Correlation of tibiofemoral joint-space width with the clinico-radiological scoring of knee osteoarthritis - a comparison between anteroposterior and lyon-schuss radiographic views

Background: The degree of joint space narrowing measured on radiographs provide a reliable estimate of the extent and severity of Osteoarthritis (OA) of the knee. While the standing antero-posterior (AP) view radiographs have been used traditionally, recent studies suggest that the Lyon-Schuss (LS) view is able to detect early OA changes better. The present study was, therefore, conducted to make an objective comparison between the two views with respect to their corelation with the patient's clinical and radiological scores. Methods: Forty patients (80 knees) were included in this cross-sectional study. Medial as well as lateral tibiofemoral joint space widths (JSW) were measured using vernier callipers on printed, calibrated radiographic images. Knee Society Score (Function) (KSS-F) was used as the clinical outcome measure while Ahlback grade was used for determining radiological severity. JSW was correlated with KSS-F and the Ahlback grade using Spearman's rho correlation coefficient. Reproducibility of the method was assessed using the intra-class correlation coefficient (ICC). Results: Average age of the participants was 60 +/- 7.65 (range 50-78) years, with 18 males and 22 females. ICC for intraobserver reliability was 0.97 and for inter-observer reliability, was 0.91 (AP view) and 0.92 (LS view), respectively. Medial JSW measurements taken on the AP view were found to have a significantly higher degree of correlation with both KSS-F and Ahlback grade (p <0.05) than those obtained from the LS view. Conclusion: Although the LS view may be more sensitive for detecting early OA changes in knee, particularly in the lateral tibiofemoral compartment, the present study shows that AP view correlates better with the patient's overall clinical and radiological profile.