Volumetric Analysis of Fat Injection by Computerized Tomography in Orthognathic Surgery: Preliminary Report on a Novel Volumetric Analysis Process for the Quantification of Aesthetic Results

Background: Integrated approaches to orthognathic surgery should include accurate volumetric evaluation of the skull and soft tissues. In patients with dentofacial deformities, the most frequent aesthetic deficits are attributable to an underdevelopment of hard and soft tissues. Traditional osteotomic procedures often fail to guarantee a stability of soft tissues over time. For this reason, in selecting a surgical strategy, the surgeon should consider not only traditional osteotomies, but also soft-tissue improving procedures, such as lipofilling. Preoperative surgical planning systems, such as the Virtual surgical planning (VSP) protocol, are based mainly on skeletal movement prediction. Quantitative estimation of soft-tissue modifications is not part of common clinical practice. Most commonly, the evaluation of soft-tissue modifications after orthognathic procedures is instead performed by clinical qualitative means. The purpose of this study was to describe a novel computed tomography (CT)-based volumetric analysis process for the quantification of injected autologous adipose tissue in patients who have undergone simultaneous orthognathic and lipofilling procedures. Methods: This was a retrospective review of consecutive patients who underwent combined orthognathic surgery and lipofilling from June 2016 to May 2017 for malocclusion with functional and aesthetic impairments. Preoperative planning included clinical evaluation and virtual osteotomy planning according to the VSP protocol. The volume of fat to be injected was estimated clinically by comparing virtual renderings with preoperative clinical photographs. The surgical technique involved Le Fort I and sagittal split mandibular osteotomies, combined with autologous fat injection in the malar and perioral regions. Postoperative evaluation was performed with a novel imaging process based on CT image segmentation to quantify the exact volume of injected fat. Skeletal stability was also evaluated at 3 months. Results: Sixteen patients were enrolled in the study, all females, with a mean age of 24.5 years (range, 18-36 years). The mean difference between the fat tissue injected and that quantified postoperatively was 6.01 cm 3. All patients had clinically satisfactory facial convexity, with complete restoration of the cheekbone contour, at 3 months. Conclusion: This study introduces a novel CT-image based technique to quantitatively assess the contribution of injected fat to the postoperative soft-tissue volume increase after combined orthognathic surgery with autologous lipofilling. In the future, this CT-based volumetric analysis technique could be the gold standard for evaluating facial lipofilling outcomes, and for assessing clinical aesthetic outcomes based on the injected volume of fat.