Anatomical Basis for Injection around First Dorsal Compartment of the Wrist: A Fresh Cadaveric Study

Abstract

Background: It is important to understand the anatomical relationship between the medial and lateral branches of superficial radial nerve (SRN) and the first dorsal compartment to prevent and minimize possible injury to these nerves during various procedures around the tip of radial styloid process (RSP). Objective: To delineate the anatomical location of the SRN in relation to the extensor pollicis brevis (EPB) and abductor pollicis longus (APL) tendons. Study Design: Observational study. Setting: Academic medical center. Methods: The width of the first dorsal compartment, distance between the EPB tendon and the closest medial branch of the SRN, and distance between the APL tendon and the closest lateral branch of the SRN were measured. The distances were measured at the RSP (the tip of the RSP) and RSP+1 (1 cm proximal to the tip of the RSP) levels. Results: The median distances between the EPB tendon and the closest medial branch of the SRN at the RSP and RSP+1 were 6.0 mm (range: 1.6 - 11.0 mm) and 3.2 mm (range: -2.0 - 9.4 mm), respectively. The median distances from the APL tendon to the closest lateral branch of the SRN at the RSP and RSP+1 were -2.0 mm (range: -9.0 - 8.4 mm) and 1.0 mm (range: -7.2 - 8.0 mm), respectively. A high percentage of overlap (up to 59%) was observed between the lateral branch of the SRN and the APL tendon. Limitation: This study is limited by its small sample size. Conclusion: Due to the anatomical proximity of the branches of the SRN and the first dorsal compartment around the RSP, physicians must be cautious during procedures near this location. It is important to approach from above the EPB, rather than from above the APL, when performing blind procedures, although ultrasound guidance is preferable.