1. A medical implant assembly having two bone attachment structures cooperating with a dynamic longitudinal connecting member, wherein the assembly comprises: a) the connecting member, the connecting member comprises: i) a first end, a transition portion and a second end; ii) a rod portion extending longitudinally from the first end to the transition portion along a longitudinal axis and running substantially parallel with the longitudinal axis; iii) a tensionable cord portion joined with the rod portion and extending from the transition portion to the second end; iv) a substantially elastic spacer portion positioned between the two bone attachment structures; v) an elastic bumper surrounding and in slidable relation with the tensionable cord portion; and vi) a blocker, the blocker being releasable such that the tensionable cord portion can be re-tensioned.
1. A medical implant assembly having two bone attachment structures cooperating with a dynamic longitudinal connecting member, wherein the assembly comprises: a) the connecting member, the connecting member comprises: i) a first end, a transition portion and a second end; ii) a rod portion extending longitudinally from the first end to the transition portion along a longitudinal axis and running substantially parallel with the longitudinal axis; iii) a tensionable cord portion joined with the rod portion and extending from the transition portion to the second end; iv) a substantially elastic spacer portion positioned between the two bone attachment structures; v) an elastic bumper surrounding and in slidable relation with the tensionable cord portion; and vi) a blocker, the blocker being releasable such that the tensionable cord portion can be re-tensioned. 18. The assembly of claim 1 , wherein the cord portion includes an elastic cord.