Broad-Based Spondylitic Ridging: Ankylosis in DISH

Broad-based spondylitic ridging describes the characteristic radiographic appearance of flowing ossification along the anterolateral aspects of vertebral bodies in Diffuse Idiopathic Skeletal Hyperostosis (DISH) (Forestier's disease).

Radiographic Features

• Continuous, wave-like ossification along ≥4 contiguous vertebral bodies.
• Bridging osteophytes spanning disc spaces, preserving disc height (unlike ankylosing spondylitis).
• Involves both anterior and posterior longitudinal ligaments – "broad-based."
• Thoracic spine predominance (T7–T11); cervical and lumbar also affected.
• No sacroiliac joint fusion (distinguishes from AS).

Pathology

• Enthesopathy – ossification at ligament/tendon insertions (entheses).
• Not inflammatory; metabolic/mechanical drivers (insulin resistance, obesity, mechanical stress).

Clinical Correlates

• Thoracic stiffness, reduced spinal mobility.
• Dysphagia (anterior cervical osteophytes compress esophagus).
• Airway obstruction (rare, large cervical masses).
• Associated with metabolic syndrome, diabetes, hyperuricemia.

Differential

• Ankylosing spondylitis: syndesmophytes (thin, vertical), SI joint fusion, inflammatory back pain.
• Degenerative disc disease: osteophytes at disc margins, disc space narrowing, vacuum phenomenon.
• Osteoarthritis: facet hypertrophy, joint space narrowing.

DISH is often asymptomatic; diagnosis is radiographic. Management focuses on mobility, metabolic control, and complications (dysphagia, fracture risk).