Purpose: In this study we attempt to evaluate whether or not osteochondral markers of the synovial fluid can be helpful in defining objectively the repair process following matrix-based autologous chondrocyte implantation (ACI) CaReS (Cartilage Regeneration System).
Methods: As a part of a clinical prospective pilot study, synovial fluid of 19 patients was examined before, as well as 6, 12, 26, and 52 weeks after matrix-based ACI. A synovial fluid analysis was performed and markers of bone and cartilage metabolism were evaluated. Molecular markers routinely examined included MMP-1, MMP-3, MMP-13, TIMP, hCOMP, PICP und MIA. The levels were referenced to the total protein concentration of the synovial fluid and compared with clinical parameters (IKDC) and magnetic resonance imaging (MRI).
Results: With the exception of MMP3 all markers showed a drop of the concentration below preoperative levels at 6 weeks. All marker levels returned to below the preoperative concentration at 26 as well as 52 weeks after surgery. The MIA, MMP-3, PICP, hCOMP and TIMP levels showed significant changes over the period of 52 weeks (p<0.01). Statistically significant correlations between the marker levels and the clinical scores could only be observed at several times of assessment.
Conclusions: Under consideration of missing correlations to clinical parameters (IKDC/MRI) non-specific osteochondral marker proteins of the synovial fluid cannot be used without further scrutiny to document changes in cartilage and osseous metabolism following matrix-supported ACI over the time of 52 weeks objectively. The drop of the concentrations below preoperative levels at 6 weeks can possibly be explained by the reduced traumatization of the joint with the CaRes procedure compared to the classic ACI. Specific markers for cartilage metabolism should be defined to permit a direct and objective comparison of the various conservative and operative methods presently available for the treatment of chondral lesions of the knee joint.