Figure 4

Typical lateral-view radiographs of a normal knee with a large PTS, and with a small PTS. The unaffected side of the knees is shown. The patient with a large PTS (left radiograph) was standing with the knee slightly flexed and the proximal tibial surface level to the ground. PTS, posterior tibial slope; PTS-H, posterior tibial slope to the horizontal line; TAT, tibial shaft anterior tilt to the vertical axis; ACL, anterior cruciate ligament.