Intramedullary Single-Kirschner-Wire Fixation in Displaced Fractures of the Fifth Metacarpal Neck (Boxer's Fracture).

UNLABELLED

The fracture of the fifth metacarpal neck (also called a boxer's fracture) is the most common fracture of the hand. Displaced fractures often result in volar angulation of the metacarpal head, shortening, and residual malrotation. The present video article demonstrates the steps of performing intramedullary single-Kirschner-wire fixation of the fifth metacarpal neck, with the aim of the procedure being to achieve a closed reduction and internal stabilization of such a fracture. Although many fractures can be treated with a splint only, surgery should be performed in patients with excessive volar angulation, relevant shortening, or rotational deformity.

DESCRIPTION

For this procedure, the injured arm of the patient is placed on an arm table. The incision is made 1 to 2 cm longitudinally over the ulnar base of the fifth metacarpal bone. The cortical bone is opened with an awl, and a bent 1.6-mm Kirschner wire is inserted into the medullary canal. After reaching the fracture region, the fracture is anatomically reduced. The Kirschner wire is then advanced into the head of the fifth metacarpal, securing the reduction. Malrotation can be addressed in this stage by rotating the wire under fluoroscopic control. After ensuring anatomical reduction clinically and by fluoroscopy, the wire is shortened under the skin, followed by closure of the incision. We utilize a mid-hand brace for splinting.

ALTERNATIVES

Nonoperative treatment is common for fifth metacarpal neck fractures in the absence of malrotation, excessive angulation, and shortening. Other surgical techniques include a similar procedure that involves the use of multiple Kirschner wires, plate fixation, transverse Kirschner wire pinning, and, less commonly, retrograde headless screw fixation.

RATIONALE

The main advantage of this technique is the preservation of the metacarpophalangeal joint and the minimal soft-tissue damage. Additionally, the use of a single Kirschner wire provides stability at low cost. With some experience, this surgery can be performed within 20 minutes.

EXPECTED OUTCOMES

This procedure provides good fracture reduction and stabilization. The outcome is usually satisfactory, with very low Disabilities of the Arm, Shoulder, and Hand scores. Malrotation, angulation, and shortening are sufficiently addressed, and the technique shows the same results as fixation performed with use of 2 intramedullary wires.

IMPORTANT TIPS

Bending the Kirschner wire to ensure easy gliding in the medullary canal provides the opportunity to reduce the metacarpal neck once the wire is safely in the head.Aim distally as you open the cortical bone with the awl in order to facilitate the insertion of the Kirschner wire.The primary reduction should be made manually, not by the wire. Subacute fractures and substantially displaced fractures require direct force for a satisfactory reduction, which cannot be achieved by rotation of the wire only.The cortical bone on the metacarpal head is very thin. Take care not to drive the Kirschner wire through the cortical bone and into the joint.Shorten the wire under the skin approximately 1 cm above the bone surface; this ensures easy removal and prevents skin irritation.

ACRONYMS AND ABBREVIATIONS

K-wire = Kirschner wire.