There is disclosed various embodiments of an implantable anchor for permanently anchoring a medical lead. The implantable anchor may include a body having a longitudinal lumen, an access opening defined within a side of the body and in communication with the longitudinal lumen, a locking opening defined on an interior surface of the body, an arm having an interior face, the arm rotatably coupled to the body such that the arm is movable from a first position in which the arm covers the access opening to a second position in which the arm does not cover the access opening, and a locking feature protruding from the interior face of the arm and sized to extend into the locking opening.
