Background/Purpose:

According to the OMERACT definitions, thickening, hypoechogenicity and power Doppler (PD) signal represent the US findings indicative of entheseal “active” inflammation. However, these US elementary findings can be detected also in healthy subjects as shown in other studies, and a variable prevalence has been reported. Despite an experts agreement has been obtained, further investigation is still required to gather more data especially regarding entheses in healthy subjects. To explore the prevalence and distribution of the US findings indicative of enthesitis, defined according to the OMERACT definitions, in a group of asymptomatic healthy subjects.

Methods:

US and clinical assessment of quadriceps, patellar and Achilles tendons, and plantar fascia entheses were performed on 82 healthy volunteer subjects. Exclusion criteria: previous surgery or procedural interventions in the knees and/or ankles, clinical enthesitis on the physical examination, history of entheseal pain in the 3 months preceding the evaluation, previous diagnosis of rheumatic disease, family history of psoriasis or inflammatory bowel disease. The US examination was carried out with a My Lab Twice (Esaote S.p.A. Genoa, Italy), working with a high frequency linear probe (6-18 MHz) and at a Doppler frequency of 9.1-11.3 MHz. The US entheseal abnormalities of “structural damage” (enthesophyte, bone erosion and calcification) and “active enthesitis” (thickening, hypoechogenity and PD signal) were identified according to the OMERACT definitions. Moreover, a semiquantitative score for the PD signal was used (0-3).

Results:

Eight hundred and twenty entheses were evaluated in 82 subjects [age (mean ±SD) 44.0±14.8, 59.8% females]. The prevalence and distribution of the US findings indicative of enthesitis are reported in Table.1. One or more US finding indicative of “active” inflammation were found in at least one enthesis in 30 out of 82 healthy subjects (34.1%), in 69 out of 820 entheses (8.4%). US findings of “active” inflammation were found as isolated in 61 out of these 69 entheses, (38 thickening, 12 hypoechogenicity, 11 PD signal) and in combination in the remaining 8 entheses (thickening + hypoechogenicity).

Conclusion:

The prevalence of the US findings of “active” inflammation, defined according to the OMERACT definitions, in a group of asymptomatic healthy subjects was low in relation to the total number of enthesis but remarkable at subject-level. Combining US elementary lesions of “active” inflammation (i.e, PD signal ≥ 1 + entheseal thickinening and/or hypoechogenicity) or considering as pathological only PD scores > 1 may increase the diagnostic accuracy of the US findings.

Reference

• Terslev L et al. Defining enthesitis in spondyloarthritis by ultrasound: results of a Delphi process and of a reliability reading exercise. Arthritis Care Res (Hoboken).2014 May;66(5):741-8.

ACR Meeting Abstracts - https://acrabstracts.org/abstract/entheseal-involvement-in-asymptomatic-healthy-subjects-prevalence-and-distribution-of-the-ultrasound-elementary-lesions-of-enthesitis-with-a-particular-focus-on-those-indicating-active/