Experimental model of tibial plateau fracture for biomechanical testing.

Although adequate reduction and stable fixation have been recognized to be the prime goals in the treatment of displaced tibial plateau fractures, the optimal fixation technique remains controversial. The lack of a reliable model and a standard methodology contribute to this situation. The purpose of this study is to develop an experimental model of a tibial plateau fracture and a testing methodology that reproduces the failure mode commonly seen in the clinical setting. Using solid-foam and composite Sawbones tibiae, three different models of bi-condylar tibial plateau fracture (solid-foam, reinforced solid-foam and composite), six specimens for each model, were created and stabilized with double plating. The specimens were subjected to cyclic axial compression with increasing maximum load until failure. A femoral component of a total knee replacement of similar size and shape to the synthetic tibial surface was used as a load applicator. The experiment was repeated on six specimens of human cadaver tibiae. Among the Sawbones specimens, only the reinforced solid-foam model was found to produce a consistent failure mode (collapse in the medial plateau) comparable to that reported clinically in the literature. This mode of failure was also confirmed by the cadaver experiments. The failure load of the reinforced solid-foam model ranged from 4150 to 4260 N with a mean +/- SD of 4201 +/- 44 N and a coefficient of variance of 0.01, whereas for the cadaver model the failure load ranged from 1675 to 6096 N with a mean +/- SD of 3768 +/- 1482 N and a coefficient of variance of 0.39. We recommend the reinforced-foam model for future mechanical tests to compare different fixation methods for tibial plateau fractures.