Osteoarthritis

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.

This article explains osteoarthritis in general. For details on the symptoms and managment of osteoarthritis for each type of joint, see wrist osteoarthritis, osteoarthritis of the fingers, hip osteoarthritis, knee osteoarthritis, and elbow osteoarthritis.

Etiology

• Prearthritic conditions
• Old age
• Overweight
• Excessive joint loading

Pathomechanism

Stress -> cartilage damage -> cartilage degeneration -> loss of joint space and bony surface -> subchondral bone becomes sclerotic

Clinical features

• Pain and stiffness
  • Patient can hardly move joint in the morning
  • Patient needs a certain time to get the joint mobile and for the pain to disappear
    • As the osteoarthritis progresses this takes longer and longer time
  • Stiffness and pain return in the evening
    • As the osteoarthritis progresses the stiffness and pain return earlier and earlier in the evening
  • The symptom-free period during the day becomes smaller and smaller as the disease progresses
• Limited ROM (contractures)
  • Occurs in any arthritis
  • Is more and more limited as the disease progresses
• Swelling
  • Due to osteophytes and free fluid
  • When the synovial membrane gets irritated due to osteoarthritis it starts to produce too much fluid -> fluid can’t drain anywhere -> swelling

Diagnosis and evaluation

No laboratory test is available for OA. The diagnosis is made based on typical clinical findings.

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.

Treatment

• NSAIDs – for pain
• Joint replacement
  • See the articles for joint-specific osteoarthritis for details