adjustment tool 313 for rotating proximal plug 310 distal plug 312 includes a smaller mating recess on its proximal end not shown configured to removably receive the smaller splined distal end of distal plug adjustment tool 314 for rotating distal plug 312 both proximal plug adjustment tool 313 and proximal plug 312 are provided with central bores that permit the distal end of distal plug adjustment tool 314 to pass therethrough through the center of cage body 308 and partially into distal plug 312 in this exemplary embodiment the proximal ends of adjustment tools 313 and 314 each have a hexagonally shaped head that permits them to be turned together in unison or individually as previously described in relation to uec 200 using wrench es socket s not shown and or by hand as shown in fig1 and 17 cage body 308 includes eight longitudinally extending beam portions 318 each separated from an adjacent beam portion 318 by a longitudinally extending gap 320 in other embodiments not shown the cage body may include fewer or more than eight beam portions and or beam portions having a different or varying cross section or shape it can be seen that in this embodiment four of the gaps 320 are formed through the middle of the four faces of cage.