AB0495 BIOMECHANICAL STRESS IN THE CONTEXT OF COMPETITIVE SPORTS TRAINING TRIGGERS ENTHESITIS
Authors: D. Simon, A. Kleyer, S. Bayat, J. Knitza, L. Valor, M. Schweiger, G. Schett, K. Tascilar, A. Hueber
Journal: Annals of the Rheumatic Diseases (2021)

Background: Preclinical models have indicated that biomechanical stress can trigger entheseal inflammation (1). Furthermore, enthesitis is a hallmark of psoriatic arthritis (PsA) and spondyloarthritis (SpA), suggesting that mechanoinflammation is an important step in their pathogenesis (2). However, the relation between mechanical stress and enthesitis in humans is poorly investigated. Competitive badminton is a demanding stop-and-go sport that strains entheseal sites in particular and provides an opportunity to assess the impact of physical activity on the development of an instant inflammatory response in the entheses. Objectives: To evaluate the influence of mechanical stress on the development of immediate enthesitis. Methods: BEAT (Badminton Enthesitis Arthrosonography Study) is an interventional study that assessed entheses in competitive badminton players before and immediately after a 60-minute intensive training session by ultrasound. Power Doppler (PD) signal and Gray-Scale (GS) changes were evaluated at the insertions sites of both Achilles tendon, patellar tendons and lateral humeral epicondyles and quantified using a validated scoring system (3). Pre- and post-training scores were compared using linear mixed-effects models. We used interaction terms to assess possible differential effects on patellar, elbow and Achilles entheses. Results: Thirty-two badminton players (22 men, 10 women) with an average age of 31.1±13.0 years were included (Table 1). On average, they had been playing badminton for 16.2±10.1 years. 192 entheseal sites were examined twice. The respective empirical total scores for PD examination were 0.1 (0.3) before and 0.5 (0.9) after training (Figure 1). Mean total GS scores were 2.9 (2.5) and 3.1 (2.5) before and after training, respectively. The mean total PD score difference of 0.4 between pre- and post -training was significant with a p value of 0.0014, whereas the p value for the mean total GS score difference of 0.2 was 0.63. Overall, seven participants (22%) showed an increased empirical total PD score. A mixed-effects model showed a significant increase of PD scores after training, with a mean increase per site of 0.06 (95%CI 0.01 to 0.12, p=0.017). Table 1. Baseline characteristics Demographic characteristics N, total 32 Females, N (%) 10 (31.3) Age, years (mean ± SD) 36.1 ± 13.0 Height, cm (mean value ± SD) 178.6 ± 9.9 Body weight, kg (mean value ± SD) 74.7 ± 13.5 Smoking, N (%) 11 (34.4) Alcohol, N (%) 24 (75.0) Concomitant Diseases Inflammatory bowel disease, N (%) 0 Psoriasis, N (%) 0 Uveitis, N (%) 0 Diabetes mellitus, N (%) 0 Hypertension, N (%) 2 (6.3) Sports history Years Badminton (mean ± SD ) 16.2 ± 10.1 Figure 1. Ultrasound scores before and after training Figure 1. A Spaghetti plots depicting inividual Gray-Scale and Power Doppler ultrasound scores before and after training Conclusion: Mechanical stress leads to rapid inflammatory responses in the entheseal structures of humans. These data support the concept of mechanoinflammation in diseases associated with enthesitis. However, while such responses may be self-contained in healthy subjects, they may be prolonged and more pronounced in certain risk groups, such as patients with PsA or SpA. References: [1]Cambré I, et al. Mechanical strain determines the site-specific localization of inflammation and tissue damage in arthritis. Nature Communications. 2018; 9:4613. [2]Schett G, et al. Enthesitis: from pathophysiology to treatment. Nat Rev Rheumatol. 2017; 13:731-741. [3]Balint PV, et al. Reliability of a consensus-based ultrasound definition and scoring for enthesitis in spondyloarthritis and psoriatic arthritis: an OMERACT US initiative. Annals of the Rheumatic Diseases. 2018; 77:1730. Disclosure of Interests: David Simon: None declared., Arnd Kleyer: None declared., Sara Bayat: None declared., Johannes Knitza: None declared., Larissa Valor: None declared., Marina Schweiger: None declared., Georg Schett: None declared., Koray Tascilar: None declared., Axel Hueber Grant/research support from: Novartis Research Grant.