A revision connector configured to couple a new spine fixation rod to a previously implanted spine fixation rod, the previously implanted spine fixation rod extending substantially along a longitudinal direction and secured to at least one vertebra, the revision connector comprising: a body including a first head and defining a first channel that extends into the first head, and further including a second head and defining a second channel that extends into the second head, the second channel. being offset relative to the first channel along a lateral direction that is substantially perpendicular to the longitudinal direction, wherein the first and second channels (208, 212) are each configured to receive respective spine fixation rods (24, 116, 247) therein, such that the received spine fixation rods extend in a caudal-cranial direction when implanted, wherein each head (206, 210) defines a respective inner vertebral-facing surface and an opposed outer surface, at least one side surface extending between the inner and outer surfaces (202, 203), and a superior end surface and an inferior end surface, the end surfaces extending between the inner and outer surfaces (202, 203), wherein the first channel extends into one or both of the end surfaces of the first head, and the second channel extends into one or both of the end surfaces of the second head, wherein the first channel further extends into the outer surface of the first head along a transverse direction that is perpendicular to both the longitudinal direction and the lateral direction, and the second channel further extends into the outer surface of the second head along the transverse direction, characterized in that the body supports an anchor seat body, wherein the anchor seat body defines an opening extending into at least a select one of the first and second heads (206, 210) along the transverse direction, the opening configured to retain a bone anchor, wherein a collet is retained within the opening, the collet having a plurality of expandable fingers that are configured to radially expand between a radially expanded configuration and a radially contracted configuration so as to receive and retain a head of the bone anchor when the body is moved relative to the bone anchor along the transverse direction such that: i) when the head of the bone anchor is retained by the fingers when the fingers are in the radially expanded configuration, the bone anchor is rotatable and pivotable with respect to the select one of the first and second heads (206, 210) having the opening, and ii) when the fingers are in the radially contracted configuration, the bone anchor is no longer rotatable and pivotable with respect to the select one of the first and second heads (206, 210) having the opening. a body including a first head and defining a first channel that extends into the first head, and further including a second head and defining a second channel that extends into the second head, the second channel. being offset relative to the first channel along a lateral direction that is substantially perpendicular to the longitudinal direction, wherein the first and second channels (208, 212) are each configured to receive respective spine fixation rods (24, 116, 247) therein, such that the received spine fixation rods extend in a caudal-cranial direction when implanted, wherein each head (206, 210) defines a respective inner vertebral-facing surface and an opposed outer surface, at least one side surface extending between the inner and outer surfaces (202, 203), and a superior end surface and an inferior end surface, the end surfaces extending between the inner and outer surfaces (202, 203), wherein the first channel extends into one or both of the end surfaces of the first head, and the second channel extends into one or both of the end surfaces of the second head, wherein the first channel further extends into the outer surface of the first head along a transverse direction that is perpendicular to both the longitudinal direction and the lateral direction, and the second channel further extends into the outer surface of the second head along the transverse direction, characterized in that the body supports an anchor seat body, wherein the anchor seat body defines an opening extending into at least a select one of the first and second heads (206, 210) along the transverse direction, the opening configured to retain a bone anchor, wherein a collet is retained within the opening, the collet having a plurality of expandable fingers that are configured to radially expand between a radially expanded configuration and a radially contracted configuration so as to receive and retain a head of the bone anchor when the body is moved relative to the bone anchor along the transverse direction such that: i) when the head of the bone anchor is retained by the fingers when the fingers are in the radially expanded configuration, the bone anchor is rotatable and pivotable with respect to the select one of the first and second heads (206, 210) having the opening, and ii) when the fingers are in the radially contracted configuration, the bone anchor is no longer rotatable and pivotable with respect to the select one of the first and second heads (206, 210) having the opening.