Intra-articular Hyaluronan Following Autogenous Osteochondral Grafting of the Knee

Purpose: The aim of this study was to assess whether intra-articular hyaluronan viscosupplementation after osteochondral grafting (mosaic arthroplasty) of the knee allowed better graft integration and function in a sheep model. Type of Study: Experimental study. Methods: Twelve adult sheep underwent a mosaic arthroplasty procedure to a standardized osteochondral defect on the medial femoral condyle. One week after surgery the animals were randomized to receive a course of weekly intra-articular injections for 5 weeks of either sodium-hyaluronate solution 25 mg/2.5 mL (HA group) or of a 2.5 mL buffer solution (control group). Synovial fluid samples were taken preoperatively, preceding each injection, and at 8 and 12 weeks. The animals were euthanized at 12 weeks, the knees dissected out, and biomechanical and histologic assessments were made. Results: There was no difference in the synovial fluid leukocyte or total protein concentration between the groups, but the hyaluronan concentration was statistically higher in the HA group. Aggregate moduli of the articular surface were statistically higher in the graft articular cartilage in the HA group than in the control group, as were the sulphated glycosaminoglycan levels. Histologic assessment found more articular cartilage flow in the HA group, whereas there was more interstitial tissue present in the interstices between the grafts in the control group. Conclusions: Results from this study suggest that hyaluronan viscosupplementation following osteochondral grafting does convey some beneficial effects on graft cartilage in the early postoperative period in an ovine model. Clinical Relevance: This study suggests that, in the early postoperative period, hyaluronan supplementation improves articular cartilage survival after osteochondral grafting.