In outpatient clinics, many of us in the Department of Bone and Joint Surgery come in to see knee pain. The symptoms vary, some say it hurts to go up and down the stairs, some say it hurts to walk, or it hurts to walk for too long, others say it hurts behind the knee, and some say it hurts to squat or squat …… etc. So what is wrong with these? The following outpatient common knee pain combined with my clinical experience to give you some introduction. A, patellar chondromalacia: mostly young people and young people, mostly climbing hills and stairs and other fatigue after the appearance of the knee joint in front that is around the patella pain, manifested as up and down the stairs pain, flat road walking without obvious discomfort. This is caused by repeated friction of the patellofemoral joint, early inflammatory edema, as long as rest or straighten the knee joint walking 2 weeks can basically improve. If cartilage wear occurs in the later stages, you may have to take some glucose capsules for cartilage repair, and then at a later stage, you will need joint replacement. Second, osteoarthritis: also known as osteoarthrosis, degenerative arthritis, age-related arthritis and hypertrophic arthritis. This is a degenerative joint disease, is a common orthopedic disease in the elderly. In general osteoarthritis does not start significantly, progresses slowly, and symptoms are seen mostly after middle age, with a significant increase in incidence with age. The main manifestations of osteoarthritis are: 1. Pain: The initial lesions of the disease are characterized by degeneration and erosion of the cartilage in the joints, and because the cartilage lacks nerve fibers to feel pain, the pain is not obvious at the onset of the disease. With the aggravation of the disease, a mild dull pain that can be tolerated gradually appears, and the pain will gradually increase and become more and more unbearable. The pain increases with activity and improves with rest. The pain is sometimes related to weather changes, cold and humidity, and other factors. 2.Rest pain: Some patients feel joint pain at rest or in the morning, and the pain is relieved after a little activity, called “rest pain”. 3.Motion disorder: Patients often feel inflexible joint movement, stiffness of the joints, clicking sound in the joints, and sometimes painful walking, which improves after rest. After sitting and standing for a long time, the joints will feel stiff and sticky. As the lesion worsens, the cartilage becomes bony, with the emergence of bone fragments (i.e., “spurs”), loss of cartilage, muscle contracture around the joint, and even joint destruction, which can lead to limited movement of the diseased joint. The development of arthritis to a certain extent, joint swelling, joint effusion, will further aggravate the movement disorders. 4, joint deformity, joint instability: With the development of the disease, cartilage gradually softening, wear, erosion, exfoliation, resulting in poor anastomosis of the diseased joint surface, muscle atrophy around the joint, joint capsule contraction, joint edge osteophytes, there will be varying degrees of joint deformity. Early treatment by reducing activities and taking non-steroidal anti-inflammatory drugs and glucose capsules can achieve a more satisfactory result. Cartilage lesions are divided into four stages, and after stage 3, the effect of medication is not good, even if the injection of sodium vitrate will not help, at that time may need joint surface replacement. Third, meniscal injury: the main manifestation of the joint has a stuck feeling, shaking the leg may be good, but also when squatting pain, squatting can not end, if the posterior horn of the meniscus injury in the back of the knee seems to have a tendon hanging like, if you have these symptoms, then may be meniscal injury. If you have these symptoms, then you may have a meniscal injury. An MRI can basically diagnose the injury, and if you have a III° injury, then arthroscopic treatment is recommended, which is generally very effective and can be repaired or shaped according to the injury. Synovitis: It is also a fatigue disease of the knee joint or an inflammatory lesion of the synovial membrane stimulated by the fallen cartilage of osteoarthritis. The main manifestation is swelling of the knee joint, and the suprapatellar capsule is mostly seen. The nuclear magnetic co-creation can see more fluid in the knee joint, and a small amount of fluid can be treated by fixing the knee joint and taking some non-steroidal anti-inflammatory drugs for 2 weeks can have significant relief. Patients with more fluid or multiple recurrent episodes may consider arthroscopic treatment to achieve the best treatment results. Fifth, the medial and lateral collateral ligament injury of the knee joint: mostly for fall sprain or pressure injury, resulting in excessive inversion or valgus of the knee joint, mainly manifested as obvious pressure pain on the medial or lateral side of the knee joint, with positive test of lateral pressure. Treatment on knee immobilization for 3 weeks can be very good to reduce the sequelae. Sixth, the cruciate ligament injury: outpatient clinic is less common, mostly due to more strenuous sports, resulting in swelling, pain, and limited activities of the knee, depending on the situation for early surgery or conservative if unstable and then the second stage of surgery. An MRI can provide a good diagnosis. The knee joint is actually very simple, the damage is mostly in the two menisci, three bones and four ligaments, even if the lesion is accurately diagnosed and treated can get a good result.