What causes radiating pain from the lower back down into the legs, besides disc herniation?

Vascular disease. Peripheral vascular disease & spinal stenosis both can cause pain into both legs mimicking sciatic pain as can other issues like hip & knee arthritis. Other causes of nerve compression in the spine due to a tumor, infection or fracture can cause this pain. Bilateral pyriformis syndrome can also cause bilateral radiating leg pain.
Leg pain not a disc. Spinal stenosis sacroilitis discogenic pain bil piriformis syndrome foraminal stenosis.