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

Abstract 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 TFCC repairs. In twenty formalin-embalmed arms, the DCBUN was dissected, and the course in each arm was mapped and categorized. Furthermore, the point where the DCBUN originates from the ulnar nerve in relation to 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 mm to 111mm (Mean 87mm; STD 14mm). The distance between the ulnar styloid process and the RUCB ranges from 1 mm 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 mm to 28 (Mean 10 mm; STD 9 mm). In general there are three dorsal digital nerves (medial-, intermediate- and lateral branch), which runs at the dorsal ulnar aspect of the hand. The RUCB is less often present and shows a large amount of variation. No complete safe zone could be identified, but a longitudinal incision for the 6R portal is advised because of course of the DCBUN. A more dorsal incision also prevents damage to the main branches of the DBCUN.