Bending stiffness of odontoid fracture fixation with one cortical screw - Numerical approach

Abstract

The anterior screw fixation of odontoid fractures is nowadays standard clinical operation. There are less biomechanical studies dealing with the problem whether one or two screws should be used for this type of stabilisation. This study used in vitro experiment and finite element simulation to investigate the bending stiffness in the sagital plane of stabilised odontoid fracture type II of the second cervical vertebra. The comparative study of one cortical screw and the cannulated one was performed. The results indicated that there are no significant differences between them. In addition, it seems from the bending stiffness point of view, tightening the screw to higher levels is quite useless, because the stiffness is not higher, but with higher stresses we can reached diminishing of the bone’s strength and stiffness, according to Wolff’s law of functional adaptation. Thus the most reasonable might be to tighten the screws to certain moment, as in the dental surgery is performed.