Intramedullary fixation is used commonly to provide stability to long bone fractures in humans. This type of fixation restores bony alignment and permits early weight bearing. The intramedullary nail serves as an internal splint with both bone and rod contributing to interfragmentary stability. Because this type of fixation is not rigid, repair occurs by secondary healing with formation of external callus. Currently, however, complications such as delayed union or nonunion may arise from excessive flexibility, rod deformation, fatigue fractures, or migration. Basic research into fracture healing is therefore essential to determine the optimum materials, geometry, and structural properties for fixation devices.
Full Article: Bone mineral density changes during fracture healing: a densitometric study in rats