Osteoarthritis of the thumb
What is it?
Osteoarthritis affecting the carpometacarpal (CMC) joint of the thumb.
The majority of patients have no or minimal symptoms, but the condition can cause stiffness, grinding, and a dull ache which becomes sharp with the use of the thumb. This particularly occurs during pinching or gripping movements that can cause the sufferer to drop objects. It is very common in women over 50 years of age and tends to run in the female side of families.
The base of the thumb may appear to be prominent. The thumb may lie more in the palm (adducted) which is secondary to subluxation of the CMC joint. There is often tenderness over the base of the thumb. Range of movement is reduced and painful.
The Grind Test (axial compression and circumduction) is painful.
- STT arthritis
- DeQuervain’s Tenosynovitis
- Scaphoid non-union +/- subsequent arthritis
True AP view of thumb base (Roberts view) and Lateral radiographs will confirm the diagnosis.
- Initially rest and modification of activities or change of work practices.
- Analgesia or anti-inflammatory medication.
- Intra-articular injection of steroid may also be given depending on the severity of the arthritic changes.
Surgery is used for disabling pain that cannot be controlled by other measures. There are several surgical procedures that can be used.
1st CMCJ Arthroscopy
The thumb base joint can be visualised directly with the use of small arthroscopes (keyhole technique). This is used rarely for very early thumb base pain in younger patients.
The metacarpal bone (at the base of the thumb) is divided and repositioned to offload the worn part of the joint. This can reduce pain and improve use of the thumb for patients with mild/early arthritis.
The trapezium (the small bone at the base of the thumb) is removed. It is sometimes necessary to stabilise the thumb by using a wrist/thumb tendon. Occasionally a pin is placed to temporarily “stabilise” the thumb base. This is the most common procedure performed in the UK for this type of arthritis.
The arthritic joint is removed and then two bones are fused together making one bone. This is most often performed in young and middle aged men who do manual work, and is thought to preserve the strength of the thumb better than other procedures.
The arthritic joint is replaced with either a Pyrocarbon or a Silicone joint. The long-term outcome of this operation is very variable. There are specific problems associated with joint replacements such as loosening and dislocation.
When to Refer
Many patients with early osteoarthritis of the thumb can be managed in the community using a combination of analgesia, splinting and activity modification. The selective use of intra-articular injections can provide excellent benefit in patients with early to moderate degenerative changes. Failure to control symptoms despite the above measures or in severe disease warrants onward referral to the Hand Clinic.