POS1009 ASYMPTOMATIC ENTHESITIS AND DOMINANT SIDE RELATED PATTERNS IN SPONDYLOARTHRITIS – THE ROLE OF ULTRASONOGRAPHY IN EVERYDAY PRACTICE

Abstract

Background:The spondyloarthritis (SpA) family includes a heterogeneous spectre of inflammatory diseases with several common features, such as the axial and peripheral joint involvement, but also trigger factors, as for instance, mechanical stress, infectious diseases or gut dysbiosis.[1,2]Entheseal inflammation is the common background in the pathogenesis of SpA, leading to osteitis, periostitis and osteoproliferation. Despite being a central feature in SpA, enthesitis remains underdiagnosed in everyday practice.[3,4]Objectives:The primary objective is to assess the frequency of ultrasound versus clinically detected enthesitis in a sample of Romanian patients with highly active SpA. A secondary objective is to determine the existence of an enthesitis pattern according to the dominant side in this sample of patients.Methods:Out of 140 SpA patients, 106 were diagnosed with axial/peripheral SpA and 34 with psoriatic arthritis (PsA), and were clinically (medical history, clinical examination) evaluated, scanned using MSUS during the same visit, then asked which was their dominant side, in order to avoid any biases. The evaluation targeted 16 entheseal sites (Achilles tendon, plantar fascia, quadriceps tendon, proximal and distal patellar tendon, triceps tendon, extensor and flexor tendons of the hand, all evaluated on both sides), reaching a total of 2240 entheses. The medical history form included questions related to present or past spontaneous pain in any of the 16 evaluated sites as well as the clinical examination that evaluated the entheseal pain upon pressure (digital pressure on the enthesis overlying skin).The MSUS evaluations were conducted using Esaote My Lab machines with 6-12/8-18 MHz linear probes. The same clinician/ultrasonographer performed all evaluations, in order to avoid interobserver variability.Results:In the studied sample of patients, 68.6% were men, had a mean age of 43,46 (+/- 11,77), 51.4% were diagnosed with peripheral SpA, with a mean disease duration of 61,60 (+/- 71,03) months, and entheseal abnormalities were found in up to 62.7% of the asymptomatic entheses, lacking both spontaneous and elicited pressure pain.The best performance of clinical and ultrasound examination was observed in the evaluation of the flexor tendons of the hand, with strong agreement between the two methods (kappa = 0,718, p = 0.001). Conversely, the lowest performance of clinical and ultrasound examination was noticed in Achilles (kappa = 0,292, p = 0.001) and distal patellar tendons (kappa = 0,202, p = 0.001), with low agreement indices.Both GS and PD abnormalities were more frequently detected on the right side, in a sample of 98.57% right handed patients. The differences were higher regarding the insertions of the triceps tendon (2.2%) and the plantar fascia (2.1%), in favour of the dominant side.Conclusion:Entheseal reported pain (spontaneous and elicited by pressure) correlates poorly with MSUS detected enthesitis. This study highlights the high rates of imaging detected, but clinically overlooked entheseal abnormalities in SpA patients.Enthesitis was more frequently detected on the dominant side, emphasizing the role of mechanical stress in the pathogenesis of this feature. This outcome also requires the selection of the most reliable entheseal sites for SpA, being a future direction of research for this ongoing study.