Production of a standard closed fracture in the rat tibia.

In order to develop a technique for producing a standard closed transverse fracture in the rat tibia, the method of Bonnarens and Einhorn was modified and tested on 176 tibiae. A 0.9-mm Kirschner wire was inserted percutaneously near the tibial tuberosity into the intramedullary canal, and a tibial fracture was created at the junction of the middle and distal third of the tibia with a blunt guillotine driven by a dropped weight. Radiographs confirmed the production of a highly reproducible transverse mid-shaft tibia fracture in 90% of the fractures. Minimal comminution of the fracture or angulation of the Kirschner wires resulted. The Kirschner wires were removed without difficulty after the rats were put to death and did not disturb the fracture site. Mechanical testing and histological studies showed that a standard fracture healing process was obtained by using this method. The results indicate that this modified method creates a standard, reproducible transverse closed fracture of rat tibia.