Langlotz U, Grützner P A, Bernsmann K, Kowal J H, Tannast M, Caversaccio M, Nolte L-P
mNemoscience, Obach-Palenberg, Germany.
Proc Inst Mech Eng H. 2007 Oct;221(7):739-53. doi: 10.1243/09544119JEIM280.
Computer assisted orthopaedic surgery (CAOS) technology has recently been introduced to overcome problems resulting from acetabular component malpositioning in total hip arthroplasty. Available navigation modules can conceptually be categorized as computer tomography (CT) based, fluoroscopy based, or image-free. The current study presents a comprehensive accuracy analysis on the computer assisted placement accuracy of acetabular cups. It combines analyses using mathematical approaches, in vitro testing environments, and an in vivo clinical trial. A hybrid navigation approach combining image-free with fluoroscopic technology was chosen as the best compromise to CT-based systems. It introduces pointer-based digitization for easily assessable points and bi-planar fluoroscopy for deep-seated landmarks. From the in vitro data maximum deviations were found to be 3.6 degrees for inclination and 3.8 degrees for anteversion relative to a pre-defined test position. The maximum difference between intraoperatively calculated cup inclination and anteversion with the postoperatively measured position was 4 degrees and 5 degrees, respectively. These data coincide with worst cases scenario predictions applying a statistical simulation model. The proper use of navigation technology can reduce variability of cup placement well within the surgical safe zone. Surgeons have to concentrate on a variety of error sources during the procedure, which may explain the reported strong learning curves for CAOS technologies.
计算机辅助骨科手术（CAOS）技术最近被引入，以克服全髋关节置换术中髋臼组件位置不当所导致的问题。现有的导航模块在概念上可分为基于计算机断层扫描（CT）的、基于荧光透视的或无图像的。当前研究对髋臼杯的计算机辅助放置精度进行了全面的准确性分析。它结合了使用数学方法、体外测试环境和体内临床试验的分析。一种将无图像技术与荧光透视技术相结合的混合导航方法被选为基于CT系统的最佳折衷方案。它引入了基于指针的数字化技术来确定易于评估的点，并采用双平面荧光透视来确定深部标志。从体外数据来看，相对于预定义的测试位置，发现倾斜度的最大偏差为3.6度，前倾角的最大偏差为3.8度。术中计算的髋臼杯倾斜度和前倾角与术后测量位置之间的最大差异分别为4度和5度。这些数据与应用统计模拟模型的最坏情况预测结果一致。正确使用导航技术可以将髋臼杯放置的变异性降低到手术安全区内。在手术过程中，外科医生必须关注各种误差来源，这可能解释了报道的CAOS技术存在较强学习曲线的原因。
