The influence of a cyclooxygenase-1 inhibitor on injured and uninjured ligaments in the rat

Background: Results of previous studies have shown that piroxicam, a cyclooxygenase-1-2 inhibitor, improves the strength of healing ligaments, whereas celecoxib, a cyclooxygenase-2 inhibitor, impairs ligament healing. Hypothesis: The selective cyclooxygenase-1 inhibitor, SC-560, will improve the strength of ligament healing in an in vivo rat model. Study Design: Controlled laboratory study. Methods: Eighty male Sprague-Dawley rats underwent surgical transection of their medial collateral ligament. Postoperatively, 20 rats were given SC-560 at a low dose and 20 at a high dose for the first 6 days of recovery; the other 40 received a normal diet. The animals were sacrificed 14 days later, and both the injured and uninjured ligaments were mechanically tested to failure in tension. Results: No significant differences in the strength of injured ligaments were found between drug and placebo treatment. However, the contralateral uninjured ligaments in the SC-560-treated groups failed at 27% higher energy and 22% higher load. Conclusions: This cyclooxygenase-1 inhibitor did not improve the strength of ligament healing but did significantly improve the strength of the contralateral uninjured ligament. Clinical Relevance: A pure cyclooxygenase-1 inhibitor is probably not indicated as a positive influence on ligament healing but might provide benefits in ligament injury prevention. (C) 2003 American Orthopaedic Society for Sports Medicine.