Comparison of X-rays and magnetic resonance imaging in the definition of tibiofemoral joint osteoarthritis

Abstract

Purpose: The aim of this study was to compare knee cartilage volume with radiological grade of joint space narrowing (JSN) in the tibiofemoral joint.Methods: The magnetic resonance imaging (MRI) determined cartilage volume was compared to the radiological JSN grade in 35 consecutive subjects (mean age 66.3±8.6 years, females 66%) participating in an intervention study of osteoarthritis.Results: A linear association was observed between the crude cartilage volume and the grading of JSN in the medial (r=−0.54, P=0.001) and lateral tibiofemoral joint (r=−0.67, P<0.001). When adjustment was made for bone size, the correlation with radiology was r=−0.77, (P<0.001) for the medial tibiofemoral cartilage and r=−0.67 (P<0.001) for the lateral tibiofemoral cartilage. A cartilage volume index of <20 discriminated between those with no, or minimal, JSN (grade 0 or 1) and those with moderate or severe JSN (grade 2 or 3) in both tibiofemoral joints.Conclusions: Cartilage volume correlates well with radiological grading of JSN. The cartilage volume adjusted for bone size discriminates between those with minimal or no JSN and those with moderate to severe JSN. Whether changes in this index will be useful for assessing disease progression in osteoarthritis (OA) will need to be determined in longitudinal studies.