Right leg is fine left leg joint soreness is joint effusion, lumbar intervertebral disc herniation, blood circulation disorders and other related. 1. Joint effusion: when the joints of the left leg have lesions or some systemic diseases, it can lead to the increase of joint fluid and the emergence of joint effusion, which will make the left leg suffer from joint soreness, discomfort, pain and other symptoms. 2. Herniated lumbar intervertebral disc: when the herniated lumbar intervertebral disc compresses the sensory fibers of the left leg, it can lead to soreness and swelling of the joints of the left leg, and when the compression is serious, it can lead to radiating pain in the lower limbs. 3. Blood circulation disorder: when the blood vessels around the left leg joints have thrombosis, varicose veins and other lesions, joint soreness and swelling can occur, and can also be accompanied by abnormal skin temperature and other symptoms. The right leg is fine, the left leg joint soreness can be related to a variety of diseases, it is recommended to go to the hospital in a timely manner, improve the knee MR and other auxiliary examinations, early treatment.