Femke Goormans1, Yi Sun2, Michel Bila3, Joseph Schoenaers1, Joris Geusens1, Heinz-Theo Lübbers4, Wim Coucke5, Constantinus Politis3. 1. Department of Oral and Maxillofacial Surgery/Faculty of Medicine KU Leuven, University Hospitals Leuven, Campus Sint-Rafaël, Kapucijnenvoer 33, 3000 Leuven, Belgium. 2. Department of Oral and Maxillofacial Surgery/Faculty of Medicine KU Leuven, University Hospitals Leuven, Campus Sint-Rafaël, Kapucijnenvoer 33, 3000 Leuven, Belgium; Department of Imaging & Pathology, OMFS IMPATH Research Group, Kapucijnenvoer 33, 3000 Leuven, Belgium. Electronic address: yi.sun@uzleuven.be. 3. Department of Oral and Maxillofacial Surgery/Faculty of Medicine KU Leuven, University Hospitals Leuven, Campus Sint-Rafaël, Kapucijnenvoer 33, 3000 Leuven, Belgium; Department of Imaging & Pathology, OMFS IMPATH Research Group, Kapucijnenvoer 33, 3000 Leuven, Belgium. 4. Clinic for Cranio-Maxillofacial Surgery, University Hospital of Zurich, Frauenklinikstrasse 24, CH-8091 Zurich, Switzerland. 5. Sciensano, J. Wytsmanstraat 14, 1050 Brussels, Belgium.
Abstract
OBJECTIVES: We evaluated the accuracy of computer-assisted mandibular reconstructions. PATIENTS AND METHODS: We retrospectively reviewed data for 26 patients who had mandibular reconstruction with a microvascular free fibula flap, January 2015 to June 2018. Postoperative mandible models were obtained from computed tomography scans. After registering the models to the corresponding preoperative plan, we performed comparative measurements. Patients were grouped by condylar involvement and subdivided based on number of fibular segments used for reconstruction. For each segment, we measured length and osteotomy angles. For the final postoperative outcome, we compared intercoronoid, intergonial, and anteroposterior distances and intersegmental plane shift. RESULTS: Means (SD) for deviation of each osteotomy angle and fibular segment length were 1.98° (2.98) and 1.78 mm (2.69), respectively, remaining constant across subgroups. Other mean values were as follows: intercoronoid distance deviation, 3.86 mm (range, 0.20-11.21 mm); intergonial distance deviation, 3.14 mm (range, 0.05-8.28 mm); anteroposterior distance deviation, 2.92 mm (range, 0.03-8.49 mm); and intersegmental plane shift, 11.00° (range, 2.76-24.15°). Where the condyle was preserved, the intercoronoid and intergonial deviation means differed significantly (respectively 5.02 mm and 4.88 mm, both P < 0.05) for one-segmented and three-segmented fibular reconstructions. Furthermore, reconstructions involving the condylar region compared with condyle preservation showed significantly different intersegmental plane shifts (7.18°; P < 0.05). CONCLUSION: Computer-assisted surgery provides cutting guides for obtaining accurate fibular segments, but current fixation methods lead to inaccuracies and reproducibility errors. In multisegmental transfer with condylar involvement, computer-assisted fixation is recommended to ensure accuracy of the preoperative plan.
OBJECTIVES: We evaluated the accuracy of computer-assisted mandibular reconstructions. PATIENTS AND METHODS: We retrospectively reviewed data for 26 patients who had mandibular reconstruction with a microvascular free fibula flap, January 2015 to June 2018. Postoperative mandible models were obtained from computed tomography scans. After registering the models to the corresponding preoperative plan, we performed comparative measurements. Patients were grouped by condylar involvement and subdivided based on number of fibular segments used for reconstruction. For each segment, we measured length and osteotomy angles. For the final postoperative outcome, we compared intercoronoid, intergonial, and anteroposterior distances and intersegmental plane shift. RESULTS: Means (SD) for deviation of each osteotomy angle and fibular segment length were 1.98° (2.98) and 1.78 mm (2.69), respectively, remaining constant across subgroups. Other mean values were as follows: intercoronoid distance deviation, 3.86 mm (range, 0.20-11.21 mm); intergonial distance deviation, 3.14 mm (range, 0.05-8.28 mm); anteroposterior distance deviation, 2.92 mm (range, 0.03-8.49 mm); and intersegmental plane shift, 11.00° (range, 2.76-24.15°). Where the condyle was preserved, the intercoronoid and intergonial deviation means differed significantly (respectively 5.02 mm and 4.88 mm, both P < 0.05) for one-segmented and three-segmented fibular reconstructions. Furthermore, reconstructions involving the condylar region compared with condyle preservation showed significantly different intersegmental plane shifts (7.18°; P < 0.05). CONCLUSION: Computer-assisted surgery provides cutting guides for obtaining accurate fibular segments, but current fixation methods lead to inaccuracies and reproducibility errors. In multisegmental transfer with condylar involvement, computer-assisted fixation is recommended to ensure accuracy of the preoperative plan.