Dynamic stabilization assembly having pre-compressed spacers with differential displacements
OwnerRoger P. Jacksoninventor
Life of this patent
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Abstract
A dynamic longitudinal connecting member assembly includes an anchor member having an integral or otherwise fixed elongate core extending through at least two elastic spacers and at least one outer sleeve or trolley. The anchor member and the outer sleeve each attach to at least one bone anchor. The spacers have differing durometers and/or geometries, resulting in greater axial movement of the sleeve in one direction than in an opposite direction. The spacers are compressed prior to attachment to the bone anchors.
Claims38
In a medical implant assembly having at least two bone attachment structures cooperating with a longitudinal connecting member, the improvement wherein the longitudinal connecting member comprises:
- a) an anchor member portion in engagement with one of the at least two bone attachment structures, the anchor member portion having a core extension of reduced width, the core extension extending from the anchor member portion along a substantially central axis of the longitudinal connecting member, the width measured perpendicular to the central axis;
- b) a first elastic outer spacer, the core extension being received in the spacer, the spacer being positioned between the at least two bone attachment structures;
- c) a second elastic outer spacer, the core extension being received in the spacer, the second spacer being more compressible than the first spacer, both the first and second spacers being pre-compressed prior to attachment of the assembly to the at least two bone attachment structures;
- and
- d) at least one substantially inelastic sleeve, the core extension being received within the sleeve and in slidable relationship therewith, the at least one sleeve being in direct engagement with the other of the at least two bone attachment structures, the at least one sleeve being disposed between the first and second pre-compressed spacers, the pre-compressed spacers exerting axial forces on the at least one sleeve.
In a medical implant assembly having at least two bone anchors cooperating with a longitudinal connecting member, the improvement wherein the longitudinal connecting member comprises:
- a) an anchor member having an integral inner core extension extending therefrom along a central axis thereof;
- b) at least one elastic and pre-compressed outer spacer, the core being slidingly received in the spacer along the axis, the spacer being positioned between the at least two bone anchors, the spacer having at least a first curved end surface;
- c) at least one inelastic sleeve, the core being slidingly received within the sleeve along the axis, the sleeve being in engagement with at least one of the bone anchors, the sleeve having at least a second curved end surface;
- and
- d) at least one elastic and pre-compressed bumper disposed near an end of the core extension, the elastic bumper being more elastic than the spacer, allowing for the sleeve to move back and forth along the core a greater distance toward the bumper than toward the at least one spacer.
In a medical implant assembly having at least two bone anchors cooperating with a longitudinal connecting member, the improvement wherein the longitudinal connecting member comprises:
- a) an anchor member having a first width, the anchor member having a core extension of a second smaller width extending therefrom along a central axis thereof, the first and second widths measured in a direction perpendicular to the axis;
- b) at least one elastic outer spacer, the core extension being slidingly received in the spacer along the axis, the spacer being positioned between the at least two bone anchors;
- and
- c) at least one inelastic sleeve, the core extension being slidingly received within the sleeve along the axis, the sleeve being in engagement with at least one of the bone attachment structures, the sleeve having an inner surface defining a through bore for receiving the core, at least a portion of the inner surface being non-linear in a cross-section taken along the axis.
Dependencies are inferred from the claim text.