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Here is a list of some of the most common mechanical causes of low back pain. Mechanical essentially means non-pathological. Mechanical causes are the major reason that people experience low back pain.
Mechanical Causes Of Back Pains include the following
- Annular tear of the disc
- Coccydynia
- Disc protrusion/herniation Disc lesion with radiculopathy Facet joint syndrome
- Failed back surgery syndrome
- Acute locked back
- Hypermobility and hypermobility syndrome
- Internal disc disruption/derangement Lumbar instability
- Muscle injuries
- Myofascial trigger points
- Nerve entrapment
- Sacroiliac joint dysfunction
- Spinal stenosis
- Spondylolysis/spondylolisthesis
- Vertebral endplate fracture
- Vertebral compression fracture
- Multiple causes of back pain
Intervertebral discs slowly degenerate with age.
This is a natural process that begins as early as 15 years of age. The rate at which a disc degenerates varies from person to person, and is dependent on the disc position in the spine. Lower discs (lumbar) have greater loads placed on them and they tend to degenerate more quickly than discs further up the spine. With age, the disc becomes less sponge-like and retain less water.
Causes of acute non-specific mechanical back pain
Cause | Percentage |
Facet joints | 10% |
Sacroiliac joint | 10% |
Unknown origin | 50-60% |
Disc without sciatica | 10-20% |
Disc with sciatica | 10% |
Source: C. Liebenson
Causes of chronic non-specific mechanical back pain
Cause | Percentage |
Internal disc disruption | 39% |
Facet joints | 15% |
Sacroiliac joint | 12% |
Unknown origin | 34% |
Sources: McGill, Liebenson
Lumbar Disc Injury
Approximately 80 per cent of all lumbar disc injuries occur in the bottom two lumbar discs (L4-5 and L5—S1), which usually degenerate quicker than the other lumbar discs. In the cervical spine a similar process occurs, with the C5—C6 and C6—C7 discs degenerating faster than the rest of the cervical spine.
Thoracic disc injuries are quite rare compared to cervical and lumbar disc injuries; however, they do occur.
Disc injuries differ from normal age-related degeneration. Degeneration is a normal process that occurs in every spine with age, while disc injuries do not occur in everyone.
Annular height loss in bulging discs can lead to more than 50 per cent of the compressive load on the lumbar spine being resisted by the facet joints instead of the discs (not a desired outcome).
With increasing age, the nucleus tends to bulge vertically into the vertebral bodies. The result is less pressure on the nucleus and more pressure on the annulus, causing the annulus to bulge outward and some¬times inward. Changes in pressure on the disc result in a marked loss of structure.
In effect, the disc behaves like a flat tyre. Once a disc is injured or damaged it will never fully heal; however, this does not imply that an injured disc will always be a painful disc. Many people go on to live pain-free lives after a disc injury.
Damaged discs react to weight bearing in a haphazard manner. Their shock-absorbing function can become reduced or disappear.
Intervertebral Discs Have Different Loads
The intervertebral discs have different loads placed on them based on your body posture/position.
This has major implications on the biomechanics and physiology of the spine. The most unloaded position for the lumbar discs is lying flat on your back, while the most loaded position is sitting slouched. It is important to know and understand these loads in order to protect your back from stressful or damaging loads. Certain postures place less load on the spine, which can help relieve back pain as well as reduce spinal wear and tear Sitting actually places greater load on the discs than lying down or standing. This does not imply that it is always best to stand or lie down; certain back conditions are most comfortable in the seated position. A general rule to follow is ‘if it hurts, don’t do it’. So if it hurts to stand upright and feels better to sit, by all means have a seat.
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