Fixation of Metacarpal Shaft Fractures: Biomechanical Comparison of Intramedullary Nail Crossed K ‐Wires and Plate‐Screw Constructs

Objectives Metacarpal ( MC ) fractures are very common, accounting for 18% of all fractures distal to the elbow. Many MC fractures can be treated non‐operatively; however, some are treated most effectively with surgical stabilization, for which there are multiple methods. It was postulated that plates would have a significantly higher ( P < 0.05) load to failure than crossed K ( XK )‐wires and that intramedullary metacarpal nails ( IMN s) and XK ‐wires would have equivalent load to failure. Methods Mid‐diaphyseal transverse fractures were created in 36 synthetic metacarpals and stabilized using nails, XK ‐wires or non‐locking plates. Three‐point bending was performed with continuous recording of load and displacement. Statistical analysis was performed using single factor ANOVA and Scheffe's test. Statistical significance was defined as P < 0.05. Results Biomechanical testing revealed significant differences between groups in load‐to‐failure. Average load to failure was significantly greater in the plate (1669 ± 322 N) than the XK ‐wire (146 ± 56 N) or IMN (110 ± 43 N) groups. The loads to failure of the K ‐wires and nails were equivalent. Plates were 11 and 15 times stronger in three‐point bending than the K ‐wires and nails, respectively. There was no statistically significant difference between strengths of the K ‐wires and nails. Conclusions Although plates are the most stable means of fixation of midshaft metacarpal fractures, if minimally‐invasive techniques are indicated, intramedullary nails may provide equivalent stability as commonly‐used XK ‐wires. Although some studies have shown favorable clinical outcomes with IMN s, additional clinical correlation of these biomechanical results to fracture healing and outcomes is needed.