Which Walch classification indicates posterior erosion with paleo- and neo-glenoid?

• A. A1
• B. B1
• C. C
• D. D

Answer: (B)

Posterior erosion with paleo- and neo-glenoid describes a pattern where the posterior rim of the glenoid has worn away and remodeling creates two distinct rims—the original posterior rim (paleo-glenoid) and a newly formed posterior rim (neo-glenoid). This chronic, eccentric posterior wear is the hallmark of a Walch B-type glenoid, which is defined by posterior wear and often posterior subluxation of the humeral head. The presence of both paleo- and neo-glenoid reflects long-standing posterior bone loss with remodeling, a scenario typically captured by the B-category rather than the centered, symmetric A-type or the more severely retroverted patterns seen in C-type (and the less standard D-type). Recognizing this posterior-dominant wear is important for planning, as it influences decisions about glenoid component positioning and whether augmented components or bone grafting may be needed.