Effect of indomethacin on collagen metabolism of rat fracture callus in vitro.

The collagen metabolism of callus tissue from closed, non-immobilized rat femoral fractures was studied in vitro after in vivo treatment with indomethacin 2 mg/kg/day for 6, 9 and 12 days after fracture. Total hydroxyproline synthesis and incorporation of hydroxyproline into collagen were found to be significantly increased after indomethacin treatment, whereas no significant difference was found regarding collagen resorption. The results suggest that the recently demonstrated inhibition of fracture healing by indomethacin is not brought about by an inhibition of collagen synthesis.