The main reasons for leg pain and swelling are lumbar spine lesions compressing the nerve root, bone and joint diseases of the lower limbs, soft tissue strains, vascular diseases or excessive fatigue. 1. Lumbar spine lesions compressing the nerve root: when there are structural changes in the lumbar spine, such as lumbar spinal stenosis or lumbar intervertebral disc herniation, it is possible to compress the nerve root, which will trigger the symptoms of leg pain and swelling. 2. Bone and joint diseases of the lower limbs: If there is inflammation of the joints of the lower limbs, or degenerative diseases, it is easy to cause joint pain and swelling, and even affect the function of movement. 3. Soft tissue strains: improper exercise in the lower extremity soft tissue strains, which can easily lead to increased exudate, thus triggering the performance of leg pain and swelling. 4. Vascular disease: If the blood vessels of the lower limbs have abnormal lesions, such as varicose veins or venous thrombosis, arterial embolism, etc., it will easily affect the blood return, which will lead to the symptoms of leg pain and swelling. 5. Excessive fatigue: If you carry weight for a long time or exercise strenuously, you may feel fatigue in the muscles of the lower limbs, which may cause excessive accumulation of lactic acid, thus forming the symptoms of leg pain and swelling. If the symptoms are more serious, you need to consult a doctor in a timely manner to clarify the cause of the disease and targeted treatment under the guidance of a professional physician, so as not to affect the motor function of the lower limbs.