Imaging in osteoarthritis: a guide to requesting plain X-rays of the degenerate knee

Plain radiography is the most important primary investigation in the diagnosis and assessment of osteoarthritis of the knee and it is perhaps surprising that a recent survey of practice amongst the British Orthopaedic community has revealed wide variations in the radiographs requested. The study identified that many surgeons continue to request non-weight bearing X-ray examinations and that the patellofemoral joint was rarely adequately assessed. There seems to remain some uncertainty as to the X-ray series of choice, resulting in potentially missed pathology and making scientific comparison of data from different units impossible. Standardised techniques would clearly be desirable and this article aims to review the evidence to date.