Spondylitis is a general term for a type of arthritis that causes inflammation in the joints of the spine and sometimes other parts of the body. It is also referred to as a spondyloarthritis. The inflammation can lead to severe pain and stiffness and, in advanced cases, new bone formation that can cause the vertebrae to fuse together.

The most common and severe form of spondylitis is Ankylosing Spondylitis (AS), also known as axial spondyloarthritis.

Key Characteristics of Spondylitis (Ankylosing Spondylitis):

Inflammatory Nature: Unlike mechanical back pain (e.g., from a pulled muscle), the pain from spondylitis is inflammatory. It tends to be worse after periods of rest, especially in the morning or during the night, and often improves with exercise and activity.

Primary Location: It typically affects the joints in the lower back, particularly the sacroiliac joints (where the spine connects to the pelvis). Over time, the inflammation can spread up the spine to the neck.

Chronic Condition: Spondylitis is a long-term, chronic disease with no cure, but treatments can help manage symptoms and slow its progression.

Genetic Link: The exact cause is unknown, but a strong genetic link exists, particularly with the HLA-B27 gene. Most people with AS have this gene, but not everyone with the gene develops the condition.

Early Onset: Symptoms often begin in late adolescence or early adulthood (typically before age 45). It affects men more than women.

Symptoms:

Chronic back pain and stiffness: Especially in the lower back and hips, and often worst in the morning or after being inactive.

Pain in other joints: Including the neck, shoulders, hips, knees, and heels.

Fatigue: A common and often debilitating symptom.

Inflammation of other body parts: Can include the eyes (uveitis/iritis), skin (psoriasis), or digestive tract (inflammatory bowel disease like Crohn's or colitis).

Stooped posture: A hunched-forward posture can develop as the spine becomes rigid and inflexible.

Limited chest expansion: If the joints between the ribs and spine are affected, it can make it difficult to breathe deeply.

Diagnosis:

Diagnosis can be challenging as symptoms can be mistaken for other conditions. It typically involves:

Physical exam and medical history.

Imaging: X-rays or MRI to look for inflammation and bone changes in the spine and sacroiliac joints.

Blood tests: To check for markers of inflammation (ESR, CRP) and for the presence of the HLA-B27 gene.