A 67-year-old with rheumatoid arthritis on biologic therapy presents with an acutely swollen knee and fever. Temperature is 38.8°C, CRP is 180 mg/L,

Question

A 67-year-old with rheumatoid arthritis on biologic therapy presents with an acutely swollen knee and fever. Temperature is 38.8°C, CRP is 180 mg/L, and radiograph shows no fracture. The joint is very painful through passive range. What is the most appropriate investigation?

Accepted Answer

Urgent arthrocentesis for synovial fluid analysis before antibiotics if feasible

Answer

D-dimer to exclude septic arthritis

Answer

MRI before any joint sampling

Answer

Serum uric acid as definitive test

Answer

Bone scan as first-line ED investigation

Septic arthritis — RCPSC EM MCQ

A 67-year-old with rheumatoid arthritis on biologic therapy presents with an acutely swollen knee and fever. Temperature is 38.8°C, CRP is 180 mg/L, and radiograph shows no fracture. The joint is very painful through passive range. What is the most appropriate investigation?