Engseth Lars H W, Øhrn Frank-David, Schulz Anselm, Röhrl Stephan M
Division of Orthopaedic Surgery, Oslo University Hospital, Oslo, Norway.
Faculty of Medicine, University of Oslo, Oslo, Norway.
Bone Joint J. 2025 Feb 1;107-B(2):173-180. doi: 10.1302/0301-620X.107B2.BJJ-2024-0356.R2.
Radiostereometric analysis (RSA) is considered the gold standard for in vivo migration analysis, but CT-based alternatives show comparable results in the shoulder and hip. We have previously validated a CT-based migration analysis method (CTMA) in a knee phantom compared to RSA. In this study, we validated the method in patients undergoing total knee arthroplasty (TKA). Our primary outcome measure was the difference in maximum total point motion (MTPM) between the differing methods.
A total of 31 patients were prospectively studied having undergone an uncemented medial pivot knee TKA. Migrations were measured up to 12 months with marker-based and model-based RSA, and CT-RSA.
Mean precision data for MTPM were 0.27 mm (SD 0.09) for marker-based RSA, 0.37 mm (SD 0.26) for model-based RSA, and 0.25 mm (SD 0.11) for CTMA. CTMA was as precise as both RSA methods (p = 0.845 and p = 0.156). At three months, MTPM showed a mean of 0.66 mm (95% CI 0.52 to 0.81) for marker-based RSA, 0.79 (95% CI 0.64 to 0.94) for model-based RSA, and 0.59 (95% CI 0.47 to 0.72) for CTMA. There was no difference between CTMA and marker-based RSA (p = 0.400), but CTMA showed lower migration than model-based RSA (p = 0.019). At 12 months, MTPM was 1.03 (95% CI 0.79 to 1.26) for marker-based RSA, 1.02 (95% CI 0.79 to 1.25) for model-based RSA, and 0.71 (95% CI 0.48 to 0.94) for CTMA. MTPM for CTMA was lower than both RSA methods (p < 0.001). Differences between migration increased between the methods from three to 12 months. Mean effective radiation doses per examination were 0.016 mSv (RSA) and 0.069 mSv (CT). Imaging time for performing RSA radiographs was 17 minutes 26 seconds (SD 7 mins 9 sec) and 4 minutes 24 seconds (SD 2 mins 3 sec) for CT.
No difference in precision was found between CTMA and marker- or model-based RSA, but CTMA shows lower migration values of the tibial component at 12 months. CTMA can be used with low effective radiation doses, and CT image acquisition is faster to perform than RSA methods and may be suitable for use in ordinary clinical settings.
放射性立体测量分析（RSA）被认为是体内移位分析的金标准，但基于CT的替代方法在肩部和髋部显示出可比的结果。我们之前已在膝关节模型中验证了一种基于CT的移位分析方法（CTMA）并与RSA进行了比较。在本研究中，我们在接受全膝关节置换术（TKA）的患者中验证了该方法。我们的主要结局指标是不同方法之间最大总点运动（MTPM）的差异。
前瞻性研究了31例行非骨水泥型内侧旋转铰链膝关节TKA的患者。使用基于标记物和基于模型的RSA以及CT-RSA测量长达12个月的移位情况。
基于标记物的RSA的MTPM平均精度数据为0.27 mm（标准差0.09），基于模型的RSA为0.37 mm（标准差0.26），CTMA为0.25 mm（标准差0.11）。CTMA与两种RSA方法一样精确（p = 0.845和p = 0.156）。在三个月时，基于标记物的RSA的MTPM平均为0.66 mm（95%置信区间0.52至0.81），基于模型的RSA为0.79（95%置信区间0.64至0.94），CTMA为0.59（95%置信区间0.47至0.72）。CTMA与基于标记物的RSA之间无差异（p = 0.400），但CTMA显示的移位低于基于模型的RSA（p = 0.019）。在12个月时，基于标记物的RSA的MTPM为1.03（95%置信区间0.79至1.26），基于模型的RSA为1.02（95%置信区间0.79至1.25），CTMA为0.71（95%置信区间0.48至0.94）。CTMA的MTPM低于两种RSA方法（p < 0.001）。从三个月到12个月，各方法之间的移位差异增大。每次检查的平均有效辐射剂量分别为0.016 mSv（RSA）和0.069 mSv（CT）。进行RSA X线片的成像时间为17分26秒（标准差7分9秒），CT为4分24秒（标准差2分3秒）。
CTMA与基于标记物或基于模型的RSA在精度上无差异，但CTMA在12个月时显示胫骨组件的移位值较低。CTMA可在低有效辐射剂量下使用，并且CT图像采集比RSA方法更快，可能适用于普通临床环境。
