Negative effects of parecoxib and indomethacin on tendon healing: an experimental study in rats

Conventional non-steroidal anti-inflammatory drugs (NSAIDs) and newer specific cyclooxygenase-2 (cox-2) inhibitors are commonly used in muscular skeletal trauma and in relation to orthopedic surgery to reduce the inflammatory response and pain. Studies have indicated that these drugs can have a negative effect on tendon healing in the early proliferative phase, but might be beneficial in the remodeling phase when inflammation might impede healing. Our study was designed to investigate if short-term administration of cox inhibitors after injury or postoperatively might have negative effects on the tendon healing. The right Achilles tendon of 60 rats was cut transversely, a 3 mm long segment of the tendon was removed and left unrepaired. The animals were then given parecoxib, indomethacin or saline intraperitoneally twice daily for 7 days. After 14 days, the animals were euthanized. The transverse and sagittal diameters in the healing area were measured and mechanical testing of the tensile strength of the tendons was performed. We found a significantly lower tensile strength in rats given both parecoxib and indomethacin compared to the control group. Stiffness in the healing tendons was significantly lower in the parecoxib group compared to both the placebo and the indomethacin groups. The transverse and sagittal diameters of the tendons were reduced in both the parecoxib and indomethacin groups. Both parecoxib and indomethacin impaired tendon healing; the negative effect was most pronounced with parecoxib.