Sciatica is leg pain often due to pressure on a nerve in your low back that connects to the sciatic nerve. This pressure may be caused by a damaged disk or by abnormal bone growth. You may feel pain, burning, tingling, or numbness that shoots down your leg.
Pressure from a Damaged Disk
Constant wear and tear on a disk can cause it to weaken. Part of the disk may push outward (herniate). Part of the disk may then press on nearby nerves. If this nerve leads to the sciatic nerve, you may feel pain down your leg.
Pressure from Bone
A disk can wear out and thin with age. This can cause the vertebrae above and below the disk to touch, putting pressure on a nerve. Abnormal bone growths called bone spurs can also form where the bones rub together. These can narrow the spinal canal and press on nerves.