不同体位加载下肱骨外侧髁的应力分析研究

Analysis of the stress distribution on humeral ectocondyle in different postures

目的 从生物力学角度研究肱骨外侧髁在不同体位加载下的应力分布规律 ,探讨其骨折发生机制。方法 分别制造儿童肱骨外侧髁三维有限元及光学弹性模型 ,模拟伸屈肘及前臂旋前、中立、旋后和内外翻等多种体位加载 ,计算分析和观察相应部位的应力分布状况。结果 半屈肘位时肱骨外侧髁区平均应力值最大 ,而伸肘时的伸肌腱作用节点应力值大于外侧髁区。内翻位伸肌腱作用下 ,肱骨外侧髁上部为拉应力条纹 ,内侧髁上部为压应力条纹。结论 半屈肘位时易发生以尺桡骨撞击力与重力的上下剪切作用为主的肱骨外侧髁骨折 ;伸肘内翻位时 ,以伸肌腱牵拉为主的弯力偶矩可拉脱外侧髁形成骨折。肱骨外侧髁骨折的复位可利用伸肌腱的牵拉作用 。

Objective To analyze the stress distribution on the humeral ectocondyle in different postures and study the biomechanics mechanism of humeral ectocondyle fracture.Methods Simulate 9 kinds of loading conditions to add on three dimensional finite elemental model and photo elastic model of humerus,then file out the stress state and observe the stress stripe of interference.Results At flection posture of elbow the average Mises Stress of lateral condylar area was largest while at extension posture the stress of nodes affected by extensor tendon was larger than those of lateral condyle.When extensor tendon tractive force acted at introversion posture,the upper area of medial condyle displayed pressure stress stripe while the upper area of lateral condyle displayed pulling stress stripe.Conclusion The fracture of lateral condyle of humerus occurred easily at the flection posture of elbow because of collision which radius and ulna struck humerus;At extension and introversion posture of elbow extensor tractive force could powerfully pull lateral condyle out of humerus and form fracture;We can use extensor tractive force to reduce the fracture of lateral condyle,and avoid extensor tractive force to fix it.