Imaging and investigations
If plain radiographs of the knee are to be obtained these should include AP, lateral and skyline projections. Wherever possible, all AP and lateral images should be obtained in weight bearing. This must be requested at the time of referral for radiograph investigation.
If an effusion is present, particularly in the absence of trauma, then a CRP blood test should be taken to help assess for a potential inflammatory arthropathy. If the CRP is raised and this relates to a known existing inflammatory disorder continue to treat and monitor this in the usual way in accordance with the patient’s usual management plan for that condition.
If CRP is raised for the first time consider whether this could be a new inflammatory arthropathy and discuss with a rheumatologist / or make a rheumatology referral. Or consider repeating the test.