The effects of hyaluronic acid on fibronectin fragment mediated cartilage chondrolysis in skeletally mature rabbits

Objective: Intraarticular Na-Hyaluronate (HA) exerts a beneficial effect on adolescent rabbits after fibronectin fragment (Fn-f) mediated cartilage injury. We extended our studies to a population of rabbits which have reached full skeletal maturity. Design: Adult male NZW rabbits received an injury with Fn-f and no further treatment; an injection of HA followed by Fn-f injury, or Fn-f injury followed by a single or weekly intraarticular injection of HA. All animals were sacrificed 38 days after receiving the Fn-f injury. After sacrifice, proteoglycan (PG) content was determined from articular cartilage from the medial femoral condyles and tibial plateaus. The patellae were processed for histology. Results: Cartilage PG contents were significantly reduced after Fn-f injection (P=0.0167) and were only slightly improved with HA pre-treatment. However, post-treatment with HA resulted in significant improvements in cartilage PG content when compared to Fn-f only (single HA, P=0.01; weekly HA, P=0.01). Loss of Safranin-O staining, cell loss, osteophyte formation and inflammation were present in the patellae following Fn-f injection. Pre-treatment with HA reduced these changes. More significant protection of cartilage and restoration of Fn-f injury were noted in animals receiving post-treatment with HA. Conclusions: These results suggest that 38 days after Fn-f injury the lost PG content induced by Fn-f injection is substantially restored by weekly post-treatment with intraarticular HA in rabbits that have reached full skeletal maturity. (C) 2003 Published by Elsevier Science Ltd on behalf of OsteoArthritis Research Society International.