A flexible stabilization assembly includes a flexible inner core, an outer spacer with an off-axis lumen that receives the inner core, and at least one end cap located on either end of the spacer and rotationally fixed with respect to the spacer. Bone screws cooperating with the end cap and spacer include structure for close cooperation and engagement with the end cap. When implanted, the flexible inner core is posteriorly biased with respect to the spacer.