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Updated: Jul 10, 2025
A Postoperative Evaluation Guideline for Computer-Assisted Reconstruction of the Mandible
Published on: January 28, 2020
Geometric Cuts by an Autonomous Laser Osteotome Increase Stability in Mandibular Reconstruction With Free Fibula
Maximilian Gottsauner1, Marta M Morawska2, Simon Tempel3
1Coordinator of the Head and Neck-Tumor-Center, Department of Oral and Maxillofacial Surgery, University Hospital Regensburg, Regensburg, Germany.
Background:
Nonunion and plate exposure represent a major complication after mandibular reconstruction with free fibula flaps. These drawbacks may be resolved by geometric osteotomies increasing intersegmental bone contact area and stability.
Purpose:
The aim of this study was to compare intersegmental bone contact and stability of geometric osteotomies to straight osteotomies in mandibular reconstructions with free fibula grafts performed by robot-guided erbium-doped yttrium aluminum garnet laser osteotomy.
Study Design, Setting, Sample:
This cadaveric in-vitro study was performed on fresh frozen human skull and fibula specimens. Computed tomography (CT) scans of all specimens were performed for virtual planning of mandibular resections and three-segment fibula reconstructions. The virtual planning was implemented in a Cold Ablation Robot-guided Laser Osteotome.
Predictor/Exposure/Independent Variable:
For predictor variables, straight and geometric puzzle-shaped osteotomies were designed at resection of the mandible and corresponding fibula reconstruction.
Main Outcome Variables:
The primary outcome variable was the stability of the reconstructed mandible investigated by shearing tests. Moreover, secondary outcome variables were the duration of the laser osteotomies, the contact surface area, and the accuracy of the reconstruction, both evaluated on postsurgical CT scans.
Covariates:
Covariables were not applicable.
Analyses:
Data were reported as mean values (± standard deviation) and were statistically analyzed using an independent-sample t-test at a significance level of α = 0.05. Root mean square deviation was tested for accuracy.
Results:
Eight skulls and 16 fibula specimens were used for the study. One hundred twelve successful laser osteotomies (96 straight and 16 geometrical) could be performed. Geometric osteotomies increased stability (110.2 ± 36.2 N vs 37.9 ± 20.1 N, P < .001) compared to straight osteotomies. Geometric osteotomy of the fibula took longer than straight osteotomies (10.9 ± 5.1 min vs 5.9 ± 2.2 min, P = .028) but could provide larger contact surface (431.2 ± 148.5 mm2 vs 226.1 ± 50.8 mm2, P = .04). Heat map analysis revealed a mean deviation between preoperational planning and postreconstructive CT scan of -0.8 ± 2.4 mm and a root mean square deviation of 2.51 mm.
Conclusion And Relevance:
Mandibular resection and reconstruction by fibula grafts can be accurately performed by a Cold Ablation Robot-guided Laser Osteotome without need for cutting guides. Osteotomy planning with geometric cuts offers higher stability and an increased bone contact area, which may enhance healing of the reconstructed mandible.
