Computer-aided craniofacial surgical planning implemented in CAD software

Abstract

Accurate presurgical planning is imperative for successful cranial surgery. This article introduces a simulation program developed in a computer-aided design environment. The neurocranium is introduced as a mathematical surface, since this is the part on which the actual operation will be performed. The viscerocranium, which serves as reference, is visualized using small triangular surfaces. The development of the program commenced with a classification of the different surgical techniques mentioned in the literature into six basic actions. The use of mathematically described surfaces has the advantage that the program can simulate actions which change the shape of a surface and perform an on-line estimation of the fracture risk during bending. Three-point bending tests were carried out to provide the necessary data to perform the mathematical check, as these data are not available in the literature. A database with reference distances was introduced to guide the surgeon to obtain the best possible results. During one clinical trial, the computer was taken into the operating room so that the surgical plan developed with the simulation program could be applied to the actual operation.

Public Domain Computer-Aided Surgery (CAS) in Orthodontic and Maxillofacial Surgery

“…Der Einwand, dass der Operateur ja auch nur die Oberfläche des Operationsitus sieht [21], ist hierbei nicht haltbar.…”

“…Furthermore, it is only surfaces that are used, with internal structures being ignored, so that the individual anatomy may be severely distorted. The fact that the surgeon may only see as far as the surface of the surgical site [21] is not a valid argument in the authors' views.…”

“…Unter der Bezeichnung CAS (Computer-Aided Surgery) findet sich eine Vielzahl von Anwendungen, die auf der Basis dreidimensionaler Daten die unterschiedlichsten Ziele verfolgen. Neben der Bildbearbeitung [1,7,9,10,12,13,28,39] sind es die Navigation [15,22,25,29], Finite-Element-Analysen [26,30,33], CAD/CAM-Anwendungen [4,11,21] und die Robotik [8,11,37,40,42], die derzeitige und zukünftige Entwicklungen der computerassistierten orthognathen und kraniofazialen Chirurgie darstellen. Letztendlich dienen alle Methoden nur dazu, den Operateur visuell und in seinem dreidimensionalen Verständnis präoperativ zu schulen oder perioperativ zu unterstützen (Abbildung 9).…”

“…Visarius et al [40] an increase in the amount of surfaces, it is not only the precision that increases but also the calculation time required. To control the time needed for planning, a large-scale data reduction of the models [21,23,45] and thus of the original information is necessary. Furthermore, it is only surfaces that are used, with internal structures being ignored, so that the individual anatomy may be severely distorted.…”

“…Diese mathematischen Modelle aus dem Bereich der Virtual Reality wurden von verschiedenen CAS-Arbeitsgruppen favorisiert [4,14,21,34,44,45]. Die Möglichkeit der nicht linearen Transformation dieser Modelle und der Datenaustausch zu FEM-und CAD/CAM-Umgebungen (s. Abbildung 9) werden als entscheidende Vorteile gesehen.…”