Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan; Department of Orthopaedic Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan; Division of Traumatology, National Cheng Kung University Medical Center, Tainan, Taiwan; Skeleton Materials and Bio-compatibility Core Lab, Research Center of Clinical Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Department of Biomedical Engineering, National Cheng Kung University, Tainan, Taiwan.
J Shoulder Elbow Surg. 2022 Sep;31(9):1947-1956. doi: 10.1016/j.jse.2022.02.031. Epub 2022 Apr 6.
The Latarjet procedure is a reliable treatment for the management of anterior glenohumeral instability with glenoid bone loss. However, the biomechanical properties of different fixation angles between screw and glenoid surface (α angle) have rarely been studied. The aim of the study was to investigate and compare the fixation stability, failure load, and failure mechanism between different α angles for Latarjet procedures, which were performed on cadaver specimens.
Twenty-four shoulder specimens (8 in each of 3 groups) were dissected free of all soft tissue, and a 25% glenoid defect was created. The coracoid process was osteomized and fixed with 2 screws at 3 different α angles: 0° (group A), 15° (group B), and 30° (group C). Specimens were mounted to a testing apparatus, and cyclic loading (100 cycles at 1 Hz) was applied with a staircase protocol (50, 100, 150, and 200 N). Gross graft displacement and interface displacement were measured. The ultimate failure loads and failure mechanisms were recorded.
There was no significant difference in gross displacement under any cyclic load between 3 groups. However, a significant larger interface displacement was noted in group C than in group A in 150-N cyclic loading (P = .017). Under failure strength testing, all 24 specimens failed because of screw cutout from the glenoid, and the ultimate failure load was similar among the three groups.
Compared with the 0° α angle, the displacement after cyclic loading did not significantly increase when the α angle was increased to 15° but significantly increased at 30° for Latarjet procedures, which were performed on cadaver specimens. The results suggest that surgeons should apply the screws as parallel as possible to the glenoid surface when performing the Latarjet procedure. Although mild deviation may not reduce fixation stability, α angles greater than 30° should be avoided.
Latarjet 手术是治疗伴盂肱关节前向不稳定和盂骨缺损的可靠方法。然而，螺钉与盂骨表面之间不同固定角度（α角）的生物力学特性鲜有研究。本研究旨在探讨和比较不同 α 角 Latarjet 手术的固定稳定性、失效负荷和失效机制，研究对象为尸体标本。
24 个肩关节标本（每组 8 个）均游离所有软组织，造成 25%盂骨缺损。喙突骨块被截骨并以 3 种不同 α 角（0°组 A、15°组 B 和 30°组 C）用 2 枚螺钉固定。标本安装在测试装置上，以 1 Hz 的频率施加 100 个循环的循环加载，并采用逐步递增协议（50、100、150 和 200 N）。测量总移植物位移和界面位移。记录最终失效负荷和失效机制。
在任何循环负荷下，3 组的总位移均无显著差异。然而，在 150 N 循环加载下，组 C 的界面位移明显大于组 A（P=0.017）。在失效强度测试中，所有 24 个标本均因螺钉从盂骨中脱出而失效，3 组的最终失效负荷相似。
与 0° α 角相比，当 α 角增加到 15°时，循环加载后的位移虽无显著增加，但在尸体标本上进行 Latarjet 手术时增加到 30°时会显著增加。结果表明，外科医生在行 Latarjet 手术时，螺钉应尽可能与盂骨表面平行。虽然轻微的偏离可能不会降低固定稳定性，但应避免 α 角大于 30°。
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