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Published on: October 27, 2023
Ankle retinacula abnormalities as features of psoriatic arthritis: An ultrasound study
Marine Forien1, Esther Ebstein1, Bastien Léger1
1Rheumatology Department, DMU Locomotion, Bichat Hospital (AP-HP), 46, rue Henri-Huchard, 75018 Paris, France.
Objective:
To compare the ultrasonography (US) assessment of the retinacula of ankles in patients with rheumatoid arthritis (RA) and psoriatic arthritis (PsA).
Methods:
This cross-sectional study included RA or PsA patients with ankle pain and healthy controls. The following US features were recorded: presence of synovitis, tenosynovitis and abnormalities of two retinacula (the superior peroneal retinaculum [SPR] and the flexor retinaculum [FR] evaluated in mode B and power Doppler).
Results:
Among the 80 included patients, 37 (46%) and 23 (29%) had RA and PsA; 20 (25%) patients were healthy controls. The FR was thicker in PsA than RA ankles 0.96±0.39 vs. 0.64±0.15, P<0.001 with no difference between RA patients and HCs. Other FR abnormalities such as hypoechogenicity, PD positivity or periostosis were more frequent in PsA than RA patients, P<0.001. On receiver-operating-characteristic curve analysis, a cut-off of 1mm FR thickness provided a sensitivity of 49% and specificity of 97% for the diagnosis of PsA. Overall, 39 and 3% of PsA and RA ankles exhibited retinaculitis of FR (thickness≥1mm with hypervascularization or hypoechogenicity). The two disease groups did not differ in the evaluation of SPR.
Conclusions:
US abnormalities of FR were more frequent in PsA than RA and appeared to be specific for PsA. US assessment of FR might be useful to distinguish RA and PsA.

