Jeremy Field - Consultant Orthopaedic and Hand Surgeon

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It is not uncommon particularly after a distal radius fracture that the tendon that extends the thumb, which means pulls the thumb away from the hand i.e. in a hitch hike position, can rupture. This commonly occurs 6 - 12 weeks following a radius fracture often when that fracture is undisplaced fracture or a simple crack of the distal radius. The fracture can occur after a fall on an outstretched hand. The patient complains of inability to straighten the end of the thumb and span of the hand is reduced and the patient might have difficulty when picking up large objects i.e. a pint glass of beer or a large vase. This tendon rupture can also occasionally occur with wrist arthritis. The tendon rupture is called an atrition rupture which means that the tendon rubs over a prominent piece of bone and essentially wears out. Because of the nature of the rupture it means that there is an area of tendon that has been damaged and that tendon cannot be repaired. As the tendon cannot be repaired a tendon is taken from somewhere else and is used to make the thumb extend. The tendon that is normally used is the tendon that allows you to point your index finger. The index finger has two tendons attached to it, one that independently extends the finger to allow it to point and the other tendon is a common tendon attached to all the fingers and makes all of them straighten. So if you take one of the tendons from the index finger and use it to power another movement the other tendon that is left still allows the index finger to extend.

ANAESTHETIC

General or regional anaesthetic.

OPERATIVE PROCEDURE

There are three incisions, one over the index finger knuckle one over the middle of the back of the wrist which is about 3cm long and a 2 - 3 cm long incision over the back of the thumb. The tendon that we use for the tendon transfer is always the tendon over the knuckle which is on the middle finger side. Through the cut over the knuckle the tendon is cut. By pulling that cut tendon you can identify where that tendon is at the back of the wrist and through the cut on the back of the wrist that tendon is pulled through the wound at the back of the wrist. Through the cut over the back of the thumb the tendon that extends the end joint of the thumb (the one that allows end joint to straighten) is identified. A tunnel is then made subcutaneously (under the skin) from the wound on the back of the wrist to wound on the back of the thumb and the tendon is pulled from the back of the wrist wound into the wound on the back of the thumb. The tendon is then attached by way of a three pass weave, which means that the tendon is passed through the tendon of the thumb three times at 90° to each other and sutured at each pass. The wounds are then closed.

POST OPERATIVELY

The hand is put in a plaster with the thumb in the hitch hiking position which is maintained for 3 weeks. Physiotherapy is then commenced at 3 weeks with the patient wearing a splint at night for a further 3 weeks. It takes a little time for the patient to use the tendon that used to point the index finger and now extends the thumb however it is amazing how quickly the brain copes with this change.

COMPLICATIONS

Infection - occurs in approximately 1% of cases and is rare in a hand that has a good blood supply.
Tendon rupture - unfortunately the repair of the tendon that has been performed can rupture and if it ruptures the procedure may need to be repeated (1-5%).
Complex regional pain syndrome