Above knee pain may be caused by over activity, acute injury, knee synovitis and other factors. 1. Excessive activity: prolonged exercise may cause the accumulation of local lactic acid metabolites, which will cause pain on the top of the knee, manifested as mild soreness, the symptom is not serious, and will not cause too much effect, and it can be restored to normal after reasonable rest. 2. Acute injury: for example, the knee was hit by external forces, resulting in local soft tissue damage or bone damage, there will be pain symptoms, accompanied by swelling, subcutaneous bruising, redness and other symptoms. 3. Knee synovitis: prolonged strenuous exercise or repeated exposure to cold may induce knee synovitis, which will cause pain on the top of the knee, which may be accompanied by redness and swelling. If there is pain above the knee and other abnormal manifestations at the same time, it is recommended to consult a doctor for examination and treatment to avoid causing other complications.