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Synovial Fluid Omentin-1 Levels Are Inversely Correlated With Radiographic Severity of Knee Osteoarthritis
  1. Lin Xu, MD*,
  2. Guang-bin Zhu, MD, PhD,
  3. Lei Wang, MD*,
  4. Dan-feng Wang, MD, PhD,
  5. Xiao-rui Jiang, MD, PhD*
  1. From the *Traumatic Orthopaedic Department, Yuhuangding Hospital, Yantai, P.R. China; †Department of Radiology, The First Affiliated Hospital of Guangzhou Medical College, Guangzhou, P. R. China; and ‡Department of Radiology, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China.
  1. Received August 28, 2011, and in revised form November 23, 2011.
  2. Accepted for publication November 23, 2011.
  3. Reprints: Xiao-rui Jiang, MD, PhD, Traumatic Orthopaedic Department, Yuhuangding Hospital, 20 Yudong Rd, 264000, Yantai, Shandong, P.R. China. E-mail: ytjiangxr{at}
  4. Lin Xu and Guang-bin Zhu contributed equally to this paper and should be considered as co–first authors.


Objective The purpose of this study was to demonstrate omentin-1 levels in serum and synovial fluid (SF) of patients with knee osteoarthritis (OA) and to investigate their correlation with radiographic disease severity.

Methods One hundred and ninety-seven patients with OA and 65 sex- and age-matched healthy controls were enrolled in this study. The radiographic disease severity of OA was assessed by the Kellgren- Lawrence (KL) grading system. The omentin-1 levels in serum and SF were determined by enzyme-linked immunosorbent assay.

Results There were no significant differences in serum omentin-1 levels between patients with OA and healthy controls (P > 0.05). There were also no significant differences in serum omentin-1 levels among patients with OA with different KL grades (P > 0.05). However, SF omentin-1 levels decreased significantly as the KL grades increased (KL grade 4 < KL grade 3 < KL grade 2; all P < 0.01) in the patients with OA. Furthermore, SF omentin-1 levels were negatively correlated with KL grades (r = −0.643; P < 0.001). Multinomial logistic regression analysis revealed that there was still a negative correlation between the SF omentin-1 levels and the KL grades after adjusting for confounding factors (P < 0.001).

Conclusions Synovial fluid omentin-1 levels showed an independent and negative correlation with radiographic severity of the disease in patients with knee OA. Omentin-1 in SF might serve as a potential biomarker for reflecting the degenerative process of primary knee OA.

Key Words
  • knee
  • osteoarthritis
  • adipokine
  • omentin-1
  • biomarker

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