Computer-aided design-based preoperative planning of screw osteosynthesis for type B condylar head fractures: A preliminary study.

Objective: To investigate the clinical application of a new computer-aided design - (CAD) based planning method for the treatment of type B condylar head fractures without fragmentation.

Methods: A total of 13 adult patients (19 sides) with type B condylar head fractures were included in the study. In all cases, imaging was performed using cone bean computed tomography (CBCT) preoperative, and Digital Imaging and Communications in Medicine (DICOM) files were imported into Simplant 11.04 software. The fracture of the mandibular condyle was reconstructed by a three-dimensional reconstruction module, and the simulation of reduction was achieved according to the morphological characteristics. Preoperative design was performed based on the CAD technology, and the three-dimensional interface was used to determine the length, location, and orientation of the positional screw. Osteosynthesis was performed with a single positional screw according to the optimum direction assessed in the preoperative planning CBCT, and the result was confirmed with postoperative CBCT scans and clinical follow-up.

Results: Preoperative computer-aided design was able to predict the length, location, and direction of the positional screw. Postoperative CBCT results demonstrated that 12 cases (18 sides) were consistent with preoperative design with exception of one case (one side) due to unexpected rupture of the fragment. Six-month follow-up showed the condylar fractures were anatomically repositioned and that healing was excellent in 12 cases (18 sides) with minor displacement and resorption in one case (one side). Postoperative occlusion in all cases was excellent, and the maximum mouth opening improved from mean 1.2 cm preoperatively to a of mean 4.3 cm at 6 months postoperatively. The data for mandibular movements at 6 months postoperatively demonstrated the recovery of protrusion, without higher grade limitations for laterotrusion. In one case, there appeared to be mandibular deviation (<0.5 cm) with mouth opening.

Conclusion: The new preoperative design provides relevant data for screw osteosynthesis to enhance the precision and effectiveness of open reduction and internal fixation type B condylar head fractures.