Ankylosing Spondylitis

Seronegative Spondyloarthropathies

Definition

• Chronic Seronegative Spondyloarthropathy
• Affects predominantly the sacroiliac joints & the spine
  • Presents similar to pauciarticular JRA
  • Usually male > 8 years of age
  • Joints assymetric;
    • Low back pain
    • hips, knees, ankles, toes, rarely U/E
  • AM stiffness
  • ESR ↑
  • ANA neg
  • RF neg
  • HLA B27+ in 90%
    • in the normal caucasion population it is 8% prevelent
  • Enthesopathy is frequent

D>Diagnostic Criteria

• Positive XR Sacroiliitis
• One or more
  • History of Lumbar Spine pain
  • Stiff Lumbar Spine
  • Chest expansion < 1″ at 4th intercostal space

E>Epidemiology

• 0.1% in Western Europe
• Regional variation +++
  • M:F – 3:1 (2:1 up to 10:1)
  • Average onset 25 years
• Family history ↑ risk
  • Genetic predisposition with parents & half first degree relatives HLA B27 positive
  • But requires additional environmental trigger
• Females
  • Less progressive spinal disease
  • More peripheral disease

Aetio>Aetiology

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HLA-B27

• 95% of cases

HLA-B27 highly variable in general population

• 8% of Caucasians
• 50% of American Indians
• Negative in Negroes

HLA-B27 linked to susceptibility factor

• Genetic predisposition acted upon by environmental trigger factors
• GUT & GIT infections can be trigger
• Klebsiella infections implicated recently due to higher incidence in AS

Patho>Pathologenesis

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Two basic lesions

• Enthesopathy
• Synovitis of Diarthrodial Synovial Joint

Enthesopathy

• Enthesis is insertion of tendon, ligament or capsule into bone
• Enthesitis affects
  • Ligament structures of Fibrocartilaginous joints
    • Intervertebral Discs
    • Manubriosternal Joints (MSJ)
    • Symphysis Pubis
  • Capsule attachments of Synovial joints
    • Hip
    • Shoulder
  • Ligament attachments
    • Spinous processes of vertebrae
    • Iliac Crests
    • Greater Trochanter
• Inflammatory process of the enthesis
  • Initial inflammatory erosion
    • Round cell infiltration (lymphocytes & plasma cells)
    • Granulation tissue
  • Repair via healing with fibrous tissue
    • Fills defect
  • Fibrous tissue ossifies
    • Forms new enthesis above original level of cortical surface
    • Result is irregular bony prominence
    • Sclerosis of adjacent cancellous bone

Synov>Synovitis

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Similar changes to RA

• Villous proliferation of synovium
• Pannus destroys articular cartilage
• Joint ankylosed by fibrous tissue or bone
• Areas of cartilage may be preserved

Axial>Axial Skeleton Pathology

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Discs

• Starts TL spine then works caudal & distal (cf. psoriatic arthritis which is opposite)
• Initially erosion of enthesis
  • Anderson lesion

• Localised area of destruction
  • Romanus lesion
• Early squaring
• Forms thin vertical projection from end plate
  • Marginal Syndesmophyte*
• Fuse leading to
  • Bamboo Spine
• *Compare with
  • Claw osteophytes
    • Seen with ageing
    • Osteophyte growing over bulging disc as it migrates anteriorly
  • Shelf osteophytes (traction osteophytes/ traction spurs)
    • With instability at that level & Osteoarthritis
    • Anterior & posterior
  • Syndesmophytes
    • Ossification of anterior annulus or ALL
    • Marginal or Non-marginal
      • Non-marginal (ALL ossification) – DISH
      • Marginal (Annulus ossification) – AS

MSJ / Pubic Symphysis / SIJ / Facet / Costovertebral Joints

• Initial inflammation
• Destruction of cartilage
• Replacement by fibrous tissue
• Finally ossification & obliteration

Large>Large Synovial Joints Synovitis

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Pannus & secondary ankylosis

Enthesopathy of capsule insertion

Ossifies

• Especially hip & shoulder

Histo>History

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Young male

Teenager or young adult (2nd-3rd decade)

Lower Back Pain

• 1st feature in 75%
  • Insidious onset
  • Usually dull & poorly localized
  • Worse in morning & after inactivity
  • Improved by warming up
  • May get referred buttock pain
    • May be diagnosed as sciatica

Back stiffness

Chest pain & ↓ expansion

Neck pain & stiffness

Pain & swelling of joints

Age < 40 years onset back pain

Gradual atraumatic onset

Duration > 3/12

Morning stiffness

Improves with exercise

if all 5 features then 95% sensitive, 85% specific for AS

Examina>Examination

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Spinal

• Altered posture
  • Loss of cervical & lumbar lordosis
  • Increased thoracic kyphosis
  • Loss of vision to several paces
• “Wall Test”
  • Occiput / Scapulae / Buttocks / Heels all against wall
  • Unable to do in AS
• Tender over spinous processes
• Stiff LS spine
  • Decreased extension earliest & most severe
  • Decreased forward flexion
    • Schober’s Test (< 4cm over 10cm)
  • Decreased lateral flexion
• Painful & tender SIJ
• SIJ Stress Tests
  • Pain on forced flexion of ipsilateral hip & hyperextension of opposite hip
  • Faber’s test (pain on downward pressure on ipsilateral knee
• Tender ASIS

Decreased chest expansion

• Due to costovertebral joint ankylosis
  • Diaphragmatic breathing
  • < 1″ at 4th ICS (should be at least 7cm in young male)

Hip & shoulder

Symptoms & Signs similar to RA

Complicat>Complications

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Spinal Fracture

• With trauma » “chalkstick fracture”
• Difficult to diagnose on XR because osseous spinal ligaments » CT useful
• May result in neurological deficit (75%)
• Epidural haematoma common

Craniocervical Instability

• Mechanism similar to RA with erosive synovitis
• Atlanto-occipital instability & Basilar invagination

Pseudarthrosis

• AKA Spondylo-discitis
• Unclear whether due to pathological fracture or erosive process of disease

Cauda Equina Syndrome

• Due to Spinal Stenosis

Extraspinal

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Pauciarticular Arthropathy

• Hips & Shoulders
• Insidious onset of pain & stiffness

Peripheral Enthesopathy

• Pain & tender at sites of Entheses
• Pelvis
  • Crests, Ischial tuberosity, Iliac spines, Pubic symphysis, Greater trochanter

• Thorax
  • MSJ, Costosternal joints
• Heels (very common)
  • Achilles, Plantar fascia

ExtraskeletalExtraskeletal

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Acute Anterior Uveitis

Aortitis

• With subsequent aortic incompetence

Pulmonary fibrosis

Colitis

Amyloidosis

• Nephrotic syndrome

Sarcoidosis

Prostatitis

Investigations<>Investigations

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ESR elevated in 75%

CRP better indicator of disease activity

HLA B27 usually positive

RF negative

Xrays

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Spinal Disease

• Loss of normal lordosis
• Erosive changes at insertion of ligaments on the spine
• Produces classical lesions
  • An area of bony erosion at the attachment of the annulus at anterolateral body
    • Anderson Lesion

• If becomes localised area of destruction (usually in lower thoracic spine) with new bone formation
  • Romanus Lesion (difficult to distinguish from discitis)
• New bone formation from edge of annulus producing vertical projection from end plate
  • Marginal Syndesmophyte
• Eventually see fusion of the syndesmophytes & ossification of the ALL
  • Bamboo Spine
• On the A-P film may see ossification of the interspinous ligament & the intertransverse ligaments
  • Tram-Track sign

Sacroiliac Disease

• Initial blurring of subchondral bone
• Then bone erosion & sclerosis
  • Postage stamp

• More on iliac side
  • Pseudowidening of joint

Pelvis

• Erosions or Whiskering at attachments of tendons / ligaments
  • At ischial tuberosities & crests

Hips & Shoulders

• Features of RA
• Bony ankylosis will follow often

Differential Di>Differential Diagnosis

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Seronegative Arthropathies

• Reiters
• CIBD

DISH (Forestier’s Disease)

• Non-inflammatory with no SI joint involvement

Other causes of mechanical low back pain

• Mechanical / Nonspecific
• Infection
• Neoplasia

Treatment

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Simple analgesia

NSAIDS

Physiotherapy

• ROM & Postural exercises
• Maintain useful, functional posture
• Does not alter natural history

Radiotherapy

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Observed to improve pain & ↓ progression

Risk of inducing malignancy ↓ the usage

May have isolated indications in peripheral involvement where NSAIDS contraindicated

Operative

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• General principles
  • Treat coexisting hip pathology first
  • Flexion extension views lumber & cervical spines
  • Measure brow-chin / vertical angles
  • Preoperative assessment C spine stability & pulmonary function
• Goals
  • Enable upright posture
  • Relieve compression of viscera
  • Improve diaphragmatic respiration
  • Improve field of vision
• Spine
  • Corrective osteotomy
    • Indications
      • Severe deformity difficult to look forwards
      • Respiratory compromise
  • Contraindications
    • Elderly
    • Aortic calcification
    • Poor general health
  • Closing Wedge Osteotomy of Posterior elements
    • Single stage posterior procedure
    • V-shaped osteotomy of posterior arch
    • Laminae undercut & canal decompressed
    • May need posterior instrumentation
  • Good correction
  • Aorta most at risk
• Hip
  • Total Hip Replacement
  • Good to excellent outcome & durability
  • No ↑ loosening
  • Main problem is Heterotropic Ossification
    • 10-20% get Brooker III or IV
    • Usual treatment indicated

Victorian Bone School Presentation – Cervical Spondylosis & Ankylosing Spondylitis