US Patent 9326805 Dynamic bone anchor

A dynamic bone anchor includes a longitudinal core member having a first end and a second end, and a longitudinal axis extending through the first end and the second end. The dynamic bone anchor further includes a plurality of tubular segments configured to be positioned around the core member, each of the tubular segments having a bone engagement structure on an outer surface thereof. In a first assembled configuration between the core member and the tubular segments, each of the tubular segments is individually movable on the core member along the longitudinal axis independent of the core member, itself, and the other tubular segments.