Background About 90% of patients with rheumatoid arthritis (RA) have their feet affected during the course of the disease but its symptoms may be underestimated1.
Objectives 1) To compare ultrasound (US) of the joints of asymptomatic feet in patients with RA with control feet; 2) to evaluate in patients with RA:the relationship between the joint US in the feet with disease activity, function, goniometry and radiography.
Methods Fifty healthy subjects and fifty with RA, all with asymptomatic feet, had their feet joints (talocrural, talocalcaneal, talonavicular, naviculocuneiform, calcaneocuboid, 5th tarsometatarsal and I – V MTP) evaluated by US (synovitis, Power Doppler (PD) and erosion) 2,3, bilaterally (100 of each joint in each group – a total of 3600 joint recesses were evaluated). The following clinical assessment instruments were utilized: the DAS-28; HAQ and Foot Functional Index (FFI); goniometry and radiography. A 5% statistical significancewas considered.
Results Higher measures were found in the RA group for synovitis (mm) in all joint recesses studied (p<0.003); for the presence of synovitis (p<0.035) (except the 5th tarsometatarsal and III MTP); for the presence of PD (p<0.029) (talocalcaneal, talonavicular, I, II, III, IV MTFs); and for the presence of erosion (p<0.003) (except in talocrural and talocalcaneal). The presence of synovitis, PD, and erosion were observed in the joint recesses of the RA and control groups, respectively: 18.3% and 3.05% (p<0.001), 5.77% and 0.22% (p<0.001) and 34.45% and 2.85% (p<0.001). Higher values of DAS-28, HAQ and FFI were associated with the ultrasonographic findings in some joints (p<0,046). The interobserver agreement analysis showed ICC ≤0.686 for semiquantitative synovitis; ≤0.641 for quantitat≤ive synovitis; ≤0.474 for semiquantitative PD; and ≤1.000 for semiquantitative erosion. Low rates of Kappa Coehn (0.084 to 0.400) were obtained from the correlation between radiography and US.
Conclusions The joint US, even in asymptomatic feet of patients with RA, showed a much larger number of inflammatory changes in current activity(synovitis, PD) and sequela changes (erosion) compared to the control feet, with good to moderate interobserver agreement.
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Riente L, Sedie AD, Iagnocco A, et al. Ultrasound imaging for the rheumatologist V. Ultrasonography of the ankle and foot. Clin Exp Rheumatol. 2006; 24:493-498.
Wakefield RJ, Balint PV, Szkudlarek M, et al. Proceedings from the OMERACT Special Interest Group for Musculoskeletal Ultrasound including definitions for ultrasonographic pathology. J Rheumatol. 2005; 32:2485-7.
Disclosure of Interest None Declared
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