Osteoarthritis (OA) Thumb Base
What is OA thumb base?
You may be experiencing pain at the base of the thumb during activity, particularly when pinching. The base of the thumb is called your Carpometacarpal (CMC) joint, and you may see it referred to as CMC OA in medical notes and clinic letters.
When OA develops in a joint, the cartilage gradually roughens and becomes thin, and the bone underneath thickens. The bones at the edge of the joint grow small bony ‘spurs’ and excess synovial fluid can be produced, causing the joint to swell. This can mean that you avoid using these joints, subsequently causing the surrounding muscles to weaken. You may subsequently lose grip strength and range of movement.
In severe OA, the cartilage no longer covers the entire joint surface and this can, over time, change the shape of the joint, creating a deformity, as the joint is no longer held in its natural position.
Diagnosis
Diagnosis is made by clinical examination, and x-rays may be required to determine the level of arthritis in the joint.
What causes OA?
This condition is most common in women but can affect men. Often there is a family history of the condition or it can be as a result of an injury or overuse.
Management
If symptoms are mild then the pain can often be managed with splints, exercises, pain relief and steroid injections, as well as task modification and other joint protection techniques. Please liaise with your therapist if you wish to discuss any of the above.
If pain is persistent and not manageable with the above management then surgery may be suggested.
Risks of surgery
As with any surgical procedure there are associated risks. These will be discussed with you by your doctors when they list you for surgery.
Trapeziectomy Surgery
The most common surgery involves removing the bone called the trapezium at the base of the thumb. Soft tissue is folded into the space and secured and tightened to keep the thumb aligned. Often extra support is provided by part of a tendon. The thumb is immobilised initially in a cast. How long you stay in the cast will depend on the type of surgery and on the surgeon. The surgery is performed as a day case procedure and a nerve block will be undertaken.
Post-operative management
After surgery your hand will be dressed and a temporary cast applied. Keep the arm elevated on a pillow when you are able. Some pain after your operation is normal; this should settle over time. Keep your shoulder, elbow and fingers moving.
At two weeks you will have a wound check and either a plaster cast reapplied or a splint fitted dependent on your surgery/consultant.
Cast
If you have a cast reapplied it is important to continue to work on keeping your fingers, elbow and shoulders moving. When your cast is removed you will be provided with exercises to move your thumb and wrist. You will be encouraged to use your hand for light activities and reviewed by your therapist when the cast is removed.
Splint
If your consultant wishes you to be in a splint, you may have a thermoplastic splint fabricated or a neoprene thumb wrap provided for you. You will need to wear this until you are 6 weeks post op or until instructed by your therapist. The thermoplastic splint is heat-sensitive so be cautious of completing tasks where heat is involved. If your splint becomes too tight/loose or is rubbing, please contact your therapist for this to be altered. Do not try to amend it yourself.
You may be provided with gentle exercises to start when you are fitted with your splint. These exercises will mean removing the splint and moving your thumb and wrist to help you to regain movement. If you have not been provided with exercises, then remain in the splint full time. At 6 weeks you can start to complete light activities with your hand and continue or start exercises provided.
Cast and splint
At 8 weeks you may return to driving if you are able to grip the steering wheel, manage gears and handbrake and perform an emergency stop. Don’t drive if your hands feel weak as you may not be able to manage these tasks. Your therapist will advise you on further exercises to encourage range of movement and start to gently strengthen your hand again.
For guidance regarding work, please speak with your therapist who can guide you in regard to your specific case.