Background/Purpose: Ultrasonography (US) has been increasingly utilized for the assessment of various musculoskeletal conditions. However, the value of this tool in diagnosis of osteoarthritis (OA) in clinical practice remains unclear. This study was to 1) to characterize ultrasonographic features of knee OA and their relationship with pain and functional levels and 2) to determine the degree of correlation and agreement between the US and conventional radiography in the assessment of knee OA.

Methods: A cross sectional study was carried out on 145 patients (83.4 % female), aged 40 years or older, with mean age of 61.7 years, and clinically diagnosed with primary knee OA, at the outpatient Rheumatology Clinic, Cho Ray Hospital in the period between August 2018 and August 2019. Patients with concomitant inflammatory joint diseases were excluded. All subjects were clinically assessed for pain using a visual analog scale (VAS) and functional status using the Western Ontario and McMaster Universities Arthritis Index (WOMAC), and underwent knee radiography and US examination. Correlation between ultrasonographic findings and clinical and radiographic features was investigated.

Results: A total of 290 knee joints were evaluated. The most common findings on the US were reduced cartilage thickness (74.5%), osteophytes (66.9%), effusion (55.9%), medial meniscal extrusion (78.6%), lateral meniscal extrusion (39.3%), thickened synovial membrane (17.2%) and Baker’s cyst (15.2%). The VAS and WOMAC pain scores correlated positively with the level of effusion and the osteophyte size, and negatively with the medial femoral cartilage thickness measured on the US. There was a positive correlation between the sonographic medial cartilage thickness and the radiographic medial joint space width (r_s = 0.3, p < 0.01), and between sonographic and radiographic osteophyte grades (r_s = 0.69, p < 0.01 and r_s = 0.47, p < 0.01 for medial and lateral joint space, respectively). Osteophytes were found on both US and radiography in 129 (44.5%) knees, only the US in 44 (34.1%) knees, and only radiography in 17 (13.2%) knees (Kappa = 0.58; p < 0.01).

Conclusion: These results support the validity of US in the assessment of knee OA lesions in comparison to conventional radiography. Moreover, US appears to be more sensitive than radiophraphy in detecting early changes of knee OA such as cartilage damage and mild osteophytes

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ultrasonographic-assessment-of-knee-osteoarthritis-and-its-agreement-with-radiography/