INNERVATION OF THE DISTAL INTERPHALANGEAL JOINTS OF THE FINGERS: ANATOMICAL AND HISTOLOGICAL STUDY AND FIRST CLINICAL APPLICATION

Abstract

The distal interphalangeal (DIP) joints of the fingers are prone to functional impotence in some degenerative diseases. In this case, different surgical techniques can be used, from DIP arthrodesis to joint denervation, much more confidential, which aims to preserve an already reduced mobility.

The four fingers (except the thumb) of 6 fresh hands from different cadavers were dissected under optic magnification. Two DIP joints were harvested from fresh dissected hands, in order to follow with the microscope the course of the nerve branchlets up to their articular entry. These two specimens were decalcified, and then embedded in paraffin. The blocks were serially cut in 5μm slices (1 slice each 250μm), which were observed at 25 and x100 magnification, after Masson’s trichrom staining.

A constant proximal articular branch, arising from the proper digital palmar nerve, was exclusively devoted to joint supply. This branch was located medially and arose in average at 7 mm from its entry point in the joint, where it was accompanied by small arterial branches. Before its entry into the inferomedial part of the DIP joint, it ran under the flexor digitorum profun-dus tendon. It then could divide into 2 or 3 branchlets. The proper digital palmar nerve abandoned, along its course, some nerve fibers to the tendinous synovium and neighboring structures. Then, ending its course, it gave off a distal articular branch, hidden among numerous cutaneous branches for the fingertip. The DIP joint nerve supply seems so under the exclusive dependence of the proper digital palmar nerve without any input from the dorsal side. On the histological slices, the nerves were mainly observed in peri- and intracapsular situation.

Could cutting these two articular nerves be sufficient to relieve pain from the DIP? This is what we are investigating through a clinical series; the first results are presented here.