Choice of Screws for Fixation of Mandibular Condyle Fractures Guided by Anthropometric Data

Abstract

Open reduction and internal fixation (ORIF) is becoming increasingly common in treatment of the condylar process, including mandible head fractures. This approach significantly improves the results in terms of anatomical reduction of bone fragments, and shortens the treatment time, allowing for early functional recovery. The success of ORIF is largely determined by the stability of the osteosynthesis. The stabilization effect depends on the screw type and length of the plate used, in addition to the diameter and length of the screws used. The aim of this study was to determine the largest possible screw length that can be used in ORIF of the mandibular condyle considering the variable bone thickness. A total of 500 condyles were examined using computer tomography (CT)-based 3D models in Caucasians. For all models, three measurements were made in the frontal projection in places typical for the stabilization of osteosynthesis plates in the fractures of the condylar process: the base, the top, and the sigmoid notch. In addition, one measurement of the mandible head was made in the place of the greatest width. The results showed that 8 mm screws should be used in the region of the condylar base as the longest anatomically justified screw, whereas in the area of a sigmoid notch only 1.5–2 mm screws should be used. Measurements in the area of the neck top revealed statistically significant differences in the measurements between the sex of patients, with average differences below 1 mm (p < 0.05). In this area, the maximal length of the screw was found to be 10 mm. In mandibular head fractures, the use of long screws is extremely important due to the desired effect of fragment compression. Statistically significant differences were found in the measurement results between women and men. The maximal screw length for bicortical fixation was found to be 22 mm in men and 20 mm in women. In post-traumatic patients, the ability to obtain a clear measurement is often limited by a deformed anatomy. Taking into account the fact that the fracture stability is influenced by both the plate length and the length of the fixation screws, an assessment of the standard measurement values in a cohort group will improve the quality of the surgical fixations of the fractures.