External fixators: looking beyond the hardware maze.

External fixation has a wide variety of orthopedic applications. Although external fixator frames may have a complex appearance, these constructs are formed from several basic components and can be broadly categorized into unilateral, circular, or hybrid designs. The introduction of computer-aided circular external fixation devices (hexapod frames) has simplified the treatment of multiaxial and especially rotational deformities. Serial radiography plays a central role in the evaluation of callus formation (at the level of treated fracture or nonunion as well as the regenerate and docking site with distraction osteogenesis), tailoring the rate and rhythm of distraction during distraction osteogenesis, evaluation of frame complications, and determination of the timing of frame removal. The goals of this article are to review: the components, types, and relevant terminology of external fixator constructs with special emphasis on the Taylor spatial frame, the principles and techniques of distraction osteogenesis, and complications of external fixation.