Pedraza William, Beckmann Johannes, Mayer Constantin, Mauch Frieder, Huth Jochen, Best Raymond
Department of Orthopaedics, Sportklinik Stuttgart GmbH, Taubenheimstraße 8, 70372, Stuttgart, Germany.
Department of Orthopedic Sports Medicine, University of Tuebingen, Hoppe Seyler Strasse 6, 72076, Tuebingen, Germany.
Int Orthop. 2016 Dec;40(12):2519-2526. doi: 10.1007/s00264-016-3247-7. Epub 2016 Jul 22.
Rotational alignment of prosthetic components after total knee arthroplasty (TKA) is predominantly monitored with computer tomography (CT), for example by relating the anatomical transepicondylar axis (a-TEA) of the native femur to the posterior bicondylar axis of the prosthetic component (PBCA). The purpose of the present study was to portray a reliable, novel plain radiographic method that likewise enables the evaluation of rotational positioning of prosthetic components in TKA. Furthermore, it was intended to evaluate the prosthetic femoro-tibial functional behavior under loaded conditions.
Modified plain axial radiographs under partial weight bearing (20 kg) were performed in 63 patients (63 knees) after TKA. On the obtained radiographs, all established, relevant anatomic, and prosthetic axis and angles reflecting the rotational position of the femoral (i.e., a-TEA/PBCA angle) and tibial component were detected twice by two independent examiners with an interval of one month. Additionally, in 14 cases with anterior knee pain after surgery, radiographic results were compared to obtained computer tomography images; intraclass coefficients (ICC's) for intra- and inter-rater reliability were calculated.
All pre-assigned axis and angles could be identified doubtlessly by both examiners in all investigated knees. For all measurements, ICC's for intra-rater and inter-rater reliability ranged from 0.75 to 0.96. The comparison of the radiographic measurements with corresponding CT results (n = 14) revealed no significant differences (p > 0.05). Rotational alignment of the tibial tray in relation to the native tibial bone was not measurable due to display overlaying. Femoro-tibial behaviour of the prosthetic components under partial loading showed a high variability.
We were able to establish a new reliable radiographic technique that is able to show the most established and relevant anatomic landmarks and prosthetic axis after TKA to assess the rotational alignment of the prosthetic components in TKA in relation to the distal femur. The evaluation of the femoro-tibal behaviour instead shows a high variability and so far does not allow valid explanatory conclusions.
全膝关节置换术（TKA）后假体组件的旋转对线主要通过计算机断层扫描（CT）进行监测，例如通过将天然股骨的解剖髁间轴（a - TEA）与假体组件的后双髁轴（PBCA）相关联。本研究的目的是描述一种可靠的、新颖的平片放射学方法，该方法同样能够评估TKA中假体组件的旋转定位。此外，本研究旨在评估负重条件下假体股骨 - 胫骨的功能行为。
对63例（63膝）TKA术后患者在部分负重（20 kg）下进行改良的平片轴向X线摄影。在获得的X线片上，由两名独立的检查者对所有既定的、相关的解剖学和假体轴以及反映股骨（即a - TEA/PBCA角）和胫骨组件旋转位置的角度进行两次检测，间隔为1个月。此外，在14例术后出现前膝痛的病例中，将放射学结果与获得的计算机断层扫描图像进行比较；计算组内相关系数（ICC）以评估评分者内和评分者间的可靠性。
两位检查者在所有研究的膝关节中都能毫无疑问地识别出所有预先设定的轴和角度。对于所有测量，评分者内和评分者间可靠性的ICC范围为0.75至0.96。放射学测量结果与相应CT结果（n = 14）的比较显示无显著差异（p > 0.05）。由于影像重叠，无法测量胫骨托盘相对于天然胫骨的旋转对线。假体组件在部分负重下的股骨 - 胫骨行为表现出高度变异性。
我们能够建立一种新的可靠的放射学技术，该技术能够显示TKA后最既定的和相关的解剖标志以及假体轴，以评估TKA中假体组件相对于股骨远端的旋转对线。然而，对股骨 - 胫骨行为的评估显示出高度变异性，目前还无法得出有效的解释性结论。
