Quantitative measures for fracture healing: an in-vitro biomechanical study.

A method is presented to assess the functional capabilities of plated osteotomized canine femora as load bearing structures and to quantify their healing status. In this method the osteotomized bones and their intact contralateral controls are tested in nondestructive bending, in twenty-four planes of loading at 15 degree angular increments. Flexural rigidity (EI), in each of the planes, is determined by using classical beam theory. It has been found that the EI values have the expected elliptical distribution. The 24 EI values, obtained for each bone, are curve fitted by regression analysis and the characteristics of each bone are described by the three parameters defining its ellipse. The parameters of the ellipses of the osteotomized bone and of its contralateral control are used to define four new parameters that may serve as measures for the healing efficiency. One of these serves as an indicator for the fragility of the healed bone and the other three add quantitative information on its mechanical state.