Spinner R J, An K N, Kim K J, Goldner R D, O'Driscoll S W
Department of Neurologic Surgery, Mayo Clinic Foundation, Rochester, Minn 55905, USA.
J Shoulder Elbow Surg. 2001 Nov-Dec;10(6):561-7. doi: 10.1067/mse.2001.118006.
Medial and lateral snapping (dislocation) of the distal triceps over the epicondyle during elbow flexion has been reported but is frequently misdiagnosed and is not well understood. In this study a mathematical model was designed to simulate the effect that bony abnormalities at the distal humerus and soft tissue variations of the distal triceps have on the line of pull of the triceps. The predictions were then tested on prefabricated and fabricated plastic elbow models, as well as 8 cadaveric elbows. When the bony alignment was altered, varus angulation had the greatest effect: 30 degrees varus malalignment of the distal humerus displaced the centroid of the triceps vector medially by approximately 2.0 cm. Valgus malalignment had a lesser effect: 30 degrees valgus displaced it laterally by 1.5 cm. Negligible effects on the triceps line of pull were seen with internal or external malrotation and with flexion or extension malalignment. Of the soft tissue alterations, displacement of the triceps insertion had a greater effect than movement of the triceps origin. The triceps vector was displaced by approximately 70% of the amount of translation of the triceps insertion. The relationship between the triceps line of pull and the bony alignment is represented by the triceps (T) angle. Our use of the T angle to understand snapping triceps is analogous to the use of the quadriceps (Q) angle for patellar subluxation/dislocation. Treatment should aim to restore normal triceps biomechanics with soft tissue or bony procedures.
据报道，在肘关节屈曲时，肱三头肌远端在内上髁上出现内侧和外侧弹响（脱位），但这种情况经常被误诊，人们对此也没有很好的理解。在本研究中，设计了一个数学模型来模拟肱骨远端的骨质异常和肱三头肌远端的软组织变化对肱三头肌拉力线的影响。然后在预制和制作的塑料肘关节模型以及8个尸体肘关节上对这些预测进行了测试。当骨对线改变时，内翻成角的影响最大：肱骨远端30度内翻畸形使肱三头肌向量的质心向内移位约2.0厘米。外翻畸形的影响较小：30度外翻使其向外移位1.5厘米。内旋或外旋以及屈伸畸形对肱三头肌拉力线的影响可忽略不计。在软组织改变中，肱三头肌止点的移位比肱三头肌起点的移动影响更大。肱三头肌向量移位的距离约为肱三头肌止点平移量的70%。肱三头肌拉力线与骨对线之间的关系由肱三头肌（T）角表示。我们使用T角来理解肱三头肌弹响类似于使用股四头肌（Q）角来评估髌骨半脱位/脱位。治疗应旨在通过软组织或骨手术恢复正常的肱三头肌生物力学。
