Ultrasound-Based Knee Osteoarthritis Severity Assessment and Its Association With Kellgren-Lawrence Grading

Kellgren-Lawrence (KL) grading is a conventional radiography (CR)-based system commonly used to assess osteoarthritis (OA). Knee OA is characterized by damage to the femoral cartilage (FC); however, CR cannot directly visualize cartilage integrity. Ultrasound (US) may be superior in detecting FC damage. This study is aimed at evaluating the US-based knee OA severity assessment and analyze its association with KL grading.

This was an analytical observational study with a cross-sectional design which included knee OA patients. All participants underwent knee US scanning by two independent raters. The severity of knee OA was assessed based on three parameters: the contour of the femoral cartilage, the presence of osteophytes, and meniscus protrusion. The results were accumulated and interpreted into grades from 0 to 4. Association between US-based knee OA assessment and KL grading was analyzed statistically.

A total of 112 knee OA patients were included in this study. The average age of participants was 61.4 years, with a higher female prevalence. Grade 3 was the most frequently recorded in both US and KL grades. The US interpretation from both raters showed a perfect agreement based on weighted kappa analysis (κ = 1.00). A chi-square test showed a significant association between the US and KL grade (p < 0.001), with a very strong association based on the Cramér's V test of 0.742 (95% CI: 0.599-0.824).

This study demonstrates the US-based knee OA severity assessment and was associated with KL grade.