Rheumatoid arthritis

A long-term inflammatory disease of the joint lining that commonly affects the small joints of the hands, including the knuckle (MCP) joints. Untreated, it can damage joints and cause deformity such as drifting of the fingers towards the little finger. It is diagnosed and treated by a rheumatologist, with disease-modifying medicines started early.

Related terms

• Anatomy

  Metacarpophalangeal (MCP) joint

  The joint at the base of each finger, between a metacarpal bone and the first bone of the finger — the knuckle seen when making a fist. It bends and straightens the finger at its base and lets the fingers spread apart.

• Treatment

  Knuckle (MCP) joint replacement

  An operation that replaces a damaged knuckle joint with an implant — either a one-piece silicone spacer or a two-part implant that resurfaces both sides of the joint. It aims to relieve pain and keep some movement; implants can break, loosen or need further surgery.

Articles mentioning this term

1. Patient information · 11 October 2026

   Knuckle joint arthritis

   Knuckle (MCP) joint pain and swelling: causes beyond osteoarthritis, tests, warning signs, non-surgical care and joint replacement.

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