Modélisation du carpe osseux et biomécanique

Computer-assisted midface reconstruction in Treacher Collins syndrome part 1: skeletal reconstruction

INTRODUCTION

Treacher Collins syndrome (TCS) is a severe and complex craniofacial malformation affecting the facial skeleton and soft tissues. The palate as well as the external and middle ear are also affected, but his prognosis is mainly related to neonatal airway management. Methods of zygomatico-orbital reconstruction are numerous and currently use primarily autologous bone, lyophilized cartilage, alloplastic implants, or even free flaps. This work developed a reliable "customized" method of zygomatico-orbital bony reconstruction using a generic reference model tailored to each patient.

METHODS

From a standard computed tomography (CT) acquisition, we studied qualitatively and quantitatively the skeleton of four individuals with TCS whose age was between 6 and 20 years. In parallel, we studied 40 controls at the same age to obtain a morphometric database of reference. Surgical simulation was carried out using validated software used in craniofacial surgery.

RESULTS

The zygomatic hypoplasia was very important quantitatively and morphologically in all TCS individuals. Orbital involvement was mainly morphological, with volumes comparable to the controls of the same age. The control database was used to create three-dimensional computer models to be used in the manufacture of cutting guides for autologous cranial bone grafts or alloplastic implants perfectly adapted to each patient's morphology. Presurgical simulation was also used to fabricate custom positioning guides permitting a simple and reliable surgical procedure.

CONCLUSIONS

The use of a virtual database allowed us to design a reliable and reproducible skeletal reconstruction method for this rare and complex syndrome. The use of presurgical simulation tools seem essential in this type of craniofacial malformation to increase the reliability of these uncommon and complex surgical procedures, and to ensure stable results over time.

Modeling of the human fetal skull base growth: interest in new volumetrics morphometric tools

BACKGROUND

Research on the skull base is important to improve our understanding of the growth and development of the modern human skull. To study the growth of the human fetal skull base, we assessed a new geometric morphometric tool, which does not require the use of bone landmarks.

MATERIAL AND METHODS

Seven dry fetal skulls of an estimated gestational age ranging from 15 to 27 weeks were studied. Each skull was scanned using a standard CT scan and the image sets were post-processed to extract volumetric data by segmenting the skull base into predefined regions of interest. Our method of analysis was based on the inertial properties of reconstructed volumes.

RESULTS

The volumetric study of the skulls highlighted an asynchronous speed of growth between the pre and post-chordal parts of the skull base whose preferential growth are in the vertical and horizontal planes. We also found different speeds of growth in the pre-chordal part depending on the type of ossification (endochondral or membranous). The overall shape of the skull base bones were preserved during the period studied except for the petrous pyramids. The expansion of bone parts was isometric with reference to a central point that was located at the intrasphenoidal synchondrosis. Finally, the analysis of the basicranial angles corroborated data from the literature in the sagittal plane and allowed their study also in the frontal and horizontal planes.

CONCLUSIONS

This three-dimensional volumetric approach is a necessary complement to studies that are performed in the sagittal plane and are based on the identification of landmarks. The geometric morphometric method used by authors permitted to obtain original informations on the growth kinetics and bone tridimensional movements of the human fetal skull base.