Biomechanical reaction of bone to intramedullary and extramedullary load bearers - the important contact

Bone reacts in a wide range of ways to the changes in its local environment imposed by implant surgery. The advantages and disadvantages of implants must be carefully weighed up, and the first step is therefore to consider the functions of implants and the requirements that they must meet. The contact zone between implant and bone is then discussed. Contact surfaces and their tendency to induce necrosis are nowadays at the forefront of interest in our studies in the realm of biomechanics, i. e., the study of the biological reaction of bone to alterations in mechanical conditions. The salient topics are: avoidance of early temporary osteoporosis, and ways of accelerating bone union, reducing the danger of refracture and enhancing resistance to infection. On the basis of new insights into the biology and biomechanics of contact zones, we can expect to see substantial improvements in the various techniques of internal fixation.