Ultrasound in finger joints: Findings in normal subjects and pitfalls in the diagnosis of synovial disease

Purpose: Grey-scale ultrasound may be used to visualise the amount of synovial tissue in patients with rheumatoid arthritis (RA). Different scoring systems have been developed. None of the scoring systems have been tested on a larger group of healthy joints, and it is therefore unknown to what extent synovial tissue is seen on grey-scale ultrasound in healthy joints. The objective of this study was to test two scoring systems on healthy volunteers. Materials and Methods: 24 healthy men and women between 30 and 54 years underwent scanning of the MCP, PIP and DIP joints of their dominant hand. Each person was scanned in 69 positions. The images were graded on a scale from 0 to 4 with two scoring systems (I and 11). Scores 0 - 1 were defined as normal and 2 - 4 as pathological. With scoring system 1, only markedly hypoechoic synoviurn was graded. With scoring system 11, marked hypoechogenicity was not a criterion. Results: With system 1, 89% of the joints obtained at least one pathological score. With system 11, 95 % of the joints obtained at least one pathological score. With both systems, women obtained higher scores than men, and the number of high scores increased with increasing age. Conclusion: An unacceptably high number of joints obtained pathological scores with both scoring systems in healthy volunteers. This indicates that many of the scores interpreted as pathological in patients with RA may just be normal findings, with increasing numbers in older patients.