For humans, the evolutionary significance of upright walking is obvious: it frees our hands and promotes human intelligence. At the same time, walking upright has also had a profound impact on human body composition, for example, the position of the foramen magnum in the human occipital bone is more anterior than in apes, which is probably the result of the adaptation of the human skeleton to the altered gravitational line after uprightness. Uprightness has also brought corresponding changes to the joints of the human lower limbs. The knee joint is close to the ground and is almost the most weight-bearing joint other than the ankle. However, unlike the weight-bearing ankle joint, the knee joint is also involved in many important movements. Running, jumping, kicking, climbing, riding, etc. all rely heavily on the knee joint to complete. Therefore, the knee joint needs to have a sturdy structure to maintain weight, but must also be designed for dexterity to meet mobility needs. For athletes in competitive sports, the condition of the knee joint often has a direct impact on career longevity and athletic career. The bony structures that make up the knee are the distal femur, the proximal tibia, and the patella. However, these bony tissues do not contribute much to maintaining the stability of the knee joint. It is the ligaments, menisci, muscles and tendons, located both inside and outside the joint, that are the main forces that bind these bony tissues together. It is easy to explain why many athletes make a good recovery even after a fracture, while those with ligament injuries and meniscus injuries often have to regretfully say goodbye to the game early. Muscle strains and contusions are also common, but muscle injuries generally do not affect athletic careers because the blood supply to the muscles is better than that of ligaments and tendons, and recovery is better with time and rest. In the knee joint, there are two ligaments that connect the femur and tibia to each other. Because the two ligaments cross each other in a cruciform pattern, they are also known as the cruciate ligament or cruciate ligament. During knee flexion, the anterior cruciate ligament prevents the tibia from moving forward, while the posterior cruciate ligament prevents the tibia from moving backward, which ensures the anterior-posterior stability of the knee joint during flexion. On the lateral side of the knee, there are medial collateral ligaments and lateral collateral ligaments, which are tightened when the knee is straightened to prevent extension and rotation of the knee joint so that we do not sway when we stand. Between the joint surfaces, each knee joint has two crescent-shaped fibrocartilages called menisci. The meniscus fills the joint space, increases the flexibility and stability of the joint, and assists in the extension and rotation of the joint. Normally, the knee joint has approximately 7 degrees of slight valgus, and when upright, the medial knee carries 60% of the load. As a result, the meniscus, collateral ligament and ACL are more closely related on the medial side of the knee, often resulting in a “triple injury” when injured. However, weight is not the greatest force on the joint. The force between the patella and femur can be as much as 5-8 times the body weight when climbing or jumping. The patella, or knee as we call it, is a delicate design given to us by nature. It not only protects the knee joint, but also acts as a lever for thigh muscle traction. Without the patella, we would have to exert an extra 30 percent of our strength to complete the kick. Severe patellofemoral injuries often result in having to remove the patella, which can also greatly affect sports and quality of life. In addition to sports injuries, as we age, the knee joint will wear out and develop a variety of problems. Therefore, it is important to take good care of the knee joint from now on. It is reasonable and effective to prepare well before exercise to avoid sudden heavy exercise; to focus on exercise to avoid trauma; to choose a flat and flexible playing field to reduce weight and avoid excessive impact on the knee joint when running; and to wear the necessary protective equipment. If you already have a knee injury, you should take adequate rest and avoid sports activities with high knee loads such as climbing, stairs, etc. Scientific exercise will help us to extend the life of the knee joint as much as possible so that we can pick up the cane later in life.