The anterior tibial artery (ATA) is the most critical anatomical structure at risk at the distal border of the posterolateral approach to the tibial plateau. This study aimed to use available lower extremity digital subtraction angiography (DSA) images to determine the distal safe limit of this approach by measuring the distance from the tibial joint line to the ATA where it pierces the interosseous membrane. Tibial plateau mediolateral width (TP-ML-W) and the perpendicular distances from the ATA to the tibial joint line and fibular head were measured on DSA images in 219 lower extremities. To normalize the distances according to the tibial dimensions, each distance was divided by the TP-ML-W, and a ratio was obtained. Popliteal artery branching pattern was categorized according to the classification proposed by Kim et al. Comparative analysis between right and left extremities, genders, and anatomical variations were performed. There were 102 male and 26 female subjects with a mean