19th January 2024

Presentation

AS usually presents with an insidious onset before the age of 30 years. Symptoms may be mild in early stages, with inflammatory back pain being a hallmark feature of the disease. Early morning stiffness is also characteristic. Systemic features and extra-articular manifestations are common.

Symptoms

• Inflammatory back pain:
  • Worse first thing in the morning and can awaken patient from sleep
  • Often improves with physical activity but not rest
  • Originates in sacroiliac joints
  • Can be felt as diffuse, non-specific buttock pain
  • Improves with NSAIDs
  • Can cause loss of spinal mobility
• Back stiffness
  • Usually occurs in the early morning
  • Improves with exercise
• Peripheral enthesitis:
  • Inflammation at points where tendons and ligaments attach to bones
  • Commonly affected sites: Achilles tendonitis, plantar fasciitis, tibial tuberosity
  • Painful lesions, especially in the morning
  • May be associated with swelling, stiffness, and reduced mobility
• Peripheral arthritis:
  • Usually monoarticular or oligoarticular
  • Usually asymmetrical and involves hips, shoulder joints, chest wall joints and pubic symphysis
  • Temporomandibular joints can also be affected occasionally
  • More common in females
• Extra-articular manifestations:
  • Uveitis
  • Psoriasis
  • Inflammatory bowel disease
  • Osteoporosis
  • Cardiac complications: aortic regurgitation, mitral regurgitation and non-aortic valvular heart disease, heart failure, arrhythmias, cardiovascular disease, AV node block
  • Lung complications: restrictive lung disease, apical fibrosis
  • Neurological complications: vertebral fractures, cauda equina
  • Renal complications: amyloidosis, IgA nephropathy
  • Systemic features: fatigue, sleep disturbance

Signs

• Loss of lumbar lordosis and increased kyphosis (in chronic cases) 🡪 ‘question mark posture’
• Reduced spinal flexion
  • Schober test: mark is made at 5th lumbar spinous process and 10cm above with patient in erect position. Distance should increase to 15cm on bending forwards in individuals without ankylosing spondylitis
• Pelvic and chest wall tenderness
• Sacroiliac joint tenderness
• Reduced chest expansion:
  • Signifies costovertebral joint involvement
  • Less than 2.5cm on deep inspiration measured at 4th intercostal space
• Increased tragus-to-wall distance
  • Measure of kyphosis and cervical mobility
  • Measured as the distance between tragus of the ear and the wall with patient standing with heels and back against the wall and head in the neutral position