Department of Orthopaedic Surgery, St Louis University, St Louis, MO 63110, USA.
J Orthop Trauma. 2012 Apr;26(4):222-5. doi: 10.1097/BOT.0b013e31822421f7.
No study to date has evaluated cortical thickness as it relates to locking plate failure or screw pullout in the proximal humerus. The purpose of this study is to determine the relationship between proximal humerus cortical thickness and locked plate hardware failure in a cadaveric proximal humerus fracture model.
Twelve humerus specimens were placed into two groups based on the proximal humerus cortical thickness on an anteroposterior radiograph: less than 4 mm and greater than 4 mm. The specimens were plated with a six-hole proximal humerus locking plate and a 15-mm resection osteotomy at the surgical neck was performed. The specimens were tested in a materials testing machine at a displacement of 5 mm/min to failure.
Load at failure, stiffness, maximum load, failure, and fracture gap closure were all statistically similar (P > 0.05) between the groups.
Our biomechanical study used modern locked plate-screw construct fixation of a simulated two-part proximal humerus fracture. The mechanical strength was unaffected based on a threshold combined proximal humerus cortical thickness of 4 mm.
目前尚无研究评估肱骨头近端皮质厚度与锁定钢板失败或螺钉拔出的关系。本研究旨在确定肱骨头近端皮质厚度与锁定钢板硬件失败之间的关系，建立在肱骨头骨折模型的尸体上。
根据前后位 X 线片上肱骨头近端皮质厚度，将 12 个肱骨标本分为两组：小于 4 毫米和大于 4 毫米。标本用六孔肱骨头锁定钢板固定，并在外科颈处进行 15 毫米的切除截骨。标本在材料试验机上以 5 毫米/分钟的速度进行测试，直至失效。
失效时的载荷、刚度、最大载荷、失效和骨折间隙闭合在两组之间均无统计学差异（P > 0.05）。
我们的生物力学研究使用现代锁定钢板螺钉构建固定模拟的两部分肱骨头骨折。基于 4 毫米的肱骨头近端皮质厚度阈值，机械强度不受影响。
