A 77 year old man presents with painful swelling of his left knee of 2 days duration. No other joints are affected and this is his first such episode.
He is afebrile but feels unwell. There is no history of trauma, knee surgery or a bleeding disorder and he denies respiratory, urinary or GI symptoms.
His comorbidities are osteoarthritis of both knees for 12 years and diabetes for 10 years. He is only on Metformin.