Lower Back Pain

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What is Lower Back Pain?

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Lower back pain: The lower back is a complex structure composed of the vertebrae (the back bones), the nerves which leave the spinal cord at that level, ligaments, muscles and other soft tissues. The back provides support, movement and protects important structures such as the spinal cord. The vertebrae (the lumbar ones at that level) articulate with each other via the facet joints at the back, and are also separated from each other by a cushion, or shock absorber called the intervertebral disc. They are held together by various ligaments, and form the site of attachment of the back muscles. Nerves exit at the side of the backbone at every level. Lower back pain means a back pain roughly between the bottom of the ribs and the top of the legs at the back. Importantly, the pain often radiates to the buttocks, and sometimes further down the leg and even to the foot. When back pain is combined with pain into the leg, travelling down below the knee, it is referred to as sciatica, because the nerve roots of the sciatic nerve at the back are being irritated by pressure on it. There are many mechanisms of back pain (see later) but the most common one is called 'mechanical' back pain or vertebral dysfunction. Vertebral dysfunction occurs due to malalignment between the lumbar vertebrae at the facet joints and/or intervertebral discs. The small degrees of disarticulation are not gross enough to be seen on an x-ray but cause painful muscle spasms and sometimes nerve impingements which contribute to symptoms.

Who gets Lower Back Pain?

Approximately 80% of individuals will experience an episode of lower back pain at some time during their life. Lower back pain is the fifth leading reason for patients visiting a doctor and the leading cause of work-related disability. However, the underlying cause is usually not serious and may not even be identified by the doctor. Lower back pain is most common in patients between the ages of 20 and 40 years but can be more severe and disabling in elderly patients. Fortunately however, the majority of patients suffering back pain will recover and only 5% go on to develop a chronic condition. Back pain is associalted with huge economic costs through medical expenditure and loss of worker productivity. Men and women are equally affected by lower back pain but the underlying causes of the pain may differ. For example, women suffer back pain during pregnancy and menstruation or from conditions such as osteoporosis f(bone thinning) or osteoarthritis (joint destruction) which are correspondingly more common in females. Men may be more likely to suffer lower back pain secondary to trauma from sporting or labour-intensive work activities. The point prevalence of lower back pain in men and women is approximately 5%. The onset of pain is most common between the ages of 30 and 50 years in both men and women. Children: Lower back pain is not common in children and when present is more likely to represent a serious underlying pathology such as maliganancy (cancer) or infection. All lower back pain in children should be considered seriously and medical advice should always be sought if the pain persists longer than a few days.

Predisposing Factors

There are many causes for low back pain - but they can be grouped roughly as follows:

Trauma
Mechanical
- Muscular pain
- Vertebral dysfunction
- Prolapsed disc (slipped disk)
- Narrowing of bony canals
- Fibromyalgia- generalised aches and pains
- Incorrect bone positions and articulation
Inflammatory
Infective lesions of the spine
Ankylosing spondylitis/ sacroileitis
Metabolic
- Osteoporosis, fracture particularly in elderly, post-menopausal women
- Paget's disease
Neoplastic (tumours/cancer)
- Metastases from tumours of other organs
- Primary bone tumours
- Multiple myeloma
Vascular - disruption of the blood supply to the spinal cord (spinal claudication)
Referred pain- pain spreads to the back from somewhere else, for example to urinary tract. More common in lederly men.
Depression

A precise cause for the back pain is only identifiable in around 15% of cases.

Children: Back pain in children is more likely to have a serious cause. The following may be present-

Developmental disorders- arthritis of the spine (spondylolysis) or slipping of the vertebral bodies across one another (spondylolisthesis).
Disc herniation (slipped disc)
Scheuermann disease- Typically in adolescent males where there is weakening of the vertebral end-plates causing crushing and painless kyphosis (increased curvature of the back producing a 'hunch').
Tumours of the bone or spinal cord.
Infection of the discs (discitis) or bone (osteomyelitis) mostly in children less than 10 years. old.
Congenital disorders such as scoliosis (lateral curvature of the spine).

Progression

This depends on many factors. Defining a precise underlying cause is often difficult, this encourages multiple medical consultations with differrent doctors, which further compounds the problem. Periods of naturally occurring improvement and flare-ups are the rule regardless of the aeitiology (cause or origin). This is especially true in lumbar disc disease and lumbosacral strain and sprain (represents most cases). The most significant factor in the outcome of low back pain is the duration of persistent symptoms. Less than 50% of patients who experience low back pain for over 6 months ever return to gainful employment.

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