Comparison of three different fixation constructs for radial neck fractures: a biomechanical study

BACKGROUND Fixation of radial neck fractures can be achieved with a plate and screw construct or with two screws. This study evaluated the biomechanical properties of three different fixation methods following radial neck fractures. METHODS Twenty-four fourth-generation composite radii were sawed to simulate an unstable radial neck fracture. They were then instrumented with a plate and screw construct or two different orientations (crossed and parallel) of screw fixation. Implants were tested under bending and torsional loads via a tension torsion composite test system. Bending and torsional failure loads were added to the remaining implant-radius constructs if they did not fail during the previous tests. RESULTS During the bending loading test, the crossed-screw group showed the greatest stiffness, followed by the parallel-screw group, the plate group demonstrating the weakest stiffness. There was no significant difference between the crossed- and the parallel-screw groups. However, there was a significant difference between the two screw groups and the plate group. During the bending failure test, the largest stiffness was found for the crossed-screw group, while the plate group exhibited the smallest stiffness. There was a significant difference between the three groups. During the torsion loading test, the highest stiffness was observed for the crossed-screw group, while the plate group showed the lowest stiffness. In the torsion failure test, the failure torques were 11.97 ± 2.659, 8.531 ± 1.768, and 7.079 ± 1.666 N m respectively for the crossed-screw, parallel-screw, and plate groups. There was a significant difference between the crossed-screw group and the two other groups. CONCLUSIONS Crossed screws and plate fixation are commonly used in clinical practice to treat simple radial neck fractures. While the present study shows that the parallel-screw method results in similar biomechanical strength as the two other techniques, it has the advantages of reaching limited wound exposure and having the implant buried. Therefore, it may be widely used in clinical practice.