■周围神经损伤是反向肩关节成形术(RSA)后公认的并发症,主要在臂丛神经及其近端分支的水平进行了研究。然而,RSA对远端周围神经的影响以及肘部和腕部位置的影响尚不清楚。这项尸体研究旨在分析RSA植入和上肢位置对远端正中神经和radial神经张力的影响。假设是RSA增加了远端神经张力,这可能会进一步受到肘部和腕部位置的影响。
■解剖了9具新鲜冷冻尸体中的12个上肢。在近端手臂的正中神经中测量神经张力,弯头,和前臂远端,在肘部的radial神经中,使用定制的三点张力计。在RSA植入前后进行测量,使用半镶嵌植入物(Medacta,CastelSanPietro,瑞士)。测试了两种不同的配置,使用最小和最大的可用植入物尺寸。考虑了三个上肢关键位置(处于危险中的神经丛,神经丛缓解,和中性),进一步测试了肘部和腕部位置的影响。
■RSA植入显着增加了整个上肢的正中和radial神经张力。远端神经段特别依赖于肘部和腕部位置。处于危险位置的神经丛在所有神经段中引起最大的张力,特别是对于大的植入物配置。另一方面,神经丛缓解位置引起的张力最小。肘部弯曲是降低所有测试神经段和关键位置的神经张力的最有效方法。腕屈显著降低正中神经的神经张力,而腕部伸展减少了桡神经的张力。
■RSA显着增加了正中和radial神经的张力,并使它们更容易受到腕部和肘部定位的影响。因此,RSA后远端周围神经病变的机制可能是由于张紧神经对解剖支点的压缩增加而不是单独的神经伸长所致。肘部屈曲是降低神经张力的最有效方法,而在植入肱骨部件时应避免肘部伸展。需要进一步的研究来评估尺神经。
UNASSIGNED: Peripheral nerve injury is a recognized complication after reverse shoulder arthroplasty (RSA) that has mainly been studied at the level of the brachial plexus and its proximal branches. However, the impact of RSA on distal peripheral nerves and the influence of elbow and wrist position is not known. This cadaveric study aimed to analyze the effect of RSA implantation and upper limb position on tension in the distal median and radial nerves. The hypothesis was that RSA increased distal nerve tension, which could be further affected by elbow and wrist position.
UNASSIGNED: 12 upper limbs in 9 full fresh-frozen cadavers were dissected. Nerve tension was measured in the median nerve at the level of the proximal arm, elbow, and distal forearm, and in the radial nerve at the level of the elbow, using a customized three-point tensiometer. Measurements were carried out before and after RSA implantation, using a semi-inlay implant (Medacta, Castel San Pietro, Switzerland). Two different configurations were tested, using the smallest and largest available implant sizes. Three upper-limb key positions were considered (plexus at risk, plexus relief, and neutral), from which the effect of elbow and wrist position was further tested.
UNASSIGNED: RSA implantation significantly increased median and radial nerve tension throughout the upper limb. The distal nerve segments were particularly dependent on elbow and wrist position. The plexus at risk position induced the most tension in all nerve segments, especially with the large implant configuration. On the other hand, the plexus relief position induced the least amount of tension. Flexing the elbow was the most efficient way to decrease nerve tension in all tested nerve segments and key positions. Wrist flexion significantly decreased nerve tension in the median nerve, whereas wrist extension decreased tension in the radial nerve.
UNASSIGNED: RSA significantly increases tension in the median and radial nerves and makes them more susceptible to wrist and elbow positioning. The mechanism behind distal peripheral neuropathy after RSA may thus result from increased compression of tensioned nerves against anatomical fulcrums rather than nerve elongation alone. Elbow flexion was the most effective way to decrease nerve tension, while elbow extension should be avoided when implanting the humeral component. Further studies are needed to assess the ulnar nerve.