Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory disease primarily affecting the axial skeleton, including the spine and sacroiliac joints. Characterized by the formation of syndesmophytes, it can lead to a rigid, fused spine, a condition known as "bamboo spine." AS is part of a group of diseases known as spondyloarthritis, which share common genetic and clinical features. The etiology of AS is complex, with genetic factors playing a crucial role, the most notable being the association with HLA-B27 antigen. The inflammation primarily begins at the entheses, where tendons and ligaments attach to bone, causing pain and stiffness that typically worsens with inactivity and improves with exercise.

Clinical manifestations of AS include chronic back pain, morning stiffness, and impaired spinal mobility, which can progress over years. Extra-articular features like uveitis, psoriasis, and inflammatory bowel disease may co-occur. Diagnosis is based on clinical criteria and imaging findings, with radiography and MRI being instrumental in detecting characteristic changes. There is no cure for AS, but treatment focuses on managing symptoms and maintaining functionality. Nonsteroidal anti-inflammatory drugs (NSAIDs) are first-line treatments; however, disease-modifying therapies, such as TNF inhibitors and IL-17 inhibitors, are indicated for more severe or refractory cases to slow disease progression and improve quality of life.