26th January 2024

A 58-year-old male presents to A&E with right knee swelling and pain.

A 58-year-old male presents to A&E with right knee swelling and pain. He was diagnosed with OA of the right knee last year, following which he was advised treatment with paracetamol and topical ibuprofen gel, which he felt had managed his condition well. Over the past few days, however, he has developed increasing pain, tenderness and swelling of the right knee. He also felt generally unwell with fatigue and chills. He cannot remember any history of trauma to the knee. He has a past medical history of hypertension, type 2 diabetes, and COPD. Examination revealed a warm, swollen and erythematous right knee.

Which investigation would be most sensitive in identifying the likely diagnosis in this scenario?

Select the SINGLE most appropriate option from the list below. Select ONE option only.