Internal fixator for use in the mouse.

Knockout techniques enable us to expand our knowledge about bonerepair processes. Since they require the use of mice, such studies necessitate the development of special technologies. Mechano-biological reactions play a determining role in fracture healing, and therefore controlled conditions of stability are essential. Achieving fixation with a low-mass implant avoids uncontrolled inertial loading and enables free ambulation. A miniaturised version of conventional internal fixation as used in humans has been developed. The method consists of a plate-like internal fixator with locked screws. It permits compression fixation or splinting fixation at selectable levels of flexibility. A guide is used for standardised application of the fixator, the screws and the osteotomy. Locking the screws to the plate enables elevation of the fixator from the bone surface; therefore, minimal contact damage to the periosteal blood supply can be expected. The technology is now in use in several laboratories.