Over 70 years old old leg weakness need to be for the cause of the corresponding treatment, the cause of osteoporosis, cerebral infarction, etc., feasible to promote bone drug treatment, surgical treatment, etc., because of individual differences, so you need to choose the right drug under the guidance of the doctor for treatment, so there is no such thing as the best treatment. 1. Osteoporosis: The body functions of the elderly gradually deteriorate with age, and the lack of calcium or the lowering of hormone levels in the body may easily lead to osteoporosis, which may cause symptoms such as weakness of the waist and knees. It can be treated by supplementing vitamin D, oral alendronate, teriparatide and other drugs. 2. Cerebral infarction: When the cerebral blood vessels are occluded, it will often cause the corresponding function to be impaired, for example, when the posterior cerebral artery is occluded, it will lead to hemiplegia, lower limb weakness and other symptoms. Common treatments include thrombolytic drugs such as urokinase, anticoagulant drugs such as heparin, and surgery to remove part of the tissue if the condition is serious. Patients should go to the hospital immediately when they experience discomfort. Medications should be used as prescribed by the doctor.