GLENOID AND CORACOID MORPHOLOGY WITH REFERENCE TO THE MODIFIED LATARJET PROCEDURE

The Latarjet procedure utilises the coracoid as a vascularised bone autograft to augment the glenoid in patients with shoulder dislocation, especially where there is a bony lesion affecting the glenoid. A modification of the Latarjet procedure, pioneered in Cape Town, South Africa, rotates the coracoid so that its curved under-surface matches that of the glenoid. The aim of this study was to measure the radii of curvature of the glenoid and the coracoid to see how well the curved under-surface of the coracoid matches the glenoid’s surface curvature. An initial study of 210 cadaveric scapulae was performed in which the radii of curvature of the surface of the glenoid and the curved under-surface of the coracoid were measured. We found that the curves are very similar. The glenoid’s surface had a median curvature of 30mm (inter-quartile range from 25mm to 30mm) and the coracoid had a median curvature of 22.5mm (inter-quartile range from 20mm to 25mm). The curvature of the glenoid in these dry specimens was slightly larger than the corresponding coracoid curvature. In life this difference would be minimised by articular cartilage, labrum and the attachment of capsule (another Cape Town modification). A further parallel CT based study was set up at Derbyshire Royal Infirmary in England. The same radii of curvature where measured and compared using 3D CT reconstruction on a further 20 scapulae from living patients. These measurements also support the cadaveric similarities with a mean glenoid curvature of 23.9mm and coracoid of 25.4mm respectively. Using a paired t-test no statiscally significant difference was found between the corresponding data (p=0.2488) This study confirms the native anatomy of the coracoid is perfectly suited for this modification of the Latar-jet procedure.