Overview
Ankylosing spondylitis is an inflammatory condition primarily affecting the spine and sacroiliac joints. Chronic inflammation can lead to new bone formation and fusion of vertebrae, reducing spinal flexibility.

Causes and risk factors
Genetic factors (such as HLA‑B27) increase risk, though not everyone with the gene develops the condition. Symptoms often begin in late adolescence or early adulthood.

Symptoms
Chronic low back pain and stiffness that improves with activity, not rest; morning stiffness; fatigue; and possible eye inflammation (uveitis). Some people experience peripheral joint or tendon pain.

Diagnosis
Diagnosis involves clinical assessment, imaging (X‑ray or MRI of sacroiliac joints), and lab tests for inflammation and genetic markers.

Treatment
Treatment includes NSAIDs, physical therapy, and in more severe cases, biologic medications that target inflammatory pathways. Posture and flexibility exercises are central to care.

Complications
Possible complications include spinal fusion, reduced chest expansion, eye inflammation, and increased fracture risk.

When to seek care
Persistent inflammatory back pain, morning stiffness, or eye symptoms should prompt medical evaluation.