Polyaxial bone screw assembly
a bone screw and assembly technology, applied in the field of polyaxial bone screws, can solve the problems of significant radially outward pressure or force being applied to the arms of the bone screw receiver, difficult or impossible to do, and difficult to handle, etc., and achieves low profile, easy to use, and low cost.
Inactive Publication Date: 2013-10-17
JACKSON
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Benefits of technology
The solution provides a stable and secure fixation of the rod within the bone screw, preventing relative motion and splaying of the screw arms, thus enhancing the durability and reliability of the spinal implant assembly.
Problems solved by technology
This is sometimes very difficult or impossible to do.
Certain prior art plug type closures have been threadably received between the opposed arms of the bone screw receiver using conventional V-shaped thread forms which has resulted in a significant amount of radially outward pressure or force being applied to the arms of the bone screw receiver.
Such outward force may result in splaying of the arms, after which the closure becomes loose which may either result in a failure of the implant by allowing the rod to slip relative to the bone screw or the closure may even come completely out of the receiver of the bone screw for total failure of the implant.
Bone screw compression inserts may desirably reduce relative motion between the rod and the bone screw, but may be undesirable in practice as they may also require separate insertion during surgery, after implantation of the bone screw shank, and may be small and thus difficult to handle.
Alternatively, compression inserts loaded in a bone screw prior to implantation may obstruct bone screw features utilized for driving the threaded bone screw shank into bone, or require less than desirable modifications in the bone screw, decreasing strength and / or requiring specialized driving tools.
Method used
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[0032]As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.
[0033]With reference to FIGS. 1-14, the reference numeral 1 generally designates a polyaxial bone screw assembly according to the present invention. The assembly 1 includes a shank 4 that further includes a body 6 integral with an upwardly extending, substantially cylindrical end or capture structure 8; a receiver or head 10; a retaining and articulating structure 12; and a compression structure 14. The shank 4, the receiver 10, the retaining and articulating...
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A polyaxial bone screw assembly for capturing a rod includes a receiver, a threaded shank body having an upper capture portion mated with a retaining and articulating structure, a compression insert and a closure having a domed bottom. The closure captures and fixes the rod within the receiver between the domed bottom and the compression insert, the insert pressing on the retaining and articulating structure to fix such structure against the receiver.
Description
CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 12 / 924,260, filed Sep. 23, 2010 that was a continuation-in-part of U.S. patent application Ser. No. 11 / 385,957, filed Mar. 21, 2006, that was a continuation-in-part of U.S. patent application Ser. No. 11 / 178,854 filed Jul. 11, 2005, now U.S. Pat. No. 7,789,896, that claimed the benefit of U.S. Provisional Application No. 60 / 655,239 filed Feb. 22, 2005 and Ser. No. 12 / 924,260 also was a continuation-in-part of U.S. patent application Ser. No. 11 / 140,343, now U.S. Pat. No. 7,776,067, all of the noted prior applications are incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]The present invention is directed to polyaxial bone screws for use in bone surgery, particularly spinal surgery.[0003]Bone screws are utilized in many types of spinal surgery, such as for osteosynthesis, in order to secure various implants to vertebrae along the spinal column for the pur...
Claims
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IPC IPC(8): A61B17/70
CPCA61B17/7037A61B17/7032A61B2090/037A61B90/03A61B17/8685A61B17/7028A61B17/7035A61B17/8625A61B17/864
InventorJACKSON
OwnerJACKSON