The prevention of infection in open fractures. An experimental study of the effect of antibiotic therapy.

Using an experimental rabbit model of a contaminated open fracture of the tibia that was fixed with an intramedullary pin, we assessed the effect of a single dose of cephradine in preventing post-traumatic osteomyelitis in which the infecting organism was Staphylococcus aureus. We paid particular attention to the effect of a delay in giving the antibiotic. The frequency of osteomyelitis in the animals in a control group (no antibiotic) was 91 per cent. When a single injection of cephradine was given one hour before inoculation with the bacteria, the rate was 30 per cent, a statistically significant reduction (p less than 0.01). When cephradine was not administered until one to four hours after inoculation with the bacteria, the average rate of osteomyelitis was 51 per cent, a 40 per cent reduction compared with the rate for the control group. The effect of the antibiotic therefore persisted even when the initial dose was delayed for four hours after bacterial inoculation.