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.
The inflammatory process is at the site of a joint or where tendons and/or ligaments grow into bone. For example, inflammatory change occurs aroundvertebral 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.
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.
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.
There are three sections:
twelve DORSAL or THORACIC and
five LUMBAR vertebrae.
Spinal Column more information
Spinal Cord more information
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.
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.