Department of Orthopaedic Surgery, Osaka General Hospital of West Japan Railway Company, Abeno-ku, Osaka, Japan.
J Knee Surg. 2022 Jul;35(9):978-982. doi: 10.1055/s-0040-1721127. Epub 2020 Nov 25.
To determine accuracy of patient-specific instrumentation (PSI), the preoperative three-dimensional (3D) plan should be superimposed on the postoperative 3D image to compare prosthetic alignment. We aimed to compare prosthetic alignment on a preoperative 3D computed tomography (CT) plan and postoperative 3D-CT image, and evaluate the accuracy of PSI during total knee arthroplasty (TKA). Thirty consecutive knees (30 patients) who underwent TKA using PSI were retrospectively evaluated. The preoperative plan was prepared using 3D CT acquisitions of the hip, knee, and ankle joints. The postoperative 3D CT image obtained 1 week after surgery was superimposed onto the preoperative 3D plan using computer software. Differences in prosthetic alignment between the preoperative and postoperative images were measured using six parameters: coronal, sagittal, and axial alignments of femoral and tibial prostheses. Differences in prosthetic alignment greater than 3 degrees were considered outliers. Two observers performed all measurements. All parameters were repeatedly measured over a 4-week interval. This measurement method's intraobserver and interobserver reliabilities were more than 0.81 (very good). For the femoral and tibial prostheses, absolute differences between the preoperative and postoperative 3D CT images were significantly larger in the sagittal than in the coronal and axial planes ( < 0.001). The outlier rate for the sagittal alignment of femoral and tibial prostheses was significantly higher than that for the alignment of coronal and axial planes ( < 0.001). However, there were no significant differences in the range of motion (ROM) before and after TKA when comparing cases with and without outliers in the sagittal plane. Even though the present study did not reveal any issues with the ROM that depended on the presence of an outlier, accurate verification of prosthetic alignment for individual PSI models may be necessary because the designs, referenced images, and accuracy are different in each model.
为了确定个体化假体设计（PSI）的准确性，术前的三维（3D）计划应与术后的 3D 图像叠加，以比较假体的对线情况。我们旨在比较术前 3D 计算机断层扫描（CT）计划和术后 3D-CT 图像上的假体对线情况，并评估 PSI 在全膝关节置换术（TKA）中的准确性。回顾性评估了 30 例连续膝关节（30 例患者）接受 PSI 的 TKA。术前计划是使用髋关节、膝关节和踝关节的 3D CT 采集来制定的。术后 1 周获得的术后 3D CT 图像使用计算机软件叠加到术前 3D 计划上。使用六个参数测量术前和术后图像中假体对线的差异：股骨和胫骨假体的冠状、矢状和轴向对线。认为假体对线差异大于 3°为异常值。两名观察者进行了所有测量。所有参数在 4 周间隔内重复测量。该测量方法的观察者内和观察者间可靠性均大于 0.81（非常好）。对于股骨和胫骨假体，术前和术后 3D CT 图像之间的绝对差异在矢状面明显大于冠状面和轴向平面（<0.001）。股骨和胫骨假体矢状对线的异常值率明显高于冠状和轴向对线（<0.001）。然而，在比较矢状面有和无异常值的病例时，TKA 前后的关节活动度（ROM）没有差异。尽管本研究没有发现与异常值有关的 ROM 存在问题，但可能需要对每个 PSI 模型的假体对线进行准确验证，因为每个模型的设计、参考图像和准确性都不同。
