A spinal stabilization system (10) including an insert (32) positionable in the channel (15) of the housing (14) of a vertebral anchor, and an associated support construct (22) including a spacer (24) and at least one cord (30) extending through the insert. In some instances the construct includes first and second cords (530a, 530b) extending through first and second bores of the insert. A clamping member (50) clamps the cord(s) in the insert. In some instances the clamping member includes first and second tabs movable in channels in first and second flanges (36, 38) of the insert.
