The external knee eye is located on the lateral side of the front of the knee. You can feel the patella, the knee, and follow the knee down the front median line of the knee joint to feel a very wide and taut ligament, the patellar tendon, and the lateral depression of the patellar tendon is the external knee eye. The external knee eye is both a very important point and a very important area to examine clinically, as follows: 1) a very pronounced pain in this area, and a pronounced sensation of ringing and movement when touched, suggesting a possible meniscal injury; 2) a pronounced elevation in this area, suggesting a possible high level of joint effusion. The inner and outer knee eyes actually refer to the tibiofemoral space of the knee joint. There is a very obvious gap between the tibia and femur of the knee joint, which is covered by abundant ligaments and muscles wrapped around the side and behind it. Only to the left and right of the patellar tendon there is no particularly obvious soft tissue covering it, so there is a very obvious depression that can be felt on the surface of the body.