The biomechanics and biology of internal fixation using plates and nails.

In fracture healing, the mechanical environment and bone biology are closely related. Furthermore, the mechanics of the medullary nail fixation are, in many aspects, different from those of compression fixation using screws and plates. A few general items will be discussed to review the basic principles of the mechanics and biology involved and to clarify the terminology. This article outlines the basic ideas of mechanical and biological interaction.