In an interview, Dr. Ziegler, Prof. Dr. José Romero from the Endoclinic Zurich at the Hirslanden Clinic, Dr. Walter O. Frey from the Trauma Center Hirslanden, Prof. Dr. Markus P. Arnold from the Hirslanden Birshof Clinic in Basel and the Andreas Clinic in Cham ZG explain why it is so important to protect the knee in the best possible way, how we should behave in the event of pain, what treatment options are available for a damaged knee joint and what a customized knee looks like with the help of a 3D printer.