Background Clinical examination may overestimate Achilles enthesitis. Ultrasonography (US) is a valuable tool for assessment of musculoskeletal inflammation including subclinical enthesitis.
Objectives The aim of our study was to compare clinical and US evaluation of Achilles enthesitis in patients with psoriatic arthritis (PsA).
Methods Patients with PsA were included consecutively in a clinical setting during 1.5 years. The Achilles insertion was examined by clinical assessment of tenderness by a trained nurse, and an experienced ultrasonographer performed US evaluation of 1) inflammatory activity defined as power Doppler (PD) signal, tendon thickening, hypoechogenicity and bursal swelling as well as 2) structural damage defined as erosions at tendon insertion, calcifications and enthesophytes. US sum scores of inflammatory activity and structural damage were assessed. Demographic variables and US scores were assessed by descriptive statistics. Proportions were analysed by Chi-Square test. Correlations were assessed by Spearman's rank correlation test (non-parametric distribution of the data).
Results A total of 141 PsA patients were included. They all fulfilled the CASPAR criteria. Mean (SD) age was 52.4 (10.2) years, disease duration 9.5 (6.6) years, BMI 28.3 (4.3) kg/m2, 50.4% were females, 10.6% used steroids, 57.4% conventional synthetic disease modifying drugs (csDMARDs), 32.6% tumor necrosis factor inhibitors (TNFi) and 20.6% both TNFi and csDMARDs.
Of 282 Achilles tendons, 88 (33.2%) were tender on palpation. By US, 6 (17%) had hypoechogenicity, 37 (13.1%) thickening, 2 (0.8%) PD activity, 14 (5%) bursal swelling, 112 (39.7%) calcifications, 77 (27.3%) enthesophytes and 4 (1.4%) erosions at tendon insertion. Inflammatory activity was found in 55 (19.5%) of the examined Achilles tendons and 148 (52.5%) had structural damage on US sum scores. No significant correlation was found between US sum scores and tenderness on palpation. 36 (18.6%) of the Achilles tendons showed subclinical inflammation on US. No significant difference of percentages of patients with Achilles inflammatory activity or structural damage was found when comparing patients currently treated or not with TNFi, csDMARDs and steroids.
Conclusions We report lack of association between palpation tenderness and US signs of Achilles enthesitis in PsA. US showed structural damage in 52.5% and subclinical inflammation in 18.6% of the examined Achilles tendons.
Disclosure of Interest B. Michelsen: None declared, A. Diamantopoulos Consultant for: Pfizer, Novartis, Speakers bureau: Abbvie, UCB, Pfizer, D. Soldal: None declared, H. Hammer Speakers bureau: AbbVie, Pfizer, Roche, UCB and BMS, A. Kavanaugh: None declared, G. Haugeberg: None declared