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Ulnar shortening

There are two bones in the forearm the one on the thumb side is called the radius and the one on the little finger side is called the ulnar. Both these bones should be about the same length. If the ulnar is slightly longer which is quite common it can lead to pain where the long bone impinges on the bones of the wrist (a patients with a positive ulnar variance) and can also lead to tears of the cartilage, which is the triangular cartilage that sits at the end of the ulnar. One way of relieving both these types of symptoms is to shorten the ulnar. This involves breaking the ulnar (which is done in a controlled fashion with a saw), and taken a segment of the bone out of the ulnar and realigning the two ends of the bone and fixing them together with a plate and screws. It is a common and successful operation for ulnar sided wrist pain. The ulnar is sub cutaneous bone i.e. you can feel most it from the tip of your elbow all the way down to the ulnar side of the wrist where there is a knobble at the level of the wrist joint on the little finger side of the forearm. An incision is made along the subcutaneous border of the ulnar.

ANAESTHETIC

General or regional anaesthetic.

OPERATIVE PROCEDURE

An 8cm long incision is made along the subcutaneous border of the ulnar. Skin flaps are raised and the bone is exposed in between two tendons on the ulnar side of the wrist one on the back of the wrist called extensor carpi ulnaris and one on the front of the wrist called flexor carpi ulnaris. There is a membrane surrounding the bone (periosteum) and this is preserved. A little cutting jig is applied to the bone and this allows the surgeon to cut a particular amount of bone out, generally 2 - 5 mm depending on how much longer the ulnar is than the radius. The bone is removed in an oblique fashion and a small 5 hole plate is applied to the bone to bring the two ends together and hold the bone in place. The wound is then closed.

POST OPERATIVELY

The hand is elevated and antibiotics are given to prevent infection. Plaster of Paris splint is applied and the patient is sent home either the same day or the following morning in a high arm sling. The patient is reviewed at two weeks when the splint is removed and sutures are removed. The wound is checked and if everything is fine then a further splint is applied for 4 weeks. The patient needs to be in some form of cast for 6 weeks following the operation. At 6 weeks the cast is removed and physiotherapy is instigated and the patient is reviewed again at 3 months when an X-ray is carried out to ensure the bones have joined.

COMPLICATIONS

  1. Infection - between 1 - 2%.
  2. Tendon damage.
  3. Nerve damage - there is a branch of a major nerve on the little finger side of the hand and this can be at risk from this procedure. If this is damaged will lead to numbness on the back of the hand although this is a rare complication.
  4. Non union - when you cut the bone this is very similar to a break in the bone and unfortunately sometimes breaks in a bone do not join and this is called in a non-union. This particularly occurs in a break to the forearm because the bone that is unbroken (the radius in this particular case) can split the broken bone apart. The non-union rate that Mr Field has is 5 - 6%.
  5. Complex regional pain syndrome