Foot and knee joint pain is usually due to trauma, infection, degenerative joint disease and other diseases. 1. Trauma: including acute injury and chronic injury. Acute injury refers to dislocation or fracture of joints, rupture and bleeding of blood vessels, and exudation of tissue fluid due to external collision, thus causing pain in foot and knee joints. Chronic injury refers to the continuous chronic mechanical injury, which can make the joint lubrication function reduced, long-term friction joint surface produces chronic injury, thus causing foot joint and knee joint pain. 2. Infection: commonly caused by staphylococcus, streptococcus pneumoniae, meningococcus and other pathogenic bacteria invading the joints, which can lead to joint infections and cause inflammatory reactions, thus leading to foot and knee pain. 3. Degenerative joint disease: usually due to the degeneration and thinning of articular cartilage, atrophy of chondrocytes, sclerosis of subchondral tissues, and the formation of bone capillaries at the edges of bone and joints, which can cause synovial congestion and edema, thus leading to pain in the foot joints and knee joints. Patients with foot and knee pain should go to a specialized hospital for further examination under the guidance of a doctor to clarify the cause of the disease and then treat the cause.