Finger joint replacement is mainly performed to provide pain relief in degenerate joints. This is usually in cases of osteoarthritis, post-traumatic arthritis or rheumatoid arthritis.
Arthritis of the distal interphalangeal joints in the fingers (the joints closest to the ends of the fingers) is most commonly treated with fusion of these joints to provide stability and reliable improvement in pain.
The proximal interphalangeal joints (the joints closer to the knuckle) however are very important for function and are relied upon for gripping and holding tasks. The metacarpo-phalangeal joints (the joints at the knuckle) are also very important in normal fist formation. If these joints become painful and degenerate, they can in some cases benefit from replacement.
Procedure
Joint replacement surgery is usually performed under general anaesthetic. A tourniquet is applied to the arm to prevent blood flow in and out of the arm. This provides a dry operating zone with very little blood loss.
Once the joint has been opened up, the degenerative bone surfaces are resected. Cutting guides and jigs are used to produce clean precise cuts in the ends of the bone to allow an accurate tight fit of the appropriate prosthesis.
In most cases of osteoarthritis where there is good quality bone stock, metallic implants are used. These are often 'press fit' implants with stems that slide into the bone to provide stability. As the bone grows tightly around the prosthesis stem, stability increases.
In cases of rheumatoid arthritis, the bone quality is sometimes less. More commonly in these situations, silastic (silicone rubber) implants are used. These are soft flexible hinge like prostheses. In rheumatoid disease, the tendons will often have slipped out of position and tendon rebalancing may be required to help correct the alignment of the fingers and restore the normal pathway of the tendons.
Post-operative Care
Following joint replacement surgery most patients will require quite extensive hand therapy to try and maximise the range of movement. Depending on the degree of soft tissue repair required, patients may need to be quite cautious with their initial progress in order to protect the soft tissue repairs.
The main aim of surgery is to provide improvement in pain. Many patients will still have some restriction in the range of movement but most people will have good improvement in their discomfort.
Risks
As with all surgery, there is a risk of infection. This is usually in the order of approximately 1%. If a patient develops an infection around a prosthesis, this can be very significant. It can be very hard to eradicate the infection without removing the prosthesis.
The risk of infection is increased with any form of immunosuppression. Infection risk is higher in patients with rheumatoid disease, especially those who are on medication to suppress their immune system. Often patients will be required to come off their medication for a period prior to surgery.
As mentioned, there is the potential for some persistent stiffness around the joints even after replacement surgery. Patients usually regain a smooth arc of movement but they may lack full extension or full flexion.
The prostheses do wear over time and on occasions patients may need to have revision surgery. This is more likely in younger patients or patients involved with heavier or repetitive use of the hands.