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INTRODUCTION
Low back pain is one of the most common symptoms that people
experience. It is estimated as the leading cause of chronic
disability in the community. More than three quarters of the
world's population experience back pain at some time in their
lives. It is also the most common cause of absence from work in
the developed countries and thus more than 50 million days are
lost from work each year.
DEFINITION
Low back pain is a pain, muscle tension, or stiffness localized
below the costal margin and above the inferior gluteal folds,
with or without leg pain. It has following varieties:
Acute: Pain lasts less than 6 weeks.
Sub-acute: Pain lasts 6-12 weeks.
Chronic: Pain lasts more than 12 weeks.
ANATOMY
The back is an intricate structure of bones, muscles, and other
tissues that form the posterior part of the body's trunk, from
the neck to the pelvis. The centerpiece is the spinal column,
the delicate nervous system structure that carries signals that
control the body's movements and conveys its sensations. Stacked
on top of one another are more than 30 bones, the vertebrae,
that form the spinal column, create a channel that surrounds the
spinal cord. Small nerves (roots) enter and emerge from the
spinal cord through spaces between the vertebrae. The spaces
between the vertebrae
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are maintained by
round, spongy pads of cartilage called intervertebral discs that
allow for flexibility in the lower back and act much like shock
absorbers throughout the spinal column to cushion the bones as
the body moves. Ligaments and tendons hold the vertebrae in
place and attach the muscles to the spinal column. The extensor
muscles are attached to the posterior of the spine enable
standing and lifting objects. These muscles include the large
paired muscles in the lower back (Erector Spinae), which helps
to hold up the spine and Gluteal Muscles. The flexor muscles are
attached to the anterior of the spine (which includes the
abdominal muscles) enable flexing, bending forward, lifting and
arching the lower back. The oblique muscles are attached to the
sides of the spine and help rotate the spine and maintain proper
posture.
EPIDEMIOLOGY
More than 70% of episodes of low back pain are of mechanical
origin. Of which most resolve spontaneously within 1 to 2 weeks;
25%-27% may suffer for months and 3% may suffer for more than 3
months as the cases of chronic low back pain. The incidence of
back pain is higher in adults over the age of 40 years. The over
all prevalence is similar in both sexes, but recurrences are
more common in men (20% in 1 year).
RISK FACTORS
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Age |
The peak
incidence of back pain at about age 40-60. It is uncommon
after the mid fifties. |
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Occupation |
Back pain is
more common in people in heavy manual occupations who
undertake heavy lifting. |
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Social Class |
There is a
relationship between prevalence of low back pain and
disability and lower social class. |
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Diet |
A diet high in
calories and fat, combined with an inactive lifestyle can
lead to obesity, which can put stress on the back.
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Genetic |
There is some
genetic risk factor for common non-specific back pain. They
are: COL9A2 & COL9A3 gene polymorphisms & Interleukin-1 gene
polymorphisms. |
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Race |
African American
women are two to three times more likely than white women to
develop Spondylolisthesis. |
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Smoking |
Smoking causes
atherosclerosis, blockage of blood vessels in the back due
to fatty plaque deposits. |
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Sex |
There is little
difference in the incidence of back pain in men and women. |
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