Patient-specific pre-contouring of osteosynthesis plates for mandibular reconstruction: Using a three-dimensional key printed solution

In mandibular reconstructive surgery, the osteosynthesis plates require contouring according to the patients' individual anatomical situation. These plates are frequently contoured around a three-dimensional (3D) printed model. However, the translation to the actual patient can introduce inaccuracies and unwanted rotations in the condyles and mandibular ramus, due to malpositioning of the pre-contoured plate. This article describes an easy-access method for exact translation of the pre-contoured plate to the patient's mandible. This is done by using 3D printed guides that allow pre-drilling of screw holes in both the contour model and the patients' mandible. The accuracy of the Key Printed Solution was analysed by comparing the anatomical landmarks on both the 3D planned and post-operative models. The method was applied to 4 cases. All landmarks were identified on both the 3D planning and post-operative computed tomographic data. This showed an average deviation of 1.0 mm between planning and the post-operative result. The inter-observer variation was 0.6 mm (intra-class correlation, 0.75). This article presents an easy-to-use method for pre-bending the osteosynthesis plate and subsequent accurate translation of the intended contour with corresponding screw hole locations. The method was proved to be accurate and time-efficient.