Ultrasound of Subtalar Joint Synovitis in Patients with Rheumatoid Arthritis: Results of an OMERACT Reliability Exercise Using Consensual Definitions

Abstract

Objective.To evaluate the intraobserver and interobserver reliability of the ultrasonographic (US) assessment of subtalar joint (STJ) synovitis in patients with rheumatoid arthritis (RA).Methods.Following a Delphi process, 12 sonographers conducted an US reliability exercise on 10 RA patients with hindfoot pain. The anteromedial, posteromedial, and posterolateral STJ was assessed using B-mode and power Doppler (PD) techniques according to an agreed US protocol and using a 4-grade semiquantitative grading score for synovitis [synovial hypertrophy (SH) and signal] and a dichotomous score for the presence of joint effusion (JE). Intraobserver and interobserver reliability were computed by Cohen’s and Light’s κ. Weighted κ coefficients with absolute weighting were computed for B-mode and PD signal.Results.Mean weighted Cohen’s κ for SH, PD, and JE were 0.80 (95% CI 0.62–0.98), 0.61 (95% CI 0.48–0.73), and 0.52 (95% CI 0.36–0.67), respectively. Weighted Cohen’s κ for SH, PD, and JE in the anteromedial, posteromedial, and posterolateral STJ were −0.04 to 0.79, 0.42–0.95, and 0.28–0.77; 0.31–1, −0.05 to 0.65, and −0.2 to 0.69; 0.66–1, 0.52–1, and 0.42–0.88, respectively. Weighted Light’s κ for SH was 0.67 (95% CI 0.58–0.74), 0.46 (95% CI 0.35–0.59) for PD, and 0.16 (95% CI 0.08–0.27) for JE. Weighted Light’s κ for SH, PD, and JE were 0.63 (95% CI 0.45–0.82), 0.33 (95% CI 0.19–0.42), and 0.09 (95% CI −0.01 to 0.19), for the anteromedial; 0.49 (95% CI 0.27–0.64), 0.35 (95% CI 0.27–0.4), and 0.04 (95% CI −0.06 to 0.1) for posteromedial; and 0.82 (95% CI 0.75–0.89), 0.66 (95% CI 0.56–0.8), and 0.18 (95% CI 0.04–0.34) for posterolateral STJ, respectively.Conclusion.Using a multisite assessment, US appears to be a reliable tool for assessing synovitis of STJ in RA.

The Elusive but Painful Subtalar Joint in Rheumatoid Arthritis

“…Among the 2 investigators, the intraobserver and interobserver reliability were good to excellent. The lateral scans were felt to be the most prevalent for synovitis, but this may be, as also stated by Bruyn, et al, due to the more superficial location of the joint recess 8 . In both studies the question arises of whether sensitivity for the detection of especially Doppler signals may be better by adjusting settings for each view and not using the same settings for all views.…”

“…In this issue of The Journal, Bruyn, et al report on reliability of sonography of the subtalar joint using consensus-driven definitions 8 . This is an interesting extension of the above-mentioned publication on the normal US anatomy of the subtalar joint 5 .…”

“…Sonographers consisted of 10 rheumatologists and 2 podiatrists. The investigators are commended on their efforts to standardize subtalar joint evaluation with sonography, but the nomenclature used by Bruyn, et al is not entirely clear 8 . The authors state that the consensus was to exclude the talocalcaneonavicular joint, which is equivalent to the ASTJ, and assess the talocalcaneal joint only, which one has to assume then is referring to PSTJ.…”

“…The PSTJ was assessed from a posterolateral scan, but then a medial scan was performed by positioning the probe on the sustentaculum tali and moving it anteriorly as well as posteriorly. The anteromedial scan as shown in Figure 2b of Bruyn, See US of subtalar synovitis, page 351 et al will examine the talocalcaneonavicular joint or ASTJ 8 . The posteromedial scan in Figure 2b in contrast will analyze the PSTJ from medial.…”

“…The technique described in Mandl, et al 5 to study the ASTJ from medial is slightly complicated, involving a rotation of the probe. The technique described by Bruyn, et al 8 of positioning the probe on the talus and sustentaculum tali and then moving anteriorly might be easier and sufficient to examine the ASTJ medially. It is nevertheless important to clearly recognize that this maneuver will examine the ASTJ, and future studies will have to evaluate whether the assessment of the ASTJ through the talonavicular view may add additional information in RA.…”