Glenohumeral relationship in the transverse plane of the body

Reconstruction of a normal glenohumeral relationship is desirable for a successful arthroplasty. Double-contrast computed tomography was performed on 49 healthy shoulders in young volunteers. For creation of a uniform spatial reference system, the subjects were positioned in a thoracobrachial orthosis with the arm adducted in the coronal plane and the forearm flexed in the sagittal plane, and they were examined in dorsal recumbency. The classical anatomic angles were measured, and the anatomic axes were determined and quantified as angles to the coronal plane. When the axis of the glenoid was correlated to the axis of the humeral head, a mean of 8.5° divergence in a clear Gaussian distribution was found. This contrasts with the variability of the version of the humeral head and of the glenoid and offers a useful guideline in difficult prosthetic surgery of the shoulder in which normal anatomic landmarks are lost because of arthritic or traumatic deformity.