Yamazaki Takaharu, Futai Kazuma, Tomita Tetsuya, Sato Yoshinobu, Yoshikawa Hideki, Tamura Shinichi, Sugamoto Kazuomi
The Center for Advanced Medical Engineering and Informatics, Osaka University, 2-2 Yamadaoka, Suita, Osaka , 565-0871, Japan,
Int J Comput Assist Radiol Surg. 2015 Apr;10(4):487-95. doi: 10.1007/s11548-014-1093-x. Epub 2014 Jun 26.
Total knee arthroplasty (TKA) 3D kinematic analysis requires 2D/3D image registration of X-ray fluoroscopic images and a computer-aided design (CAD) model of the knee implant. However, these techniques cannot provide information on the radiolucent polyethylene insert, since the insert silhouette does not appear clearly in X-ray images. Therefore, it is difficult to obtain the 3D kinematics of the polyethylene insert, particularly the mobile-bearing insert. A technique for 3D kinematic analysis of a mobile-bearing insert used in TKA was developed using X-ray fluoroscopy. The method was tested and a clinical application was evaluated.
Tantalum beads and a CAD model of the mobile-bearing TKA insert are used for 3D pose estimation of the mobile-bearing insert used in TKA using X-ray fluoroscopy. The insert model was created using four identical tantalum beads precisely located at known positions in a polyethylene insert using a specially designed insertion device. Finally, the 3D pose of the insert model was estimated using a feature-based 2D/3D registration technique, using the silhouette of beads in fluoroscopic images and the corresponding CAD insert model. In vitro testing for the repeatability of the positioning of the tantalum beads and computer simulations for 3D pose estimation of the mobile-bearing insert were performed.
The pose estimation accuracy achieved was sufficient for analyzing mobile-bearing TKA kinematics (RMS error: within 1.0 mm and 1.0°, except for medial-lateral translation). In a clinical application, nine patients with mobile-bearing TKA were investigated and analyzed with respect to a deep knee bending motion.
A 3D kinematic analysis technique was developed that enables accurate quantitative evaluation of mobile-bearing TKA kinematics. This method may be useful for improving implant design and optimizing TKA surgical techniques.
全膝关节置换术（TKA）的三维运动学分析需要对X线透视图像和膝关节植入物的计算机辅助设计（CAD）模型进行二维/三维图像配准。然而，这些技术无法提供关于射线可透过的聚乙烯垫片的信息，因为垫片轮廓在X线图像中显示不清晰。因此，很难获得聚乙烯垫片的三维运动学信息，尤其是活动平台垫片。利用X线透视技术开发了一种用于TKA中活动平台垫片三维运动学分析的技术。对该方法进行了测试并评估了其临床应用价值。
使用钽珠和活动平台TKA垫片的CAD模型，通过X线透视对TKA中使用的活动平台垫片进行三维姿态估计。使用专门设计的插入装置，将四个相同的钽珠精确放置在聚乙烯垫片的已知位置，从而创建垫片模型。最后，利用透视图像中珠子的轮廓和相应的CAD垫片模型，采用基于特征的二维/三维配准技术估计垫片模型的三维姿态。对钽珠定位的重复性进行了体外测试，并对活动平台垫片的三维姿态估计进行了计算机模拟。
姿态估计精度足以分析活动平台TKA的运动学（均方根误差：除内外侧平移外，在1.0毫米和1.0°以内）。在临床应用中，对9例使用活动平台TKA的患者进行了深屈膝运动的研究和分析。
开发了一种三维运动学分析技术，能够对活动平台TKA的运动学进行准确的定量评估。该方法可能有助于改进植入物设计和优化TKA手术技术。
