Anatomical study of the dorsal cutaneous branch of the ulnar nerve (DCBUN) and its clinical relevance in TFCC repair.

The aim of this study was to define a detailed description of the dorsal cutaneous branch of the ulnar nerve (DCBUN) in particular in relevance to triangular fibrocartilage complex (TFCC) repairs. In 20 formalin-embalmed arms, the DCBUN was dissected, and the course in each arm was mapped and categorized. Furthermore, the point of origin of the DCBUN, that is, from the ulnar nerve in association with the ulnar styloid process, was defined. Finally, the distance between the ulnar styloid process and the branching of the radial-ulnar communicating branch (RUCB) and the first branch of DCBUN was measured. The distance between the origin of the DCBUN in relation to the ulnar styloid process ranges from 55 to 111 mm (mean 87 mm; STD 14 mm). The distance between the ulnar styloid process and the RUCB ranges from 1 to 54 mm (mean 19 mm; STD 12 mm). Finally, the distance between the ulnar styloid process and the lateral distal branch shows a range of -6 to 28 mm (mean 10 mm; STD 9 mm). In general, three dorsal digital nerves (medial, intermediate, and lateral branch), run at the dorsal ulnar aspect of the hand. The RUCB is often less abundant and shows a large amount of variation. No complete safe zone could be identified; the course of the DCBUN suggests a longitudinal incision for the 6R portal. In fact, a more dorsal incision also prevents damage to the main branches of the DCBUN.