AN INTRODUCTION TO
ANKYLOSING SPONDYLITIS
by The National Ankylosing Spondylitis Society
Ankylosing Spondylitis
Ankylosing spondylitis is a painful, progressive rheumatic disease, mainly
of the spine. It can also affect other joints, tendons and ligaments and other
areas, such as the eyes and heart.
Ankylosing means fusing together (ankylosis). Spondylitis indicates
inflammation involving the joints of the spine and is derived from the Greek
words describing the building blocks of the spine (spondylos) and
"itis" meaning inflammation. However, it is important to be aware
that the entire fusing of the spine, as implied by the name of the condition,
is not the norm. Many people will only have partial fusion, sometimes limited
to the pelvic bones.
What happens?
The inflammatory process is at the site of a joint or where tendons and/or
ligaments grow into bone. For example, inflammatory change occurs around
vertebral joints and areas of ligament attachment, for example, at the bone
(ischial) you sit on in your buttocks, or breast bone, or where the tendon
inserts into the heel.
As a reaction to the inflammation, a small amount of bone erosion occurs.
After the inflammation has subsided, a healing process takes place with the
growth of new bone (reactive bone). After repeated attacks, this additional
bone growth can surround the disc. Therefore, two vertebrae can become one by
this merging process. The exercises we should be carrying out are designed to
prevent or slow down this process.
What causes Ankylosing Spondylitis?
The cause is not yet known. However, there have been many important
discoveries since the early 1970s. One is that about 96% of the estimated
80,000 clinically diagnosed people in this country all share the same genetic
cell marker 'HLA B27' (Human Leucocyte Antigen B27). This is related to white
blood cells and is quite different from red cell groups such as A, B, O and
rhesus markers.
There is evidence that an outside environmental process must be responsible
for initiating the condition and its flare-ups. It could be that a normally
quite harmless micro-organism, which would be dealt with by our immune system,
sets up an adverse reaction after coming into contact with the B27 individual.
In most cases, this leads to inflammation of the sacroiliac joints and to
different areas of the spine.
Who gets Ankylosing Spondylitis?
It had been observed and documented for many decades that the disease seemed
to occur from time to time in some families. Not until the link with HLA B27
became apparent was it known why. The inherited susceptibility will be
discussed later in these pages. The average age of onset is twenty four years
old and the sex distribution is two and a half to three males for every one
female.
The formation of the spine
The spine is made up of 24 vertebrae and 110 joints. There are three
sections: seven CERVICAL, twelve DORSAL or THORACIC and five LUMBAR vertebrae.
The cervical, or neck section, is the most mobile. In the dorsal section
each vertebra has a rib attached to it on each side. Below the lumbar section
is the diamond shaped sacrum which locks like a keystone into the pelvis. The
joints between the sides of the sacrum and the rest of the pelvis are called
the sacroiliac joints. This is often the starting-point of the condition where
the low back pain and AS begin.
Other back pain and Ankylosing Spondylitis
Back problems are some of the most common complaints seen in the doctor's
surgery. Only a very few of these people will have AS. Doctors have the problem
of recognising the different types of back complaints presented to them by
their patients. This will partly explain why several wrong labels were pinned
to many of the people reading this booklet before finally receiving the correct
diagnosis - back strain, slipped disc and sciatica being among the most common
ones.
The condition is also sometimes confused with SPONDYLOSIS, a term relating
to "wear and tear". This is more common in older people and the
vigorous therapy associated with AS might be harmful to such individuals.
|
