Patients with weak legs and weakness are commonly caused by the following: First, lumbar disc herniation or osteoarthritis of the knee joint: If the weakness and weakness of one lower limb is considered to be lumbar disc herniation or osteoarthritis of the knee joint, the patient will have clinical symptoms of weakness and weakness of the legs, which will also be accompanied by lumbar pain, limited lumbar spine activities, knee pain, limited knee joint activities, and even deformities of the knee joint changes, such as inversion deformity and valgus deformity. Second, thoracic or cervical spine lesions: if the lower extremities are soft and weak, usually need to consider thoracic or cervical spine lesions, such as disc protrusion, spinal stenosis, will lead to continuous nerve compression, affecting the nerve conduction function, the patient will also show clinical symptoms of leg weakness, weakness, while occurring in the bilateral lower extremities, the patient will have significant walking difficulties. The specific location and the exact extent of the lesion can be detected through MRI. Early diagnosis and early treatment can lead to rapid relief of the clinical symptoms of leg tenderness, and the protection of the above areas should be strengthened in general to enhance the muscle strength of the lower extremities and prevent the occurrence of symptoms.