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. The shank mates and polyaxially rotates with the retaining ring inside the head. 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.

1 . A method of implanting a bone screw in a patient comprising the steps of:
 a) providing a bone screw head having a lower aperture, a cavity, a rod receiving channel wherein the aperture and channel communicate with opposite sides of the cavity;   b) providing an elongate shank having a lower threaded portion and an upper portion;   c) providing a retainer for mating with the shank that is sized and shaped to be received in the head;   d) after steps a), b) and c), loading the retainer into the head and thereafter loading said shank upper portion into said head from below and through the aperture;   e) positioning the shank upper portion to polyaxially rotate with the retainer and so as to extend above the retainer after the shank mates with the retainer; and   f) placing the rod into the channel and securing the rod in the channel.   
     
     
         2 . The method according to  claim 1  including the step of extending the shank upper portion into the channel so as to engage the rod when the rod is received in the channel. 
     
     
         3 . A method of implanting a bone screw in a patient comprising the steps of:
 a) providing:
 i) a bone screw head having a lower aperture, an interior cavity, and a rod receiving channel wherein the cavity communicates with the channel and the aperture; and 
 ii) an elongate shank having a lower threaded portion and an upper portion; then 
   b) loading said shank upper portion into said head cavity from below through said aperture; and   c) capturing said shank inside said head while allowing pivoting of said shank relative to said head during positioning and locating the shank so as to receive a downward locking force to fix the position of the shank relative to the head when fully assembled;   d) implanting the shank into a bone of a patient;   e) positioning said head into a selected angular configuration with respect to the shank; followed by   f) placing said rod into said channel;   g) applying a downward force to the upper portion of the shank; followed by   g) installing a closure in the head that closes the channel and biases against the rod.   
     
     
         4 . The method according to  claim 3  including wherein the step of implanting is performed prior to placement of the shank into the head. 
     
     
         5 . The method according to  claim 3  including wherein the step of implanting is preformed after the placement of the shank into the head. 
     
     
         6 . A method of implanting a polyaxial bone screw in a patient wherein the bone screw has a shank and a head wherein the head has a channel adapted to receive a rod comprising the steps of:
 a) providing a separate retainer to capture the shank and loading the retainer into the head;   b) uploading said shank into said head so as to be captured therein by the retainer;   c) providing the shank with an upper engagement end; and   d) positioning the shank upper engagement end above the retainer, such that the shank upper engagement end receives a downward locking force from above to fix the shank in position relative to the head when fully assembled.   
     
     
         7 . A method of assembling a bone screw for a patient comprising the steps of:
 a) providing a shank with an upper capture portion;   b) providing a bone screw head having a lower aperture, an upper channel adapted to receive an implant and an internal cavity communicating with the aperture and the channel;   c) providing a capture structure separate from the shank and the head;   d) loading the capture structure into the cavity;   e) loading the shank capture portion into the cavity; and   f) joining the capture structure to the shank upper capture portion in the cavity such that the shank thereafter polyaxially rotates together with the capture structure relative to the head.   
     
     
         8 . The method according to  claim 7  including the steps of:
 a) implanting the shank in a patient's bone; 
 b) thereafter, polyaxially rotating the shank relative to the head to a selected angular configuration of the head in comparison to the shank by rotating the shank in combination with the capture structure relative to the head; and 
 c) thereafter, locking the selected angular configuration of the shank relative to the head. 
 
     
     
         9 . The method according to  claim 8  wherein the step of implanting in the bone is performed prior to loading the shank into the head. 
     
     
         10 . The method according to  claim 8  wherein the step of implanting in the bone is performed after loading the shank into the head. 
     
     
         11 . A method constructing a polyaxial bone screw including providing a shank and a head and including the steps of:
 a) providing a retaining structure that is non-integral with said shank and loading the retaining structure separately into said head;   b) uploading of an upper portion of the shank through the aperture into the head after the retaining structure;   c) mating the retaining structure with and capturing the shank in said head wherein the retaining structure is secured to the shank and polyaxially pivots with the shank during positioning; and   d) positioning a surface of said shank upper portion above the retaining structure so as to directly receive a downward force to lock the shank with respect to the head when fully assembled.