Purpose. Open lower leg fractures are frequently associated with severe soft tissue damage, followed by osteomyelitis. Using an animal experimental model, we investigated the effect of timing of coverage of a tibial fracture with a local muscle flap. Methods. 80 rabbits had a tibial fracture induced in a standardised fashion, which was stabilised by screw osteosynthesis. After 3 (group A; n=40) and 7 days (group B; n=40), respectively, the tissue defect was covered by a local gastrocnemius flap. In increasing intervals from 1 to 2, 4, 8, and 16 weeks, the rabbits from each group were killed and the bone fracture was analysed histomorphologically Cortical microcirculation was measured by 2-channel laser doppler flowmetry. Results. Muscle flaps after 3 days improved perfusion significantly as compared with 7 days (24 Flux [standard error, 5 Flux] versus 10 Flux [3 Flux]; baseline, 1.4 Flux). Group A animals also displayed a lower rate of necrosis (0 versus 38). The incidence of osteomyelitis was higher in group B than in group A (24% versus 0%). Conclusion. Laser doppler flowmetry was proven to be a reliable, minimally invasive means for identifying avital tissue, leading to reduction in the loss of vital bone tissue in experimental settings.
Development of animal experimental model for bacterial peritonitis