The anterior cruciate ligament injury is one of the most common sports injuries. With approximately 28,000 surgeries performed each year, it ranks at the top of surgical procedures on the knee. This book exclusively addresses this topic and explains in a complex and structured manner the anatomical, physiological, pathophysiological, and biomechanical foundations of both healthy and injured anterior cruciate ligaments. The path to diagnosis as well as therapeutic options, both conservative and surgical, are illustrated with instructive images. Another focus of the book is early functional rehabilitation, the effects of immobilization and training on the support and movement organs, as well as the fundamentals of strength and muscle-building training – an excursion into general training theory.