Bioengineering provides a good example of an interdisciplinary subject that involves the merging of the philosophies and technologies of living systems and engineering. There are many different aspects to bioengineering, one of the most important being that of implantable devices. These are man-made structures that are placed within the body for diagnostic, therapeutic or reconstructive purposes, some obvious examples being joint replacements, prosthetic heart valves, indwelling catheters, intraocular lenses and so on. The series is intended for research and graduate scientists in medical engineering - bioengineering, biomaterials science and medical technology, to clinicians in orthopaedic, cardiovascular, dentistry/maxillofacial and general surgery, and general readers in the health care industry, the medical device industry in particular. Volume 2 contains contributions in the areas of ligament protheses, heart valves, vascular grafts, the use of collagen as a biomaterial, and a survey of hearing aid devices.