Purpose: Most metacarpal fractures are stable and can be treated with nonsurgical stabilization. However, some metacarpal fractures are treated with open reduction and internal fixation because of an open fracture, instability, or multiple fractures. Newer plate designs have emerged that allow a shorter plate and screw construct. We sought to determine the relative strength of 3 different methods of metacarpal plating for unstable fractures.
Methods: We tested our hypothesis in a transverse metacarpal fracture model using fourth-generation, biomechanical testing grade composite sawbones (Sawbones; Pacific Research Laboratories, Vashon, WA). The metacarpals were divided into 3 groups of 15 bones. Group 1 was plated with a standard 6-hole, 2.3-mm plate with 6 nonlocking bicortical screws in standard AO fashion. Group 2 was plated with a 6-hole, double-row, 3-dimensional (3D) plate with 3 nonlocking screws on either side of the fracture aiming for convergence of the screws. Group 3 was plated with a 2.4-mm plate using 6 nonlocking screws and standard AO technique. The metacarpals were then tested to failure in cantilever bending mode.
Results: All constructs broke through the bone. No plate failure or screw pullout was seen. Group 1 had a load to failure of 264 N +/- 14. Group 2 had a load to failure of 302 N +/- 17. Group 3 had a load to failure of 274 N +/- 20. The load to failure was highest in group 2 (3D plate). All differences were statistically significant.
Conclusions: All 3 methods produced a strong construct. The load to failure was highest in group 2 (3D plate). Double-row plates with converging screws provide adequate or superior strength of fixation when compared with standard plate constructs.