Examination of the knee joint and the assessment of capsular ligament lesions require profound anatomical and biomechanical knowledge. Particular importance attaches to detailed information about the mechanism of the accident and to stability testing; these allow the establishment of diagnosis in the majority of cases. The diagnosis should take account of the anatomical structures damaged, thus defining both the location and the functional significance of the lesion, which are also important for therapeutic strategy. Arthroscopy makes it possible to solve almost all diagnostic problems and also to apply adequate therapeutic measures. This has necessarily had a considerable influence on strategies for the management of patients with knee injuries. Therapeutic considerations should include the critical evaluation of indications for surgery.