Pathogenesis, pathological anatomy, diagnosis and therapy of meniscus lesions especially by soccer players and other sportsmen are represented. However, soccer has by far the highest percentage of incidence of meniscus lesions. Because the efficiency of the knee after meniscectomy is decreased, maintenance and restitution of adequate quadriceps strength are important for an uneventful postoperative course. As far as possible an individual after-care and excerise programme have to be made. Some aspects of pathogenesis of arthrosis deformans after meniscectomy are shortly discussed. The author points to the functional union of the femoro-tibial and femoro-patellar part of the knee joint.