If the patient has pain in both lower extremities at the same time, consider the following diseases may exist: 1. It may be caused by polyarthritis, such as rheumatic and rheumatoid arthritis, which may lead to inflammation of multiple symmetrical joints throughout the body and subsequently lead to significant pain, and the simultaneous onset of pain in both lower extremities is very common. Severe osteoarthritis on both sides, such as bilateral knee osteoarthritis, may also lead to significant pain in the lower extremities.2. It may be caused by a severe lumbar disc herniation, and severe lumbar disc herniation or spinal stenosis may cause simultaneous pain in both lower extremities.3. It may be caused by a vascular-related lesion, such as the presence of deep vein thrombosis or thrombo-occlusive vasculitis. 4.It may be caused by overexertion, such as patients do strenuous activities or high intensity labor, resulting in a large amount of lactic acid deposition in the muscles of bilateral lower extremities, after which bilateral lower extremity pain may also occur. 5.It may also be caused by osteoporosis, patients with osteoporosis often have bony pain in multiple places throughout the body, and bilateral lower extremity pain at the same time is also more common. The situation is also more common.