Which Walch classification is posterior erosion of the glenoid cavity that causes definitive paleo-glenoid and neo-glenoid?

• A. A1
• B. B1
• C. C
• D. D

Answer: (B)

The question tests recognizing a glenoid pattern where posterior wear creates two distinct concavities, described as the paleo-glenoid and the neo-glenoid. This is characteristic of a Walch B-type glenoid with a biconcave appearance due to posterior erosion and posterior subluxation of the humeral head. In this scenario, one concavity reflects the residual native glenoid (the paleo-glenoid) and the second is a newly formed posterior recess from bone loss (the neo-glenoid), giving a classic two-concavity, or biconcave, glenoid.

This pattern is different from the other types, which either lack significant posterior erosion or produce a single concavity rather than two distinct surfaces. So the description of posterior erosion with definitive paleo- and neo-glenoid formation fits the B2 (biconcave) pattern of Walch classification.