Background:Entheseal involvement is a frequent and distinctive feature of psoriatic arthritis (PsA), often under diagnosed. It is especially associated with nail involvement. Because clinical examination is not sensitive enough for the detection of early signs of this involvement, US may be considered as an alternative imaging technique in the diagnosis of enthesopathy.Objectives:The aim of the present study is to evaluate US entheses abnormalities in PsA and their correlation with clinical characteristicsMethods:The study included patients diagnosed with PsA according to the CASPAR criteria. They underwent a thorough clinical examination with special regard to the presence of enthesitis using the Spondyloarthritis Research Consortium of Canada (SPARCC) Enthesitis Index.The US study bilaterally explored entheses at six sites: proximal plantar fascia, distal Achilles tendon, distal and proximal patellar tendon insertion, distal quadriceps tendon and distal brachial triceps tendon. We evaluated the following elemental lesions of enthesis at each site: thickness and structure of the tendon, calcifications, bursae, erosions, power Doppler signal in bursa or enthesis full tendon.Results:Of the 33 patients, 39.4 % were male. The mean age was 51.2±12.5 years. The mean disease duration was 13.5±10.2 years.The mean DAPSA was 22.8± 19.7 [0.1-84.5]: remission(n=9), low activity (n=5),moderate activity (n=11),high activity(n=8).At inclusion, 11 patients (33.4%) patients presented with psoriatic onychopathy (45 fingernails) with a mean mNAPSI of 14.1±16. Out of the 528 entheseal sites, 92 were tender at the palpation (17,4%) with a mean SPARCC at 2.87.A total of 396 entheseal sites were examined by US. In 140 of them (35.35%), US found at least 1 sign indicative of enthesopathy. The most affected tendon was the distal Achilles tendon (42/396), followed by proximal plantar fascia (32/396), distal patellar tendon (20/396), quadriceps tendon (20/396), distal brachial triceps tendon(14/396) and finally proximal patellar tendon (12/396).The most common elemental lesions were enthsophytes (176), erosions (114) and calcifications (50).We found a positive correlation between age and both calcification (r=0,4, p=0.021) and enthesophytes (r=0.479, p=0.005).We found a positive correlation between enthesophyte and the tender and swollen joints count (r= 0.352, p=0.045, r=0.378, p=0.03) and the SPARCC score (r=0.397, p=0.022).Patients with higher BASDAI had thicker tendons (r=0.355, p=0.05).Patients with nail dystrophy had more bursitis and erosions.US scores did not correlate with sexe, disease duration and disease activity measures (ASDAS, DAPSA, DAS28 and PASI). Patients with subclinical entheseal involvement didn’t have higher inflammatory biomarkers (ESR, CRP).Conclusion:US subclinical enthesopthy are not rare in psoriatic arthritis, in particular in patients with active disease.Clinical nail involvement was associated with bursitis and erosions. New studies including larger study groups are required to verify the findings of the present studyDisclosure of Interests:None declared
AB1088 NAIL PSORIASIS: THE UNDERESTIMATED DISORDER IN PSORIASIS AND PSORIASIS ARTHRITIS. CAN ULTRASOUND AND CAPILLARY MICROSCOPY IN PATIENTS WITH NAIL PSORIASIS SPEED UP OUR DIAGNOSIS AND THERAPY?