SLR - April 2019 - John Greaves

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

Reference: Bruyn, G. A., Siddle, H. J., Hanova, P., Costantino, F., Iagnocco, A., Delle Sedie, A., & Micu, M. C. (2018). Ultrasound of subtalar joint synovitis in patients with rheumatoid arthritis: results of an omeract reliability exercise using consensual definitions. The Journal of Rheumatology, jrheum-171490.

Scientific Literature Review

Reviewed by: John Greaves, DPM
Residency Program: Northwest Medical Center, Margate FL

Podiatric Relevance: As medicine and everyday practice head further in the direction of evidence-based medicine, I found this article interesting because it develops a scoring system in a subset of patients with rheumatoid arthritis (RA) for evaluating the amount of synovitis in the subtalar joint using ultrasound. The authors hypothesized that ultrasound as an imaging modality may be a viable noninvasive test to evaluate the amount of synovitis in the subtalar joint in patients with RA.

Methods: The study defined the definition of joint synovitis by performing a literature review and then using this information to perform a consensus process, which would define the anatomical landmarks and staging criteria. A Delphi process was then carried out in three rounds to finally narrow down a concise ultrasound protocol and criteria for scoring. The second portion of the study consisted of performing a reliability assessment of ultrasound in scoring STJ synovitis in RA patients. Ten patients with RA were assessed with ultrasound at predetermined sites along the subtalar joint and then scored on a scale of 0–3 for synovial hypertrophy and power Doppler signal and a scale of 0–1 for joint effusion. The area of maximum pathology was also recorded.

Results: The patient-based study showed that:
--Average prevalence of ultrasound detected synovial hypertrophy was 47 percent
--Average prevalence of power doppler signal was present in 13 percent
--Average prevalence of joint effusion was 35 percent

When looking at the prevalence of pathology per side the study found:
--Average prevalence of SH, PD and JE for the anteromedial side was 52 percent, 11 percent and 41 percent
--Average prevalence of SH, PD and JE for the posteromedial side was 48 percent, 18 percent and 23 percent
--Average prevalence of SH, PD and JE for the posterolateral side was 50 percent, 10 percent and 43 percent

When using both b-mode and doppler mode, a good intraobserver reliability was found when assessing for both synovial hypertrophy and power doppler.

Conclusions: The studies aim was to develop a standardized method for evaluating synovitis in the STJ of patients with RA. The reliability was found to be dependent on both the pathology evaluated and position of the probe. Good scores were found for assessing synovial hypertrophy. Moderate to good results for power doppler signals and poor results for assessing joint effusions. The posterolateral site showed to be the most reliable for assessment of synovitis in the STJ of RA patients. The authors discussed how joint effusion is a hallmark lesion of synovitis, but this study showed poor interobserver reliability. The authors stated that it should not be used for indicating level of synovitis. This study shows that experienced sonographers can reliably assess STJ synovitis in patients with RA using ultrasound. This study also developed a consensus-driven U.S. protocol and scoring system that I feel could be extrapolated to less experienced users with the correct training. I feel this study is important to our field because ultrasound is a noninvasive, inexpensive way of assessing the anatomy of the foot, and now joint synovitis, without exposing the patient to radiation. 

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