Heyse Thomas J, Tibesku Carsten O
Department of Orthopedics and Rheumatology, University Hospital Marburg, Baldingerstrasse, 35043, Marburg, Germany,
Arch Orthop Trauma Surg. 2015 May;135(5):697-701. doi: 10.1007/s00402-015-2157-2. Epub 2015 Apr 1.
Patient-specific instrumentation (PSI) was introduced in an attempt to reduce positional outliers of components in total knee arthroplasty (TKA). It was hypothesized that PSI could help with the positioning of tibial components in optimal rotational alignment.
A magnetic resonance imaging (MRI) analysis of 58 patients following TKA was conducted. Of these, 30 operations were performed using PSI and 28 using conventional instrumentation. The rotation of the tibial components was determined in MRI using three different reference lines: a tangent to the dorsal tibial condyles, the tibial epicondylar line, and the tibial tubercle. Deviations >9° were considered outliers. Also internal rotation >1° was considered an outlier. Data were analyzed statistically for positional outliers using the Chi-squared test.
There was excellent inter- and intraobserver reliability with low standard deviations for the determination of tibial component rotation using the tangent to the dorsal condyles and the tibial epicondylar line as reference. Using the dorsal tangent as reference, there were eight components in excessive external rotation (28.6 %) and one component being in relative internal rotation (5.4°) in the conventional group, while there were two components in excessive external rotation in the PSI group (6.7 %). Using the tibial epicondyles as reference, there were seven components in excessive external rotation (21.4 %) and one component being in relative internal rotation (4.4°) in the conventional group; while there were two components in excessive external rotation in the PSI group (6.7 %). These differences were statistically significant (p < 0.05). Measurements based on the tibial tubercle showed poor reproducibility in terms of intra- and interobserver reliability and was of little use in the context of the research question.
In this setup, PSI was effective in significantly reducing outliers of optimal rotational tibial component alignment during TKA. Anatomy of the proximal tibia does not deliver clear landmarks that are prominent and consistent. This makes both, MRI analysis as well as cutting jig production and intraoperative placement a challenge.
引入患者特异性器械（PSI）旨在减少全膝关节置换术（TKA）中组件的位置异常值。据推测，PSI有助于将胫骨组件定位在最佳旋转对线位置。
对58例TKA术后患者进行磁共振成像（MRI）分析。其中，30例手术使用PSI，28例使用传统器械。在MRI中使用三条不同的参考线确定胫骨组件的旋转：胫骨背侧髁的切线、胫骨上髁线和胫骨结节。偏差>9°被视为异常值。此外，内旋>1°也被视为异常值。使用卡方检验对位置异常值数据进行统计学分析。
以胫骨背侧髁切线和胫骨上髁线为参考确定胫骨组件旋转时，观察者间和观察者内的可靠性极佳，标准差较低。以背侧切线为参考，传统组中有8个组件过度外旋（28.6%），1个组件相对内旋（5.4°），而PSI组中有2个组件过度外旋（6.7%）。以胫骨上髁为参考，传统组中有7个组件过度外旋（21.4%），1个组件相对内旋（4.4°）；而PSI组中有2个组件过度外旋（6.7%）。这些差异具有统计学意义（p<0.05）。基于胫骨结节的测量在观察者内和观察者间可靠性方面显示出较差的可重复性，在研究问题的背景下用处不大。
在这种设置下，PSI在显著减少TKA期间胫骨组件最佳旋转对线的异常值方面是有效的。胫骨近端的解剖结构没有提供突出且一致的清晰标志。这使得MRI分析以及切割夹具的制作和术中放置都成为一项挑战。
