Defining a safe zone of dissection during the extensor digitorum communis splitting approach to the proximal radius and forearm: an anatomic study.

Purpose: The extensor digitorum communis (EDC) splitting approach is a direct lateral approach that can provide greater visualization of the proximal radius than the posterolateral approach to the elbow. The purposes of this study were to identify the anatomic relationships of the posterior interosseous nerve (PIN) during the EDC splitting approach to the proximal radius and to determine its safe zone.

Methods: A fellowship-trained attending hand surgeon performed the EDC splitting approach on 15 cadaveric arms, exposing the EDC origin from the lateral epicondyle and dissecting distally to expose the supinator muscle. Calipers were used to measure the distance from the PIN to the radiocapitellar joint and to the lateral epicondyle in neutral position, full supination, and full pronation. The depth of the nerve from the most superficial aspect of the EDC was recorded for each cadaver.

Results: The average distances from the radiocapitellar joint to the PIN in neutral, supination, and pronation were 44.5 +/- 7.9, 40.8 +/- 8.1, and 48.2 +/- 7.9 mm, respectively. The average distances from the lateral epicondyle to the PIN in neutral, supination, and pronation were 61.7 +/- 10.9, 57.6 +/- 9.1, and 64.7 +/- 11.5 mm, respectively. The shortest distance measured from the radiocapitellar joint to the PIN in pronation was 29 mm; the shortest distance measured from the lateral epicondyle to the nerve was 42 mm. The average depth of the nerve from the most superficial aspect of the EDC was 10.2 +/- 2.4 mm.

Conclusions: The PIN is generally safe when dissecting up to 29 mm from the radiocapitellar joint and up to 42 mm from the lateral epicondyle with the forearm in pronation.