Chondroprotection in Models of Cartilage Injury by Raising the Temperature and Osmolarity of Irrigation Solutions

OBJECTIVES: During arthroscopic or open joint surgery, articular cartilage may be subjected to mechanical insults by accident or design. These may lead to chondrocyte death, cartilage breakdown and posttraumatic osteoarthritis. We have shown that increasing osmolarity of routinely used normal saline protected chondrocytes against injuries that may occur during orthopedic surgery. Often several liters of irrigation fluid are used during an orthopedic procedure, which is usually kept at room temperature, but is sometimes chilled. Here, we compared the effect of normal and hyperosmolar saline solution at different temperatures on chondrocyte viability following cartilage injury using in vitro and in vivo models of scalpel-induced injury. DESIGN: Cartilage injury was induced in bovine osteochondral explants and the patellar groove of rats in vivo by a single pass of a scalpel blade in the presence of normal saline (300 mOsm) or hyperosmolar saline solution (600 mOsm, sucrose addition) at 4°C, 21°C, or 37°C. Chondrocytes were fluorescently labeled and visualized by confocal microscopy to assess cell death. RESULTS: Hyperosmolar saline reduced scalpel-induced chondrocyte death in both bovine and rat cartilage by ~50% at all temperatures studied (4°C, 21°C, 37°C; P < 0.05). Raising temperature of both irrigation solutions to 37°C reduced scalpel-induced cell death (P < 0.05). CONCLUSIONS: Increasing the osmolarity of normal saline and raising the temperature of the irrigation solutions to 37°C reduced chondrocyte death associated with scalpel-induced injury in both in vitro and in vivo cartilage injury models. A hyperosmolar saline irrigation solution at 37°C may protect cartilage by decreasing the risk of chondrocyte death during mechanical injury.