Morphologic study of the glenoid in primary glenohumeral osteoarthritis

We studied the natural course and the possibility of making a prognostic cl assification of glenoid morphology in primary glenohumeral osteoarthritis ( GHOA). For this purpose, serial computed tomography scans of 113 osteoarthr itic shoulders were reviewed. The position of the humeral head with respect to the glenoid seems to be an important predictor of the glenoid morpholog ic evolution. Three main glenoid types were defined: Type A, Type B, Type C . Type A (59%) was marked by a well-centered humeral head and a balanced di stribution of strengths against the surface of the glenoid. The symmetric e rosion was explained by the absence of subluxation. In Spr B (32%), the pos terior subluxation of the humeral head was responsible for the asymmetric l oad against the glenoid and was implicated in the development of primary GH OA, particularly the exaggerated posterior wear pattern. Type C (9%) was de fined by a glenoid retroversion of more than 25 degrees, regardless of eros ion; retroversion was primarily of dysplastic origin and explained the earl y event of osteoarthritis. In primary GHOA, this classification of the glen oid can discriminate retroversion between posterior erosion and dysplasia.