Prosthetic replacement of ligaments is a problem which still has not been solved. Despite the development of different synthetic implants and better knowledge of the ligament biomechanics, there is currently no prosthesis that shows satisfactory results. The purpose of this book is to provide an overview of the growing knowledge of natural ligaments and to review, using a biomimetical approach, the different concepts and designs of artificial ligaments developed during the last decades. This approach is undertaken in an effort to better understand why artificial ligaments fail, to redefine design criteria, and stimulate the development of a new generation of more effective replacement devices.