First-in-human application of dynamic fluoroscopic analysis to quantify intersegmental motion in mandibular free flap reconstruction

Osseous non-union following free flap reconstruction of segmental mandibular defects can prolong patients' dental rehabilitation. Various plating systems have been developed to optimize biomechanical fixation, but healing may be retarded. Quantifying intersegmental micromovements could help monitor healing but remains challenging. This study investigates a novel method to visualize segmental movements during healing using a fluoroscopy-based approach. To track segment movements, tantalum beads were implanted intraoperatively in the osseous flap and native mandibular segments. Additionally, single-plane fluoroscopic imaging was performed to assess bead position at maximum mouth opening and intercuspation. Bead positions were merged as three-dimensional objects. Intersegmental movements were quantified using model-based roentgen stereophotogrammetry (mbRSA). Exemplarily, preliminary images were collected from one patient. Fluoroscopic imaging with mbRSA effectively displayed movements and allowed quantification. Translation and rotation were assessed between the native mandible and the flap during maximum mouth opening and intercuspation. For the first time, our analyses demonstrate the feasibility of quantifying segment mobility during healing. This first in men study illustrates the feasibility of the method to monitor intersegmental movements in cases of maxillofacial reconstructions. Further research involving larger patient cohorts is necessary to identify relevant thresholds and differentiate from those that result in lack of healing.