The sub pronator approach to the coronoid process.

Abstract

Introduction: The aim of our study was to describe a new anteromedial approach that allows exposure of the anteromedial facet of the coronoid process and to characterize the position of the median nerve's motor branches relative to this approach in relation to elbow positioning.

Material and methods: We performed 16 anteromedial approaches on fresh anatomical specimens. The minimum distance between the medial edge of the trochlea and the second branch of the median nerve was measured in three elbow positions: forearm in supination with the elbow extended, forearm in pronation with the elbow extended, and forearm in supination with the elbow flexed at 90 °. The distance between the joint space and the origin of the first two motor branches of the median nerve was then measured with the elbow extended.

Results: The mean distance between the second motor branch of the median nerve and the medial edge of the trochlea was 13 mm ± 3 mm with the elbow extended and forearm supinated; 5 mm ± 3 mm with the elbow extended and forearm pronated; and 11 mm ± 4 mm with the elbow flexed at 90 ° and forearm supinated. There was a significant difference in distance between the measurement in the pronated position and the two measurements in the supinated positions. However, there was no significant difference between the measurement with the elbow flexed in supination and the elbow extended in supination (p < 0.06).

Conclusion: The subpronator approach is a reproducible and reliable approach that allows exposure of the tip of the coronoid process and its anteromedial facet, up to the insertion of the anterior bundle of the medial collateral ligament on the sublime tubercle. We have shown that placing the forearm in supination moves the motor branches at risk of injury away from the surgical site.

Level of evidence: V.