FRCA Notes

Ankylosing Spondylitis

The curriculum asks for knowledge of 'the perioperative implications of rheumatological disease, including... ankylosing spondylitis'.

The topic featured as as CRQ in 2020 (24% pass rate) which had examiners 'surprised at the lack of knowledge on this topic', although more specific feedback wasn't forthcoming.

The question was repeated in 2024 and 'was well answered on the whole'.

Resources

  • Ankylosing spondylitis is an autoimmune, seronegative, spondyloarthropathy
  • It causes a painful, chronic, inflammatory arthritis characterised by periods of quiescence and intermittent flares/exacerbations
  • Affects 0.5% (female) to 1% (male ) of Caucasians
  • More common in males
  • Peak onset at 20 - 30yrs old (80%) although may be juvenile (4%) or after 30yrs (5%)
  • Distribution of disease tends to be gender-specific:
    • Male; more severe spinal and pelvic disease
    • Female; greater peripheral involvement (wrists, knees, ankles)

  • The initiating cause is not known, but is an interaction between:
    • Genetic susceptibility (HLA-B27, -B60, MHC genes, TNFɑ and IL-1ra)
    • Environment (bacterial or viral infection)
    • Non-modifiable risk factors (gender, age, ethnicity)

HLA-B27

  • 80 - 90% of patients are positive for HLA-B27 alleles
    • However, only 5% of HLA-B27 positive individuals will develop ankylosing spondylitis
    • Accounts for up to 50% of the genetic susceptibility in ankylosing spondylitis
  • May be associated with earlier onset disease

Hypotheses

  • Arthrogenic peptide hypothesis
    • HLA-B27 positive individual is exposed to an antigenic pathogen
    • Consequent cytotoxic T-cell mediated autoimmune response occurs in the joints

  • HLA-B27 folding hypothesis
    • Abnormal conformation/misfolding of HLA-B27 heavy chains results in accumulation within the endoplasmic reticulum
    • This generates pro-inflammatory mediators, which themselves activate NF-𝜅β
    • There is consequent transcription of genes encoding cytokines, TNFɑ, IL-1 and IL-6, causing an inflammatory response

  • Gram-negative bacteria
    • Campylobacter, Salmonella, Shigella, Yersinia
    • Cause a reactive arthropathy, which later causes development of ankylosing spondylitis

Spinal disease

  • Primarily affects the spine and sacro-iliac joints
    • Persistent pain of lower spine and SIJ
    • Morning stiffness, improves with exercise
    • Fusion of the spine can occur (bamboo spine)
    • Enthesopathy; pathological changes at sites of ligament/tendon insertion

  • Bony fusion occurs in 70% of patients
  • Ectopic bone formation leads to syndesmophyte formation
  • There is increased risk of osteoporosis

  • Consequently there is
    • Higher risk of compression fractures
    • Rigid hyperkyphotic deformity
    • Increased risk of iatrogenic spinal cord injury when transferring patients

Complications of spinal disease

  • Atlanto-axial subluxation (47%) i.e. increase in pre-odontoid peg space to >3mm
  • Vertebral fractures without (or only small) trauma
    • Including commonly C5/6 fracture merely from hyperextension
  • Collapse of vertebral end-plates
  • Spinal nerve root compression causing peripheral nerve lesions
  • Spinal cord compression including CES
  • Vertebro-basilar insufficiency

Peripheral joint disease

  • Peripheral joints are involved in 50% of patients
  • Hips and shoulders are most commonly affected, including need for early hip replacement

Airway involvement

  • TMJ involvement in up to 40% of patients, which may limit mouth opening
  • Crico-arytenoid arthritis is a rare feature, but can cause dyspnoea, hoarseness and vocal cord fixation

Extra-articular manifestations

Pulmonary Cardiovascular Other systems
Upper lobe/apical fibrosis Aortic insufficiency due to fibrous proliferation of tunica intima Anterior uveitis (20 - 40%)
↓ chest wall compliance from costovertebral joint involvement Mitral valve disease Psoriasis (9%)
Restrictive lung defect with reduced VC and FRC Cardiac conduction defects due to Purkinje fibre involvement Inflammatory bowel disease (6%)
↑ risk of myocardial infarction Prostatitis (85%)

Associated diseases

  • Ulcerative colitis
  • Crohn's colitis
  • Psoriatic arthritis
  • Uveitis (Reiter's syndrome)

  • Clinical and radiological criteria are used to diagnose ankylosing spondylitis
  • Absence of rheumatoid factor
  • Modified New York Criteria are used to confirm diagnosis
  • MRI used for radiological diagnosis

Bloods

  • Normochromic anaemia
  • Elevated ESR (50%)
  • Raised serum IgA levels
  • HLA-B27 positive

Reduce inflammation

  • NSAIDs (COX-2 inhibitors) first line

  • DMARDs
    • Methotrexate | sulfasalazine | leflunomide
    • Provide analgesia from synovitis but not spinal pain in axial joints

  • Bisphosphonates may be beneficial for osteoporosis and spinal symptoms
  • Radiologically-guided, intra-articular corticosteroid injection is more effective than oral steroid therapy

  • Anti-TNFɑ agents
    • Infliximab | adalimumab | etanercept
    • Usually provides improvement within 2 weeks of starting therapy
    • 2x increased risk of bacterial/viral infections in patients taking these drugs, especially TB and reactivation of hepatitis B
    • Can themselves induce auto-immune disease e.g. Guillain-Barre syndrome
    • Can cause a vasculitis (type 3 hypersensitivity reaction) and should be avoided in patients with cardiac failure and demyelinating disease e.g. MS

Maintain posture and function

  • Education
  • Physiotherapy
  • Exercise e.g. hydrotherapy/swimming

Perioperative management of the patient with ankylosing spondylitis


  • Patients may present for:
    • Treatment of consequences of the disease e.g. TKR, THR, corrective spinal surgery
    • Surgery unrelated to their disease process

History and examination

  • Full history to evaluate disease severity and presence of extra-articular features
  • Any pre-operative neurological deficits should be documented
  • Full airway assessment

Investigations

  • ECG is mandatory to assess for conduction defects
  • TTE to check for (mitral) valvular disease
  • Lung function tests; restrictive lung defect
  • Imaging of cervical spine may be required

Optimisation

  • Surgeons may wish a cessation of DMARD therapy for a period pre-operatively to reduce risk of perioperative infection
  • No clear consensus on management of anti-TNFɑ drugs in perioperative period

General management

  • Meticulous care positioning and moving the patient as high risk of iatrogenic injury
  • Antibiotic prophylaxis and strict asepsis for invasive procedures as risk of infection due to DMARDs and/or anti-TNFɑ agents

Airway management

  • Difficult intubation should be anticipated due to:
    • Cervical spine involvement with limited neck movements
    • Atlanto-axial subluxation
    • Fixed cervical flexion deformities limiting front-of-neck access options
    • TMJ joint involvement
    • Cricoarytenoid joint involvement
    • Difficulty in positioning for optimal airway manipulation
      • Risk of neurological injury from excessive extension
      • Risk of vertebrobasilar insufficiency due to bony encroachment on the vertebral arteries
  • Pre-operative FNE may prove invaluable

  • Awake tracheal intubation is considered the safest option if intubation is required, although other options include:
    • Intubating LMA, which may facilitate blind intubation
    • Retrograde intubation

Regional anaesthesia

  • Neuraxial anaesthesia is technically more difficult, due to fusion and poor positioning
  • There is an increased risk of complications, including:
    • Accidental IO injection of LA
    • Spinal or epidural haematomas
    • Difficulty placing epidural due to narrower or obliterated epidural space
    • Higher block due to rapid rise of epidural LA as the space is narrower (infuse more slowly)

Corrective spinal surgery

  • Severe C-spine deformity may require surgical correction to improve functional and psychological status
  • Issues include:

Parturient with ankylosing spondylitis

  • Neuraxial anaesthesia likely to be more difficult
  • If GA required may need ATI in left lateral position
  • Need early Obstetric and Anaesthetic review and planning

  • Same precautions with positioning and neck movement at emergence and post-operatively
  • Increased risk of respiratory complications:
    • Mutli-modal opioid-sparing analgesia
    • Early physiotherapy & deep breathing exercises
    • Early mobilisation