Thumb-base arthritis

Wear of the cartilage in the saddle-shaped joint between the trapezium and the base of the thumb metacarpal. The commonest site of hand arthritis after the fingertip joints, more frequent in women and with age; it causes pain at the base of the thumb on pinching and gripping, and in late stages a zigzag deformity. X-ray severity correlates poorly with symptoms.

Related terms

• Anatomy

  Trapezium

  The most radial bone of the distal carpal row, articulating with the first metacarpal at the trapeziometacarpal joint. Forms the radial wall of the carpal tunnel together with the scaphoid.

• Treatment

  Trapeziectomy

  Removal of the trapezium so that the worn thumb-base joint no longer exists; the space fills with scar tissue and the thumb settles slightly. The standard operation for painful thumb-base arthritis, with good pain relief in about four in five people at five to eighteen years; pinch strength does not return to normal. Adding a tendon sling or spacer makes little or no difference.

• Treatment

  Thumb joint replacement

  Replacement of the worn thumb-base joint with a small ball-and-socket implant, keeping the thumb at its full length. Compared with trapeziectomy in randomised trials it gives similar pain relief and hand-function scores, faster recovery and a stronger pinch, with a risk of implant loosening, dislocation or wear; ten-year results for modern dual-mobility designs are not yet available.

• Treatment

  Thumb splint

  A splint that supports the base of the thumb, worn at night or during heavy tasks. In a randomised trial a custom splint made no difference at one month but reduced pain and disability at twelve months; a rigid splint holding both thumb joints was the one non-operative treatment with a clear medium-term benefit in a review of 22 trials.

Articles mentioning this term

1. Patient information · 26 September 2026

   Thumb-base arthritis

   Thumb-base (CMC) arthritis: symptoms, splints, exercises, injections, and how trapeziectomy compares with joint replacement in recovery, strength and risk.

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