A leg and knee pain may have the following reasons: first, osteoarthritis, when osteoarthritis is more serious, there can be obvious pain in the knee, and then we should carry out the relevant X-ray examination of the knee joint for early diagnosis and treatment; second, synovitis, synovitis patients can have obvious pain in the knee, and in severe cases, there will be swelling and effusion; third, tumor, when there are synovial tumors or bone tumors in the knee joint, there can be serious leg pain, often accompanied by local swelling and elevated skin temperature, then we should carry out X-ray and nuclear magnetic examination of the knee joint for early diagnosis and treatment. Third, tumor, when there is synovial tumor or bone tumor in the knee joint, there can be severe leg pain, often accompanied by local swelling and elevated skin temperature, then we should carry out X-ray and magnetic examination of the knee joint for early diagnosis and treatment; Fourth, when there is gout or tuberculosis or rheumatoid arthritis in the knee joint, there can be obvious pain in the knee joint, then we should carry out the relevant blood test for early diagnosis and treatment. In this case, relevant blood tests should be conducted for early diagnosis and treatment.