To investigate the reliability of ultrasonographic assessment of osteophytes and explore the concordance of osteophytes detected by ultrasound, MRI, conventional radiography (CR) and clinical joint examination in patients with hand osteoarthritis (HOA). The study included 127 HOA patients (116 women, mean age 68.6 years (SD 5.8)) with ultrasound, CR and clinical examination of both hands and MRI of dominant hand. Osteophytes were assessed by all imaging modalities on 0-3 scales, whereas clinical bony enlargement was assessed as absent/present. An ultrasound atlas of ostephytes was developed, and the intra and inter-reader reliability of scoring ultrasound osteophytes on still images using the atlas as reference was examined. The reliability for ultrasound readings was examined with κ and percentage exact agreement (PEA) and percentage close agreement (PCA), and the sensitivity, specificity and PEA/PCA of ultrasound was calculated in comparison with MRI, CR and clinical examination. Ultrasound had high sensitivity (0.83) and specificity (0.75) in detecting osteophytes compared with MRI, with excellent PCA (96.1%). Moderate/large osteophytes (grade 2-3) were demonstrated more often by ultrasound (n=401) than by MRI (n=288) in 851 interphalangeal joints. Ultrasound detected more osteophytes (53.2%) than CR (30.0%) and clinical examination (36.9%). Intra and inter-reader reliability of ultrasound was excellent (PEA >88%, PCA 100% and weighted kappa >0.91). Ultrasound can reliably assess osteophytes in patients with HOA. Good agreement was found between osteophytes detected by ultrasound and MRI, while ultrasound was more sensitive than CR and clinical examination, which could be due to a multiplanar joint demonstration by ultrasound.
