Motivation


conventional planning

pre-surgical
situation

conventional
planning

post-surgical
situation

Introduction

There is a wide spectrum of facial malformations which maxillofacial and craniofacial surgeons have to take care of. This includes but is not restricted to diseases like fractures and tumors as well as deformities due to inherited syndromes or diseases acquired during childhood or adolescence. For patients seeking for surgical treatment in order to correct such malformations the accurate prediction of the post-surgical facial shape is of paramount importance. Further, facial surgery has to strive for the reconstruction of a balanced face as even very fine variations of facial proportions can affect the appearance of a face strongly and thus distort its beauty.

Therefore, both surgeons and their patients have a strong need for a method which enables them to compute highly realistic 3D pictures of the expected post-surgical shape during the planning of a surgical procedure.

Today's Method

Such prediction and planning of surgical procedures to correct aberrant skeletal anatomy can to date only be performed in a two-dimensional way from one single perspective, most often the profile view of the patient, such as illustrated in the X-ray image in the figure above. All other views only can be estimated roughly. Hence, the fullness of the lips, the width of the nose, the width and projection of the cheekbones and the influence of the surgery on the appearance of the eyes cannot be predicted. For the time being, only the surgeon's experience gives information on the overall outcome of the patient's facial appearance.
envisioned planning

physically-based
model

simulation of
surgical procedure

error
visualization

The FACE Project

The FACE project aims at a new, more exact and more reliable way of facial surgery planning. We present a framework for facial surgery simulation which is based on volumetric finite element modeling. In various preprocessing steps a 3D physically-based facial model is reconstructed from CT and laser range scans. All geometric and topological changes corresponding to the actual surgical procedure are modeled by means of a commercially available modeling system (ALIAS). Using fully 3D volumetric elasticity allows us to represent volumetric effects such as incompressibility in a natural and physically accurate way.

The image above depicts on the left hand side the physical model resulting from CT and laser range data. Bone movements due to a surgical procedure and the visualization of prediction errors are shown in the middle and on the right respectively. Red colors indicate the post-surgical surface lying in in front of the predicted one while green colors indicate the contrary. Much of the errors in the region of the cheek bones ist due to swelling which can take several months to unswell.

For more technical information we refer to the section Technical Overview or the Publications. Results and videos can be found in the Image Gallery and Videos sections respectively.