Carpometacarpal Joint Osteoarthritis

What is Carpometacarpal joint (CMCJ)?

The carpometacarpal CMC joints are articulations between the carpal and metacarpal bones of the hand. These bones are connected by the carpometacarpal ligaments. The thumb basal joint (trapeziometacarpal joint) is the most specialized and flexible of the five CMC joints. The CMC joints that connect the medial four metacarpal bones are functional plane synovial joints. The intercarpal joints are also plane synovial joints. 

The trapezium, trapezoid, capitate, and second metacarpal bones articulate to form the second CMC joint. Between the capitate and the third metacarpal bone is the third CMC joint. The triangular and often concave distal surface of the capitate articulates with a convex area on the metacarpal base. Along with the fourth metacarpal, capitate and hamate bones form the fourth CMC joint. 

A fibrous capsule surrounds and stabilizes the four CMC joints. A synovial membrane lines this fibrous capsule, secreting viscous synovial fluid that serves as a lubricant. Three sets of interosseous ligaments stabilize the CMC joints.


What is Carpometacarpal joint (CMCJ) Osteoarthritis (Basal Joint Arthritis)?

The two types of hand arthritis are outlined below:

Inflammatory arthritis includes psoriatic arthritis, rheumatoid arthritis, septic arthritis, and gouty arthritis.

Degenerative or osteoarthritis is the more common of the two. It occurs following the premature wear to cartilage surfaces in a joint and may be either primary or secondary. Osteoarthritis is caused by age-related degeneration or unnecessary wear and tear, which develops because of chronic overuse of a single joint. Previous joint damage or developmental defects resulting in joint deformities are examples of secondary causes.


CMCJ Osteoarthritis Symptoms

When a person grips or pinches an item, the first sign of thumb arthritis is typically discomfort at the base of the thumb. Also, when they apply force with their thumb, they may experience pain.

  • Swelling and tenderness at the base of the thumb
  • An aching discomfort after prolonged use of thumb
  • Reduced pinch strength
  • Reduced grip strength
  • An enlarged, “out-of-joint” appearance
  • Appearance of a bony prominence or bump over the joint
  • Limited range of movement

The seriousness of the symptoms can vary. Symptoms may start out mild and then worsen over time, particularly if an individual does not seek care.


Diagnosing CMCJ Osteoarthritis

Since osteoarthritis is typically a clinical diagnosis, doctors may make a diagnosis using finding on the patient’s illness history and physical examination. 

CMCJ Grind  Test

CMCJ grind test is performed during the examination and involves holding the joint firmly while moving the thumb. If there is pain or a gritty feeling, or if the examiner can hear a grinding sound (crepitus), meaning the bones are rubbing directly against each other, indicating arthritic changes.

Carpal tunnel syndrome is common in people with arthritis at the base of the thumb, so your doctor may look for that as well. 

Plain radiography can help confirm the diagnosis and rule out other possibilities. Advanced imaging methods, such as computed tomography or magnetic resonance imaging, are only used when the presence of CMCJ osteoarthritis and another aetiology, such as a meniscal tear, is suspected.


Causes & Risk Factor of CMCJ Osteoarthritis?

Base of thumb arthritis is a natural occurrence when people become older. It may also be caused by previous damage or injury to the joint.

The cartilage protects the ends of the bones in a normal thumb joint, serving as a brace and allowing the bones to glide effortlessly over each other. The sturdy appearance of the cartilage that coats the ends of the bones deteriorates with thumb arthritis. Friction and joint trauma occur as the bones brush against each other.

Harm to the joint may result in the formation of bone spurs (new bone growth along the sides of an existing bone), which may cause visible lumps on the thumb joint.

The following factors increase the risk of having CMCJ osteoarthritis

  • Female sex.
  • Age > 40.
  • Obesity.
  • Certain inherited disorders, such as joint ligament laxity and malformed joints
  • Thumb joint injuries, such as breaks and sprains.
  • High-stress activities and work for the thumb joint.


Treatment for CMCJ Osteoarthritis

Treating osteoarthritis in the thumb follows the same rules as treating osteoarthritis in other joints in the body:

Non-operative treatments aim to minimize load-bearing by the joint, reduce swelling, manage discomfort, and slow down or avoid progressive degeneration. They include :

  1. Activity modification
  2. Custom-moulded rigid splints or over-the-counter braces to limit range of motion.
  3. Non-steroidal anti-inflammatory drugs (NSAIDs) for pain relief and joint supplements like glucosamine and calcium.
  4. Corticosteroids (potent anti-inflammatory agents) or viscoelastic formulations like hyaluronic acid are injected intra-articularly.

Surgical care options include the following:

  1. Debridement (cleaning up) of the joint with arthroscopic surgery (key-hole surgery).
  2. Joint balancing procedures include cutting bone, changing joint angles, and fixing the joint with metal implants.
  3. Arthroplasty (joint-moulding) procedures: It involves ligament reconstruction and tendon interposition. There are three types.
  • Excisional arthroplasty (removal of the sore joint) with or without additional bone stabilization procedures.
  • Interpositional arthroplasty (joint-cushioning techniques) cushions worn-out cartilage and relieves inflammation by using the patient’s tissue (usually tendon grafts).
  • The normal joint is removed and replaced by an artificial joint implant in replacement arthroplasty. 

When joint discomfort persists after using all other non-surgical solutions, surgery is recommended. The type of operation is also determined by the degree of degenerative changes and the predicted joint functionality after surgery. Recovery can take anything from 8 weeks to a year. Occupational or physical therapists may provide recovery care during this period.


Possible Complications for CMCJ Osteoarthritis

Infection, bleeding from the surgical site, and damage to adjacent nerves and tendons leading to transient or permanent dysfunction of the related nerve or tendon are possible surgical complications.

The following are some of the potential complications associated with various types of hand surgery for osteoarthritis:

  • Arthroscopic surgery: Septic arthritis, iatrogenic cartilage fracture requiring more wear
  • Joint balancing procedures that include osteotomy (bone cutting) and implant fixation: Attrition against the metal implant causes non-union of the desired fixation site and inflammation of the surrounding tissue.
  • Excisional and interpositional arthroplasty: Subsidence of the bone following joint removal, instability, and pain recurrence.
  • Replacement arthroplasty: Dislocation of the artificial joint, loosening of the implant, and premature wear of the artificial joint’s plastic components.

Many of the above complications may be treated and managed non-operatively or operatively if appropriate.



Many people with basal joint arthritis will be able to control their symptoms and reduce their discomfort with medication. Arthritis typically deteriorates with time. 

It’s important to see a doctor if thumb arthritis is making everyday operations uncomfortable or painful.

Speak to our hand care team to find out if this is the medical condition you have at +65 6733 9093. Or book an appointment with our hand specialists for a consultation on your symptoms and treatment options.