Polyaxial bone anchor with pop-on shank and friction fit retainer with low profile edge lock
View Patent ↗A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in an integral receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. A down-loadable compression insert, a down-loadable friction fit split retaining ring having inner and outer tangs and an up-loadable shank upper portion cooperate to provide for pop- or snap-on assembly of the shank with the receiver either prior to or after implantation of the shank into a vertebra. The shank and receiver once assembled cannot be disassembled.
1. A bone anchor assembly including:
a) a body for attachment to a bone;
b) a receiver having a vertical first axis and a pair of spaced upstanding arms forming a channel therebetween, the channel having a second axis transverse to the vertical first axis;
c) a sleeve having a body with opposed end surfaces, a top surface, and a first smooth through bore being in the direction of the second axis and extending through the opposed end surfaces and a second smooth through bore being transverse to the first smooth through bore extending through the top surface only and into the first smooth through bore, the second smooth through bore having a third axis, the sleeve body being sized and shaped to be received in-between the pair of spaced upstanding arms in a final position such that the third axis remains co-axially aligned with the vertical axis.
2. The bone anchor assembly according to claim 1 , the sleeve having a portion at least partially overlapped by a spacer.
3. The bone anchor assembly according to claim 2 , wherein the spacer overlaps at least the top of the sleeve portion.
4. A bone anchor assembly including:
a) a body for fixation to a bone;
b) a receiver having a first vertical axis extending vertically through a pair of spaced upstanding arms forming a channel therebetween, the channel having a second axis transverse to the first vertical axis;
c) a sleeve having a body with a longitudinal opening and at least one protruding portion that extends outward from the receiver channel in the direction of the second axis; and wherein
d) the sleeve includes a smooth aperture on a top surface thereof communicating with the longitudinal opening, the smooth opening having a third axis, the sleeve body being sized and shaped such that the third axis remains co-axially aligned with the first vertical axis when the sleeve is positioned in the receiver channel in a final position.