Osteoarthritis (OA) is a degenerative joint disease that primarily affects the cartilage that covers the ends of bones where they meet to form a joint. The imaging signs of OA vary depending on the stage and severity of the disease. The most common imaging modalities used to diagnose and evaluate OA are X-rays, magnetic resonance imaging (MRI), and computed tomography (CT) scans.
X-rays are often the first imaging test performed to evaluate OA. Typical imaging signs seen on X-rays include:
- Joint space narrowing: As the cartilage wears away, the space between the bones in the joint becomes smaller.
- Osteophytes: Also known as bone spurs, these are bony projections that develop at the edges of the joint.
- Sclerosis: Hardening of the bone around the joint due to the increased stress on the joint.
- Subchondral cysts: Fluid-filled sacs that develop in the bone beneath the cartilage.
- Deformities: Changes in the shape of the bone around the joint.
MRI is a more sensitive imaging test than X-rays and can detect early signs of OA. Common imaging signs seen on MRI include:
- Cartilage loss: A thinning or loss of the cartilage covering the bone ends in the joint.
- Bone marrow edema: Swelling or inflammation in the bone caused by increased stress on the joint.
- Synovitis: Inflammation of the joint lining.
- Ligament and tendon tears: Damage to the tissues that support the joint.
CT scans are less commonly used for diagnosing OA, but they can provide a detailed view of the bones and joints. CT scans can show bone spurs, joint space narrowing, and other changes in the bone around the joint.
