Metzger Marc Christian, Hohlweg-Majert Bettina, Schön Ralf, Teschner Matthias, Gellrich Nils-Claudius, Schmelzeisen Rainer, Gutwald Ralf
Department of Craniomaxillofacial Surgery, Albert-Ludwigs University Freiburg, Freiburg, Germany.
Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007 Oct;104(4):e1-10. doi: 10.1016/j.tripleo.2007.04.015. Epub 2007 Jul 26.
Computer-aided surgery (CAS) has proved to be useful in reconstructive craniomaxillofacial surgery. Preoperative creation of virtual models by segmentation of the computerized tomography (CT) dataset and mirroring of the unaffected side allows for precise planning of complex reconstructive procedures. The aim of this study was to evaluate the accuracy of the preoperative planning and the postoperative result regarding the skeletal reconstruction.
In a first step, the symmetry of unaffected human skulls and faces were evaluated by 20 midface CT data of skulls and 20 surface-scan data of healthy individuals. By mirroring and adjusting the original and mirrored datasets using a 3-dimensional modeling software, an automatic measurement procedure could evaluate the mean and the maximal modulus of the distances between both datasets. In a second step, 18 consecutive cases were selected which had been treated with CAS support. Group 1 consisted of orbital floor and/or medial wall fractures (n = 12), group 2 consisted of zygomatic bone fractures (n = 4), and group 3 included 2 patients who were treated by secondary orbital reconstruction including reosteotomy of the zygomatic bone (n = 2). To verify the surgical result, the preoperative CT dataset including the virtual planning and the postoperative CT dataset were compared by using image fusion. Additionally, postoperative surface scans and the clinical symptoms of the patients were evaluated.
No differences between the skull and face symmetry were found. Mean values for distances considering the skull symmetry were 0.83 mm for male and 0.71 mm for female and for the face symmetry 0.65 mm for male and 0.76 mm for female. Comparing the preoperative planning with the postoperative outcome, a mean accuracy of 1.49-4.12 mm with maximum modulus of 2.49-6.00 mm was achieved. Orbital true-to-original reconstructions and the secondary reconstructions were more precise than the reposition of the zygomatic bones. The postoperative acquired surface scans resulted in mean distances from 0.89 to 1.784 mm. Despite these deviations, all patients demonstrated satisfying clinical outcome.
The natural asymmetry in humans influences the accuracy of preoperative planning procedure, when the mirroring tool is used. The accuracy transforming the preoperative planning to the surgical reconstruction using CAS depends on location, surgical approach, and matter of reconstruction.
计算机辅助手术（CAS）已被证明在颅颌面重建手术中有用。通过对计算机断层扫描（CT）数据集进行分割并镜像未受影响侧来创建术前虚拟模型，有助于精确规划复杂的重建手术。本研究的目的是评估术前规划的准确性以及骨骼重建的术后结果。
第一步，通过20例颅骨的面中部CT数据和20例健康个体的表面扫描数据评估未受影响的人类颅骨和面部的对称性。使用三维建模软件对原始数据集和镜像数据集进行镜像和调整后，自动测量程序可以评估两个数据集之间距离的平均值和最大模量。第二步，选择18例接受CAS支持治疗的连续病例。第1组包括眶底和/或内侧壁骨折（n = 12），第2组包括颧骨骨折（n = 4），第3组包括2例接受二次眼眶重建（包括颧骨截骨术）治疗的患者（n = 2）。为了验证手术结果，通过图像融合比较包括虚拟规划的术前CT数据集和术后CT数据集。此外，评估了术后表面扫描和患者的临床症状。
未发现颅骨和面部对称性之间存在差异。考虑颅骨对称性时，男性距离的平均值为0.83 mm，女性为0.71 mm；考虑面部对称性时，男性为0.65 mm，女性为0.76 mm。将术前规划与术后结果进行比较，平均准确度为1.49 - 4.12 mm，最大模量为2.49 - 6.00 mm。眼眶原位重建和二次重建比颧骨复位更精确。术后获得的表面扫描结果显示平均距离为0.89至1.784 mm。尽管存在这些偏差，但所有患者的临床结果均令人满意。
当使用镜像工具时，人类的自然不对称性会影响术前规划程序的准确性。使用CAS将术前规划转化为手术重建的准确性取决于位置、手术方法和重建事项。
