title: Synovial tissue volume: a treatment target in knee osteoarthritis (OA).
abstract: BACKGROUND
  Synovitis occurring frequently in osteoarthritis (OA) may be a targeted outcome. There are no data examining whether synovitis changes following intra-articular intervention.
  
  
  METHODS
  Persons 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.
  
  
  RESULTS
  120 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 mm(3); 95% CI -1839 mm(3) to -303 mm(3), 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 mm(3); 95% CI 25 mm(3) to 2414 mm(3), p=0.05). 23 were persistent responders at 6 months and, in these, STV did not increase (mean change=-202 mm(3); 95% CI -2008 mm(3) to 1604 mm(3), 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 mm(3) 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.
  
  
  CONCLUSIONS
  Synovial 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.
  
  
  BACKGROUND
  ISRCTN07329370.
authors.affiliation: Faculty of Medical and Human Sciences, Arthritis Research UK Centre for Epidemiology, Institute of Inflammation and Repair, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK NIHR Manchester Musculoskeletal Biomedical Research Unit, Central Manchester NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK Department of Rheumatology, Salford Royal NHS Foundation Trust, Salford, UK.
authors.forename: Terence W
authors.initials: TW
authors.lastname: O'Neill
authors.affiliation: Faculty of Medical and Human Sciences, Arthritis Research UK Centre for Epidemiology, Institute of Inflammation and Repair, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK NIHR Manchester Musculoskeletal Biomedical Research Unit, Central Manchester NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.
authors.forename: Matthew J
authors.identifier: http://orcid.org/0000-0002-1574-9933
authors.initials: MJ
authors.lastname: Parkes
authors.affiliation: Faculty of Medical and Human Sciences, Arthritis Research UK Centre for Epidemiology, Institute of Inflammation and Repair, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK NIHR Manchester Musculoskeletal Biomedical Research Unit, Central Manchester NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.
authors.forename: Nasimah
authors.initials: N
authors.lastname: Maricar
authors.affiliation: Faculty of Medical and Human Sciences, Arthritis Research UK Centre for Epidemiology, Institute of Inflammation and Repair, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK NIHR Manchester Musculoskeletal Biomedical Research Unit, Central Manchester NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK.
authors.forename: Elizabeth J
authors.initials: EJ
authors.lastname: Marjanovic
authors.affiliation: Centre of Imaging Sciences, Institute of Population Health, University of Manchester, Manchester, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Hodgson
authors.affiliation: Centre of Imaging Sciences, Institute of Population Health, University of Manchester, Manchester, UK.
authors.forename: Andrew D
authors.initials: AD
authors.lastname: Gait
authors.affiliation: Centre of Imaging Sciences, Institute of Population Health, University of Manchester, Manchester, UK.
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Cootes
authors.affiliation: UK Warwick Medical School, The University of Warwick, Coventry, UK.
authors.forename: Charles E
authors.initials: CE
authors.lastname: Hutchinson
authors.affiliation: Faculty of Medical and Human Sciences, Arthritis Research UK Centre for Epidemiology, Institute of Inflammation and Repair, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK NIHR Manchester Musculoskeletal Biomedical Research Unit, Central Manchester NHS Foundation Trust, Manchester Academic Health Science Centre, Manchester, UK Clinical Epidemiology Unit, Boston University School of Medicine, Boston, Massachusetts, USA.
authors.forename: David T
authors.initials: DT
authors.lastname: Felson
mesh_terms: D000368:Aged; D000893:Anti-Inflammatory Agents / Q000008:administration & dosage*; D000069237:Arthrocentesis; D003287:Contrast Media; D005260:Female; D006801:Humans; D007270:Injections, Intra-Articular; D008279:Magnetic Resonance Imaging; D008297:Male; D008775:Methylprednisolone / Q000008:administration & dosage*; D008875:Middle Aged; D009929:Organ Size / Q000187:drug effects; D020370:Osteoarthritis, Knee / Q000188:drug therapy* / Q000473:pathology; D012008:Recurrence; D012720:Severity of Illness Index; D016037:Single-Blind Method; D011795:Surveys and Questionnaires; D013583:Synovial Membrane / Q000187:drug effects / Q000473:pathology*; D013585:Synovitis / Q000188:drug therapy* / Q000473:pathology*; D016896:Treatment Outcome
chemical_list: D000893:Anti-Inflammatory Agents; D003287:Contrast Media; D008775:Methylprednisolone
keywords: Inflammation; Knee Osteoarthritis; Synovitis