Ankylosing Spondylitis

Overview

  • Seronegative spondyloarthropathy strongly linked to HLA-B27
  • Sacroiliitis, then ascending ankylosis with syndesmophytes and bamboo spine
  • Fixed kyphotic deformity
  • Low energy cervical fractures, often through the disc space, highly unstable
  • Epidural haematoma and neurological injury are frequent
  • Immobilise in the usual posture, never force into neutral
  • Long construct fixation, osteotomy to restore horizontal gaze

Western Health Orthopaedic Registrar presentation – Arthropathy of the Spine by Dr Devinder Garewal

Clinical Features

  • Inflammatory back pain with morning stiffness that improves with exercise
  • Reduced chest expansion and positive modified Schober test
  • Cervical kyphosis with loss of horizontal gaze, and atlantoaxial subluxation in some
  • Anterior uveitis, aortitis, conduction defects, apical pulmonary fibrosis and inflammatory bowel disease

Investigations

Ankylosing Spondylitis, radiograph showing bamboo spine in ankylosing spondylitis
Radiograph showing bamboo spine in ankylosing spondylitis. Image by Stevenfruitsmaak, Wikimedia Commons, CC BY-SA 3.0.
  • Sacroiliitis is usually the earliest radiographic finding
  • Romanus lesions, shiny corners and vertebral squaring
  • Thin marginal syndesmophytes progressing to bamboo spine
  • Dagger sign and trolley track sign

Management

  • Treat neck pain after trauma as a fracture until proven otherwise
  • Fractures cluster at the cervicothoracic junction, through all three columns
  • Whole spine CT, and MRI for epidural haematoma
  • Immobilise in pre-injury kyphosis, avoiding flat boards and standard collars
  • Long-segment posterior instrumentation, as anterior fixation alone has a high failure rate
  • Halo vest is poorly tolerated
  • Chin on chest deformity is measured by chin brow vertical angle with hips and knees extended
  • Correct hip flexion contractures first
  • Simmons C7 to T1 extension osteotomy, now often C7 pedicle subtraction with neuromonitoring
  • C7 is chosen as the vertebral artery enters at C6, the canal is wide and C8 loss is tolerated
  • Leave slight residual flexion to see the ground

Complications

  • C8 radiculopathy
  • Cord injury and quadriplegia
  • Subluxation at the osteotomy and non-union

Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 10 October 2026.