In this book, the effectiveness of various physical therapies in the conservative treatment of Achilles tendinopathy are reviewed. An evaluation on the length changes in the Achilles tendon in humans is explored as well. The tendon is considered to have a significant role in human movement because it can store and release elastic energy, which enhances the force-generating capability of the muscle-tendon complex. The third chapter outlines the advantages and disadvantages of the Achilles tendon and highlights some theories as to why humans may have evolved to have it. The last chapter discusses the basic biomechanical characteristics and forces acting on the ankle under static conditions and their influences on artificial total ankle replacement designs.