人工膝関節置換術における脛骨回旋設置の信頼度

—術中Akagi’s Line同定の正確性の検討—

抄録

Objective: Accurate rotational alignment in total knee arthroplasty (TKA) is essential for successful outcomes. The Akagi’s line, which connects the middle of the posterior cruciate ligament and the medial border of the patellar tendon attachment, is widely recognized as a reliable reference axis indicating the anteroposterior orientation of the tibia. The aim of this prospective study was to investigate the accuracy of intraoperative identification of the Akagi’s line in TKA.

Methods: Twenty-two patients with knee osteoarthritis were enrolled in this prospective study. Preoperative computed tomography (CT) scans were performed to identify the Akagi’s line. The line was incorporated in the CT-based navigation system and defined as CT-Akagi’s line. Two observers (observer A/B) determined the Akagi’s line manually (M-Akagi’s line) without referring to navigation before or after the proximal tibial cut. The angle between CT-Akagi’s line and M-Akagi’s line and the outlier of the angle were investigated.

Results: The angles between CT-Akagi’s line and M-Akagi’s line for observer A was 2.5°, and for observer B was −0.1° preoperatively, and those for observer A was 1.1° and for observer B was −3.1° postoperatively. The rate of outliers for observer A was 23%, and for observer B was 18% preoperatively, and that for observer A was 18%, and for observer B was 23%, postoperatively.

Conclusion: Although the manual identification of Akagi’s line is generally consistent, it is still necessary to recognize possible outliers.