Which part of P3 is primarily involved in sole ulcers?

• A. Apex
• B. Proximal articular surface
• C. Flexor tuberosity
• D. Dorsal edge

Answer: (C)

The main idea is that sole ulcers start where the deep digital flexor tendon inserts into P3, creating a focused pressure point under weight bearing. The flexor tuberosity is that exact spot on the solar surface of P3 where the tendon pulls, producing concentrated load and shear on the solar corium. Over time this pressure necrosis leads to a sole ulcer. Other parts, like the apex, the proximal articular surface, or the dorsal edge, are not the primary sites where this focal pressure causes ulceration, so they’re less involved in the typical development of sole ulcers.