Correlation of knee ultrasonography and Western Ontario and McMaster University (WOMAC) osteoarthritis index in primary knee osteoarthritis

Abstract

BackgroundKnee osteoarthritis (KOA) is the most common cause of a painful joint, and it is associated with significant health economic consequences. About literature, KOA is usually diagnosed according to changes seen on conventional radiography, but the radiographic features of OA do not correlate with its symptoms. Nowadays, ultrasonography is becoming a non-invasive imaging tool for OA in the clinical setting. Thus, the purpose of this study was to evaluate the correlation between musculoskeletal ultrasound (MSK US) and the Western Ontario and McMaster University (WOMAC) osteoarthritis index findings in patients with primary knee osteoarthritis (KOA).MethodsBetween August 2015 and October 2017, 50 patients with a mean age of 46.72 ± 9.12 years who fulfilled the American College of Rheumatology (ACR) criteria for KOA were included. All the patients underwent a clinical assessment with the calculation of the WOMAC index, and they underwent knee US examination and conventional radiography (CR). Spearman’s rho was used to assess the association between MSK US findings and the WOMAC index.ResultsThe mean pain score was 10.08 ± 2.89, stiffness was 3.34 ± 1.72, physical function was 26.26 ± 9.6, and the total WOMAC score was 39.68 ± 12.83. Forty-seven knees showed radiographic femorotibial degenerative signs. The mean thicknesses of the ultrasound-measured articular cartilage of the medial condyle (MC), intercondylar notch area (IA), and lateral condyle (LC) were 0.23 ± 0.60 cm, 0.33 ± 0.69 cm, and 0.30 ± 0.81 cm, respectively. The US findings also included suprapatellar joint effusion (50%), medial meniscal extrusion (40%), and osteophytes (70%). A positive correlation was found between the mean articular cartilage thickness of the IA, mean pain score, and stiffness subclasses of the WOMAC score (r = 0.342, p = 0.015; r = 0.414, p = 0.003), respectively.ConclusionsThe severity of KOA, based on articular cartilage thickness, showed good correlation with the pain and stiffness subclasses of the WOMAC score.