Relationship between knee alignment and radiographic markers of osteoarthritis: a cross-sectional study from a Korean population

Abstract

Aim: The purpose of this paper was to investigate the relationship between static varus knee alignment and the radiographic markers of knee osteoarthritis (OA), including joint space narrowing (JSN) and Kellgren-Lawrence (K-L) grading scale. Method: Knee alignment was measured by mechanical axis from weight-bearing anteroposterior (AP) radiographs of 251 symptomatic knees with radiological signs of OA (K-L grade 1). Linear correlation between knee varus alignment and variables, including joint space width (JSW) and K-L grades of tibiofemoral (TF) joint in extension or 45 degrees flexion and patellofemoral (PF) joints were investigated. Multiple linear regression analyses were also performed to examine independent associations between varus knee alignment and JSW. Analysis of covariance (ancova) was performed to analyze the difference in knee alignment among K-L grade category groups adjusted for physical variables. Results: Varus knee alignment was negatively correlated with JSW of medial TF joint in extension AP (r=-0.460, P=0.0001) and 45 degrees flexion PA views (r=-0.476, P=0.0001) and PF JSN (r=-0.168, P=0.008). Multiple linear regression analysis adjusted for physical variables showed that the varus knee alignment was negatively associated with the JSW of medial TF joint in extension AP (P=0.0001) and 45 degrees flexion PA view (P=0.0001). ancova adjusted for physical variables showed that knees in K-L grade 4 had significantly greater varus alignment than those in K-L grades 1-3 in AP (P=0.0001), 45 degrees flexion PA view (P=0.0001), and PF joint (P=0.0001 similar to 0.001). Conclusion: Varus knee alignment is associated with the radiographic measures of knee OA severity.