Forefoot pathology in rheumatoid arthritis identified with ultrasound may not localise to areas of highest pressure: cohort observations at baseline and twelve months

BackgroundPlantar pressures are commonly used as clinical measures, especially to determine optimum foot orthotic design. In rheumatoid arthritis (RA) high plantar foot pressures have been linked to metatarsophalangeal (MTP) joint radiological erosion scores. However, the sensitivity of foot pressure measurement to soft tissue pathology within the foot is unknown. The aim of this study was to observe plantar foot pressures and forefoot soft tissue pathology in patients who have RA.Methods A total of 114 patients with established RA (1987 ACR criteria) and 50 healthy volunteers were assessed at baseline. All RA participants returned for reassessment at twelve months. Interface foot-shoe plantar pressures were recorded using an F-Scan® system. The presence of forefoot soft tissue pathology was assessed using a DIASUS musculoskeletal ultrasound (US) system. Chi-square analyses and independent t-tests were used to determine statistical differences between baseline and twelve months. Pearson’s correlation coefficient was used to determine interrelationships between soft tissue pathology and foot pressures.ResultsAt baseline, RA patients had a significantly higher peak foot pressures compared to healthy participants and peak pressures were located in the medial aspect of the forefoot in both groups. In contrast, RA participants had US detectable soft tissue pathology in the lateral aspect of the forefoot. Analysis of person specific data suggests that there are considerable variations over time with more than half the RA cohort having unstable presence of US detectable forefoot soft tissue pathology. Findings also indicated that, over time, changes in US detectable soft tissue pathology are out of phase with changes in foot-shoe interface pressures both temporally and spatially.Conclusions We found that US detectable forefoot soft tissue pathology may be unrelated to peak forefoot pressures and suggest that patients with RA may biomechanically adapt to soft tissue forefoot pathology. In addition, we have observed that, in patients with RA, interface foot-shoe pressures and the presence of US detectable forefoot pathology may vary substantially over time. This has implications for clinical strategies that aim to offload peak plantar pressures

Validity and Responsiveness of Combined Inflammation and Combined Joint Damage Scores Based on the OMERACT Rheumatoid Arthritis MRI Scoring System (RAMRIS)

Objective: The RAMRIS [Outcome Measures in Rheumatology rheumatoid arthritis (RA) magnetic resonance imaging (MRI) Scoring system] is used in clinical RA trials. We have investigated methods to combine the RAMRIS features into valid and responsive scores for inflammation and joint damage. Methods: We used data from 3 large randomized early RA trials to assess 5 methods to develop a combined score for inflammation based on RAMRIS bone marrow edema, synovitis, and tenosynovitis scores, and a combined joint damage score based on erosions and joint space narrowing. Methods included unweighted summation, normalized summation, and 3 different variants of weighted summation of the RAMRIS features. We used a derivation cohort to calculate summation weights to maximize the responsiveness of the combined score. Construct validity of the combined scores was examined by assessing correlations to imaging, clinical, and biochemical measures. Responsiveness was tested by calculating the standardized response mean (SRM) and the relative efficiency of each score in a validation cohort. Results: Patient characteristics, as well as baseline and followup RAMRIS scores, were comparable between cohorts. All combined scores were significantly correlated to other imaging, clinical, and biochemical measures. Inflammation scores combined by normalized and weighted summation had significantly higher responsiveness in comparison to unweighted summation, with SRM (95% CI) for unweighted summation 0.62 (0.51–0.73), normalized summation 0.73 (0.63-0.83), and weighted summation 0.74 (0.64–0.84). For the damage score, there was a trend toward higher responsiveness for weighted summation. Conclusion: Combined MRI scores calculated by normalized or weighted summation of individual MRI pathologies were valid and responsive