Definition

A seronegative inflammatory arthropathy affecting the spine and SI joints

 Epidemiology

• Males are more commonly affected than females.
• Patient present at young age 15-25 yrs old.
• 90% of patients are associated with HLA-B27 (8% of the normal population are associated with HLA-B27).
• Proposed reactive arthritis to bacterial infection with Klebsiella.

 Pathology

• Synovitis of diarthrodial joints (joints are freely moveable joints held together by a joint capsule, such as the knee and shoulder).
• Enthesopathy – inflammation of fibro-osseous junction of syndesmotic joints and tendons. 
• Ossification of the annulus fibrosus and the Anterior longitudinal ligament (ALL).

 Clinically

• Insidious onset of backache and stiffness
  • Morning symptoms
  • Gradually becoming continuous
• General fatigue, pain, and swelling of other joints

 Skeletal manifestations

• Posture
  • Loss of lumbar lordosis, increase thoracic kyphosis, forward thrust of the neck. Deformity proceeds from distal to proximal – lumbar spine preceding cervical spine.
  • Compensatory hip and knee flexion.
  • Cervical kyphosis may develop – may result in a “chin-on-chest” deformity.
• Global loss of spinal movement with extension is lost first.
• Propensity for spinal fractures
  • Due to the rigidity of the spine
  • Have a high index of suspicion – may even have spontaneous fractures.
  • Low energy trauma or new neck pain should be investigated with plain radiographs or CT scan.
  • High incidence of spinal cord injury (SCI).
  • Usually all 3 column injury (because of spine rigidity), and haematoma has nowhere to go.
  • Better survival with internal fixation.
• Atlanto-axial instability.
• Due to increase stress at C0_C1 instability due to spinal rigidity and erosion of the transverse atlanto-axial and alar ligaments.
• Peripheral joint involvement in 1/3 – more common in females
  • Shoulder
  • Hips
  • Knees

Extra-skeletal manifestations

• Eyes – acute anterior uveitis.
  • 30% of cases – most common manifestation
  • Unilateral
• Heart – Complete heart block, aortitis, aortic regurgitation
• Lung – Pulmonary fibrosis, and chest wall rigidity
• Kidney - Amyloidosis
• Prostate – Prostatitis

Diagnosis

• Clinical
  • History.
  • Wall test – Heels, buttock, scapulae, and occiput should all touch the wall simultaneously.
• Laboratory
  • ESR raised
  • RF negative
  • HLA-B27 positive
• Radiology
  • Erosion of the sacro iliac joints (SI).
  • Vertebral changes.
  • Squaring of the vertebral body.
  • Flattening of the anterior concavity.
  • Bridging syndesmophytes – marginal.
  • Osteoporosis.

Differential

• DISH – ESR is normal, stiffness is uncommon, syndesmophytes are non-marginal.
• Other seronegative’s.
  • Psoriatic.
  • Reiters.
  • Ulcerative colitis (UC).
• Mechanical disorders.
• Osteitis condensans lili.
• Whipples disease.
• Behchet’s syndrome.

Treatment

Non-operative

• Physio – Posture training.
• Sleep with a flat pillow.
• No contact sport.
• NSAIDs.
• Ca and Vit D.
• Sulphasalazine. May be useful in peripheral disease, and possibly slow central disease

Surgical

• General principles
  • Get C-spine flex/ex views.
  • Consider awake fibre-optic intubation.
  • HO prophylaxis.
• Lumbar or cervical osteotomy
  • Lumbar – Transpedicular subtraction osteotomy with vertebral body decancellisation.
  • Generally done at L2/L3 – below the conus.
  • Correction < 50°.
• Cervical – C7 osteotomy
• Widest part of C-spine canal, vertebral artery is not in the foramen (just anterior to it), and C8 nerve is reasonably flexible. Done under LA with the patient seated
• Fracture management
• Neurology
  •  à Anterior and posterior fusion + decompression (to let haematoma out). 
  • Fuse more levels than normal.
• No neurology à prolonged HALO (20 weeks).