A 54-year-old man presents with an acutely swollen, hot, painful right knee and fever of 38.3°C. He has difficulty weight-bearing and flexion is severely limited. There is no history of trauma. What is the most appropriate next step?AStart oral Ibuprofen and review in 1 weekBArrange urgent joint aspiration and send synovial fluid for microscopy, culture, and sensitivityCOrder plain X-ray only and await resultsDStart high-dose oral Prednisolone immediatelyERefer to physiotherapy for early mobilisationCheck my answer