Osteoarthritis

Question 1

How common is it?

Answer 1

Estimated it causes joint pain in 8.5 million people in the UK (13%)

Question 2

Who does it affect?

Answer 2

The prevalence of osteoarthritis of the knee, hip and hand increase with age. Most people with it are past working age (but a lot aren’t). The prevalence of radiographic osteoarthritis is higher in women than men. The difference is most marked after 50 years of age and for hand and knee arthritis.

Question 3

What causes it?

Answer 3

In synovial joints, a variety of minor incidental traumas and abnormal biomechanics can trigger repair processes.

All the joint tissues (cartilage, bone, capsule) take part in repair

Repair often results in a structurally altered but symptom free joint

In some people the repair process cannot fully compensate for traumatic damage, and symptomatic osteoarthritis can occur.

Genetic factors are important in determining the outcome of the repair process

Question 4

What risk factors are there?

Answer 4

Genetic factors: Heritability estimates for hand, knee, and hip osteoarthritis are high; around 40-60%. The responsible genes are largely unknown.

Constitutional factors: Ageing, female sex, obesity, high bone density (risk for developing it)., low bone density (risk factor for progression of knee and hip osteoarthritis).

Local, largely biomechanical risk factors: Joint injury, occupational and recreational stresses on joints, reduced muscle strength, joint laxity, joint malalignment.

Question 5

How does it present?

Answer 5

Older than 45 with the following symptoms:

• Affected joints are painful when used – the person may have pain at rest, crepitus, or a limited range of movement
• Affected joints become stiff after resting
• There are no obvious signs of inflammation, such as prolonged morning stiffness, a large effusion, or hot joint.

Question 6

Signs on examination?

Answer 6

Gelling- pain and stiffness caused by inactivity. When activity resumes, the pain and stiffness resolve more quickly that with inflammatory types of arthritis (i.e. within 30 minutes). 
Bony swellings and joint deformities
crepitus
restricted range of joint movement
joint tenderness
muscle wasting and weakness
joint effusions (uncommon except for the knee)
warmth and instability. 

Usually only one or a few joints are problematic at any one time. Its uncommon before middle age.

Question 7

Investigations

Answer 7

A working diagnosis can be made without radiological or laboratory investigations. But typical radiological features of an osteoarthritic joint are: loss of joint space, osteophytes, subchondral bone thickening and/or cysts.

Question 8

Treatment

Answer 8

Physio to strengthen surrounding muscle can help.
Painkillers such as paracetamol, NSAIDs, and opioids if it gets very bad (codeine first).
Topical capsaicin can be considered for hand or knee arthritis.
Intra-articular corticosteroids.
Finally, surgery, most commonly for the knee or hip.

Question 9

Conditions that would present similarly

Answer 9

Inflammatory arthritis: Suspect if stiffness lasts longer than 30 minutes, pain is worse at night, or stiffness and pain are relieved by activity and metacarpophalangeal (MCP0, wrist, elbow or ankle joints are involved. Consider: Rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, gout, pseudo gout, reactive arthritis, arthritis associated with connective tissue disorders such as SLE.

Fibromyalgia.

Septic arthritis.

Fracture of bone adjacent to joint, major ligamentous injury (recent + old injuries).

Bursitis.

Cancer.