Ring and little finger metacarpal fractures: mechanisms, locations, and radiographic parameters.

PURPOSE

To describe a series of ring and little finger metacarpal fractures with regard to mechanism, location, midshaft diameter, and isthmus diameter, to better define injury patterns and assist the surgeon in selection of appropriately sized implants.

METHODS

We reviewed all metacarpal fractures in skeletally mature patients who presented to a single surgeon over a 2-year period. Fractures of the ring and little finger metacarpals were analyzed with regard to mechanism and fracture location. Metacarpal midshaft and minimum isthmus diameters were measured on posteroanterior radiographs.

RESULTS

A total of 101 fractures involved the ring and little finger metacarpals. Punching-type injuries accounted for most fractures in the little finger metacarpal (49 of 67) and ring finger metacarpal (26 of 34). Among these punching-related ring and little finger metacarpal fractures, the most common fracture location was the little finger metacarpal neck (34 of 75), followed by the ring finger metacarpal shaft (21 of 75). Among men in this series, the metacarpal midshaft and minimum isthmus diameters were significantly narrower in the ring finger metacarpal than in the little finger (7.4 vs 8.7 mm, p < .001; and 2.2 vs 3.8 mm, p < .001).

CONCLUSIONS

Whereas punching injuries tended to cause neck fractures in little finger metacarpals in this series, they caused shaft fractures in ring finger metacarpals, which may thus be considered a variant boxer's fracture. Furthermore, in men with fractures, the ring finger metacarpal is significantly narrower than the little finger, both in midshaft diameter and isthmus diameter, which surgeons should consider when planning internal fixation.

TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic IV.