8th September 2020

A 64-year old lady presents with acute, severe constant pain in her left knee

A 64-year old lady presents with acute, severe constant pain in her left knee. She recalls tripping over and injuring her left knee 3 days ago but experienced no pain after the incident until now. She has never experienced this pain before. She is usually fit and well and does not suffer from any medical disorders. Physical examination reveals a tender, swollen left knee joint with reduced range of movements. All of her basic observations are normal. An X-ray of her joint is performed which rules out fractures and major degenerative abnormalities. Synovial fluid analysis viewed under polarised light shows positively birefringent rhomboid-shaped crystals.

For the patient above, please select the SINGLE most likely diagnosis. Select ONE option from the list above.