Fig. 1

Walch classification: in type A glenoids, the humeral head is centered and the erosion is central. The severity of the erosion is either minor (A1) or major (A2). In type B, there is asymmetric posterior wear of the glenoid associated with posterior subluxation of the humeral head. In type B1, the erosion is minor with joint space narrowing, subchondral sclerosis, and osteophytes. In type B2, the erosion is major and the glenoid has become biconcave. Type C is defined as a dysplastic glenoid with retroversion of more than 25°; the head remains centered