CT-based study on the safety margin of the anteromedial portal in elbow arthroscopy

With the increasing use of elbow arthroscopy, there is a growing concern about the risk of injury to neural structures, particularly the median nerve, when the anteromedial portal is created. This risk, which was previously underestimated, underscores the need for a guide to safe access that can significantly impact surgical practices and patient outcomes. We retrospectively evaluated 83 computer tomographies of the elbow without a higher grade of osteoarthritis and surgical treatment. In a 3D reconstruction, the median nerve was located, and a circle was set around it with a radius of 1.5 cm. This was supposed to represent a safety distance. Now, a tangent line was drawn from the tip of the processus coronoideus along the created circle, and the angle to the trans epicondylar plane was measured. The two legs of the angle crossed the skin. Therefore, the distance between these two intersections was also measured. Using IBM SPSS, we tested the data for normal distribution. The mean angle was 57.38°, and the mean distance between the skin intersections was 4.77 cm. The results suggest that the anteromedial portal, approximately 4.77 cm ventrally, measured from the medial epicondyle and at an angle of 57.38° in the trans epicondylar axis, can be suggested as a safe portal placed with reduced risk of damage to the median nerve based on imagining, with a safety distance of 1.5 cm. This can be helpful during elbow arthroscopy; clinical validation is yet to be performed.