This is a chronic inflammatory arthritis especially affecting sacroiliac joints and spine and characterized by progressive stiffening and fusion of the axial skeleton. It is one of the seronegative spondyloarthropathies.
It is most commonly seen in the age range of 20 to 30 years and male to female ratio is 4: 1 . More than 90% of affected persons carry the histocompatibilty antigenHLA B27
Clinical Signs and Symptoms
Onset is usually insidious. There are recurring episodes of low back pain and stiffness sometimes radiating to the buttocks or thigh. Pain is worse in early morning and after inactivity.
Some patients complian of chest pain aggravated by breathing that is due to involvement of costovertebral joints. There is occasionally heel pain due to plantar fasciitis .
On examination there is failure to obliterate lumbar lordosis on forward flexion. There is pain on sacroilliac compression and tenderness over bony prominenece such as illiac crest, ischial tuberosity and greater trochanter.
There is restriction of movement of lumbar spines in all directions. As the disease progresses stiffness increases throughout the spine.
Associated Clinical findings
- Iritis occurs in about 25% of patients.
- Aortic regurgitation, heart blocks and anterior uveitis
- Pulmonary fibrosis of the upper lobes with progression to cavitation mimicking tuberculosis.
- ESR is often raised.
- RA factor is absent.
- HLA B 27 seen in 90% of cases
X Ray Lumbar spine
The sacroilliac joints are eroded with irregular margins and sclerosis of adjacent bone. As the disease advances , the sacroilliac joints may fuse.