10. A medical implant assembly comprising: a) first and second bone anchors cooperating with a longitudinal connecting member having a tensioned cord and a spacer, the spacer located between the first and second bone anchors and having a first through bore, the tensioned cord extending through the spacer, each of the first and second bone anchors having a first pair of opposed upstanding arms and a compression insert, each compression insert having a second pair of upstanding arms forming an insert channel therebetween, each second pair of upstanding arms of the compression inserts having a top surface; b) a sleeve for attachment to one of the bone anchors, the sleeve having: i) a second through bore sized and shaped for slidably receiving the tensioned cord, ii) an aperture formed in the sleeve substantially transverse to the second through bore, the aperture sized and shaped for receiving a lower extension of a cord gripping closure top, iii) first and second body portions, the first body portion sized and shaped for being closely received within a respective channel of the second pair of upstanding arms of a respective compression insert and the second body portion being sized and shaped to be received between the first pair of opposed upstanding arms of a respective bone anchor and also engage the top surfaces of the second pair of upstanding arms of the respective compression insert.
10. A medical implant assembly comprising: a) first and second bone anchors cooperating with a longitudinal connecting member having a tensioned cord and a spacer, the spacer located between the first and second bone anchors and having a first through bore, the tensioned cord extending through the spacer, each of the first and second bone anchors having a first pair of opposed upstanding arms and a compression insert, each compression insert having a second pair of upstanding arms forming an insert channel therebetween, each second pair of upstanding arms of the compression inserts having a top surface; b) a sleeve for attachment to one of the bone anchors, the sleeve having: i) a second through bore sized and shaped for slidably receiving the tensioned cord, ii) an aperture formed in the sleeve substantially transverse to the second through bore, the aperture sized and shaped for receiving a lower extension of a cord gripping closure top, iii) first and second body portions, the first body portion sized and shaped for being closely received within a respective channel of the second pair of upstanding arms of a respective compression insert and the second body portion being sized and shaped to be received between the first pair of opposed upstanding arms of a respective bone anchor and also engage the top surfaces of the second pair of upstanding arms of the respective compression insert. 15. The medical implant assembly of claim 10 , wherein the sleeve is made of a rigid material.