The possible causes of knee popping pain include osteoarthritis, meniscus injury, synovitis and so on. 1. Osteoarthritis: Osteoarthritis may be related to heredity, patient’s age, obesity, inflammation, trauma and other factors, and is prevalent in the knee joint, which may cause joint pain, swelling, deformity, popping and other symptoms. 2. Meniscus injury: If acute knee sprain occurs, knee ligament injury caused by knee instability, meniscus injury can occur, or long-term weight-bearing squatting action such as weightlifting athletes, can also occur in the meniscus of the chronic strain, which will cause rattling and pain and so on. 3. Synovitis: It may be caused by immunity, infection, trauma, long-term weight bearing and other factors, resulting in synovitis, pain, swelling, popping and other symptoms when the joint activities. Knee popping pain may also have other causes, it is recommended to go to the regular hospital in time to improve the relevant examination, clear the cause of the disease, under the guidance of the doctor for targeted treatment or treatment.