Radiological images are shadows of reality

442 Freely available online open Access bJr radiological imaging is the bedrock of investigations in the management of patients with orthopaedic disorders. Articles in this journal show a particular interest in the state of the articular cartilage: assessed in this month's issue by narrowing of the joint space 1 and in July's issue, by signal changes on mrI. 2 the problem arises, however, in how we define 'normal' and 'abnormal'; especially what is normal ageing and what is osteoarthritis? pinsornsak et al 1 aimed to improve the assessment of joint space narrowing seen on plain knee radiographs in the management of patients presenting with painful knees. they correctly state that the decision for an operation requires consideration of both the symptoms of pain, and evidence of significant joint space narrowing on the radiograph. It should be noted that the American College of Rheumatology define osteoarthritis (if radio-graphs are available) as pain arising from the knee on most days in the previous month, crepitus on active movement, morning stiffness for less than 30 minutes, age over 50 years, and osteophytes on radiographs. 3 the points to note are firstly that the pain must arise from the knee joint, yet knee pain may be referred from the hip or back; and secondly , the key radiographic finding is osteo-phytes not joint space narrowing. Any bearing surface will wear over time, so joint space narrow on its own may be due to normal ageing and may not be a sign of osteoar-thritis. A further problem arises in that even if the plain radiograph shows severe degenera-tion, it is not possible to say whether the patient experiences pain or not. It therefore follows that the cause of the pain is not from any effect of the articular cartilage loss, or osteophytes, as seen on the plain radiograph. An excellent example of this is often seen in isolated patellofemoral degenerative changes which are found independently of any symptoms. In my opinion, for a patient to have a diagnosis of osteoarthritis of the knee, and to consider surgery, there must be a history of effusions, or an effusion present. this implies articular cartilage damage has resulted in the production of wear particles which have been taken up by the synovium and created an inflammatory response. If I see a patient with anterior knee pain, and bone-on-bone changes in the patellofemoral joint, no history of effusions and …