The effect of early hyaluronic acid delivery on the development of an acute articular cartilage lesion in a sheep model

Background: Partial-thickness articular cartilage lesions occur with knee trauma and may progress to osteoarthritis. This study evaluates the effectiveness of hyaluronic acid on cartilage healing after acute knee injury in sheep. Hypothesis: Early administration of hyaluronic acid to an acute cartilage injury will prevent chondrocyte death and improve cartilage metabolism. Study Design: Controlled laboratory study. Methods: A 10 × 10 mm partial-thickness articular cartilage lesion was created on the medial condyle of 16 adult sheep stifles (hindlimbs). Eight sheep received intra-articular hyaluronic acid injections at days 0, 8, and 15, and 8 controls received saline. Contralateral stifles were nonoperated controls. All sheep were sacrificed at 12 weeks after surgery. Synovial fluid was drawn before surgery and after euthanasia for collagen II, nitric oxide, and interleukin-1 beta analysis. The medial condyle was analyzed by gross appearance, confocal laser microscopy for cell viability, histologic analysis for cartilage morphology, and dimethylmethylene blue assay for proteoglycan. Results: At 12 weeks, histologic analysis revealed that the hyaluronic acid group had significantly better scores than the saline group (P = .001). The hyaluronic acid group had significantly greater glycosaminoglycan content than the saline group (P = .011), and showed a trend of reduced chondrocyte death compared with the saline group (P = .07). Synovial fluid showed no significant differences between the groups in collagen II, nitric oxide, and interleukin-1 beta levels. Conclusion: The results demonstrated that early administration of hyaluronic acid shows a significant improvement in cartilage histologic analysis and increased glycosaminoglycan content after acute traumatic cartilage injury. Clinical Relevance: Early hyaluronic acid treatment for acute partial-thickness articular cartilage lesions may decrease or delay articular degeneration.