Basal Joint (CMC) Thumb Arthritis

What is Basal Joint (CMC) Thumb Arthritis?

Basal joint thumb arthritis or carpometacarpal (CMC) joint arthritis, is the gradual loss of the cartilage that normally exists in the joint at the base of the thumb near the wrist. It is one of the most common joints in the hand to develop osteoarthritis (degenerative or “wear-and-tear arthritis”). The specialized shape of the joint at the base of the thumb allows the thumb its wide range of movement – up and down, across the palm, and the ability to pinch with the fingers.

With arthritis, the cartilage that normally serves as a shock absorber and allows for smooth gliding of the bone surfaces is worn away. It is twice as common in women as it is in men and can present itself as early as the age of 40. The cause of this condition is unknown; however, previous fractures to the joint or other thumb injuries may increase the likelihood of developing it.

What are some of the symptoms  of basal joint thumb arthritis?

  • A deep, aching pain at the base of the thumb that worsens with time
  • Pain and/or loss of strength in gripping, twisting or pinching activities
  • Swelling and tenderness at the base of the thumb
  • Development of a bony prominence or bump at the joint
  • Stiffness and/or limited range of motion

Treatment for basal joint (CMC) thumb arthritis

Early stage thumb arthritis can respond to non-surgical treatment options:

  • Ice on the joint several times a day for 5 – 15 minutes
  • Anti-inflammatory medications (NSAIDs) to help reduce inflammation and swelling
  • A supportive splint can be worn overnight or intermittently throughout the day to limit the thumb’s movement and allow the joint to rest
  • Corticosteroid injections directly into the joint can provide relief


Unfortunately, arthritis is a degenerative disease that may worsen over time. Surgery may be an option when non-operative treatments become ineffective. Your physician will discuss the surgical options that are best suited to your individual condition. Following surgery, your hand will be immobilized for 4-6 weeks, followed by physical therapy to regain strength and mobility.