Ankylosing spondylitis

Ankylosing spondylitis is a chronic inflammatory arthritis that primarily targets the spine and sacroiliac joints — the joints connecting the base of the spine to the pelvis. Over time, inflammation triggers new bone formation that bridges vertebral gaps, fusing sections of the spine into a rigid, inflexible structure. When the rib cage is involved, breathing depth decreases.

The exact cause is unknown, but the HLA-B27 gene is strongly associated with the condition — most people with ankylosing spondylitis carry this gene, though not everyone who has it develops the disease. Men are affected more than women; onset typically occurs in late adolescence or early adulthood.

**Commonly affected areas:** - Sacroiliac joint (between the spine base and pelvis) - Lumbar vertebrae - Entheses — attachment points of tendons and ligaments to bone, especially along the spine and back of the heel - Costochondral junctions (breastbone–rib cartilage) - Hip and shoulder joints

**Symptoms** begin as pain and morning stiffness in the lower back and hips that improves with movement and worsens with rest. Neck pain and fatigue are common. Over time, spinal rigidity develops and posture changes.

**Complications** in severe disease include: - Spinal fusion causing a permanently stooped posture - Reduced lung capacity from rib cage stiffening - Uveitis (eye inflammation) — rapid-onset eye pain, light sensitivity, and blurred vision requiring urgent treatment - Vertebral compression fractures due to bone weakening - Aortic valve involvement (enlarged inflamed aorta)

Treatment is most effective before irreversible joint damage occurs. Goals are pain relief, stiffness reduction, posture preservation, and slowing progression.