Expansible two-part self-tapping orthopaedic bone screw - has auxiliary screw fitting into threaded portion of main screw body with radially-slotted threaded shank to cause radial expansion

摘要

The screw has a head (11) at one end of a threaded shank (12) which includes a number of radial slots (14) running longitudinally and communicating with an axial bore. The bore includes a central portion (18a) with an internal thread, linking a wider smooth proximal portion (18) to a narrower distal extension (19). An auxiliary screw (20) is threaded for insertion into the axial bore of the screw, such as to engage with its central threaded portion and enter the narrower portion, causing radial expansion of the distal end of the screw. The auxiliary screw has a threaded shank portion longer than the threaded portion of the bore of the main screw. ADVANTAGE - Combined self-tapping and expansible actions, giving greater flexibility of application.