12 Types of Arthritis and How They Differ

4. Ankylosing Spondylitis - The Spine's Silent Stiffener

Ankylosing spondylitis primarily affects the spine and sacroiliac joints, causing inflammation that can eventually lead to fusion of vertebrae and significant spinal rigidity. This chronic inflammatory condition typically begins in early adulthood, with men being affected more frequently than women, though recent research suggests the gender gap may be narrower than previously thought. The hallmark symptom is inflammatory back pain that improves with exercise and worsens with rest, often causing patients to wake up in the early morning hours due to stiffness and discomfort. Unlike mechanical back pain from injury or degenerative changes, ankylosing spondylitis pain is typically worse in the morning and after periods of inactivity, improving throughout the day with movement. The condition has a strong genetic component, with over 90% of patients carrying the HLA-B27 gene, though having this gene doesn't guarantee development of the disease. As the condition progresses, inflammation can cause the formation of syndesmophytes, bony growths that bridge vertebrae, potentially leading to a completely fused spine known as "bamboo spine." Extra-articular manifestations include acute anterior uveitis (eye inflammation), inflammatory bowel disease, and cardiovascular complications. Early diagnosis and treatment with anti-TNF biologics or IL-17 inhibitors can significantly slow disease progression and maintain spinal mobility, emphasizing the importance of recognizing symptoms in young adults with chronic back pain.