Minimizing risk to the dorsal sensory branch of the ulnar nerve in wrist arthroscopy: an anatomical study.

Wrist arthroscopic procedures using ulnar wrist portals, such as the 6-ulnar and direct foveal portals, have a risk of injuring the dorsal sensory branch of the ulnar nerve. This study investigated the anatomy of the dorsal sensory branch of the ulnar nerve and its positional changes during supination, neutral rotation and pronation at specific landmarks to find an optimal forearm position to minimize the risk of iatrogenic nerve injury during arthroscopy. The concept of 'nerve density' was introduced to quantify the likelihood of encountering the dorsal sensory branch of the ulnar nerve within different sectors, correlating to the risk of nerve injury. Our findings indicate that the sectors containing the 6-ulnar and direct foveal portals showed very low risk (≤5% risk) in supination and neutral rotation, but moderate risk (30-60% risk) in pronation. These results suggest that maintaining the forearm in neutral rotation or supination reduces the risk of injury to the dorsal sensory branch of the ulnar nerve during procedures that use these portals.Level of evidence: IV.