The reasons for sitting up and not being able to walk with leg pain include knee joint lesions, hip joint lesions and thoracolumbar spine lesions. 1. Knee joint lesions: common knee joint diseases such as knee osteoarthritis, knee synovitis, knee meniscus injury and so on, leading to aseptic inflammation of the knee joint, meniscus injury and so on. When standing up, because of the increased load on the knee joint, it can trigger or aggravate the pain in the knee joint. 2. Hip joint lesions: common hip joint diseases include femoral head necrosis, femoral head fracture, degenerative changes in the hip joint, etc., because of bone destruction, ischemic necrosis of the femoral head and bone, and synovial inflammation, etc. When standing up, the pain in the knee joint can be triggered or aggravated because of the increased load on the knee joint. When standing up, the phenomenon can also occur because of the increased load on the hip joint. 3. Thoracolumbar spine lesions: common lumbar spine diseases include lumbar spinal stenosis, lumbar intervertebral disc herniation, etc., which can cause nerve compression and radioactive pain in the lower limbs. Caused by sitting up leg pain causes more, may also be related to diabetic foot, rheumatoid arthritis, rheumatoid arthritis and other diseases, if the symptoms continue to be unrelieved, it is recommended to consult a doctor in a timely manner to clarify the cause of the disease, targeted treatment.