The risk of posterior interosseous nerve (PIN) injury during surgical approaches to the lateral elbow varies depending on chosen approach, level of dissection, and rotational position of the forearm. Previous studies evaluated the trajectory of the PIN in specific surgical applications to reduce iatrogenic nerve injuries. The goal of this study is to examine the location of the PIN using common lateral approaches with varying forearm rotation. The Kaplan, EDC split and Kocher approaches were performed on 18 cadaveric upper extremity specimens. Measurements were recorded with a digital caliper from the radiocapitellar (RC) joint and the lateral epicondyle to the point where the PIN crosses the approach in full supination, neutral, and full pronation with the elbow at 90 degrees. The ratio of the nerve's location in relation to the entire length of the radius was also evaluated to account for different sized specimens. The PIN was not encountered in the Kocher interval. For Kaplan and EDC split, with the forearm in full supination, mean distance from lateral epicondyle to PIN was 52.0 ± 6.1mm and 59.1 ± 5.5mm respectively, and mean distance from RC joint to PIN was 34.7 ± 5.5mm and 39.3 ± 4.7mm respectively; with the forearm in full pronation, mean distance from lateral epicondyle to PIN was 63.3 ± 9.7mm and 71.4 ± 8.3mm respectively, and mean distance from RC joint to PIN was 44.2 ± 7.7mm and 51.1 ± 8.7mm respectively. The PIN is closer to the lateral epicondyle and radiocapitellar joint in the Kaplan than EDC split approach and is not encountered during the Kocher approach. The PIN was not encountered within 26mm from the radiocapitellar joint and 39mm from the lateral epicondyle in any approach and forearm position and is generally safe from iatrogenic injury within these distances.
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