Ultrasound (US) is a highly sensitive, reliable and non-invasive tool, which allows for the assessment of lesions of tendons and entheseal sites. The aim of this systematic review and meta-analysis is to identify differences in US lesions of the Achilles tendon (AT) between people with inflammatory arthritis (IA) and healthy controls.
An electronic literature search was performed on Medline, CINAHL, SportDiscus and The Cochrane Library. Methodological quality was assessed using a modified Quality Index. Odds ratios with 95% confidence intervals (CI) were determined. Meta-analysis was conducted on those studies that were considered to be homogenous.
A total of 13 high-to-medium quality studies met the inclusion criteria. The majority of studies reported US lesions in spondyloarthropathy (SpA), with limited evidence for other forms of IA. US lesions were not consistently defined with regard to Outcome Measures in Rheumatology Clinical Trials (OMERACT) definitions, and numerous scoring systems were used across the majority of studies. The mean AT thickness at the enthesis in people with SpA was 0.54mm thicker (95% CI: 0.10-0.97mm) with more frequent erosions in people with SpA (odds ratio = 7.43, 95% CI: 1.99-27.77, P = 0.003) and rheumatoid arthritis (RA) (odds ratio = 9.60, 95% CI: 1.23-74.94, P = 0.03), compared to controls. There was no significant difference in the frequency of enthesophyte formation in people with SpA compared to the controls (odds ratio = 2.48, 95% CI: 0.64-9.70, P = 0.19).
The systematic review identified that a majority of studies reporting US lesions were in SpA, but limited evidence relating to other forms of IA. Consistent application of the OMERACT US definitions and scoring of US lesions is required in future studies of AT disease in IA. Further work is also required to distinguish between US lesions reflective of inflammation and structural damage.