Knee ligament injuries can be diagnosed from the following aspects: 1. Anterior cruciate ligament injury Joint pain and swelling with significant restriction of motion and positive Lachman test. The anterior drawer test is also significantly positive, and the floating patella test is positive. x-rays show that the tibial tuberosity is more than 5 mm anteriorly displaced during the anterior drawer test of the knee, and sometimes an avulsion fracture of the intercondylar ramus is seen. 2, posterior cruciate ligament injury joint pain, restricted movement, positive posterior drawer test on knee flexion, tibial tuberosity shifted downward compared to the contralateral side when the upper part of the knee is lifted flat. x-ray shows that the tibial condyle shifted backward on the posterior drawer test of the knee.