Soreness and weakness in the lower leg below the knee can be caused by the following diseases: 1. Diseases of the orthopedic system, commonly chronic strain or injury, lumbar disc herniation, where the patient will experience numbness, limited movement, weakness, and even muscle atrophy of the lower extremity as the condition progresses. Patients with early diagnosis should be given pain relief and nerve nutrition therapy, and in severe cases of lumbar disc herniation, surgery needs to be selected if necessary; 2. Lower limb atherosclerosis occlusive disease, with the development of the disease, there will be distal limb ischemia, and patients will experience pain, especially when the symptoms are more pronounced during activity, and even accompanied by fever and other manifestations. In severe cases, there will also be obvious ischemia, and drugs to improve microcirculation should be given; 3. Some patients are caused by varicose veins in the lower limbs, and even also prone to thrombophlebitis or deep vein thrombosis, which will also present symptoms of soreness and weakness.