Mandible reconstruction using patient-specific pre-bent reconstruction plates: comparison of standard and transfer key methods

Mandible reconstruction with reconstruction plates requires bending the plates during the operation and fixation using the standard method (ST-method). The ST-method is limited when a pathological process has perforated the mandibular outer cortex. A transfer key method (TK-method) was developed where plates are pre-bent using a patient-specific mandible model and positioned on the mandible with the help of transfer keys. The ST-method and TK-method were compared in a clinical trial. Mandibular reconstruction was performed on 42 patients in this study: 22 were performed using the TK-method and 20 using the ST-method. Pre- and postoperative CT scans were evaluated by measuring the distances between six corresponding landmarks on the mandibular condyles and rami. The difference between pre- and postoperative distances was used to evaluate reconstruction accuracy. The median deviation of the unsigned/ absolute values of all six distances was 1.07 mm for the TK-method and 1.67 mm for the ST-method. The TK-method showed significantly better results. For the signed values, the median deviation of the six distances was 0.6 mm for the TK-method and 1.47 mm for the ST-method, indicating that the mandibles became narrower with both methods. This width difference was not statistically significant. The TK-method was more accurate than the ST-method in a clinical trial. The TK-method was effective and accurate for mandible reconstruction using pre-bent fixation plates.