Modelling of Facial Soft Tissue Growth for Maxillofacial Surgery Planning Environments

When maxillofacial surgery is proposed as a treatment for a patient, the type of osteotomy and its influence on the facial contour is of major interest. To design the optimal surgical plan, 3D image-based planning can be used. However, prediction of soft tissue deformation due to skeletal changes, is rather complex. The soft tissue model needs to incorporate the characteristics of living tissues. Since surgeon and patient are interested in the expected facial contour some months after surgery when swelling has disappeared, features specific to living tissues need to be modelled. This paper focusses on modelling of tissue growth using finite element methods. This growth is induced by stress resulting from the surgical procedure. We explain why modelling growth is needed and propose a model. We apply this model to 4 patients treated with unilateral mandibular distraction and compare these soft tissue predictions with the postoperative CT image data.