In-house In-and-out technique for mandibular reconstruction analysis: a 3D comparison against CAD-CAM designs for fibula flap reconstruction.

Abstract

Mandibular reconstruction following segmental mandibulectomy presents significant functional and aesthetic challenges. Virtual surgical planning (VSP) and 3D printing improve surgical precision but are often costly and time-consuming. In-house protocols have emerged as alternatives to reduce costs and accelerate the workflow. The In-and-Out technique is an innovative in-house method that employs a 3D-printed biomodel to transfer reconstruction plate positioning to cutting guides. A retrospective cohort study compared mandibular reconstruction accuracy using the In-and-Out technique versus a CAD-CAM protocol (Computer Aided Desing and Manufacturing) of the reconstruction plate. Fourteen patients underwent fibula flap mandibular reconstruction between May 2022 and February 2024. There were 7 patients in each group. Postoperative CT scans were compared to preoperative Stereolithographic (STL) models to evaluate volumetric accuracy using CloudCompare®. Intercondylar and intergonial distances were assessed with MeshLab®. Non-parametric tests were used for superiority and non-inferiority studies. Median STL deviation was 0.21mm (IQR:0.15-0.26mm) for the In-and-Out group and 0.18mm (IQR:0.17-0.21mm) for the control group. Median intercondylar deviation was 2.11mm (IQR:1.26-2.32mm) for In-and-Out versus 1.89mm (IQR:0.92-3.41mm) in the control group. Median intergonial deviation was 1.86mm (IQR:1.38-2.41mm) for In-and-Out versus 1.95mm (IQR:1.14-2.93mm) for the control group. Cost was reduced in more than 75% and workaround time from 2 weeks to 2 days. Biopsy-to-surgery time was reduced in 8 days. The In-and-Out technique can become a viable alternative to outsourced CAD-CAM workflows for mandibular reconstruction at a fraction of the cost. Specially for simpler cases and those requiring shorter workaround time.