Knee soreness may be caused by meniscus injury, knee synovitis, osteoarthritis of the knee, knee ligament injury and so on. 1. Meniscus injury: meniscus injury is most likely to occur in athletes, usually occurs in excessive exercise or external injuries, which may lead to meniscus cracks, at this time, the knee area will have a feeling of soreness and swelling, and there will be pain affecting the normal life. 2. Synovitis of knee joint: it may be related to overstrain and traumatic factors, if not eliminated in time, it will easily lead to adhesion of joints, and the patient will feel pain and soreness in the joints. 3. Osteoarthritis of the knee: more likely to appear in the middle-aged and elderly people, and overweight load has a certain relationship, the knee joints will have a feeling of soreness and swelling, and the joints will have friction sound when moving. 4. Knee ligament injury: the general stability of the knee joint is relatively poor, if the external force caused by the valgus, may cause collateral ligament injury, there is an obvious feeling of soreness and swelling. There may be some other reasons for joint soreness and swelling, if there is no improvement, it is recommended to go to the regular hospital in time for examination and treatment.