Between each vertebra there is a disc (intervertebral). The disc fits between each vertebral body. The discs act like shock absorbers to let the spine bend and twist.
Behind the discs are nerve roots, which leave the spinal cord to supply various parts of the body e.g. the legs, arms, etc. The nerves (called nerve roots) come out of the spinal canal at regular intervals and join up to form major nerves. The nerve roots pass through gaps in the bony arches. Each gap is called a foramen.
The spinal nerves and cord carry feeling impulses from the body up to the brain and other impulses down from the brain to the muscles. The lowest spinal nerves run to the buttocks and bladder.
The spinal nerves run close to small joints on the sides of the bony arches. These joints, called facet joints, let one vertebra move on another, as you bend and twist your spine.
What has gone wrong?
As you get older wear and tear (degenerative changes) starts to affect the spine. Sometimes underlying conditions of the spine can lead to earlier degenerative changes. These changes can include:
- Arthritis causing changes resulting in bony spurs which press on the nerve roots (facet joint enlargement). These bony spurs press on the nerves just outside the arches
- The ligaments in the spinal canal get thicker with age and press on the nerve roots. There is not enough room for your nerve roots within your spinal canal. This is called spinal stenosis
- The discs between the vertebrae dry out with age. This allows the vertebrae to close together so that the gaps between the arches become smaller. The nerve root gets squashed as it passes though the foramen
The aim is to make more room for the nerves by removing the bone or ligament that is pressing on the nerves.
The operation should stop the pain in your legs. If you have back pain this may improve. It will also help any weakness you may have.
Are there any alternatives?
Painkillers and anti-inflammatory drugs can help the pain. Some patients find that an injection of anti-inflammatory steroid around the nerves in the back can control the pain, but not the weakness. This injection is called an epidural. However, the pain can come back when the injection wears off.
Physiotherapy or osteopathy can help reduce back pain, but does not usually reduce leg pain or weakness.
What if you do nothing?
If you do not have an operation, your pain is likely to continue and may get worse over time. If you have weakness or numbness, this may also get worse.
Who should have it done?
If you have numbness and weakness (neurological symptoms) or difficulties passing or controlling your urine, you should have an operation.
If you do not have neurological symptoms, you should have the operation if ALL of the following apply to you:
- Tablets do not control your pain
- Your leg pain is worse than your back pain
- Your leg pain is interfering with your quality of life
- You have had a special scan that shows that you have compression of the nerves in your back (trapped nerves)
Who should not have it done?
The aim of the operation is to cure your leg pain. Your back pain may still be there after the operation. If your back pain is more of a problem than your leg pain, you may need a different operation.
Author: Mr Boyd Goldie MBBS FRCS BSC DHMSA. Consultant in orthopaedics & trauma.
© Dumas Ltd 2006