TABLE OF CONTENTS In this chapter I propose to deal with a number of material applications where the devices are implanted into the body for a relatively short period of time. They are then either removed, or tend to become absorbed by the body once their function has been completed. Obvious examples of the former include plates and traction devices, which are used either to ensure that fractured bones may complete their healing process in the correct alignment, or where it may be necessary to extend the length of a bone. The latter categories include such topics as soluble stitches, and the biodegradable "scaffolding" used to promote organ growth (see Chapter 10).
I have also made the rather arbitrary decision to include mechanical hearts in this discussion, since it can be argued that they should be included in Chapter 7 with pacemakers &c. However, they were originally intended to serve only until a donor heart became available. Also, current experience with "permanent" implantation, although encouraging, is still very recent and cannot yet provide any reliable data.
In many cases, heart disease may be so advanced that there is no chance of the patient surviving until a suitable donor heart can be located. Therefore, in the early 1950s, medical scientists and engineers set out to design a device that would keep the patient alive for the intervening period. Although in this search, a wide variety of different solutions was produced, and the principles often overlapped, the methods of...
