Fibroblast Growth Factor 2 in Synovial Fluid from an Osteoarthritic Knee with Cartilage Regeneration

The levels of fibroblast growth factor 2 (FGF2) in synovial fluid of osteoarthritic knees were measured. The correlation between FGF2 and the severity of cartilage degeneration in varus-deformed knees with medial compartmental osteoarthritis or the articular cartilage regeneration that occurs after high tibial osteotomy (HTO) were investigated. Knees that underwent total knee arthroplasty (TKA) were categorized as either mildly or severely degenerated according to a modified Outerbridge's grading system for degeneration of articular cartilage. Regeneration of articular cartilage was observed in a biopsy specimen from the medial femoral condyle removed with the patient's consent during hardware removal approximately 2 years after HTO. The joint fluid FGF2 level was measured at that time using an enzyme-linked immunosorbent assay. Cartilage regeneration was classified as immature or mature according to the staging for regeneration of articular cartilage. The histological findings were analyzed using Pineda's evaluation method for cartilage regeneration. The mean concentration of FGF2 was 57.4 +/- 17.6 pg/ml in the joint fluid from knees with severely degenerated cartilage. This was higher than the FGF2 concentration found in the mildly degenerated group. Approximately 2 years after HTO the FGF2 level in synovial fluid was lower in knees with mature regenerated cartilage than in those with immature regeneration. Osteoarthritic knees at a more mature regeneration stage had a lower Pineda's histological score. This result suggested that the FGF2 concentration in knees with osteoarthritis was influenced by articular cartilage degeneration and regeneration, and it correlated with the histological evaluation.