Background

Pulleys are crucial to convert flexor tendon excursion into angular motion at the metacarpophalangeal and interphalangeal joints. Loss of pulley function can lead to significant impairment of hand function and may require surgical reconstruction. This reconstruction can be achieved using different flexor tendons grafts, such as the intrasynovial flexor digitorum superficialis (FDS) or the extrasynovial palmaris longus (PL). However, there is limited knowledge on the micromorphology of human pulleys and the suitability of flexor tendon grafts for their reconstruction remains elusive.

Methods

In the present cadaver study A2 and A4 pulleys were compared with FDS and PL tendons by means of scanning electron microscopy (SEM), histology and immunohistochemistry. Surface morphology, core structure and vascularization of the specimens were analyzed.

Results

SEM imaging of the gliding surfaces revealed morphological differences between tendons and pulleys. Moreover, the core structure of FDS samples was characterized by bundles of individual collagen fibrils whereas PL tendons exhibited a less hierarchical microstructure. In contrast, pulleys consisted of lamellar sheets of densely packed collagen fibrils. Finally, immunohistochemical analyses revealed that the flexor tendons and pulleys contain similar numbers of CD31⁺ microvessels, indicating a comparable tissue vascularization.

Conclusion

This study provides novel SEM and immunohistochemical insights into the micromorphology of human pulleys and flexor tendon grafts. Intrasynovial flexor tendons may be particularly suitable for pulley reconstruction and preserving the paratenon may be crucial for graft revascularization.

中文翻译：

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滑轮重建的屈肌腱移植物-形态学方面。

背景

带轮对于将屈肌腱偏移转化为掌指和指间关节的角运动至关重要。滑轮功能丧失可能导致手功能严重受损，可能需要进行手术重建。这种重建可以使用不同的屈肌腱移植物来实现，例如，滑膜内指浅屈肌（FDS）或滑膜外掌长肌（PL）。然而，关于人类滑轮的微观形态的知识还很有限，屈肌腱移植物对其重建的适用性仍然难以捉摸。

方法

在本尸体研究中，通过扫描电子显微镜（SEM），组织学和免疫组织化学方法将A2和A4滑轮与FDS和PL肌腱进行了比较。分析了标本的表面形态，核心结构和血管化。

结果

滑动表面的SEM图像显示了腱和滑轮之间的形态差异。此外，FDS样品的核心结构的特征是成束的单个胶原蛋白原纤维束，而PL肌腱则显示出较少的分层微观结构。相反，滑轮由密集堆积的胶原纤维的层状薄片组成。最后，免疫组织化学分析显示，屈肌腱和滑轮含有相似数量的CD31 ⁺微血管，表明组织血管形成具有可比性。

结论

这项研究为人类滑轮和屈肌腱移植物的微观形态提供了新颖的SEM和免疫组织化学见解。滑膜内屈肌腱可能特别适合于滑轮重建，而保留椎腱对于移植血管重建至关重要。