HUMERUS RETROVERSION AND SHOULDER ARTHROP LASTY

Purpose of the study From a theoretical point of view, humeral torsion is described as the angle between the transcondylar plane and the pos teromedially facing joint surface of the humeral head. In this study, humeral torsion was also identified as the angle between the anatomica l 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 axies were defined and measured by CT Scans . Methods The orientation of the cartilage of the humeral head was det ermined 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 cent er of the humeral head. The rotation axis of the elbow was defined as the line passing through the centers of the capitellum and the trochle ar sulcus. Results The angle between the orientation of the humeral he ad and the orientation of the transcondylar line averaged 23 degrees. The angle between the humeral neck and the orientation of the transcon dylar 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 tak ing into account the axis system and the anatomical planes in shoulder arthroplasty.