1. Ankylosing Spondylitis ( A.S.)
Seronegative spondyloarthritic diseases
Chronic, systemic, inflammatory disease that affects primarily the sacroiliac joints and spine.

2. Certain peripheral joints and tendons can also be affected, and extra-articular manifestations may be present.
The disease typically affects young adults, and there are strong genetic features.
Genetic factors including the human leukocyte antigen (HLA) B27 gene. Axial involvement, including sacroiliitis, or inflammatory changes of the tendon and ligament attachment to bone.
The spondyloarthritides share many extra-articular features including uveitis, dermatitis, and colitis.

3. Etiology Ankylosing spondylitis remains unclear.
Genetic component and risk
The HLA B27 gene is commonly present.

4. The prevalence of A. S. is 0. 1% to 1
The prevalence of A.S. is 0.1% to 1.4%, depending on the population studied.
The disease is more common in Caucasians than in other races. the prevalence reflects the associated prevalence of the HLA B27 gene in that population.
A.S. is discovered to be the etiology in 4% to 5 % of patients with chronic low back pain.
In North American Caucasians, the HLA B27 gene is found in 7% of the normal population and in more than 90% of patients with ankylosing spondylitis.
HLA B27 positive has a 5% to 6% chance of developing the disease.4 The

5. A.S. was thought to be an overwhelmingly male disease, but the actual male-to-female ratio is closer to 3:1.
The median age of onset is 23 years.
A.S. rarely has its initial manifestation after age 40 years.

6. Pathogenesis
The pathogenesis of A.S.remains unclear to date. It is assumed to be immune mediated.
There is an obvious cytokine role, because patients show improvement with anti–tumor necrosis factor α (anti–TNF-α) agents.
Genetic component, and the HLA B27 gene is found in more than 90% of patients with A.S.
Enthesitis, in both the axial and the appendicular skeleton, is the primary pathologic feature of the spondyloarthritides.
The progression is typically edema of bone followed by erosion, then ossification, then finally ankylosis.

7. The sacroiliac joints exhibit inflammation followed by ankylosis.
In the spine, inflammation at the junction of the annulus fibrosis of the disk cartilage with the margin of vertebral bone. Ultimately, this leads to formation of syndesmophytes, with bridging that leads to the radiographic appearance of a bamboo spine . The spinal facet joint can exhibit synovitis followed by ankylosis.

8. Signs and Symptoms
Spinal and sacroiliac symptoms are typically early and the most prominent.
Low back pain is the first symptom in more than 75% of patients. In some patients, the symptoms are more in the buttock.
limited spinal mobility I
dentifying features of inflammatory low back pain includes onset before the age of 40 years, insidious onset, chronic (>3 months) pain, morning stiffness for longer than 30 minutes, improvement with exercise, awakening with pain in the second half of the night, and alternating buttock pain

9. Enthesopathic symptoms can be spinal or peripheral
Enthesopathic symptoms can be spinal or peripheral. Axial enthesitis includes costovertebral, manubriosternal, sternal clavicular, and costochondral.
Some patients experience decreased chest expansion.
Examples of extraspinal enthesisits include dactylitis (sausage digit), Achilles tendinitis, and plantar fasciitis.
Inflammatory arthritis likewise can be axial or appendicular. The hips and shoulders are commonly involved.
In the peripheral skeleton, patients typically experience lower extremity and asymmetric patterns of involvement.
Eye involvement is the most common, with anterior uveitis (or iritis) seen in 25% to 40% of patients

10. Extra-articular Manifestations of A.S.
Ocular Iritis
Conjunctivitis (reactive arthritis)
Cardiovascular
Valvular heart disease
Aortitis
Conduction disturbance
Pulmonary restrictive lung disease
Upper lobe fibrosis
Colitis
Cauda equina syndrome
C1-C2 subluxation

11. Physical Findings
decreased range of motion and tenderness. When examining the neck, one sees decreased range of motion and increased occiput-to-wall distance.
In the thoracic spine, decreased chest expansion, kyphosis, and costochondral tenderness.
Several maneuvers elicit pain in the sacroiliac joints: the FABER (flexion abduction external rotation), or Patrick’s test; Gaenslen’s test; anteroposterior and lateral pelvic compression; and tenderness of the sacroiliac joint with direct pressure
Enthesitis can be demonstrated on the axial and peripheral examination. Common locations are the costochondral and Achilles regions.
Peripheral arthritis can be observed. The hip joints are most common, but one can also see an asymmetric arthritis, which is more common in the lower extremities.

12. Diagnosis
The diagnosis of A.S. is made on the basis of a combination of suggestive symptoms, physical examination findings, and imaging.

13. Summary
Inflammatory low back pain
Physical examination findings of decreased range of motion in the spine or limited chest expansion, or both
Laboratory testing (relatively unhelpful)
MRI findings of sacroiliitis in the appropriate historical setting with plain films normal

14. Treatment : Goals of treatment : No known curative treatment for A.S.
Reduce pain and stiffness, slow progression of the disease, prevent deformity, maintain posture, and preserve function.
Physical therapy, exercise, and medications are the main forms of treatment.
Rare opportunities for surgical intervention.

15. Medical Options : * Nonsteroidal anti-inflammatory drugs (NSAIDs)
* Cyclooxygenase-2 inhibitors
* Sulfasalazine
* Methotrexate
* Biologic Agents : Enbrel Humira
* Anti–TNF-α agents
Tumor anti necrosis factor
(infliximab, golimumab, etanercept, and
adalimumab)

16. Surgical Options: Total hip replacement is the most common surgery.
Revision surgery may be necessary, because these patients typically present at a young age and when they are still active.
Heterotopic ossification following joint replacement is a unusual complication following hip replacement.
Cervical fusion is indicated for the rare patient with neurologic complications of atlantoaxial subluxation.

17. Suggested Readings:
“Ankylosing Spondylitis". NIAMS. June Archived from the original on 28 September Retrieved 28 September 2016.
Ankylosing Spondylitis. Oxford University Press. p. 15. ISBN Archived from the original on 8 September 2017.