Described are computer-based methods and apparatuses, including computer program products, for implant planning for multiple implant components using constraints. A representation of a bone and a representation of a first implant component are displayed with respect to the representation of the bone. A representation of a second implant component is displayed, wherein the first implant component and the second implant component are physically separated and not connected to each other. A positioning of the representation of the second implant component that violates at least one positioning constraint is prevented, wherein the positioning constraint is based on the representation of the first implant component.