Objectives

To test PEEK implant-associated MRI artifacts, a method for blinding MRI readers, the repeatability of cartilage thickness measures before and 6 weeks after high tibial osteotomy (HTO), and the sensitivity to change of cartilage thickness 12 months after HTO.

Materials and methods

Ten patients underwent HTO using a PEEK implant and 3 T-MRI before, 6 weeks and 12 months after surgery. Masks were applied to hide implant visibility on 48 MRI pairs, which were assessed by 7 readers (blinded to time). One blinded reader measured femorotibial cartilage thickness from masked MRIs.

Results

No artifacts were produced. Readers were unable to identify scans by time greater than by chance. Cartilage thickness before and 6 weeks after surgery was not significantly different and indicated excellent repeatability. Medial cartilage thickness increases 12 M postoperatively approached statistical significance (p = 0.06), with no lateral changes observed. Half of the participants had an increase in medial cartilage thickness at 12 M that exceeded the minimal detectable change. Standardized response mean values were moderate-to-large.

Discussion

Postoperative measures of cartilage thickness are repeatable, consistent and sensitive to change when artifact is eliminated, and a validated blinding technique is used. These results provide proof of concept for accurately measuring increases in medial knee articular cartilage after medial opening wedge HTO.

中文翻译：

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核磁共振成像技术用于测量术后膝关节软骨的新型致盲方法的验证

目标

为了测试与PEEK植入物相关的MRI假象，一种使MRI读取器致盲的方法，高胫骨截骨术（HTO）之前和之后6周的软骨厚度测量值的可重复性，以及HTO后12个月对软骨厚度变化的敏感性。

材料和方法

十名患者在手术前，术后6周和12个月使用PEEK植入物进行了HTO，并进行了3次T-MRI检查。戴上口罩以隐藏48对MRI对上的植入物可见性，并由7位阅读器（按时盲目）对其进行了评估。一位不知情的读者通过蒙面MRI测量了股骨软骨厚度。

结果

没有产生伪像。读者无法通过时间识别扫描，而无法通过偶然的机会识别扫描。术前和术后6周的软骨厚度没有显着差异，显示出极好的可重复性。术后内侧软骨厚度增加12 M，达到统计学显着性（p  = 0.06），未观察到外侧变化。一半的参与者在12 M时软骨内侧厚度增加，超过了可检测到的最小变化。标准化的响应平均值为中等到较大。

讨论

当消除伪影时，可对软骨厚度进行术后测量，测量结果可重复，一致且对变化敏感，并使用经过验证的致盲技术。这些结果为准确测量内侧开口楔形HTO后内侧膝关节软骨的增加提供了概念验证。