Efficiency of Miniplates Fixation in Mandibular Oblique Fractures

At present, the topic of traumatism of the maxillofacial region is topical and requires the search for contemporary biomechanical solutions. It is known that the problem of mandibular traumatism ranks first among all injuries of the maxillofacial region. Treatment of mechanically failured human mandible was considered as the example of its body fracture in accordance with European classification of maxillofacial trauma. This type of injury was chosen because of its widespread, statistically supported incidence. The treatment method was based on the use of osteosynthesis systems, widely used in the healthcare systems of Western European countries. The purpose of the study was in biomechanical support of existing clinical protocols for the osteosynthesis system elements application to ensure positive treatment prospects. Finite element analysis of acting deformations and displacements in the adjacent bone tissues was carried out for the case of reconstruction of the lower jaw damaged by an oblique fracture in its middle part (body) using two mini-plates in accordance with current clinical protocol. In our case, fracture was fixated with two 1.25 mm in thickness titanium mini-plates. Two types of mini-plates with lengths of 27 mm (long) and 20.5 mm (short) between the axes of the outer holes were analyzed. The results was revealed that osteosynthesis systems technology provides the conditions for the fixed mandible ridges healing under gentle functional loading due to safe micromotions which do not exceed 150 micrometer threshold of safe displacements (0.15 mm for long mini-plate 27×2.5×1.25 mm and 0.13 mm for short mini-plate 20.5×3.5×1.25mm). Also, the largest sliding distance in the fracture section are 0.11 mm for long mini-plate 27×2.5×1.25 mm and 0.06 mm for short mini-plate 27×2.5×1.25 mm. From this viewpoint, short mini-plate is recommended as preferable. However, care should be taken in transferring the results to the clinical situation. First of all, the wider range of possible bone fractures and their actual shapes with possible deviations from a flat contour should be taken into account. Also, more adequate simulation of the crack ridges interface should be provided to answer the question on micromotion data accuracy influencing the crack fixation and the success of the bone healing.