The most common causes of knee pain when climbing stairs are ligament injury, meniscus tear, osteoarthritis, chondromalacia patella, etc. If the symptoms persist, it is recommended to seek medical treatment in time. 1. Ligament injury: If ligament injury or rupture occurs, the pressure on the knee increases when climbing stairs, which will cause pain. 2. Meniscus tear: If there is a tear in the meniscus caused by strenuous exercise or a history of trauma, it will cause pain when the pressure on the knee is too great when climbing stairs. 3. Osteoarthritis: The joint cartilage of the human body will undergo degenerative changes with age, forming osteoarthritis. Excessive pressure on the knee when going up the stairs will cause pain in the knee joint. 4. Chondromalacia patella: the cartilage surface of the patella is broken, dislodged and swollen due to various reasons, which in turn causes pain in the cartilage of the knee joint and aggravates the symptoms when going up and down the stairs. Caused by climbing stairs knee pain causes more, but also may be related to fractures, synovitis, osteophytes and other diseases, if the symptoms continue to be unrelieved, it is recommended to go to the hospital in a timely manner by the doctor to identify the cause of the disease, targeted treatment.