A new method of transoral endoscopic-assisted treatment for mandibular subcondylar fractures using a template-guided patient-specific osteosynthesis implant: the Ulm protocol

Intraoral subcondylar fracture repair still remains one of the most controversial and discussed topics in the field of maxillofacial trauma. Despite transoral endoscopic-assisted reduction and internal fixation has attracted wide attention, the surgical approach still is technically challenging and specialised instruments are mandatory. Trauma surgeons need to go through a shallow learning curve in order to achieve suitable and predictable surgical results comparable to the standard extraoral approaches. In our clinic the transoral endoscopic-assisted approach without the use of transbuccal trocars for reduction and osteosynthesis of non comminuted subcondylar fractures has been exclusively practising for more than 17 years. The current work presents a novel concept for surgical treatment of subcondylar fractures, namely the preoperatively CAD/CAM planned, template-guided, patient-specific osteosynthesis to facilitate precise and effective outcome. At first step, a preoperative 1 mm-layer CT imaging is used for the segmentation and virtual 3D reduction of the dislocated condyle fragment. At second step, CAD/CAM techniques are applied for manufacturing of a patient-specific osteosynthesis implant (PSOI) according the "backward planning" concept with the "one-fit-only" design at the condylar fragment and patient-specific surgical guide for positioning at the ascending ramus to replace the conventional osteosynthesis miniplates in the trajectory area of the ascending ramus according to established osteosynthesis principles. The patient- and fracture-morphologically individualized implant design allows the development of a reliable workflow to ensure maximum surgical precision and predictability of the anatomical and functional outcome combined with possible shortening of operation duration and reduction of perioperative complications. Hereby, the technically demanding fracture treatment can be significantly simplified by using a patient-specific reduction and osteosynthesis tool. This workflow was shown to be applied predictably and accurately in a clinical setting. The patient- and fracture-morphologically individualized "one-fit-only" implant design could allow the development of a reliable workflow to ensure maximal surgical precision intraoperatively. We consider this novel method of template-guided, patient-specific osteosynthesis of subcondylar fractures combined with modern CAD/CAM technology as evolution for the transoral endoscopic-assisted approach.