TECHNIQUE FOR PRODUCING CONTROLLED CLOSED FRACTURES IN A RABBIT MODEL

We describe a new technique to produce a closed fracture of the rabbit tibia with reproducible location and shape of the fracture. The hindl imb of a New Zealand White rabbit was enclosed in a bivalved cast, a 1 .5 mm diameter hole was drilled through the lateral tibial cortex, and the tibia was fractured by loading in three-point bending in an arbor press. The cast protected the soft tissues from being crushed while i t concentrated the bending moment at the intended fracture site. The c ortical hole functioned as a stress riser and fracture initiation site , such that the influence of the loading rate on the fracture characte ristics was minimized. Transverse fractures or oblique fractures at an y desired angle could be produced by variations of the position of the cortical drill hole relative to the central loading point. Thirty-fou r tibial fractures (18 transverse and 16 oblique) were produced. The r abbits were killed immediately, and the fracture angle and the extent of tissue damage were evaluated radiographically, as well as macroscop ically This method produced a consistent location of the fracture, wit h 88% reproducibility of the fracture angle and only minor damage to t he adjacent soft tissues.