The thickness of the two legs of normal people is slightly different. If there is a significant difference between the thickness of the two legs, the following diseases should be excluded: a. Unilateral lower limb artery or vein thrombosis, the affected limb will appear swelling, pain, feasible lower limb vascular Doppler examination to clarify the diagnosis. The lymphatic reflux of unilateral lower limb is obstructed, resulting in the accumulation of lymphatic fluid in the subcutaneous tissue, causing swelling, skin thickening and roughness of the affected limb. III. Lumbar spine lesion, which compresses the sciatic nerve and causes muscle atrophy of one lower limb. Fourth, during the sequelae of cerebrovascular lesions, the paralyzed limb may become thin due to muscle atrophy caused by lack of movement.