Inter- and intra-observer reliability of radiological grading systems for knee osteoarthritis

Introduction Radiographs are the first-line investigation for knee osteoarthritis (OA). Antero-posterior (AP) and Rosenberg views have demonstrated varying sensitivities in detecting severe OA. There is a multitude of radiological grading systems described. The aim of this study was to assess four commonly used grading systems in terms of inter- and intra-observer reliability and correlate the results with patient-reported symptom severity. Materials and methods This study included 100 patients who had undergone both AP and Rosenberg X-ray views of the knee and evaluated using four radiological grading systems. These included Kellgren & Lawrence (K&L), International Knee Documentation Committee (IKDC), Ahlbäck and Fairbank. Evaluations were performed by two observers, independently, at two separate time points, 8 weeks apart. The data was then statistically analysed and inter- and intra-observer reliability calculated. Results A significant difference was found between AP and Rosenberg views for all four grading systems ( p