The long-term effects of hyaluronan during development of osteoarthritis following partial meniscectomy in a rabbit model

Objective: The long-term effect of hyaluronan (HA) on meniscus remodeling a nd articular cartilage preservation was assessed during the development of osteoarthritis following partial meniscectomy in a rabbit model. Design: Approximately 60% of the region of each medial meniscus of 20 rabbi t knees was excised bilaterally. The left knee joint was treated with five weekly intraarticular injections of 0.3 mi of HA. beginning 1 week after su rgery. The right control knee was injected with PBS on the same schedule. S ix months after surgery, animals were killed and the medial menisci and tib ial articular cartilage were evaluated morphologically, histologically and biochemically. Results: Meniscal regeneration was observed as newly synthesized translucen t tissue, and image analysis revealed that the amount of this tissue was si gnificantly greater in the HA-treated menisci than in the vehicle-treated m enisci. Safranin-O staining and image analysis revealed the increased prese nce of glycosaminoglycans in the HA-treated menisci relative to vehicle-tre ated menisci while vascularity and biochemical parameters (hydration, total GAGs and reducible collagen crosslinks) were statistically similar in HA- and vehicle-treated menisci. Gross morphologic grading with India ink revea led a trend for less deterioration of tibial articular cartilage in the HA group (P=0.09) while Mankin's score of the HA-treated tibial articular cart ilage was marginally lower than that of the vehicle group (P=0.06). Biochem ical assessments showed a trend for higher total GAGs concentration in the HA-treated articular cartilage when compared to the vehicle treatment group (P=0.06). Conclusion: The present study has demonstrated that following partial menis cectomy, treatment with hyaluronan can enhance meniscal regeneration and ma y inhibit articular cartilage degeneration as long as six months post surge ry. (C) 2000 OsteoArthritis Research Society international.