| 摘要 |
Fasteners particularly useful as orthopedic screws comprise an external fastening member having a shank formed with a head at one end, external spiral threads extending to the opposite end, an internal bore extending axially through the head of the shank, and a plurality of side slits formed radially through the tip at the opposite end of the shank to the bore to provide a plurality of outwardly expansible tips at the latter end. The fastener also includes, an internal spreading member axially movable within the bore to engage the tips of the fastening member and thereby to outwardly spread them.
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