The mineralization patterns at the subchondral bone plate of the glenoid cavity in healthy shoulders.

The distribution of mineralization of the subchondral bone plate (DMSB) is used as a parameter for the individual stress distribution of joints. In this study the DMSB of the glenoid from healthy glenohumeral joints was analyzed. In a standardized manner, 44 macroscopically normal shoulder specimens (28 individuals aged 18 to 96 years) were selected and DMSB of the glenoid was evaluated by computed tomography osteoabsorptiometry. The mineralization patterns were described, and the 2 most frequent maxima of density were localized and statistically assessed to analyze any influence of age, side, or shape of the glenoid on DMSB. An anterior-superior maximum was found in 100% and a posterior maximum in 82%. Three different patterns of DMSB were distinguished in relation to the constant anterior-superior maximum: 68% were not combined with a further central or anterior-inferior maximum (type A), whereas a central maximum coexisted in 18% (type B) and an anterior-inferior maximum in 14% (type C). The localization of the anterior-superior and posterior maxima was independent of age or side of the glenoid, indicating a constant long-term stress distribution in healthy glenohumeral joints. The typical localization of the density maxima showed that stress distribution is usually peripherical (82%) and often bicentric. Functional aspects related to internal rotation of the arm support a more constant anterior than posterior stress on the glenoid surface.