Department of Orthopedic Surgery, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8521, Japan.
Department of Hand Surgery, Nara Medical University, 840 Shijo-cho, Kashihara, Nara, 634-8521, Japan.
BMC Musculoskelet Disord. 2022 Sep 1;23(1):829. doi: 10.1186/s12891-022-05786-9.
Cubital tunnel syndrome can be caused by overtraction and dynamic compression in elbow deformities. The extent to which elbow deformities contribute to ulnar nerve strain is unknown. Here, we investigated ulnar nerve strain caused by cubitus valgus/varus deformity using fresh-frozen cadavers.
We used six fresh-frozen cadaver upper extremities. A strain gauge was placed on the ulnar nerve 2 cm proximal to the medial epicondyle of the humerus. For the elbow deformity model, osteotomy was performed at the distal humerus, and plate fixation was performed to create cubitus valgus/varus deformities (10°, 20°, and 30°). Ulnar nerve strain caused by elbow flexion (0-125°) was measured in both the normal and deformity models. The strains at different elbow flexion angles within each model were compared, and the strains at elbow extension and at maximum elbow flexion were compared between the normal model and each elbow deformity model. However, in the cubitus varus model, the ulnar nerve deflected more than the measurable range of the strain gauge; elbow flexion of 60° or more were considered effective values. Statistical analysis of the strain values was performed with Friedman test, followed by the Williams' test (the Shirley‒Williams' test for non-parametric analysis).
In all models, ulnar nerve strain increased significantly from elbow extension to maximal flexion (control: 13.2%; cubitus valgus 10°: 13.6%; cubitus valgus 20°: 13.5%; cubitus valgus 30°: 12.2%; cubitus varus 10°: 8.3%; cubitus varus 20°: 8.2%; cubitus varus 30°: 6.3%, P < 0.001). The control and cubitus valgus models had similar values, but the cubitus varus models revealed that this deformity caused ulnar nerve relaxation.
Ulnar nerve strain significantly increased during elbow flexion. No significant increase in strain 2 cm proximal to the medial epicondyle was observed in the cubitus valgus model. Major changes may have been observed in the measurement behind the medial epicondyle. In the cubitus varus model, the ulnar nerve was relaxed during elbow extension, but this effect was reduced by elbow flexion.
肘管综合征可由肘部畸形的过度牵引和动态压迫引起。肘部畸形对尺神经张力的影响程度尚不清楚。在这里，我们使用新鲜冷冻的尸体研究了尺骨外翻/内翻畸形引起的尺神经张力。
我们使用了六个新鲜冷冻的尸体上肢。在肱骨内上髁近端 2cm 处放置应变计。对于肘畸形模型，在远端肱骨处进行截骨，并用钢板固定以创建尺骨外翻/内翻畸形（10°、20°和 30°）。在正常和畸形模型中测量肘弯曲（0-125°）引起的尺神经张力。比较每个模型在不同肘弯曲角度下的应变，比较正常模型和每个肘畸形模型在肘伸展和最大肘弯曲时的应变。然而，在尺骨内翻模型中，尺神经的偏转而超过应变计的可测量范围；60°或更大的肘弯曲被认为是有效值。使用 Friedman 检验对应变值进行统计学分析，然后使用 Williams 检验（用于非参数分析的 Shirley-Williams 检验）。
在所有模型中，从肘伸展到最大弯曲时，尺神经张力显著增加（对照：13.2%；尺骨外旋 10°：13.6%；尺骨外旋 20°：13.5%；尺骨外旋 30°：12.2%；尺骨内旋 10°：8.3%；尺骨内旋 20°：8.2%；尺骨内旋 30°：6.3%，P<0.001）。对照和尺骨外旋模型的值相似，但尺骨内旋模型表明这种畸形导致尺神经松弛。
在肘弯曲过程中，尺神经张力显著增加。在尺骨外旋模型中，在内上髁近端 2cm 处没有观察到应变的显著增加。在测量内上髁后面可能观察到较大的变化。在尺骨内翻模型中，尺神经在肘伸展时松弛，但这种效果在肘弯曲时减少。
