Effect of diclofenac sodium on union of tibial fractures in rats.

Nonsteroidal anti-inflammatory drugs are often used for 7 to 10 days after fracture because of their effects on bone metabolism. This study evaluated the effect of diclofenac sodium, administered at clinical dosage and duration, on bone union. Fifty-four male Wistar rats were randomly and equally divided into three groups: control, diclofenac 1 mg, and diclofenac 2 mg. Closed diaphyseal fractures were induced in the right tibias of all rats; the two diclofenac groups received intramuscular injections in the contralateral hips for 10 days. All animals were immobilized in circular casts on the upper thighs. Six rats in each group were sacrificed at weeks 2, 4, and 6, and bony union was evaluated clinically, radiologically, and histologically. At the end of 2 weeks, clinical examinations showed subjective differences between the two treated groups and control animals, with more stable callus formation in controls. Radiologic evaluation of the callus showed numeric, but not significant, differences between control and treated animals. At 4 and 6 weeks, clinical and radiologic findings were comparable among groups. Histologically, no significant differences in callus formation were evident at any evaluation.