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Background: Articular cartilage has limited self-healing potential. The repair of a chondral lesion is often unsuccessful unless subchondral bone plate is penetrated. However, the quality of the regenerated fibrocartilage is mechanically inferior to that of hyaline cartilage.
Objective: To investigate the combined effect of hyaluronan (HA) and subchondral bone drilling (SBD) on the repair of full-thickness chondral defect (FTD) in rabbits.
Materials and Methods: Male New Zealand rabbits, 3-4 months old were used. A 5 mm x 12 mm FTD was created on the patellar groove of both knees and only the left knee was drilled to make six small holes (1 mm diameter) inside the FTD to induce fibrocartilage generation. A week after the surgery, the animals were treated weekly with 0.3 ml intra-articular HA injection for 5 consecutive weeks while the control group was injected with normal saline solution (NSS). One month after the treatment, the animals were sacrificed and the lesions were examined macroscopically, histologically, and immunohistochemically for the presence of type-I and type-II collagen as well as for chondrocyte proliferation.
Results: New tissue grossly formed around SBD areas with histological appearance of fibrocartilage. FTD plus SBD in HA treated group showed significantly better histological grading than FTD treated with HA alone. Comparing the SBD lesion between HA-treated with the control group, the former showed histological evidence of better healing with increased chondrocyte proliferation and type II collagen content than the latter.
Conclusions: Intraarticular injection of HA administered after SBD can enhance, at least in part, the quality of the repaired chondral tissue for FTD by increasing chondrocyte proliferation and type II collagen production.
Keywords: Osteoarthritis, hyaluronan, subchondral drilling, full-thickness defect
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