Imaging of Musculoskeletal Disorders
Osteoarthritis

Key features of osteoarthritis

  • Joint space narrowing
  • Osteophytes
  • Articular irregularity and/or sclerosis
  • Sub-cortical cysts (geodes)
  • Intra-articular loose bodies
  • Note: Erosions are NOT a feature

Osteoarthritis can affect any synovial joint. The hands, wrists, hips, knees, and feet are most commonly involved.

Osteoarthritis results in characteristic X-ray appearances including joint space narrowing, formation of osteophytes (bone spurs), articular surface cortical irregularity and/or sclerosis, and formation of sub-cortical cysts (geodes).

These features can be seen in isolation but commonly two or more signs are present.

Note: Erosions are not a feature of osteoarthritis and if seen should raise the suspicion of an inflammatory arthritis such as rheumatoid arthritis.

Osteophytes - Knee

Hover on/off image to show/hide findings

Tap on/off image to show/hide findings

Click image to align with top of page

Osteophytes - Knee

  • The formation of osteophytes (bone spurs) is a common feature of osteoarthritis
  • This AP view of the knee shows osteophytes of the tibia and femur
  • Small osteophytes have also formed at the tibial spines (tibial spiking)
  • The knee joint spaces are narrowed and irregular
  • See an example of a normal knee X-ray

Joint space narrowing

Hover on/off image to show/hide findings

Tap on/off image to show/hide findings

Click image to align with top of page

Joint space narrowing

  • The medial side of the knee joint is severely narrowed such that the femur and tibia are touching
  • The lateral side of the joint is widened and there is abnormal (varus) angulation of the tibia
  • Increased density indicates articular surface sclerosis

Articular surface cortical irregularity and/or sclerosis

Hover on/off image to show/hide findings

Tap on/off image to show/hide findings

Click image to align with top of page

Articular surface cortical irregularity and/or sclerosis

  • The joint space is narrowed and the cortical surface is irregular
  • Increased density of the articular surface indicates sclerosis
  • Small sub-cortical cysts have formed

Sub-cortical cysts (geodes)

Hover on/off image to show/hide findings

Tap on/off image to show/hide findings

Click image to align with top of page

Sub-cortical cysts (geodes)

  • Although sub-cortical bone cysts are a characteristic finding of osteoarthritis, they are only visible in approximately one third of X-rays of osteoarthritic joints
  • This hip joint is narrowed and large osteophytes have formed
  • Note: These cysts may be called ‘sub-chondral cysts’, ‘sub-cortical cysts’, or 'geodes' – any of these terms are acceptable

Multiple osteoarthritic changes

Hover on/off image to show/hide findings

Tap on/off image to show/hide findings

Click image to align with top of page

Multiple osteoarthritic changes

  • Large osteophytes (arrowheads) have formed at the joints of the fingers
  • These osteophytes correspond to the clinical finding of bony swelling at the distal interphalangeal joints (Heberden’s nodes) and the proximal interphalangeal joints (Bouchard’s nodes)
  • The joints are severely narrowed (arrows)
  • Large sub-cortical cysts have also formed in this patient with severe osteoarthritis of the finger joints
  • The ring could no longer be removed

Intra-articular loose bodies

Hover on/off image to show/hide findings

Tap on/off image to show/hide findings

Click image to align with top of page

Intra-articular loose bodies

  • In some patients calcified loose bodies may be seen within an osteoarthritic joint
  • These are fragments of bone or cartilage which have detached from the joint surfaces and remain in the joint capsule
  • This lateral view of the knee also shows severe osteoarthritis of the patellofemoral joint which is very narrow
  • Note: Do not mistake a fabella for a loose body - see an example of a normal fabella

Page author: Salisbury NHS Foundation Trust UK (Read bio)

Page edited by: Dr Richard Smith BSc MSc MBBS FRCP PGDip - Consultant Rheumatologist (Read bio)

Last reviewed: January 2020