Gellrich Nils-Claudius, Schramm Alexander, Hammer Beat, Rojas Sergio, Cufi Daniel, Lagrèze Wolf, Schmelzeisen Rainer
Department of Oral and Maxillofacial Surgery, Albert-Ludwigs-University, Freiburg, Germany.
Plast Reconstr Surg. 2002 Nov;110(6):1417-29. doi: 10.1097/01.PRS.0000029807.35391.E5.
Until now, computer-assisted surgery has not been practiced as part of the surgical routine of posttraumatic orbital reconstruction. The purpose of this study was to investigate the use of a navigation system for computer-assisted preoperative planning with virtual reconstruction to obtain symmetry of the orbits and intraoperative control of virtual contours in comparison with the clinically achieved surgical results. A further objective of the computer-assisted orbital analysis was to use an ideal measurement for the two-dimensional and three-dimensional changes following orbital reconstruction and to check the equality of the postoperative values for the affected orbits in comparison with those of the unaffected sides. Patients with unilateral posttraumatic orbital defects (n = 18) underwent computer-assisted surgery and preoperative planning using a spiral computed tomography database. Surgical procedures were preplanned with virtual correction by mirroring an individually defined three-dimensional segment from the unaffected side onto the deformed side, creating an ideal unilateral reconstruction. These computer-models were intraoperatively used as virtual templates to navigate the preplanned contours and the globe projection using the Stryker-Leibinger navigation system. Individual noninvasive registration with an overall inaccuracy of approximately 1 mm was achieved by using a maxillary occlusal splint with four markers. The mirroring of the unaffected side allowed an ideal virtual reconstruction. A mean decrease in enlarged orbital volume of 4.0 (SD +/- 1.9) cm was achieved, as was a mean increase in the sagittal globe projection of 5.88 (SD +/- 2.98) mm. With a paired Student test, the decrease between the preoperative and postoperative differences of the affected and unaffected sides was proved significant for orbital volume, globe projection, and computed tomography-based Hertel scale changes (p < 0.01). In 15 of 18 cases, simultaneous malar bone advancement resulted primarily in an additional increase in orbital volume before intraorbital augmentation with calvarial split-bone grafts could be performed. Intraorbital bony augmentation included one (n = 1), two (n = 7), three (n = 8), and all four (n = 2) orbital walls. Computer-assisted preoperative planning enables the surgeon to predict reconstructive surgical steps before the operation. Highly vulnerable structures such as the optic nerve can be detected and avoided intraoperatively, and virtually preplanned bone graft positions and/or orbital frame contours can be checked. Computer-assisted preoperative planning and surgery thus advance the difficult surgical field of orbital reconstruction, particularly through a greater exploitation of radiologic information without additional radiation to the patient.
到目前为止，计算机辅助手术尚未作为创伤后眼眶重建手术常规的一部分来实施。本研究的目的是调查使用导航系统进行计算机辅助术前规划及虚拟重建，以实现眼眶对称，并与临床手术实际结果相比，在术中控制虚拟轮廓。计算机辅助眼眶分析的另一个目标是为眼眶重建后的二维和三维变化采用一种理想的测量方法，并检查患侧眼眶术后数值与未受影响侧数值的相等情况。18例单侧创伤后眼眶缺损患者使用螺旋计算机断层扫描数据库进行了计算机辅助手术及术前规划。手术程序通过将从未受影响侧单独定义的三维节段镜像到变形侧进行虚拟校正来预先规划，从而创建理想的单侧重建。这些计算机模型在术中用作虚拟模板，使用史赛克-莱宾格导航系统来引导预先规划的轮廓和眼球投影。通过使用带有四个标记的上颌咬合夹板实现了总体误差约为1毫米的个体无创配准。未受影响侧的镜像实现了理想的虚拟重建。眼眶扩大体积平均减少4.0（标准差±1.9）立方厘米，眼球矢状面投影平均增加5.88（标准差±2.98）毫米。通过配对t检验，患侧与未受影响侧术前和术后差异在眼眶体积、眼球投影和基于计算机断层扫描的赫特尔量表变化方面被证明具有显著性（p<0.01）。在18例中的15例中，同时进行颧骨前移主要导致在使用颅骨劈开骨移植进行眶内增大之前眼眶体积进一步增加。眶内骨性增大包括一个（n=1）、两个（n=7）、三个（n=8）和全部四个（n=2）眶壁。计算机辅助术前规划使外科医生能够在手术前预测重建手术步骤。术中可以检测并避开视神经等高风险结构，并且可以检查虚拟预先规划的骨移植位置和/或眼眶框架轮廓。因此，计算机辅助术前规划和手术推动了眼眶重建这一困难的手术领域的发展，特别是通过更多地利用放射学信息，而无需对患者进行额外辐射。
