Osseous morphology of the medial epicondyle: an anatomoradiological study with potential clinical implications

The cubital tunnel is limited anteriorly by the medial epicondyle (ME), laterally by the medial collateral ligament, and superiorly by Osborne's fascia and the cubital tunnel retinaculum. Previous studies were mostly dedicated to the roof of the cubital tunnel, in the way that the study of the groove for ulnar nerve and ME anatomy is relatively scarce in the literature. We sought to describe the radiological anatomy of the groove for ulnar nerve and ME in healthy volunteers with multiplanar computed tomography (CT).

We analyzed 3D CT images of 30 healthy volunteers (mean age 39 years, range 18-66 years). Nine variables were measured from the right elbow, including sizes, areas and angles in two different planes (coronal and axial).

Mean ME width and length were 17.3 ± 3.5 mm and 31.7 ± 4.5 mm, respectively. According to categorical correlation studies, ME width (X) was deemed the most representative morphological characteristic because of the positive correlation to five other different anatomical measurements. A three-tiered anatomical classification was proposed based on data distribution.

Large individual variation is found in the shape of ME, both in coronal and axial planes. The knowledge of individual osseous morphology is of great value potentially contributing to the surgical decision-making in patients affected by cubital tunnel syndrome.