Three-dimensional titanium miniplates for fixation of subcondylar mandibular fractures: Comparison of five designs using patient-specific finite element analysis.

PURPOSE: The purpose of the current study is to compare the performance of five designs of three-dimensional titanium miniplates (lambda, strut, delta, rhombic and trapezoid) for fixation of subcondylar mandibular fracture.

MATERIALS AND METHODS: Three-dimensional models were constructed for the five miniplates with their screws and integrated into a virtually fractured mandible that was derived from a computed tomographic image of living human. Patient-specific finite element models were analyzed to compare the performances of the miniplates. Miniplates were compared for titanium hardware volume, condylar head displacement, bone strains and miniplates' stresses.

RESULTS: Least condylar head displacement, and thereby best fixation primary stability, was found in the trapezoid miniplate. On the other hand, the greatest displacements were found in lambda and strut miniplates. Bone strains, as an indicator of secondary stability, predicted high strains in bone around the screws affixing the delta miniplate. Therefore, high risk of failure due to screws loosening is expected when using the delta miniplate. Stresses in miniplates were excessive in the strut and lambda miniplates, which implies a high risk of miniplate fracture.

CONCLUSIONS: The current findings predicted significant differences in performance among the different designs of three-dimensional miniplates. The trapezoid miniplate seems to have the best performance, as it provided the greatest rigidity with relatively low bone strains.