What causes lumbar spinal stenosis?

The most common cause of lumbar spinal stenosis is changes in the spine that can happen as you get older.

These changes include thickening of soft tissues, development of bony spurs and gradual breakdown of spinal discs and joints. Any of these conditions can narrow the spinal canal.

Spinal stenosis usually happens gradually. Symptoms may start when the changes begin to squeeze the spinal cord or its nerve roots.

These age-related changes often happen when you have certain disorders:

• Arthritis of the spine wears away joint cartilage and causes bony growths (spurs).
• Certain bone diseases, such as Paget's disease and ankylosing spondylitis, may soften the spinal bones or cause too much bone to grow.
• Certain bone diseases, such as Paget's disease and ankylosing spondylitis, may soften the spinal bones or cause too much bone to grow.

Also, other conditions may cause spinal stenosis, such as:

• An abnormally narrow spinal canal, which can be an inherited condition.
• Spondylolysis, which is a defect or fracture on one or both of the wing-shaped parts of a vertebra. A vertebra may slide forward or backward over the bone below and may squeeze the spinal cord or a nerve root.
• Spinal fracture.
• Cancer.
• Fibrosis, which is excess, ropy tissue much like scar tissue. It can come from having spine surgery in the past.