History A 75-year-old man has presented to the emergency department with severe pain in his knee. This started two days ago and he is now unable to walk. He has a history of hypertension and heart failure for which he has been taking lisinopril, bisoprolol, aspirin, simvastatin and bendroflumethiazide. Recently furosemide was added to his treatment because of increasing ankle oedema. Examination This elderly man’s left knee is swollen with evidence of an effusion, and it is erythematous and tender to the touch and painful on any movement. No other joints are affected.
There is no skin rash. A sample of fluid aspirated from the knee is initially bloodstained; then straw-coloured turbid fluid is obtained. Observations: temperature 37.9°C, blood pressure 142/86 mmHg, heart rate of 76/min, respiratory rate 18/min. A knee X-ray reveals no bony abnormalities. Investigations: Synovial fluid: …
