US Patent 7695497 Implant system for osteosynthesis

A anti-splay and rod securing member for use with vertebral implants of the hook, monoaxial and polyaxial types, in which a pair of arcuate upstanding internally threaded posts define a transverse opening for securing a rod to immobilize bone segments comprises an integrally formed cap and set screw with the cap having opposed curved side walls extending around the posts and flat end walls, the set screw being positioned within the posts and free to rotate within the cap so that rotation of the set screw will advance the cap and set screw in unison along the implant posts to clamp the rod and implant together. The implant may be provided with opposed catch basins for releasably securing the distal end of a rod persuasion instrument.