Silicone knuckle joint replacement for rheumatoid arthritis

These joints are known medically as MCPJs (metacarpo-phalangeal joints).  This is a very useful operation that we perform for patients with severe rheumatoid arthritis.  The main reason for performing the operation is pain, and worsening deformity, with consequent loss of hand function.  Because of weakening of the ligaments surrounding the joints, the fingers become angled away from the hand.  The joints may also be stiff.  If the wrist is angled in the opposite direction (towards the thumb), then treatment for that may be needed first.

The operation

The operation is performed either under General Anaesthetic, or with the arm numbed from the shoulder down.  The surgery takes approximately two hours.  You will go home later the same day, or more often the next morning.

The operation is performed from the back of the hand, with an incision either straight across the back of the hand, or along each knuckle individually.  The diseased joint and inflamed tissues are removed, and the joint replaced with a specially designed silicone replacement.  This has shaped ends to fit into the shafts of the metacarpal (hand) and phalangeal (finger) bones.  This gives renewed stability to the joint whilst it heals.

The next, and most important part of the operation, is to repair, strengthen and rebalance the ligaments and tendons around the joints that caused the deformity in the first place.

Finally, the incisions are closed with either dissolveable or removeable sutures.   Dressings and a plaster-of-paris splint are applied to the hand and wrist to support the fingers, but still allow some early movement.

In the next few weeks

It is extremely important to keep the hand elevated high for the first 48 hours, usually on pillows.  There may be a special elevation sling whilst in hospital.  The hand will be in a plaster splint.  At the first clinic visit (at one to two weeks after the operation) this will be removed, the dressings changed, stitches removed if necessary, and physiotherapy started.  A new plastic splint will be supplied by the physiotherapist, and worn until six weeks after the operation.   The exercises taught by the physiotherapist are absolutely vital in regaining the best possible hand function.  However, one should not be tempted to “overdo it”, as the delicate ligament and tendon reconstructions can be damaged.

What are the results of the operation?

Most patients say they have a good result following this operation, with better hand function, and less or no residual deformity.

Are there any risks?

  • It is sometimes not possible to fully correct the deformity, especially if this has been severe or long-standing.
  • There is a small (<1%) risk of wound infection, which settles with antibiotics.
  • There is a small (<1%) risk of damage to a nerve in a finger, especially the outside of the little finger, leading to permanent numbness.
  • There may be residual stiffness. The range of motion usually achieved is approximately half to two-thirds of the 90° seen in a normal knuckle joint.
  • Sometimes the silicone implants can break or “dislocate” out of the bones. This is usually not a problem if it occurs a year or more after the operation, as they will have performed their job of stabilising the joint whilst the tendon and ligament reconstructions healed.  Occasionally, an early implant failure might need revision surgery.  This is very rare.
  • Chronic Regional Pain Syndrome “CRPS”. This is a rare but serious complication, with no known cause or proven treatment.  The nerves in the hand “over-react”, causing swelling, pain, discolouration and stiffness, which very slowly improve, but may leave stiffness. This is treated with physiotherapy, and sometimes tablets.
  • The original deformity often gradually starts again in the very long-term (>5-10 years). This is usually much less than the original deformity, and certainly less that it would have been if left untreated.  This risk is probably higher if the wrist has a deformity.