title: Concentrations of synovial fluid biomarkers and the prediction of knee osteoarthritis 16 years after anterior cruciate ligament injury.
abstract: To describe the longitudinal patterns of release, and investigate the association between a set of synovial fluid biomarkers at the acute and chronic stage and the development of radiographic knee osteoarthritis (OA) after an anterior cruciate ligament (ACL) injury.
  
  
  
  Synovial fluid was aspirated from the acutely ACL-injured knee within the first 2weeks (acute samples), and yearly (chronic samples) up to 7.5 years after injury in 88 subjects (60% men). Non-injured subjects (n = 12) were used as reference group. Aggrecan, cartilage oligomeric matrix protein (COMP), matrix metalloproteinase (MMP)-3 and tissue inhibitor of metalloproteinase (TIMP)-1 in synovial fluid were quantified by immunoassays. The presence of radiographic tibiofemoral (TF) or patellofemoral (PF) OA [Kellgren and Lawrence (K&L) ≥2] was examined with weight-bearing knee radiography 16 years after the ACL injury.
  
  
  
  The average acute and chronic SF concentrations of COMP and aggrecan were elevated in comparison with the reference group (P < 0.001). The levels of COMP and aggrecan clearly decreased approximately half a year after the ACL injury, and returned to reference values during the 7.5 years of follow-up. Using logistic regression analysis neither acute nor chronic concentrations of the four biomarkers were associated with the development of radiographic knee OA at the 16 year follow-up.
  
  
  
  Increased synovial fluid concentrations of aggrecan and COMP was related to knee injury, but acute and chronic synovial fluid concentrations of aggrecan, COMP, MMP-3 and TIMP-1 failed to predict knee OA 16 years after ACL injury.
authors.affiliation: Orthopedics, Department of Clinical Sciences, Malmö, Lund University, Sweden. Electronic address: paul.neuman@skane.se.
authors.forename: P
authors.initials: P
authors.lastname: Neuman
authors.affiliation: Orthopedics, Department of Clinical Sciences, Malmö, Lund University, Sweden; Orthopedics, Department of Clinical Sciences, Lund, Lund University, Sweden.
authors.forename: L E
authors.initials: LE
authors.lastname: Dahlberg
authors.affiliation: Clinical Epidemiology Unit, Orthopedics, Department of Clinical Sciences, Lund, Lund University, Sweden; Clinical Epidemiology Research & Training Unit, Boston University School of Medicine, Boston, MA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Englund
authors.affiliation: Orthopedics, Department of Clinical Sciences, Lund, Lund University, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Struglics
mesh_terms: D000328:Adult; D053674:Aggrecans / Q000378:metabolism*; D000070598:Anterior Cruciate Ligament Injuries / Q000150:complications / Q000378:metabolism*; D064236:Cartilage Oligomeric Matrix Protein / Q000378:metabolism*; D016022:Case-Control Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008297:Male; D019278:Matrix Metalloproteinase 3 / Q000378:metabolism*; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000209:etiology / Q000378:metabolism*; D011379:Prognosis; D011446:Prospective Studies; D011859:Radiography; D013582:Synovial Fluid / Q000378:metabolism*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000378:metabolism*; D055815:Young Adult
chemical_list: D053674:Aggrecans; D064236:Cartilage Oligomeric Matrix Protein; D019278:Matrix Metalloproteinase 3; D019715:Tissue Inhibitor of Metalloproteinase-1; C560822:TIMP1 protein, human; C511768:MMP3 protein, human; C577553:TSP5 protein, human
keywords: ACL; Biomarkers; Knee OA; Synovial fluid