[Humeral retroversion and shoulder prosthesis].

PURPOSE OF THE STUDY

From a theoretical point of view, humeral torsion is described as the angle between the transcondylar plane and the posteromedially facing joint surface of the humeral head. In this study, humeral torsion was also identified as the angle between the anatomical neck of the humerus and at the inferior part the axis of rotation of the elbow and the axis of the forearm.

MATERIALS

60 cadaveric humeral shafts were obtained. The axis were defined and measured by CT Scans.

METHODS

The orientation of the cartilage of the humeral head was determined as a line perpendicular to the limits of the joint area of the humeral head. The axis of the humeral anatomical neck was defined as the plane that contains both the long axis of the humerus and the center of the humeral head. The rotation axis of the elbow was defined as the line passing through the centers of the capitellum and the trochlear sulcus.

RESULTS

The angle between the orientation of the humeral head and the orientation of the transcondylar line averaged 23 degrees. The angle between the humeral neck and the orientation of the transcondylar line averaged 38 degrees. The angle between the humeral neck and a line perpendicular to the axis of the forearm averaged 41 degrees.

DISCUSSION

It is important to analyse humeral head retroversion by taking into account the axis system and the anatomical planes in shoulder arthroplasty.