患者固有の3Dモデルを用いた前頭洞手術：顔面マスク誘導による精度向上

In osteoplastic frontal sinus surgery, the precision of initial bony incisions is critically important. Conventional techniques such as 6-ft Caldwell radiographs, burr holes method, transillumination and navigation systems are widely used. Recently, publications on the use of three-dimensional (3D) printed models in surgical navigation have increased. We aimed to enhance the accuracy of 3D model navigation-a cost-effective and accessible method that can be used alone or alongside conventional approaches-by developing a novel facial mask component not previously described. We developed a patient-specific planning system using open-source segmentation software and a desktop 3D printer. Computed tomography scans were segmented to isolate the anterior table, the sinus walls, and the osteoma when present. A novel feature was the custom-designed facial mask, which ensured accurate alignment of the incision guide. The mask, designed from tissue landmarks, incorporated a locking cylinder mechanism. All parts were printed in polylactic-acid at a cost of approximately 1$, with production times under 8 hours. The system was tested on two patients. In case-1, a patient with an anterior table defect, the 3D-printed model provided accurate incision guidance when navigation failed intraoperatively. In case-2, a frontal sinus osteoma was visualized with 1:1 scale printed models, which facilitated surgical planning. Surgeons reported better anatomical orientation, increased confidence in performing incisions, and more effective preoperative and intraoperative planning. The application of a facial mask to the 3D model has shown promising initial results. Further refinements and comparative studies are needed to standardize production, demonstrate accuracy, and validate its broader clinical utility.