22. Imaging of degenerative joint diseases.

Osteoarthritis (OA), also called degenerative joint disease, is a common chronic disorder characterised by degeneration of the articular cartilage in the joint, causing friction and inflammation between bones. It's the most common type of arthritis. It usually affects weight-bearing joints like the knees, hips, feet, as well as joints of the spine and hands. It's a progressive disease.

Imaging

Radiography is the gold standard imaging modality for evaluation of OA. In case of OA, the following findings are typical:

• Joint space narrowing
  • Hyaline cartilage is translucent on x-ray, making it look like there is a space between the joint
  • When there is loss of hyaline cartilage it looks like the joint “space” becomes smaller
• Subchondral sclerosis
• Subchondral cysts
• Osteophytes

However, many of the above findings are present in asymptomatic people, and many people with clinically certain OA have few findings on imaging. In other words, the severity of the x-ray findings do not correlate with the severity of the symptoms. It is therefore important to focus on the clinical findings for the diagnosis. Imaging may be used for follow-up or to rule out differential diagnoses.