proximal barb section 111 may be twice the length of the distal barb section 113 the width of the hilt 102 indicated by 112 in fig1 may be about 0 0 mm to about 5 0 mm each barb may have a barb angle 114 being symmetrical to the center line of the pin of for example approximately 15 u00b0 to approximately 25 u00b0 details of the barbs will now be described with reference to fig1 a barb crest 121 may be pointed or dull a frustum connection 122 which connects each barb with an adjacent barb may be sharp or rounded a barb minor diameter 123 may be approximately 65 to approximately 75 of a barb major diameter 124 and the barb major diameter 124 may be approximately 130 to approximately 150 of the barb minor diameter 123 half of the difference between the barb major diameter 124 and the barb minor diameter 123 yields the barb height 126 a barb frustum angle 127 may be obtuse creating a dull crest or acute yielding a sharp and pointed crest the barb length 125 may be approximately 1 0 mm to approximately 3 0 mm and may vary from barb to barb on the same pin a third exemplary embodiment of the present invention will now be described with reference to fig1 13 in the first and second exemplary embodiments the barbs are depicted as being frustoconical the outer surface of each barb is continuous and each cross section taken perpendicular to the main axis of the pin may be defined by a circle in the third exemplary embodiment by contrast various voids are created in each barb resulting in spokes 131 a fourth exemplary embodiment of the present invention will now be described with reference to fig1 15 similar.