A reliable and reproducible method for repositioning 3D images to calculate changes in facial volume after orthognathic surgery

Purpose: An accurate, reproducible method to calculate post-operative facial swelling in patients who have undergone orthognathic surgery is important to evaluate the effects of different therapies and surgical techniques on edema. The purpose of this study was to describe such a method and assess its reliability. Materials and methods: A prospective study of patients undergoing orthognathic surgery was conducted. 3D facial photographs were taken on these patients immediately postoperatively, and again at least 21 days later using the 3DMD face system (3DMD LLC., Atlanta, GA, USA). These were cropped using specific anatomic points and the difference in facial volume between the photographs was calculated. Intra-rater reliability and inter-rater reliability were assessed using the Intraclass Correlation Coefficient (ICC).Results: 30 patients were included in the study for analysis. When the difference in facial swelling was calculated twice by the same rater, the mean difference between the two measurements was 4.0 +/- 4.2 mL. When calculated by two separate raters, the mean difference was found to be 5.0 +/- 3.8 mL. The ICCs for intra-rater and inter-rater reliability were excellent at 0.979 and 0.981 respectively. Conclusion: This method allows for reproducible calculation of post-operative facial swelling and could be useful to evaluate the effects of different therapies used to limit swelling and to track the resolution of swelling. It can also potentially be used as a visual aid for patient counseling during the pre-surgical visits.(c) 2023 Elsevier Masson SAS. All rights reserved.