By Andrea Stephens, OTC
Reprinted with permission from The Journal, 10(2), 8-10.

Metacarpal fractures account for 30% to 40% of all hand fractures. These injuries can result from direct or indirect force. Metacarpal neck fractures, sometimes called "boxer's fractures" because they often come from hitting an object with a closed fist, are the most common metacarpal break. Although these breaks happen most often to the fourth and fifth metacarpals, this type of injury, as well as other fractures, can also occur in the third metacarpal.
A nondisplaced fracture to the third metacarpal is usually treated conservatively in a short-arm cast that extends to the tips of the fingers and is positioned in intrinsic plus. While this is an effective approach, it has several drawbacks.

Potential problems and contraindications
The first problem is skin maceration between the fingers. If the orthopaedic technologist does not place gauze or some type of absorptive barrier between the fingers in the cast, the skin tends to retain moisture and macerate. Even then, the barrier is sometimes accessible to the patient and can be removed. The build-up of dead skin, sweat, and body oil between the fingers can also cause the cast to have an unpleasant odour and, in this position, the patient is not able to clean his or her hand.

Fingers can inadvertently become cramped together in this cast, which can be uncomfortable for the patient. Uninvolved fingers maintained in the cast are better suited out of the cast entirely to maintain range of motion in these joints and promote better skin condition. A cast can be constructed in such a way as to immobilize the third metacarpal up to the proximal interphalangeal (PIP) of the long finger without immobilizing uninjured fingers

This cast is appropriate for treatment of a transverse fracture of the third metacarpal only and should not be used for other fracture patterns that may be angulated, displaced, comminuted, rotated, or spiral. An angulated fracture needs to be reduced or surgically corrected if it is greater than 10 degrees. A displaced fracture would need open reduction internal fixation (ORIF) to return it to the anatomical position. A comminuted fracture may shorten in a cast if the bone ends do not maintain their lengths. Rotation does not remodel over time and, therefore, would not be ideally treated in this cast. A longitudinal spiral fracture has a tendency to bayonet when treated conservatively and may not have an ideal outcome for the patient in this cast.