The strength of different fixation techniques for bicondylar tibial plateau fractures––a biomechanical study

Objective. To compare the mechanical strength of fixation of bicondylar tibial plateau fractures using internal and external fixation techniques. Design. A randomised laboratory testing of fixation methods currently in clinical use. Background. To reduce the high complication rate associated with the double plating, many surgeons have started to use less invasive techniques. However the literature comparing the mechanical performance of these methods is still scarce. Methods. Bicondylar tibial plateau fractures were simulated on Sawbones tibiae and fixed with one of the five fixation methods: dual plating, a two-ring hybrid fixator with inter-fragmentary screws, a ring-bar hybrid fixator with inter-fragmentary screws, lateral plate and medial monolateral external fixator, lateral plate and medial inter-fragmentary screws. Following statistical power calculations, seven tibiae were used for each fixation method. The specimens were tested in cyclical compression to failure. The vertical subsidence in the medial or lateral plateau was measured using extensometers. Results. In all cases the mode of failure was consistent with collapse occurring in the medial plateau. There was no significant difference in the failure load between dual plating and the two-ring hybrid fixator (4218 N and 4184 N respectively; P=0.28, t-test). Failure was seen at significantly lower loads with the other fixation systems. Conclusion. Weight-bearing mobilisation of the patient may be undertaken earlier with more confidence by using the double plating or two-ring hybrid fixator rather than other less strong techniques. The choice on which of these two methods to use may depend on tissue viability and surgeon preference.