A flexible connection unit for use in a spinal fixation device that includes: a longitudinal member having first and second ends and a flexible member interposed between the first and second ends, at least one of the first end and second end configured to be engaged by a first bone securing member and at least one spacer located between the first and second ends, the spacer comprising a resilient element and a ring element encircling at least a portion of the resilient element, wherein the ring element is configured to be engaged by a second bone securing member.
