Humeral retrotorsion and glenohumeral relationship in the normal shoulder and in recurrent anterior dislocation (scapulometry).

The authors' roentgenographic technique provides precise assessment of the glenohumeral relationship on the basis of two-plane examination. A group of 50 normal male subjects serve as the basis for determining normal values for the following angles or lines: projected and corrected cephalodiaphyseal angle, projected and corrected humeral retrotorsion, glenoid inclination, angle of attack, glenoid retroversion, dimension of glenoid, width of humeral head, and contact index. Two groups of patients suffering from recurrent anterior dislocation (RAD) are compared with the normal group. The shoulders with RAD do not differ significantly from the normal ones. Humeral retrotorsion, in particular, is identical. Significant differences are found between affected and unaffected sides in unilateral RAD. The diameter of the glenoid and the contact index are smaller on the dislocated side. Because the projected values seldom differ by more than 10 degrees from the calculated values, if the authors' roentgenographic technique is used, the figures can generally be accepted without correction.