19th January 2024

A 34-year-old female presents to ED with an acutely swollen right knee.

A 34-year-old female presents to ED with an acutely swollen right knee. She has a past medical history of COPD and depression, and is not on any regular medication. On examination, she is afebrile, and has a tender and warm right knee with limited flexion, but no crepitus. She admits to having multiple sexual partners and occasionally has had unprotected sexual intercourse. She has also noticed purulent urethral discharge over the past 3 weeks.

A joint fluid analysis is carried out, which reveals the following:

Colour: Yellow 

White cell count: 4000 cells/mm3

Viscosity: decreased 

Neutrophils: 50%

Crystals: pending 

Gram stain: pending 

What is the most likely diagnosis?

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