Implant fixation assemblies having a screw and C-shaped fixation collar

摘要

A system for anchoring implants to bones comprises a screw and fixation collar that when connected together inhibit axial movement of the screw and that when connected to an implant with a compatibly shaped aperture inhibit the screw's ability to back out from the bone and back out from the implant. The fixation collar includes a substantially C-shaped configuration partially surrounding a void, with first and second ends defining a gap that is slightly narrower in width than the diameter of the screw and being partially flexible to allow compression and expansion of the fixation collar to snap fit the collar around the screw.

主权项

1. A screw and collar assembly comprising:
a screw comprising a head, a shoulder beneath the head, a groove between the head and shoulder, and a threaded shaft beneath the shoulder; and a C-shaped fixation collar comprising a sidewall at least partially surrounding a void that is substantially in the center of the collar and extends along an axis that is parallel to the vertical axis of the fixation collar, the sidewall comprising a recessed top portion that forms a ridge on which the bottom of the head sits when the screw is inside of the void, a bottom portion that engages the groove when the screw is inside of the void, end regions that are partially flexible along an axis that is perpendicular to the vertical axis of the fixation collar, and a first end and second end defining a gap in communication with the void, each end comprising a first notch above the ridge and a second notch below the ridge; wherein the gap has a width slightly narrower than the inner diameter of the groove, and the void has a diameter narrower than the outer diameter of the shoulder such that the screw may not be moved axially through the fixation collar, at least higher than the shoulder.