Possible causes of knee creaking and pain when bending include meniscus lesions, knee osteoarthritis, villous nodular synovitis, patellofemoral joint disorder and synovial chondroma. 1. Meniscus lesion: including meniscus injury, discoid meniscus, meniscus calcification or formation of cysts, etc., manifested as pain, creaking when bending, and a more pronounced sense of stuttering when moving. 2. Knee osteoarthritis: caused by knee degenerative disease, long-term strain, obesity, etc. Typical symptoms are friction sound, pain and joint swelling during activities. 3. Choroidal nodular synovitis: caused by trauma, excessive exercise, metabolic abnormalities, etc., the main manifestations of the knee mild pain, swelling, creaking when bending, joint activities are affected by small. 4. Patellofemoral joint disorder: caused by heavy physical labor, improper sports posture, etc., with knee pressure and pain, friction or twisting sound in front of the knee when bending. 5. Synovial chondroma: commonly caused by long-term strain, chronic infection and other tumor-like lesions, in addition to knee pain, creaking when bending, but also in front of the knee to feel the swelling. Knee creaking when bending also pain also involves synovial crease syndrome, exfoliative osteochondritis dissecans, etc., based on this symptom can not be clear cause, it is recommended to go to the medical institution, improve the relevant examination, treatment under the guidance of the doctor.