Knee pain when going down stairs without pain on the level road may be caused by knee degeneration, as well as synovitis or osteophytes. 1. Knee degeneration: If the knee degeneration is serious, the cartilage at the knee joint may be damaged, and the knee joint will be pulled more when going down the stairs, which will lead to different degrees of pain, but there is no pain when walking on the level road. 2. Synovitis: When the synovium is irritated by inflammation, the knee joint will swell and become painful. Pain is felt when a strong force is applied to the knee when going down the stairs, but no pain is felt when walking on a level road. 3. Osteomalacia: Osteomalacia is easily formed if the knee is subjected to far more weight than it can bear for a long time. Patients do not have obvious pain when walking, but there will be pain when the load increases on the stairs, and some are even accompanied by lumbago. It is recommended that patients who have knee pain when walking down stairs and no pain when walking on a flat road should go to the hospital in time for relevant examinations, and the cause of the disease should be clarified under the guidance of the doctor, and then give targeted treatment.