Pain or grinding at the base of the thumb during the grind test indicates which condition?

• A. Arthritis of the thumb
• B. Carpal tunnel syndrome
• C. De Quervain's tenosynovitis
• D. Trigger finger

Answer: (A)

Pain or crepitus at the base of the thumb during the grind test points to osteoarthritis of the first carpometacarpal joint. The grind test compresses the base of the thumb and rotates the joint between the first metacarpal and the trapezium. If the joint surfaces are worn from OA, this movement produces painful grinding and often a palpable crepitus because cartilage loss and subchondral changes expose rough bone surfaces. This specific joint is essential for thumb opposition and pinch, so degeneration here causes focal pain and functional difficulty with thumb use.

In contrast, carpal tunnel syndrome causes symptoms like numbness, tingling, and weakness in the median nerve distribution rather than a localized grind at the thumb base. De Quervain’s tenosynovitis produces radial wrist and thumb pain, typically with swelling along the first dorsal compartment and a positive Finkelstein test. Trigger finger involves catching or locking of a finger due to stenosing tenosynovitis of the flexor tendon sheath, not joint-wide grinding at the thumb base.