved from our image database. One line was drawn through the vertices of the intertubercular sulcus of the humeral head in the coronal view, and another line was drawn through the longest axis between the medial and lateral condyles in the coronal view. The angle between these two lines was measured at least 3 times for each scan. RESULTS The profile of the intertubercular sulcus tangent line of the humeral head and the axis of the distal humerus was identified as the most accurate method for assessing the precision of torsion during MIS for humeral shaft fractures. The transepicondylar axis line is more internally rotated than the intertubercular sulcus tangent line. The mean angle was measured to be 41.1 degrees. CONCLUSIONS The axis of the distal humeral condyles is internally rotated by approximately 41.1 degrees compared with the intertubercular sulcus tangent line of the humeral head. Minimally invasive surgeries can be performed by using these palpable landmarks. The torsional deformities can be reduced with the proper angle adjustment without the need for fluoroscopy. It can also be used to treat unstable comminuted humeral fractures. LEVEL OF EVIDENCE Retrospective Study, Diagnostic study, Level III.

中文翻译：

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用于评估肱骨扭转排列的几何分析。

背景与其他类型的手术相比，肱骨干骨折的微创手术（MIS）具有较少的桡神经损伤、较少的软组织损伤和较高的愈合率。然而，当使用闭合复位方法时，MIS 中经常发生旋转不良。本研究旨在定义特定的可触及标志，以帮助外科医生确定正确的扭转角度并减少旋转不良的发生率。方法 从我们的图像数据库中检索 28 个正常肱骨计算机断层扫描。一条线穿过冠状视图中肱骨头结节间沟的顶点，另一条线穿过冠状视图中内侧髁和外侧髁之间的最长轴。每次扫描至少测量这两条线之间的角度 3 次。结果 肱骨头结节间沟切线与肱骨远端轴线的轮廓被认为是评估肱骨干骨折 MIS 期间扭转精度的最准确方法。经上髁轴线比结节间沟切线更内旋。测量的平均角度为 41.1 度。结论 与肱骨头结节间沟切线相比，肱骨远端髁轴内旋约41.1°。可以利用这些可触及的标志进行微创手术。通过适当的角度调整可以减少扭转畸形，无需透视。它还可用于治疗不稳定的粉碎性肱骨骨折。证据级别 回顾性研究，诊断性研究，III 级。