Neuroanatomical Analysis of the Carpus and the Base of the Thumb: Advancing Denervation-Based Interventions.

Background: Joint denervation procedures continue to demonstrate promise in the management of chronic pain and functional improvement in joint pathology of the hand and wrist. As our understanding of these techniques evolves, a detailed comprehension of neuroanatomy, including the precise relationships and contributions of sensory innervation to targeted joints, is critical for optimizing outcomes.

Methods: Freshly thawed frozen upper extremity cadaveric specimens were analyzed under the direction of two fellowship-trained hand surgeons. Each extremity was dissected from the mid-humerus to the fingertip, following all named nerve branches distally to their specific innervation targets, including the first carpometacarpal (CMC) joint, radiocarpal joint (RCJ), triangular fibrocartilage complex (TFCC), and distal radioulnar joint (DRUJ). Under loupe magnification, each target was evaluated based on the following criteria: direct innervation with visualized nervous interdigitation, close proximity (<2 mm) without visualized innervation, and proximity >2 mm or not visualized.

Results: Ten cadaveric specimens were dissected. The first CMC joint was innervated by the recurrent branch of the median nerve (RBM) in 10 (100%) cases. Additionally, the lateral antebrachial cutaneous nerve (LABCN), superficial branch of the radial nerve (SBRN), and palmar cutaneous branch of the ulnar nerve (PCBUN) directly innervated the CMC joint in eight (80%) cases and were in close proximity in the remaining two (20%). The RCJ was innervated either directly or in close proximity in at least eight (80%) specimens by the anterior interosseous nerve (AIN), posterior interosseous nerve (PIN), LABCN, PCBUN, and SBRN. In all 10 (100%) specimens, the DRUJ was innervated either directly or in close proximity by the AIN, the PIN, the dorsal cutaneous branch of the ulnar nerve (DCBUN), or the PCBUN. The TFCC was innervated either directly or in close proximity in all 10 (100%) by PIN, AIN, and DCBUN. The TFCC was directly innervated by PCBUN in only five (50%) specimens, while the medial antebrachial cutaneous nerve was observed in close proximity in two (20%).

Conclusion: Despite slight variability between specimens, a general pattern of innervation for the first CMC, RCJ, TFCC, and DRUJ was observed. Our results provide recommendations for specific nerve targets in the wrist to treat chronic pain and arthritis. As our understanding of these neuroanatomic structures and patterns continues to expand, so too will our ability to tailor denervation procedures to patient-specific pathologies.