Sometimes we find that when we squat or jump, our knees will pop, some people may pop once and then stop, others may pop as soon as they squat. This kind of ringing is called popping. In the case of squatting once and then not ringing, it is a physiological ringing, just like the sound we make when we break or press our fingers, and does not cause arthritis or swelling of the joint. In the latter case, it is a different story, as the ringing represents wear and tear in the joint, which can lead to arthritis and degenerative changes in the knee joint. Causes of physiological popping There is joint fluid in the joint cavity, which serves as a lubricant. The joint cavity is under negative pressure, which keeps the joint structure stable. When the joint is pulled or flexed (pulling or breaking fingers can make a popping sound), the pulling force exceeds the negative pressure of the joint cavity, and a clear cavity will appear, and the surrounding gas will diffuse rapidly into the cavity and vibrate together with the fluid, resulting in a crisp sound. In other words, physiological popping is caused by the vibration of the gas in the joint cavity. How can I tell if it is a physiological ringing? Usually, physiological popping meets these conditions: 1) the sound is crisp, single and non-repetitive; 2) it occurs only when the joint is suddenly pulled or flexed; 3) there must be a rest period between popping; 4) it is accompanied by slight pain or discomfort, and there is often a sense of relief after the popping. When you feel that your knee ringing does not belong to the above situation, then you may have a pathological change in the knee joint, which may be due to meniscal injury, disc meniscus, osteoarthritis, synovial crepitus syndrome, ligament damage within the knee joint, and so on. In young people, knee rattling is mostly a problem of the patellofemoral joint, which means that the patella moves medially or laterally, resulting in a change in the displacement pathway of the patella during knee flexion, which impacts other tissues and results in a popping sound. These patients usually have inversion or valgus of the knee joint. How can I tell if the popping is caused by the patellofemoral joint? How: Have someone help you move the patella outward, then squat down and feel the following knee joint for popping. If so, move the patella medially and squat again. If the popping sound of the knee disappears when the patella is fixed on either side, this indicates that the popping sound of the knee is caused by the displacement of the patella. Cause: Excessive tightness of the medial muscles will shift the patella inward, while excessive tightness of the lateral muscles will cause the patella to shift outward. Treatment: The treatment for this knee popping is of course to strengthen the medial or lateral femoral muscles and loosen the lateral or medial femoral muscles. Of course, there is also the possibility that tension in the iliotibial bundle and other muscles may cause the patella to shift. The exact cause varies from person to person. Meniscal injury is also a common cause Meniscal injury: located in the medial or lateral space of the tibiofemoral joint, with a crisp sound and high frequency, often with joint locking (stuck, painful), which is also associated with the quadriceps and N muscles. Milder meniscal injuries are not painful, and walking or even jogging is not affected, so they are easily overlooked. Long-term non-diagnosis can easily result in articular cartilage damage, which may eventually lead to osteoarthritis, even to the point of knee replacement. Therefore, minor injuries to the meniscus should be treated as early as possible. Knee instability Ligamentous laxity: When the joint moves too much, the ligament stretches and then returns with a muffled sound, which usually occurs on both sides and is likely to occur in thin people. There are many other causes of knee popping: such as disc meniscus, synovial crepitus syndrome osteoarthritis, joint free bodies, old damage to the cruciate ligament, insufficient joint fluid, etc.