Comparative biomechanical analysis of two techniques of radiolunate plate-fusion: oblique screw vs. parallel screws

The purpose of this prospective randomized comparative biomechanical study on four pairs of human cadaveric forearms was to discern whether primary stability following plate arthrodesis differs from the position of the screws. Four wrists were randomly assigned to either group such that one wrist of each pair was fixed via parallel screws and the other via an oblique screw crossing the radius and the lunate. Under fluoroscopic guidance, passive extension and flexion of each wrist was performed using a spring balance. Traction force increased by 5 N at each step, ranging from 0 N to a maximum of 100 N. Fixation using a plate and oblique screw demonstrated lower recoverable deformation of the implant and a higher primary stability at the fusion site than parallel screws. The current investigators conclude that an oblique screw crossing radius and lunate increase primary stability which is consistent with the radiological results of comparable clinical trails.