An implantable medical device comprising: a housing having an outer surface; ; a plurality of protrusions , wherein the plurality of protrusions are configured to reduce at least one of rotational, translational, and lateral movement of the implantable medical device within a patient's tissue after implantation in the patient; a core assembly comprising a core assembly housing , the core assembly having a first end and a second end ; and a header coupled at a first header end to the first end of the core assembly housing , the header comprising a header housing having an outer surface extending from the first header end to a second header end , wherein the plurality of protrusions extends from the outer surface of the header housing , wherein the plurality of protrusions are shaped to provide a complementary fit to a plurality of teeth of a medical insertion or extraction tool, wherein the outer surface of the header housing includes a first side and a second, opposite-facing, side, the plurality of protrusions comprising a plurality of rows of protrusions , each row extending at least partially across a width of the first side, wherein each of the plurality of rows of protrusions includes at least two protrusions or at least one elongate protrusion, wherein each of the plurality of rows of protrusions is oriented parallel to a first axis , wherein the first axis is perpendicular to a second axis , the second axis comprising an axis of symmetry of the header , extending from the first header end to the second header end , characterized in that the header further comprising a second set of protrusions, arranged near the first header end , the second set of protrusions including two elongated protrusions , each oriented at an angle to the other, the two elongated protrusions each being oriented at an angle to the second axis , which angle is not parallel or perpendicular to the second axis . a housing having an outer surface; ; a plurality of protrusions , wherein the plurality of protrusions are configured to reduce at least one of rotational, translational, and lateral movement of the implantable medical device within a patient's tissue after implantation in the patient; a core assembly comprising a core assembly housing , the core assembly having a first end and a second end ; and a header coupled at a first header end to the first end of the core assembly housing , the header comprising a header housing having an outer surface extending from the first header end to a second header end , wherein the plurality of protrusions extends from the outer surface of the header housing , wherein the plurality of protrusions are shaped to provide a complementary fit to a plurality of teeth of a medical insertion or extraction tool, wherein the outer surface of the header housing includes a first side and a second, opposite-facing, side, the plurality of protrusions comprising a plurality of rows of protrusions , each row extending at least partially across a width of the first side, wherein each of the plurality of rows of protrusions includes at least two protrusions or at least one elongate protrusion, wherein each of the plurality of rows of protrusions is oriented parallel to a first axis , wherein the first axis is perpendicular to a second axis , the second axis comprising an axis of symmetry of the header , extending from the first header end to the second header end , characterized in that the header further comprising a second set of protrusions, arranged near the first header end , the second set of protrusions including two elongated protrusions , each oriented at an angle to the other, the two elongated protrusions each being oriented at an angle to the second axis , which angle is not parallel or perpendicular to the second axis . <EOS>