[Modern knee replacement and aftercare].

In recent years, patient specific alignment (PSA) philosophies have emerged as a promising approach to enhance patient satisfaction following knee replacement. PSA requires a detailed preoperative 3D analysis of the leg geometry as well as precise and accurate intraoperative implementation of the patient-specific planning. Technical support, such as navigation-based or robot-assisted systems, is essential for the success of this complex challenge. This article presents the essentials of patient-specific alignment and the intraoperative use of a robot- assisted system.