alternatively the segments 20 60 could be grasped at their proximal ends 28 68 through an appropriate attachment mechanism inboard of the top and bottom surfaces and lateral surfaces of the segments 20 60 so that the tongs 90 or other placement tool would not add to a cross sectional diameter needed for the cannula through which the segments 20 60 would be passed with particular reference to fig1 and 17 details of an alternative offset hinge 102 are described such an offset hinge 102 is shown on a first alternative primary segment 100 however the offset hinge 102 could similarly be located on a secondary segment such as a modification of the secondary segment 60 fig1 14 the offset hinge 102 advantageously allows a single pintle to pass through all leaves of the offset hinge 102 fig1 the offset hinge 102 thus avoids the necessity of two partial pintles on opposite sides of a passage 40 fig8 or bore 80 fig1 otherwise the alternative primary segment 100 of fig1 and 17 is similar to the primary segment 20 of the preferred embodiment of the implant assembly 10 of this invention fig1 shows a second alternative primary segment 110 featuring a split hinge 112 this split hinge 112 on the second alternative primary segment 110 is generally similar to the hinge 25 of the primary segment 20 of the preferred embodiment fig8 however the overlapping leaves place the pintles of the split hinge 112 in a slightly different position the second alternative primary segment 110 and split hinge 112 of fig8 illustrate one of the many different hinge configurations which the segments 20 60 of the implant assembly 10 of this invention can have.