Assessing Free Flap Reconstruction Accuracy of the Midface and Orbit Using Computer-Aided Modeling Software

Importance: Aesthetically pleasing and functionally stable total maxillectomy reconstruction is among the greatest of challenges within head and neck surgery. Maintaining presurgical midface projection, contour, and cheek volume requires high-fidelity restorative control incorporating the provision of stable osseous support to prevent the relatively commonplace complications of lower lid and globe malposition. Objective: To determine the difference in position of the reconstructed infraorbital rim compared with the contralateral normal side, and its effect on globe position, lower eyelid position, orbital volume, and soft tissue contour. Design, Setting, and Participants: This was a case series from 2011 to 2018 in a tertiary academic center. Twelve adult patients underwent free flap reconstruction of the maxilla and inferior orbit by the senior surgeon. Patients with bilateral defects, intact orbital floors, or orbital exenterations were excluded, as were patients without high-resolution postoperative computed tomography (CT) scans. Exposures: Fibular free flaps with orbital floor plates were used in all but one patient, in whom an anterolateral thigh free flap with mesh was used instead. Digital three-dimensional models of the bone and soft tissue were generated from postoperative CT scans using open-source software. Main Outcomes and Measures: Differences in vertical height and anterior projection of the infraorbital rim on the reconstructed side were compared with the normal side. Differences in globe position and lower lid margin were obtained, as were orbital volumes. Differences in soft tissue contour were also examined in six patients who had CT scans at least 6 months after surgery and/or radiation therapy. Results: The absolute mean differences in infraorbital rim height, globe height, lower lid height, and orbital volume were 3.5 mm, 2.5 mm, 3.2 mm, and 2.4 cm³, respectively. The absolute mean difference in soft tissue contour was 10.3 mm for those patients with >6 months follow-up. Differences in infraorbital rim height and globe height were highly correlated (R = 0.77, p = 0.004), as were differences in infraorbital rim height and lower lid height (R = 0.76, p = 0.004). Conclusions and Relevance: Accurate orbitomaxillary free flap reconstruction is possible with precise positioning of the reconstructed infraorbital rim, as this likely affects the position of the lower lid and globe. This methodology of computer-aided modeling with free open-source software may lay the groundwork for future studies seeking to quantify results of facial reconstruction. Level of Evidence: 4.