Approach - Joint pain

Question 1

What are the (3) types of joint disorders?

Answer 1

•Disorders of the cartilage
–eg osteoarthritis
•Disorders of the synovial membrane
–eg rheumatoid arthritis
•Disorders of the synovial fluid
–eg gout, septic arthritis

Question 2

(3) findings of OA on XR

Answer 2

1. osteophytes
2. Reduced joint space
3. Sclerosis of subchondral bone

Question 3

A 32yo female, 6 wks of gradually worsening pain & stiffness in joints of hands, wrist & feet. Worse in the morning for several hours & improves a little after lunch time. FMHx of RA. 5-10cigarettes per day, no rashes/bowel symptoms. Sleeping poorly & not coping. Previously well.

(4) DDx? Ix?

Answer 3

–Rheumatoid arthritis
–Systemic lupus erythematosus
–Viral arthritis (parvovirus, Ross River Virus etc)
–Psoriatic arthritis

Ix:
•FBE 
•ESR 
•Rheumatoid factor 
•CCP antibody 
•ANA 
•CUE, LFTs 
•CRP

Question 4

Sensitivity & specificity of rheumatoid factor in RA

Answer 4

• Sensitivity – 70%

* Specificity – 80%

Question 5

Sensitivity & specificity of CCP antibodies in RA

Answer 5

• Sensitivity – 70%
• Specificity – 90%

I.e. same specificity as rheumatoid factor but more specific.

Question 6

How do you diagnose RA?

Answer 6

ACR 1987 Classification criteria for rheumatoid arthritis

Patients must have 4 of 7 criteria:
•Morning stiffness of greater than 1 hour*
•Swelling in 3 or more joints*
•Swelling in hand joints*
•Symmetric joint swelling*
•Erosions or decalcification on X-ray
•Rheumatoid nodules
•Abnormal serum rheumatoid factor

• Must be present for at least 6 weeks