If the patient feels weak in both legs, there may be the following diseases: First, peripheral neuropathy, such as spinal cord cervical spondylosis or lumbar intervertebral disc herniation, these diseases will lead to the vertebral canal of the occupation, or the spinal cord, nerve root compression of the situation, once this situation occurs, often lead to the lower limbs pain, numbness, weakness and a series of symptoms. Second, lower limb osteoarthritis, if both lower limbs have osteoarthritis of the knee joint, the patient will often manifest as bilateral knee pain, and there is obvious weakness of both lower limbs. Third, osteoporosis, the most common in the elderly or severe osteoporosis patients, in the early stage, often manifested in the circumference of the indefinite pain, as well as the circumference of the severe weakness. Fourth, wasting muscle atrophy, this situation is most common in long-term bedridden patients, or long-term sitting and standing work, no exercise, inactive patients, these patients, once suddenly out of bed activities, due to muscle wasting, muscle atrophy, muscle strength, which will make the patient feel the lower limbs of severe weakness.