A 56-year-old man presents with a hot, swollen knee and severe pain on weight-bearing. He has a temperature of 38.3°C and is unable to move the joint. There is no history of trauma or gout. What is the most appropriate next step?AStart oral NSAIDs and review in 1 weekBArrange outpatient MRICUrgent joint aspiration and IV antibiotics after cultures, with orthopaedic reviewDStart high-dose oral prednisolone and defer investigationsEApply ice and elevate onlyCheck my answer