title: Association of follistatin-like 3 concentrations in serum and synovial fluid with the radiographic severity of knee osteoarthritis.
abstract: OBJECTIVE
  Follistatin-like 3 (FSTL3), a circulating glycoprotein, is correlated with obesity and inflammation, which are potential mechanisms of osteoarthritis (OA). This study aims to determine the correlation of FSTL3 concentrations in serum and synovial fluid (SF) with the radiographic severity of OA.
  
  
  METHODS
  This study consisted of 200 patients with knee OA and 148 healthy controls. The radiological grading of OA in the knee was performed in accordance with Kellgren-Lawrence (KL) grading system.
  
  
  RESULTS
  Knee OA patients had higher serum FSTL3 concentrations compared with healthy controls. Knee OA patients with KL grade 4 showed significantly elevated FSTL3 concentrations in serum and SF compared with those with KL grades 2 and 3. Moreover, knee OA patients with KL grade 3 had significantly higher FSTL3 concentrations in serum and SF compared with those with KL grade 2. FSTL3 concentrations in serum and SF of knee OA patients were significantly correlated with KL grading criteria.
  
  
  CONCLUSIONS
  FSTL3 concentrations in serum and SF are correlated with the radiographic severity of OA.
authors.affiliation: Department of Spine Surgery, Tianjin Hospital Tianjin, PR China.
authors.forename: Gang
authors.initials: G
authors.lastname: Liu
authors.affiliation: Department of Radiology, Tianjin Hospital Tianjin, PR China.
authors.forename: Si
authors.initials: S
authors.lastname: Chen
authors.affiliation: Department of Spine Surgery, Tianjin Hospital Tianjin, PR China.
authors.forename: Shucai
authors.initials: S
authors.lastname: Deng
authors.affiliation: Department of Spine Surgery, Tianjin Hospital Tianjin, PR China.
authors.forename: Xinlong
authors.initials: X
authors.lastname: Ma
authors.affiliation: Department of Spine Surgery, Tianjin Hospital Tianjin, PR China.
authors.forename: Yonghong
authors.initials: Y
authors.lastname: Hao
authors.affiliation: Department of Spine Surgery, Tianjin Hospital Tianjin, PR China.
authors.forename: Guoyun
authors.initials: G
authors.lastname: Bu
keywords: Follistatin-like 3; osteoarthritis; serum; severity; synovial fluid