KIRSCHNER WIRE FIXATION OF BASAL FRACTURES OF THE FIRST METACARPAL

Indications

Fractures of the base of the first metacarpal tend to dislocate owing to forces from the tendons (e.g. abductor pollicis longus (APL) tendon in Bennett's fracture). Therefore operative treatment is necessary if stable retention cannot be achieved by casting. Closed reduction and internal K-wire fixation can be performed for:

1. (a) Fractures with small fragments.

2. (b) Fractures with good alignment after closed reduction but no stable retention without fracture fixation, in the absence of large impression defects.

Pre-operative planning

Clinical assessment

• Pain and swelling localized to carpometacarpal joint I.

• Assess and document neurovascular status of thumb.

Radiological assessment

• Standard anteroposterior (AP) and lateral radiographs of the trapezium (Kapandji) obtained by placing the hand for a true lateral view, with abduction of the thumb and directing the imaging beam centred over the trapeziometacarpal joint.

• Computed tomography helps to define the degree of comminution within a fracture, as well as suspected impaction of the articular surface.

Operative treatment

Anaesthesia

• Brachial plexus block, intravenous regional anaesthesia or general anaesthesia.

• Prophylactic antibiotic according to the local hospital protocol (e.g. 2nd generation cephalosporin).

Table and equipment

• Hand surgery instrumentation set, K-wires: 1.2mm.

• Radiolucent armtable.

• Upper armtourniquet.

• Image intensifier.

Table set up

• The instrumentation is set up on the side of the operation.

• Image intensifier is from the front side of the arm table.

Patient positioning

• Supine, supinated armextended on armtable.

Fracture reduction

• Gentle axial traction and pressure on the displaced fragment usually reduces displaced fractures.

• Open anatomical reduction is indicated if closed reduction fails and/or stable reduction cannot be achieved.