The Association Between Synovial Fluid Biomarkers and The Development of Knee Osteoarthritis After An Anterior Cruciate Ligament Injury
Osteoarthritis (OA) of the knee is a common health issue among aging people. It is characterized by degeneration and destruction of the articular cartilage with secondary induction of hydrarthrosis and synovitis by inflammatory cytokines and growth factors from the destroyed cartilage and synovial membrane. In advanced OA, hyaluronic acid (HA) is decreased in the synovial fluid (SF) and the SF viscosity and chondroprotective function are also reduced. These alterations further leads to destruction of the articular cartilage. Secondarily, synovitis is also related to the joint destruction and OA progression.
Neuman P et al conducted a study to describe the longitudinal patterns of release of synovial fluid biomarkers and to investigate the association between a set of synovial fluid biomarkers at the acute and chronic stage and the development of radiographic knee osteoarthritis after an anterior cruciate ligament (ACL) injury.
The study included 88 participants and synovial fluid was aspirated from the acutely ACL-injured knee within the first two weeks for up to 7.5 years after injury from all participants. Non-injured subjects were considered as a reference group. Aggrecan, cartilage oligomeric matrix protein (COMP), matrix metalloproteinase and tissue inhibitor of metalloproteinase (TIMP)-1 in synovial fluid were quantified by immunoassays. While, the presence of radiographic tibiofemoral (TF) or patellofemoral (PF) OA was examined with weight-bearing knee radiography of 16 years after the ACL injury.
On completion of the study, the average acute and chronic SF concentrations of COMP and aggrecan were elevated as compared to the reference group. The levels of COMP and aggrecan clearly decreased approximately half a year after the ACL injury and returned to the reference values during the 7.5 years of follow up. Statistical results were carried out using the logistic regression analysis and neither acute nor chronic concentrations of the four biomarkers found associated with the development of knee OA at the 16 year of follow up.
Therefore, it can be concluded that the 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 the ACL injury.