Weakness in both knees can be identified in Chinese medicine and Western medicine. In Chinese medicine, weakness in the knees is a deficiency, often caused by kidney deficiency in men and blood deficiency in women. In Western medicine, there are problems with the skeletal muscle system, the nervous system, and the endocrine system that lead to weakness in both knees. Endocrine system problems, such as periodic hypokalemia and transient hypoglycemia, can also cause weakness in both knees. Neurological problems, such as transient cerebral insufficiency, acute cerebrovascular disease, acute cerebral embolism, and acute cerebral infarction, can also cause weakness in both knees.