The application of holography to examine plated fracture fixation systems

Abstract

The determination of the real strain patterns across a plated fractured bone is important in developing alternative and improved fracture fixation devices. Bone is strain sensitive, and therefore controlling the displacement or strain at the fracture site or near the fracture plate will effect the bone's response to the fixator. Holographic interferometry is shown to be a useful technique for examining very small displacements, in particular relative displacements between two separate parts of the bone-screw-plate system. Relative movement between the bone ends can be reduced by angling an osteotomy, by interlocking a natural fracture or, most efficiently, by applying compression across the fractured bone ends. Increasing the number of fixation points from four to six reduces the slip between the plate and the bone.