Synovial tissue volume: a treatment target in knee osteoarthritis (OA)

Abstract

BackgroundSynovitis occurring frequently in osteoarthritis (OA) may be a targeted outcome. There are no data examining whether synovitis changes following intra-articular intervention.MethodsPersons aged 40 years and older with painful knee OA participated in an open label trial of intra-articular steroid therapy. At all time points they completed the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire. They had a contrast-enhanced (CE) MRI immediately prior to an intra-articular steroid injection with a repeat scan within 20 days. Response status was assessed using the Osteoarthritis Research Society International (OARSI) response criteria. OARSI responders were followed until their pain relapsed either within 20% of baseline or 6 months, shortly after which a third MRI was performed. Synovial tissue volume (STV) was measured on postcontrast knee images. We looked at changes in the STV and in pain, and their association.Results120 subjects with preinjection and postinjection CE MRI were followed. Their mean age was 62.3 years (SD=10.3) and 62 (52%) were women. The median time between injection and follow-up scan was 8 days (IQR 7–14 days). 85/120 (71%) were OARSI responders. Pain decreased (mean change in KOOS=+23.9; 95% CI 20.1 to 27.8, p<0.001) following steroid injection, as did mean STV (mean change=−1071 mm3; 95% CI −1839 mm3 to −303 mm3, p=0.01). Of the 80 who returned for a third MRI, pain relapsed in 57, and in the 48 of those with MRI data, STV increased between follow-up and final visit (+1220 mm3; 95% CI 25 mm3 to 2414 mm3, p=0.05). 23 were persistent responders at 6 months and, in these, STV did not increase (mean change=−202 mm3; 95% CI −2008 mm3 to 1604 mm3, p=0.83). Controlling for variation over time, there was a significant association between synovitis volume and KOOS pain (b coefficient—change in KOOS pain score per 1000 mm3 change in STV=−1.13; 95% CI −1.87 to −0.39, p=0.003), although STV accounted for only a small proportion of the variance in change in pain.ConclusionsSynovial tissue volume in knee OA shrinks following steroid therapy, and rebounds in those whose pain relapses. It can be considered a treatment target in symptomatic knee OA.Trial registration numberISRCTN07329370.

Measurement of synovial tissue volume in knee osteoarthritis using a semiautomated MRI‐based quantitative approach

“…Manual segmentation is considered to be an accurate and reliable method for the assessment of synovitis on CE‐MRI, and effusion‐synovitis on noncontrast enhanced MRI, with intraobserver agreement up to 0.94 and 0.97 . Manual segmentation is, however, time‐consuming for the measurement of synovitis and can take between 45 to 120 min per case .…”

Interobserver and Intraobserver Reliability of Clinical Assessments in Knee Osteoarthritis

“…Men and women aged 40 years and over were recruited from primary and secondary care clinics for participation in an open-label study (TASK)13 looking at the efficacy of intra-articular steroid therapy in symptomatic knee OA (ISRCTN: 07329370). Subjects were included in the trial if they met the American College of Rheumatology (ACR) criteria including moderate knee pain for more than 48 hours in the previous 2 weeks or scored greater than 7 out of 32 on the Knee Injury and Osteoarthritis Outcome Score (KOOS), questions P2 – P9.…”

Dietary fatty acids for the treatment of OA, including fish oil

“…We have recently shown that intra-articular steroids relieve pain in part by reducing synovitis within the knee. 3 Ongoing studies are evaluating whether reduction in synovitis can not only reduce pain but also stanch the progression of structural disease. It stands to reason that any treatment targeting inflammation within the joint might be expected to reduce pain and maybe even delay structural deterioration in the diseased joint.…”