The theoretical application of inclined hinges with the Ilizarov external fixator for simultaneous angulation and rotation correction.

The mathematical concepts of single-cut osteotomies for simultaneous correction of angulation and rotation have been adapted and simplified for gradual distraction-osteogenic correction with the Ilizarov external fixator. Validation studies were performed analytically, using a solid modeling analysis, and experimentally with an Ilizarov external fixator mounted on a wood dowel. The resultant equations have been simplified and are easy to use. Starting from the hinge which would correct the angulation, the axis must be reoriented in the horizontal plane by half the rotation deformity (R/2) and given an inclination slope equal to the rotation divided by the angulation (R/A).