Lee H, Sumino T, Suzuki T, et al. - This study was attempted to explore if the medial tangent angle of the tibia (MTAT) could be useful in determining the anteroposterior axis of the tibia. Researchers conducted this study on 103 lower limbs in 53 patients who had undergone primary total hip arthroplasty. They evaluated MTAT, comprising the medial tangent of the proximal tibia and the anteroposterior (AP) axis of the tibia on three horizontal planes: at the distal edge of the tibial tubercle (A), at 5 cm distally (B), and at 10 cm further distally (C) using computed tomography images. The findings exhibited that at level A, MTAT was approximately 45°, and reproducibility was the highest among the three groups. The data suggested that two points forming the valley on the tibial medial surface were bony ridges. Thus, at level A, the medial tangent of the tibia could be easily ascertained. The results revealed that because the distal edge of the tibial tubercle exists at the surgical area and the extra-articular area, it can be a suitable intraoperative, extra-articular landmark in ascertaining the tibial AP axis, even for revision total knee arthroplasty.