POS0538 RELATIONSHIP BETWEEN HINDFOOT DEFORMITIES AND ULTRASOUND TENOSYNOVITIS IN RHEUMATOID ARTHRITIS
Authors: K. Maatallah, H. Boussaa, H. Riahi, H. Ferjani, M. Habechi, W. Triki, D. Ben Nessib, M. Bouaziz, D. Kaffel, W. Hamdi
Journal: Annals of the Rheumatic Diseases (2021)

Background: Rheumatoid arthritis (RA) is an inflammatory disease that frequently affects the joints and soft tissues of the feet. Tibialis posterior tenosynovitis has a reported prevalence between 13 and 64% in RA. The condition is associated with a progressive flat foot deformity and significant gait disability. However, few studies have investigated the relationship between foot deformities and the involvement of tendons. Recently, ultrasonography (US) has been reported as the gold standard for the investigation of tendons. Objectives: This study aimed to assess the relationship between hindfoot deformities and US tenosynovitis in RA. Methods: We conducted a cross-sectional study including patients with RA (ACR/EULAR 2010). Demographic data and disease parameters were collected. For each patient, a podoscope examination of both feet was performed by a rheumatologist. A radiologist experienced in musculoskeletal imaging performed a US examination using a Philips HD11 device with a high-frequency linear transducer. The assessed lesions were synovitis of the tibiotalar, talonavicular, and subtalar joints, and tenosynovitis of tibialis anterior (TA), extensor hallucis longus (EHL), extensor digitorum longus (EDL), tibialis posterior (TP), flexor digitorum longus (FDL), flexor hallucis longus (FHL), fibularis brevis (FB) and fibularis longus (FL) tendons. The presence or absence of synovitis and tenosynovitis was recorded, and the composite synovitis score (power doppler/grayscale ultrasound (PDUS)) was measured for each joint. The US score of each patient was defined by the sum of the composite scores of the joints studied (0-30). A p-value &lt;0.05 was considered significant. Results: Sixty-two feet were examined in 31 RA patients (25 women and six men) with a mean age of 54.8±10.8 years old [32-70]. The mean disease duration was 8.5±7.2 years [1-37]. Rheumatoid Factor (RF) and Anti-Citrullinated Peptides Antibodies (ACPA) were positive in respectively 61.3% and 83.8% of cases. The mean DAS28 ESR was 3.8±1.5 [0.6-7]. Podoscope examination revealed pes planus valgus (PPV) in 55.6% of cases and pes cavus varus (PCV) in 18.5% of cases. US showed tibiotalar synovitis in 59.3% of cases, talonavicular synovitis in 64.8% of cases, and subtalar synovitis in 46.3% of cases. In the anterior compartment, tenosynovitis of TA was noted in 5.6% of cases, of EHL in 1.9% of cases, and EDL in 9.3% of cases. In the medial compartment, tenosynovitis of TP was found in 22.2% of cases, of FDL in 5.6% of cases, and FHL in 0% of cases. In the lateral compartment, tenosynovitis of FB and FL was found in 25% and 11.1% of cases respectively. An association between PPV and synovitis of the tibiotalar joint (p&lt;0.001) and the subtalar joint (p=0.007) was found. An association was also noted with FL tenosynovitis (p=0.045) but not with the other assessed tendons. No association was noted between PCV and synovitis or tenosynovitis of the assessed structures. Conclusion: PPV was frequent among RA patients. This condition was associated with tibiotalar and subtalar synovitis and FL tenosynovitis. It is important to detect and correct foot deformities in order to ensure optimal control of the disease. Disclosure of Interests: None declared