Which plantar surface sign indicates cuboid dysfunction?

• A. Tenderness medial to the navicular
• B. Swelling at the calcaneus
• C. Prominence on the plantar surface of the lateral foot near the 5th metatarsal tuberosity
• D. Pain at the first MTP joint

Answer: (C)

Cuboid dysfunction involves abnormal movement or subluxation of the cuboid bone in the lateral midfoot. A key sign is a prominence felt on the plantar surface of the foot just lateral to the base of the fifth metatarsal tuberosity; when the cuboid is displaced, this area can become a palpable bump with tenderness during weight bearing. This plantar prominence is characteristic of cuboid involvement, whereas tenderness medial to the navicular points to navicular/medial foot issues, swelling at the calcaneus suggests heel-related problems, and pain at the first MTP joint points to first-ray or hallux issues.