Variable height, multi-axial bone screw assembly
OwnerPeter M. Simonsoninventor
Life of this patent
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Abstract
A variable height, multi-axial bone screw assembly including a bone screw, a collet, a tulip shaped connector, a crown member, a rod and a set-screw. The bone screw has threads at its lower end and a generally cylindrical shaft at its upper end. The collet has a cylindrically shaped lower end to hold and grasp the bone screw shaft as well as a generally bulb shaped upper end to be received by the tulip shaped connector. By changing the position of the bone screw shaft grasped by the collet, the height of the bone screw vis-à-vis the tulip shaped connector can be varied. All the elements of the bone screw assembly are combined together by placing the collet head, crown member and rod within a central bore of the connector and firmly tightening them in place using the set screw.
Claims11
A bone screw assembly comprising:
- a bone engaging fastener having a lower portion configured to attach to a bone and an upper portion;
- a collet having a generally bulb shaped upper portion and a lower portion configured to connect to the upper portion of the bone engaging fastener at variable positions;
- a connector configured to receive and retain the generally, bulb shaped upper portion of said collet while allowing angular movement of the collet along multiple axes;
- and,
- a compression member adapted for insertion into said connector to hold said collet and said bone engaging fastener at fixed positions vis-à-vis said connector.
A method for assembling a bone screw assembly comprising the steps of:
- selecting a connector with an internal bore;
- inserting a collet having a generally bulb shaped upper portion and a narrower lower portion into said internal connector bore so that said generally bulb shaped upper portion is retained within said connector but said lower portion protrudes from said connector;
- selecting a bone engaging fastener having a lower portion configured to attach to a bone and an upper portion configured to connect to the lower portion of said collet at variable positions;
- inserting a compression member into said connector to hold said collet bulb in said connector and affix the upper portion of said bone engaging fastener to the lower portion of said collet at a desired position.
A method for assembling a variable height, multi-axial bone screw assembly:
- sliding a bone screw shaft into the inner bore of a collet;
- adjusting said bone screw shaft to a desired height within said collet;
- inserting said collet holding said bone screw shaft into a tulip shaped connector at a desired angular orientation;
- placing a rod into a U-shaped channel of said tulip shaped connector over said collet and bone screw shaft;
- and
- screwing a set-screw tightly onto said rod to lock together all components of said bone screw assembly.
Dependencies are inferred from the claim text.