Continuing Medical Education: Spondyloarthropathies.
Edited By: Gregory C. Gardner, M.D.
Last updated Friday, January 07, 2005
Ankylosing spondylitisWhat is AS? Ankylosing spondylitis (AS) is the prototypic spondyloarthropathy. The
term comes from the Greek ankylos (bent or crooked) and spondylos
(vertebra). There is evidence of AS in ancient Egypt as far back as
2900 B.C. The prevalence in the U.S. population in between 0.5 and 1.0
percent. The prevalence figures for certain Native Americans are as
high as 18-50 percent. The sex ratios are almost equal but the disease
is more often clinically apparent in males. The usual age of onset for
AS is between the second and fourth decade of life.What is the pathology of ankylosing spondylitis? If rheumatoid arthritis is thought of as a disease of the synovium then
AS is a disease of the enthesis which is the site where ligaments,
tendons, and joint capsules insert into bone. At these sites,
inflammation occurs leading to fibrosis and ossification. These changes
have a predilection for the enthesis about vertebrae, facet joints, and
feet. Inflammation is followed by fibrosis which is followed by
ossification leading to the ankylosis so characteristic of this
disorder.What are the clinical features of ankylosing spondylitis? - Axial Skeleton
The symptoms of AS are typically insidious in nature. Patients complain
of morning low back stiffness lasting 30 minutes to several hours. Pain
and stiffness at night and with prolonged sitting is also
characteristic. The discomfort is felt in the low back and buttock area
and is improved with exercise. If the disease progresses, immobility
occurs due to fibrosis and ossification of enthesis about the spine.
The entire spine may be affected and in severe cases, patients may
develop the so called "bamboo spine". The insertions of the ribs into
the spine and intercostal enthesis can also be affected leading to
pleuritic-like chest pain with deep breathing and with time fibrosis of
these attachments may cause decreased inspiratory excursion of the
chest. Sacroiliac joints are usually involved symmetrically but one
side may be more involved than another. Sternoclavicular and
tempromandibular joints can also be affected.
Spinal mobility can be measured by the Schober test done by drawing
a 10 cm line up from the midposterior iliac spines (the "dimples").
Have the patient bend forward and measure the distraction. Normal is
greater than five cm.
- Peripheral Joints
AS can also affect the peripheral joints in particular the hips, the
shoulders, and the ankles. Overall, 35 percent of patients may have
peripheral joint manifestations. This is said to occur more frequently
in females. Peripheral joint disease is usually asymmetric.
- Enthesopathy
The Achilles tendon and the plantar fascia are frequently affected
causing considerable discomfort. The Achilles tendon may be quite
swollen and tenderness and is usually at the insertion into the
calcaneous. Dactylitis (diffuse swelling of the fingers or toes also
called sausage digits) may also be present representing diffuse
enthopathy.
- Eye Disease
As many as 25 percent of patients with AS may have this
manifestation during the course of their illness. Anterior uveitis or
iritis is typically episodic and unilateral. Blindness is rare but the
uveitis may be severe enough to require local or even systemic
corticosteroids. Eye involvement appears to be more common in patients
with peripheral joint disease.
- Cardiovascular Disease
This complication usually occurs in patient with long standing
severe AS with peripheral joint involvement. Aortic incompetence may be
a combination of aortic valve cusp fibrosis and or aortitis distal to
the valve itself. Complete atrioventricular block with Stokes-Adams
attacks may occur. Cardiac involvement is found in up to 10 percent of
patients after 10 years of disease.
- Pulmonary Disease
Patients with severe spondylitis may develop upper lobe fibrosis.
Cysts formation may occur and these may be colonized by Aspergillus.
Patients may succumb to massive hemoptysis. Restrictive lung disease
may be present but is normally mild.
- Important Spinal Complications
The immobile spine fractures easily with even minor trauma. The most
common site is the cervical spine. Most fractures center around C5 and
are transverse through the disc space. Gross instability can occur
leading to impingement on the cord or vertebral arteries. Fracture may
not be apparent on X-ray and may require CT scan or bone scan to
localize. This is a true rheumatologic urgency.
The cauda equina syndrome may cause insidious onset of pain in the
buttocks or legs associated with bowel and bladder symptoms. This is
due to spinal cord compression at the level of the cauda equina.
Myelogram or MRI demonstrate lumbar diverticuli. Therapy, including
surgery and high dose steroids, have not been satisfactory.
Spinal stenosis can also occur due to bone over growth and nerve impingement. This may respond favorably to surgery.
Spondylodiscitis occurs at a vertebral disc space (usually in the
thoracic spine) that has become mobile. It is a source of
mechanical-type back pain and although not usually unstable, can be a
source of significant pain. On X-ray, there is usually erosion of the
vertebral end plates and may mimic an infectious process. Treatment is
by surgical fusion or trial of bracing to allow the segment to refuse
on its own.
What are the radiographic features of ankylosing spondylitis? - Sacroilitis
Initial changes include blurring of the joint margins and reactive
sclerosis. With progression there may be complete fusion of the joints.
Bilateral sacroilitis occurs in AS. Early changes at the sacroiliac
joints are nicely demonstrated by CT scan.
- Syndesmophytes
These occur from ossification of the area of the annulus fibrosus
and bridge adjacent vertebrae. With advancing disease, these can give
the spine a bamboo appearance. - Vertebral Squaring
Erosions at the vertebrae occur first at the anterosuperior anteroinferior corners. This leads to the appearance of squaring. - Reactive Sclerosis
The anterior edges of the vertebrae can develop reactive sclerosis
and have a so-called "shining corner" appearance. Reactive
sclerosis/"fluffy" periostitis can also develop at the symphysis pubis
and the ischium. - Calcaneal Spurs/Erosions
Erosions can develop around the Achilles tendon insertion and
calcaneal spurs are also common. Periostitis can occur at the calcaneus
giving a "fluffy" appearance to the heel.
How is ankylosing spondylitis treated? - Education
Patients need to know the nature of their illness and its treatment.
An extensive discussion is important for those who are recently
diagnosed. There are educational materials available through the Arthritis Foundation, the Spondylitis Association of America, and on this web site. - Physical Therapy
All patients should be sent to see a physical therapist when
diagnosed to learn techniques for good posture and daily stretching.
Patients should be encouraged to stay active! Swimming is an excellent
activity for patients with arthritis. - Medication
- NSAIDs are the mainstay of
treatment. Patients usually have very immediate relief. Indomethicin or
phenylbutazone (now under restricted use) are felt to be the most
effective but most NSAIDs will work. Patients on these medication long
term need to be monitored on a regular schedule (at one month then
every three to twelve months thereafter).
- Corticosteroids
are useful for intra-articular use for peripheral joints but are not
felt to be effective for spinal disease.
- Sulfasalizine
has recently been found useful for both the peripheral joint
involvement but also shows promise in the spinal disease as well.
- Other
medications: Methotrexate is used by many rheumatologists but there are
few studies. Of historic interest is the use of radiation which
apparently did wonders for the spinal disease but lead to high a
incidence of leukemia.
- Surgery
There is a limited role for surgery except in patients with severe
hip or shoulder disease. A neurosurgeon or orthopaedic spine surgeon
should be consulted early for spine fractures, cauda equina syndrome or
spondylodiscitis.
How serious is ankylosing spondylitis? The prognosis is dfficult to assess but overall the disease is less
severe in women. Most patients have a good prognosis with a minority
progressing to significant disability as was seen in the past. There is
about a 10-20% risk for offspring of developing the disease. The key
may be early diagnosis and institution of NSAIDs to reduce pain and
mobility exercises to prevent fusion.Surgery for arthritis at the University of Washington If you are interested in making an appointment to discuss this procedure, you can request an appointment using our online referrals website. To request a referral online, please click here. You can also call 206-598-4288 (outside the Seattle area: 800-440-3280) to make an appointment.
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