青少年运动员正处于生长发育阶段,机体耐受性和协调性较差,多因其肌肉、韧带力量较弱,关节稳定性差,不能负担较大的运动负荷;再加上动作技术不熟练没有参加系统的训练,如果运动中的身体姿势不正确,或者变换步伐不得当时,都容易引起关节的损伤,特别是膝关节。膝关节由软骨、韧带、含有润滑液的关节囊组成,关节软骨为关节表面的薄层透明软骨,表面光滑,可减小关节运动时的摩擦力。关节软骨含水约80%,固体胶原、蛋白聚糖及其他约 Juvenile athletes are in the stage of growth and development, poor tolerance and coordination of the body, mostly due to the weak muscles, ligaments, joint stability is poor, can not afford a large exercise load; coupled with inexperienced motor skills did not participate in the system Of the training, if the movement of the body posture is not correct, or change the pace of improper, are likely to cause joint damage, especially the knee. The knee joint consists of cartilage, ligaments and joint capsule containing lubricating fluid. The articular cartilage is a thin layer of transparent cartilage on the joint surface with a smooth surface, which can reduce the friction force during joint movement. Articular cartilage contains about 80% moisture, solid collagen, proteoglycans and others