The course of posterior interosseous nerve in the wrist capsule. An anatomical study using the modified Sihler’s staining

The aim of the study was to assess the course of posterior interosseous nerve in the wrist capsule in the transparent method of nerve staining. Material and Methods: Thirty dorsal wrist capsules were collected bilaterally from 15 donors (thirty capsules) within 12 hours of death. By the dorsal incision the capsules were collected in the same manner. The specimens were stained according to the protocol of modified Sihler’s staining technique. The preserved capsules were analysed under 8–16× magnification of optical microscope for the presence of major posterior interosseous nerve trunks, their major and minor branches, and nerve connections. Results: Three main types of nerve course were identified within the joint capsule. Type I — the most common, with the presence of a single trunk with the excursion of the first main branch on the radial side, two main branches on the ulnar side, the presence of the prevailing number of small branches on the radial side and the presence of 3–4 branches extending beyond the level of the carpo-metacarpal joints. Type II with the presence of two main nerve trunks, running almost in parallel with the first main branch on the radial side, two main branches on the ulnar side with presence of a predominant number of small branches on the radial side and the presence of 3–4 branches running beyond the level of carpo-metacarpal joints. Type III (least often) with the presence of crossed main nerve trunks. Conclusion: The modified Sihler’s staining technique allows for transparent visibility of the nerves innervation the dorsal wrist capsule. However does not allow accurate assessment as histological examination, especially in evaluation of nerve endings, but it gives a significantly larger area of nerve observation.