A method and system to align a pin or drill a tunnel along a single line in space with a two degree of freedom (2-DOF) surgical device in a patient is provided. A plane is defined relative to a desired location for an implant or tunnel on a bone, where the implant or tunnel has an axis. An end-effector of the 2-DOF surgical device is aligned coincident with the plane, and the 2-DOF surgical device is moved side-to until a first indicator signals when the end-effector aligns with an entry point for the desired location for the implant or tunnel on the bone. A tip of the end-effector is anchored into the bone at the entry point； and the 2-DOF surgical device is rotated about the anchored tip until a second indicator signals when the end-effector aligns with the axis of the implant or tunnel at the desired location.
