thread geometry the threads will exert a radially inwardly directed force along the direction of the double ended arrows b whereas in the prior art conventional fasteners induced radially outwardly spreading the opposite direction from arrow b the instant invention provides radially inwardly or a drawing force b as well as the compressive force a the threads 60 of fastener 10 for threads 12 and 14 are actually one continuous helically wound thread which begins at the ends and spirals towards the medial portion of shaft 32 as it migrates from the ends please see fig3 the threads 60 include a sharpened crest 70 defining a major diameter 62 of the threads and a root 80 defining a minor diameter 64 of the threads 60 as shown in detail in fig3 the threads 60 have an upper surface 66 which extends from a bottom edge 84 of the root 80 to the sharpened crest 70 the threads 60 also include a lower surface 68 which extends from a top edge 82 of the root 80 to the sharpened crest 70 both the upper surface 66 and lower surface 68 angle toward the medial portion of the fastener as the surfaces 66 68 extend from the root 80 to the crest 70 in section the surfaces 66 68 extend linearly from the root 80 to the sharpened crest 70 however as this contour is rotated helically about the threaded shaft 32 along with the threads 60 the upper surface 66.