EFFECT OF NONSTEROIDAL ANTIINFLAMMATORY DRUGS ON FRACTURE-HEALING - ALABORATORY STUDY IN RATS

We studied the effects of two nonsteroidal antiinflammatory drugs (NSA IDs) on fracture healing in rats: ibuprofen (30 mg/kg/day) and indomet hacin (1 mg/kg/day). Femoral fractures were induced via a three-point bending technique. NSAIDs were administered orally for 4 or 12 weeks. Control animals received no medication. In each group a minimum of six animals were killed at the following intervals: 2, 4, 6, 8, 10, and 1 2 weeks postfracture. Fracture healing was determined by mechanical te sting and histologic evaluation. The bending strength of each fracture d femur was expressed as a percentage of the strength of the intact, c ontralateral femur. Histologic evaluation was performed on serial long itudinal sections stained with hematoxylin and eosin using a qualitati ve score of maturity of the callus. Ibuprofen and indomethacin both re tarded fracture healing, with significant differences in ''mechanical healing'' found between the control and experimental groups after 10 w eeks of drug administration. Both drugs also induced qualitative histo logic changes manifested by delayed maturation of callus, which was no ticeable earlier than the difference found by mechanical testing of ba ne. Our data suggest that NSAIDs have an inhibitory effect on fracture repair that is reversible after cessation of indomethacin but not ibu profen.