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Extended report
Synovitis in knee osteoarthritis: a precursor of disease?
  1. I Atukorala1,2,
  2. C K Kwoh3,
  3. A Guermazi4,
  4. F W Roemer4,5,
  5. R M Boudreau6,
  6. M J Hannon6,
  7. D J Hunter1
  1. 1Institute of Bone and Joint Research, Kolling Institute, University of Sydney, Australia and Royal North Shore Hospital, St Leonards, New South Wales, Australia
  2. 2University of Colombo, Colombo, Sri Lanka
  3. 3University of Arizona, Tucson, Arizona, USA
  4. 4Boston University School of Medicine, Boston, Massachusetts, USA
  5. 5Klinikum Augsburg, Augsburg, Germany
  6. 6University of Pittsburgh, Pittsburgh, Pennsylvania, USA
  1. Correspondence to Dr Inoshi Atukorala, Department of Clinical Medicine, Faculty of Medicine, University of Colombo, PO Box 271, 25 Kynsey Road, Colombo 8 08000, Sri Lanka; inoshi.atu{at}


Objectives It is unknown whether joint inflammation precedes other articular tissue damage in osteoarthritis. Therefore, this study aims to determine if synovitis precedes the development of radiographic knee osteoarthritis (ROA).

Methods The participants in this nested case–control study were selected from persons in the Osteoarthritis Initiative with knees that had a Kellgren Lawrence grading (KLG)=0 at baseline (BL). These knees were evaluated annually with radiography and non-contrast-enhanced MRI over 4 years. MRIs were assessed for effusion-synovitis and Hoffa-synovitis. Case knees were defined by ROA (KLG≥2) on the postero-anterior knee radiographs at any assessment after BL. Radiographs were assessed at P0 (time of onset of ROA), 1 year prior to P0 (P-1) and at BL. Controls were participants who did not develop incident ROA (iROA) from BL to 48 months).

Results 133 knees of 120 persons with ROA (83 women) were matched to 133 control knees (83 women). ORs for occurrence of iROA associated with the presence of effusion-synovitis at BL, P-1 and P0 were 1.56 (95% CI 0.86 to 2.81), 3.23 (1.72 to 6.06) and 4.7 (1.10 to 2.95), respectively. The ORs for the occurrence of iROA associated with the presence of Hoffa-synovitis at BL, P-1 and P0 were 1.80 (1.1 to 2.95), 2.47 (1.45 to 4.23) and 2.40 (1.43 to 4.04), respectively.

Conclusions Effusion-synovitis and Hoffa-synovitis strongly predicted the development of iROA.

  • Knee Osteoarthritis
  • Magnetic Resonance Imaging
  • Synovitis

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