The Difference in Supine versus Standing Plain Radiograph of the Knee in Patients with Knee Osteoarthritis

Knee osteoarthritis is a degenerative joint disease attributed to failure in joint repair process. Key aspect of the diagnosis relies on thorough history, along with physical examination and radiology findings. The conventional weight-bearing plain radiograph remains the key modality to determine the severity of the condition and helps to plan the surgery. Nevertheless, not all patients can undergo weight-bearing plain radiographs, especially those who are wheelchair-bound or have severe deformities. The purpose of this study is to investigate whether a weight-bearing plain radiograph of the knee is essential in all patients with knee osteoarthritis.

A prospective cohort study on patients with knee osteoarthritis receiving treatment in a single tertiary hospital was conducted. All patients consented to participate in this study. Patients were assessed functionally with the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) and radiologically with plain radiographs. Patients were subjected to undergo both supine and standing plain radiographs of the knee in the same setting for comparison purposes where measurement is done following patient functional outcome and radiological measurement for the patient.

Our study shows that reduction in joint space is more obvious in weight-bearing radiographs, however in severe or higher-grade osteoarthritis, a supine radiograph is adequate to diagnose knee osteoarthritis.

Standing radiograph of the knee is preferred to a supine knee radiograph wherever possible due to the additional value it brings, however, in certain patient conditions, a supine radiograph is still acceptable.