3D evaluation of the scapular morphology in primary glenohumeral arthritis, rotator cuff arthropathy and asymptomatic shoulders.

AIM AND BACKGROUND Recently, the 3D morphology of the coracoacromial complex in non-pathologic shoulders have been described. The aim of this study was to evaluate and compare the coracoacromial complex in pathological shoulders (glenohumeral osteoarthritis (GHOA) and cuff tear arthropathy (CTA)) with non-pathological shoulders (NL). METHODS A 3D CT-reconstruction of 205 scapulae was performed (GHOA (49), CTA (48), NL (108)). Subsequently, the center of the glenoid circle and several points at the coracoid, acromion and glenoid were determined. The distances between these points and the rotation of the coracoacromial complex were calculated and the acromioglenoidal angle was measured. RESULTS Our study showed the acromial overhang to be significantly different in the NL group (37 mm) versus CTA (35 mm) (p=0.045), and CTA versus GHOA (33mm) (p=0.010). The acromioglenoidal angle showed a significant difference between NL (mean 50°) and GHOA (mean 42°) (p<0.001) and between CTA (mean 50°) and GHOA (p<0.001). Furthermore a significant difference was found in the acromial height, which was larger in the GHOA group (36mm) than the CTA group (30mm) (p<0.001) or the NL group (30mm) (p<0.001). CONCLUSION This 3D morphologic study showed that the acromial part of the complex was turned more posteriorly in both pathologic groups. Furthermore, we found the coracoacromial complex to be more cranial to the glenoid center in the GHOA group. Finally, a significant difference in lateral overhang of the coracoacromial complex was observed between the three groups. The NL group was found to have a larger overhang than CTA, and CTA in turn had a larger overhang than GHOA.