Upload shank swivel head bone screw spinal implant

Abstract

A polyaxial bone screw having a bone implantable shank, a head and a retaining ring. The retaining ring includes an outer partial hemispherical surface and an inner bore with radially extending channels and partial capture recesses. The shank includes a bone implantable body with an external helical wound thread and an upwardly extending capture structure. The capture structure includes at least one spline which extends radially outward and has a wedged surface that faces radially outward therefrom. The capture structure operably passes through a central bore of the retaining ring while the spline passes through a suitably shaped channel so that the spline becomes positioned above the head at which time the shank is rotated appropriately and the shank is drawn back downwardly so that the spline engages and seats in the capture recess. The head includes an internal cavity having a spherical shaped surface that mates with the ring surface and has a lower restrictive neck that prevents passage of the ring once the ring is seated in the cavity.

Description

RELATED APPLICATIONS[0001]This application is a continuation of U.S. patent application Ser. No. 10 / 818,554, filed Apr. 5, 2004, now U.S. Pat. No. ______, which is a continuation of U.S. patent application Ser. No. 10 / 464,663, filed Jun. 18, 2003, now U.S. Pat. No. 6,716,214, and a continuation-in-part of U.S. patent application Ser. No. 10 / 651,003, filed Aug. 28, 2003, now U.S. Pat. No. ______, each of which is incorporated herein in its entirety by reference.BACKGROUND OF THE INVENTION[0002]The present invention is directed to a polyaxial bone screw for use in spinal surgery and the like and especially to such a screw adapted to receive a rod member and secure the rod member to a vertebra or the like.[0003]Many spinal surgery procedures require securing various implants to bone and especially to vertebrae along the spine. For example, elongate rods are often required that extend along the spine to provide support to vertebrae that have been damaged or weakened due to injury, disea...

AI Technical Summary

Problems solved by technology

This is sometimes very difficult or impossible to do so polyaxial bone screws are commonly used.

It is very undesirable for pieces of the implant to be free to move around within the body after surgery is completed and it also assures that the implant retains an ability to correct the structural problem for which it was implanted.

Images