Figure 3. Definition of the three the humeral head component positioning parameters.

: humeral head position (left) relative to the greater tuberosity indicated by the black line; retroversion (middle) of the humeral component was measured as the angle between the green line (i.e. the diametrical line across the humeral head component) and the purple line (i.e. the line that joins the bicipital groove to the centre of the femoral shaft); Glenohumeral misalignment (right) was measured as the distance between the white line (i.e. the centre of the humeral head) and the purple line (i.e. the centre of the glenoid component).