MSK and Rheumatology

Question 1

Gout vs pseudogout differentiation?

Answer 1

Pseudogout:
-knee, wrist and shoulders most commonly affected
-joint aspiration: weakly-positively birefringent rhomboid-shaped crystals
-x-ray: chondrocalcinosis
in the knee this can be seen as linear calcifications of the meniscus and articular cartilage

Gout:
Gout crystals are negatively birefringent

Question 2

Osteomalacia bloods profile?

Answer 2

low vitamin D levels
low calcium, phosphate (in around 30%)
raised ALP (in 95-100% of patients)

Question 3

Osteomalacia features?

Answer 3

bone pain
bone/muscle tenderness
fractures: especially femoral neck
proximal myopathy: may lead to a waddling gait

Question 4

Bone pain, tenderness and proximal myopathy (→ waddling gait) indicates?

Answer 4

Osteomalacia

Question 5

Abs present in RA?

Answer 5

Anti-cyclic citrullinated peptide antibodies are associated with rheumatoid arthritis (anti-CCP)

Question 6

Abs in SLE?

Answer 6

99% are ANA positive
this high sensitivity makes it a useful rule out test, but it has low specificity

20% are rheumatoid factor positive

anti-dsDNA: highly specific (> 99%), but less sensitive (70%)

Question 7

Ankylosing spondylitis exam findings?

Answer 7

Clinical findings in anylosing spondylitis include reduced chest expansion, reduced lateral flexion and reduced forward flexion (Schober’s test)

Question 8

What drug combination causes severe pancytopenia?

Answer 8

Methotrexate + trimethoprim (co-trimoxazole)