Basal thumb osteoarthritis
What is it?
In a normal joint the articulating bone ends are covered with a smooth layer of cartilage which allows free and painless movement. In osteoarthritis (degenerative arthritis) the cartilage thins and eventually the bone ends articulate against each other. The joint capsule may also thicken and there may be additional bone formation. The result is pain, stiffness, loss of movement and in some cases deformity. This joint is the second most common site in the body for osteoarthritis with nearly all individuals aged 65 affected but fortunately only a few are symptomatic.
What is it?
How is it diagnosed?
Basal thumb osteoarthritis is diagnosed on the basis of the history described above, and by clinical examination. Plain x-rays usually confirm the diagnosis.
What is my approach to treatment?
Initially rest, non-steroidal anti-inflammatory tablets, physiotherapy and steroid injection into the joint may help to control symptoms. If the condition progresses and or the above measures fail then surgery can be undertaken. There are many different operations described for this condition. My preferred option is trapeziectomy with ligamentoplasty, as it usually yields a predictably good result.
What does an operation involve?
Surgery is normally carried out as a day case under general anaesthetic. A tourniquet is applied to the upper limb to provide a clear view of the operative field for surgery. Through a small incision at the base of the thumb the trapezium (one of the arthritic bones) is removed, to relieve pain. A nearby tendon (flexor carpi ulnaris) is then mobilised and brought into the gap using two small incisions in the forearm. The tendon is passed via a drill hole at the base of the thumb and sutured to itself, stabilising the thumb in position. The remaining tendon is folded using suture and placed into the remaining gap at the base of the thumb, to act as a shock absorber. The joint capsule and skin are closed with non-absorbable sutures. A long acting local anaesthetic injection is then administered to provide pain relief. Finally, a dressing, bandaging and temporary plaster cast are applied.
What is the recovery period?
Once the local anaesthetic has worn off, normally 6 to 8 hours, simple analgesics and anti-inflammatory tablets may be used for pain. The hand should be kept elevated as much as possible during the first week after the operation, although shoulder and elbow movements are to be encouraged. A high-arm sling may be useful for this purpose. Bandaging and Sutures are removed in the clinic after two weeks. A plaster cast to protect the thumb is applied for a further 2 weeks. Prior to this it’s possible to shower by keeping the extremity dry with a plastic bag secured over the limb using an elastic band or a purpose made shower cover. Once the plaster cast is removed at 4 weeks, thumb movements are encouraged. Most pain and swelling will have settled by this stage although full recovery usually takes 3 months. Driving is usually possible four weeks after the operation, once the plaster cast has been removed. When a patient is ready to return to work depends on their specific job role and may also vary from individual to individual. It may be possible to return to light keyboard work after two weeks. Manual tasks should be avoided for 8 to 12 weeks. If heavy manual tasks or impacts are anticipated then alternative surgical techniques are advisable.
Are there any possible complications?
Over 90% of patients are satisfied with the final result. However, as with any treatment, there are always risks involved: Infection: 2%, Chronic regional pain syndrome: 2%, Nerve injury (sensory): 2%, Persistent pain: less than 5% In most cases patients can expect complete pain relief, with 90% of the strength and 90% range of motion when compared to a normal thumb.
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