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 because muscle blood supply is better than ligaments, tendons and other tissues, rest over time to recover better, so muscle injuries generally do not affect the athletic career.