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M:F 3:1
2nd to 4th decade
6 per 10,000 of G. population
Autosomal inheritance, with 70% penetrance in males, 10% in females.
90% pts have HLA B- 27 antigen.
Increased incidence among relatives. EPIDEMIOLOGY<br>
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Located in the short arm of chromosome 6
One of the series of closely linked polymorphic loci in that region.
Incidence in N. population – 8% in Caucasians, 4% in blacks.
Neither necessary nor sufficient to cause AS
Positive individuals tends to have early onset.
No correlation with severity. HLA B- 27<br>
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Carriers of this gene have a 16% to 50% increased risk of developing AS,
Virtually absent among the aboriginal populations of Australia and South America.
Negative individuals doesn’t have family history.
Susceptibility to AS almost entirely determined by genetic factor with HLA constituting about 1/3 of genetic component.<br>
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autoimmune disorder
subsequent to a Klebsiella pneumoniae infection in HLA-B27–positive individuals,
Molecular mimicry,
incidence of AS in patients with idiopathic bowel disease is approximately 3.7%. ETIOLOGY<br>
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ENTHESOPATHY , Hall mark of AS.
combination of inflammation and bony destruction at the site of tendon insertion
Ass with prominent edema of the adj bone marrow & is often characterised by erosive lesions that eventually undergoes ossification. PATHOGENESIS<br>
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Distribution of lesion: in synovium, articular capsular & ligamentous attachments to bones.
Articular lesions due to 2 primary mech, synovitis, enthesitis
2 subsidiary mech, enchondral & trauma.
In spine: early, there is inflammatory granulation tissue at the jn of AF of disc cartilage with the margin of V.B.
Outer AF is replaced by bone – bony osteophytes, fusion of adj V.B.<br>
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Aches in buttocks.
Lower lumbar aches
Bony tenderness.
Peripheral jt involvement [girdle jts]
Inflammatory back ache.
< 40 yrs onset
Insidious onset
Duration > 3 months
Morning stiffness
Improvement with exercise. CLINICAL FEATURES<br>
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Extra articular invoivement
Most C. anterior uveitis. [30%]
AR, Third degree heart block.
Subclinical pulm. Lesion, cardiac dysfn.
Cauda equina syn & slow progressive upper lobe fibrosis in long standing cases.
Progression of the diseases monitored by Pt Ht, chest expansion, schober's test, occiput to wall distance.
Jaw involvement- old pts.
Thorax involvement.<br>
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Loss of lumbar lordosis
Exaggerated kyphosis
Head & neck move forwards on the shoulder
Mister punch posture: rounded dorsal spine, flattened chest & protrubent abdomen.
Wide bases stance. Posture & stance<br>
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I – phase: Isolated phases characterised by attacks of pain & stiffness occuring in increasingly frequent intervals, corresponding to pre-ankylosing stage.
II- phase: continuous symptoms & constitutional upset.
III- phase: declining disease activity & reduced symptoms with episodic minor relapses. West – Phases of AS<br>
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Early stage of the disease with typical symptoms od spondylitis in absence of definite radiological changes in the SI jt.
Associated with systemic symptoms include anorexia, Wt loss, fatique, low grade quotidion fever. Pre- ankylosing stage of Scott<br>
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Iridocyclitis
Cardiovascular complications
Lung changes
Neurological changes
Amyloidosis
Complication of treatment. Complications<br>
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ESR, CRP
HLA B-27
Raised globulin fraction
Alkaline phosphatase.
RA factor negative
Rise in CSF protein level
Urinary 17- ketosteroid levels increase, Lab<br>
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ASCA IgA levels are significantly high in AS & other SpA than in healthy controls & Pt with RA
I Serological marker ass. With SpA
Can be marker of radiological damage & more severe course in A.S Anti saccharomyces cervicisae<br>
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Blurring of cortical margins of subchondral bone sclerosis & erosion pseudowidening of jt space fibrous & bony ankylosis
Shiny corner sign- vetebral squarring
Star sign- SI jt.
Rail road track lines – zygoapophyseal jts
Marginal syndesmophytes
Bambo spine X-RAY<br>
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Bone scan
MRI – si jt in early stages, more sensitive & specific
DEXA- reduced BMD
Falsely elevated reading related to spinal ossification can be avoided by using lateral projection of L3 vetebrae.<br>
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The Modified New York Criteria for Diagnosing Ankylosing Spondylitis Clinical Criteria
1. Low back pain of at least 3 months' duration improved by exercise and not relieved by rest
2. Limitation of lumbar spine motion in sagittal and frontal planes
3. Chest expansion decreased relative to normal values for age and sex
Radiographic Criteria
4. Bilateral sacroiliitis, grade 2-4
5. Unilateral sacroiliitis, grade 3-4<br>
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graded 0 (normal),
1suspicious,
2 minimal sacroiliitis
3 moderate sacroiliitis
4 ankylosis Sacroiliitis Radiological Grading<br>
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NSAIDS
Indomethacin
Phenyl butazone
Sulphasalazine
Anti TNF -alpha Treatment<br>
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Definitive diagnosis of AS;
presence of the disease for at least 4 weeks;
presence of refractory disease(defined by the failure of two types of NSAIDs during a single 3-month period);
failure of local corticosteroid injection into inflamed sacroiliac joints;
failure of sulfasalazine in patients with peripheral disease;
no medical contraindications to the initiation of treatment. Anti TNF-Alpha<br>
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Infliximab: anti TNF – alpha monoclonal Ab
5 mg/kg body wt repeated 2 wks later, again 6 wks later, then at every 8 wks interval.
Etanercept: 25 mg by S.C inj twice weekly<br>
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Bisphosphate Pamidronate at a dose of 60 mg monthly IV
Thalidomide 200 mg / day [inhibit TNF]
Alpha emitting isotope 224 Ra at a dose of 1 MBq. Newer drugs<br>
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Thirty percent to 50% of patients with AS exhibit involvement of the hips; of those, 90% present bilaterally.
THR is the most common surgery done in AS.
Mobilizing the hip by THR before spinal osteotomy makes easier to determine desired degree of correction in spine. SURGICAL<br>
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AS patients are more prone to anterior dislocation when acetabular components are placed in their normal position relative to the pelvis.
When positioning the acetabular component in a patient with AS, one must account for the relationship of the pelvis to the lumbar spine in the sagittal plane in order to avoid an excessively hyperextended hip once the patient resumes an upright position.<br>
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GT – not to be osteotomised
Due to osteoporosis & extensive capsular & pericapsular fibrosis during dislocation of the hip, increased chance of fracture.
Osteotomy of the neck & head can be removed as piecemeal.
Capsulectomy should be adequate.
Precautions to avoid postop dislocation.<br>
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The level of risk for heterotopic bone formation after THA in patients with AS remains controversial.
The proportion of AS patients with functional ankylosis secondary to HO following THA is likely substantially lower than previously thought.
High-risk patients with preoperative ankylosis, with previous hip surgery, with previous infection, and/or in whom a trans trochanteric approach to the hip was used should be considered for HO prophylaxis<br>
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To improve the erect position there by to balance the effect of gravity
To increase the respiratory function
To increase the GI fn.
Smith Peterson O.
Confined to the laminae & articular facets.
Ideally done at L2 & L3 levels. Spine osteotomy<br>
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Surgical intervention also may be indicated for management of deformity, pseudarthrosis, fracture, and spondylodiscitis.<br>
