Department of Orthopedics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg; Department of Orthopedics, Sahlgrenska University Hospital, Gothenburg, Sweden.
Acta Orthop. 2022 Apr 22;93:459-465. doi: 10.2340/17453674.2022.2528.
Computed tomography micromotion analysis (CTMA) can be used to determine implant micro-movements using low-dose CT scans. By using CTMA, a non-invasive measurement of joint implant movement is enabled. We evaluated the precision of CTMA in measuring early cup migration. Standard marker-based radiostereometric analysis (RSA) was used as reference. We hypothesised that CTMA can be used as an alternative to RSA in assessing implant micromotions.
We included 30 patients undergoing total hip arthroplasty (THA). Acetabular cup migration at 1 year was measured with RSA and CTMA. To determine the precision of both methods, 20 double examinations (postoperatively) with repositioning of the patients were performed. The precision was calculated from zero by assuming that there was no motion of the prosthesis between the 2 examinations.
The precision of RSA ranged from 0.06 to 0.15 mm for translations and 0.21° to 0.63° for rotations. Corresponding values for CTMA were 0.06 to 0.13 mm and 0.23° to 0.35°. A good level of agreement was found between the methods regarding cup migration and rotation at 1 year.
The precision of CTMA in measuring acetabular cup migration and rotation is comparable to marker-based RSA. CTMA could possibly thus be used as an alternative method to detect early implant migration.
计算机断层扫描微动分析（CTMA）可用于通过低剂量 CT 扫描来确定植入物微动。通过使用 CTMA，可以实现对关节植入物运动的非侵入性测量。我们评估了 CTMA 在测量早期杯体迁移中的精度。标准的基于标记的放射立体测量分析（RSA）被用作参考。我们假设 CTMA 可替代 RSA 用于评估植入物微动。
我们纳入了 30 例接受全髋关节置换术（THA）的患者。采用 RSA 和 CTMA 测量术后 1 年髋臼杯的迁移情况。为了确定两种方法的精度，对 20 例患者进行了两次（术后）重复检查并重新定位。通过假设两次检查之间假体没有运动，将精度从 0 开始计算。
RSA 的精度范围为 0.06 至 0.15mm 用于平移，0.21°至 0.63°用于旋转。CTMA 的相应值为 0.06 至 0.13mm 和 0.23°至 0.35°。两种方法在术后 1 年时对杯体迁移和旋转的测量结果具有较好的一致性。
CTMA 在测量髋臼杯体迁移和旋转方面的精度与基于标记的 RSA 相当。因此，CTMA 可能可用作检测早期植入物迁移的替代方法。
