Bone screw retaining system

Abstract

A bone screw retention system is provided for a plate which defines a plurality of transversely extending bores that are configured to receive a bone screw for engaging the plate to the cervical spine. One or more retention members, having an elliptical, arcuate, straight, u-shaped, or other shape, can be positioned therein a cavity of the plate such that portions of the retention member(s) extend into a portion of an upper region of each bore to retain a bone screw therein. A bone screw removal device is provided, having at least one tongue member configured to selectively displace the one or more retention members to allow the bone screw to be removed from the respective bore.

What is claimed is: 
     
         1 . A bone screw retention system for retaining bone screws therein, and releasing bone screws therefrom, a plate that defines a plurality of transversely extending bores configured for receiving bone screws and a retention member cavity corresponding to each bore, the retaining system comprising:
 a non-circular elastically deformable retention member having a length and a width that is shorter than the length, wherein at least a portion of the retention member is positioned therein each at least one cavity such that portions of the at least one retention member extend into an upper region of each of the bores, wherein the retention member is configured to mount therein the at least one cavity and is movable between a first relaxed position and a second expanded position, wherein, in the first relaxed position, a portion of the retention member extends inwardly substantially transverse to and toward the longitudinal axis of the respective bore and into the upper region of the bore, which decreases an effective inner diameter of the upper region of the bore, and wherein, in the second expanded position, portions of the retention member are medially biased outwardly away from the longitudinal axis of the bore towards an outer wall of the upper region of the bore, which increases the effective inner diameter of the upper region of the bore, and wherein, in the first relaxed position only two points along the length of the retention member are in contact with and substantially retain a portion of the bone screw.   
     
     
         2 . The bone screw retention system of  claim 1 , wherein, in the first relaxed position, the retention member is substantially oval in shape. 
     
     
         3 . The bone screw retention system of  claim 1 , wherein, in the first relaxed position, the retention member is substantially elliptical in shape. 
     
     
         4 . The bone screw retention system of  claim 1 , wherein, in the first relaxed position, the retention member is substantially rectangular in shape. 
     
     
         5 . The bone screw retention system of  claim 1 , wherein the elastically deformable retention member comprises a plurality of elastically deformable retention members. 
     
     
         6 . The bone screw retention system of  claim 5 , wherein the elastically deformable retention member is positioned therein each at least one cavity such that a center of the retention member is substantially the same geometrically when the at least one retention member is in the first relaxed position and the second expanded position. 
     
     
         7 . The bone screw removal system of  claim 1 , further comprising a means for engaging portions of the retention member thereby medially biasing portions of the retention member away from the longitudinal axis of the bore towards an outer wall of the upper region of the bore increasing the effective inner diameter of the upper region of the bore. 
     
     
         8 . The bone screw retention system of  claim 1 , further comprising a bone screw removal system. 
     
     
         9 . A bone screw retention system comprising:
 a plate that defines a plurality of transversely extending bores configured for receiving bone screws and a retention member cavity corresponding to each bore;   a non-circular elastically deformable retention member having a length and a width that is shorter than the length, wherein at least a portion of the retention member is positioned therein each at least one cavity such that portions of the at least one retention member extend into an upper region of each of the bores, wherein the retention member is configured to mount therein the at least one cavity and is movable between a first relaxed position and a second expanded position, wherein, in the first relaxed position, a portion of the retention member extends inwardly substantially transverse to and toward the longitudinal axis of the respective bore and into the upper region of the bore, which decreases an effective inner diameter of the upper region of the bore, and wherein, in the second expanded position, portions of the retention member are medially biased outwardly away from the longitudinal axis of the bore towards an outer wall of the upper region of the bore, which increases the effective inner diameter of the upper region of the bore, and wherein, in the first relaxed position only two points along the length of the retention member are in contact with and substantially retain a portion of the bone screw; and   a bone screw removal system.