Spinal motion preservation devices and methods of use

Abstract

Orthopedic implants are adapted to replace the function of a natural disc of the spine. In an embodiment, the implant can be placed across the disc space through a trans-pedicular corridor using a substantially posterior surgical approach. In another embodiment, an implant can be placed across the disc space at a different level through a substantially lateral or anterior approach.

1 . An orthopedic implant adapted to provide and maintain motion between adjacent vertebral bodies of a human or animal subject, comprising:
 a member sized and shaped to be positioned within a pathway in a first sacral vertebra along a trajectory that has a starting point lateral to a posterior sacral foramen and medial to a sacro-iliac joint, wherein the trajectory transverses a portion of one sacral pedicle and portion of a first sacral vertebral body and enters the disc space immediately superior to the sacrum;   wherein a first portion of the implant transverses the first sacral vertebra and is adapted to adhere to the vertebral bone, and wherein a second portion of the implant positions within the disc space immediately above the sacrum and wherein the second portion is adapted to provide movement between the sacrum and the vertebra immediately above the sacrum.   
   
   
       2 . An implant as in  claim 1 , wherein the implant has a substantially curvilinear configuration. 
   
   
       3 . An implant as in  claim 1 , wherein the implant has a substantially straight configuration. 
   
   
       4 . A method for the implantation of an orthopedic device that maintains motion between adjacent vertebrae, comprising:
 positioning the device within a pathway in a first sacral vertebra along a trajectory that has a starting point lateral to a posterior sacral foramen and medial to a sacro-iliac joint, wherein the trajectory transverses a portion of one sacral pedicle and portion of a first sacral vertebral body and enters the disc space immediately superior to the sacrum, wherein the implant has a portion imparts motion, the portion being contained within the disc space.   
   
   
       5 . A method for the implanting an orthopedic device in a subject, comprising:
 implanting the orthopedic device through a lateral entry site to the spine;   positioning a distal aspect of the implant to contact a vertebra at a level other than a vertebral level from which the implant insertion was started, wherein the insertion site is initiated through the lateral entry site in the spine.   
   
   
       6 . A method as in  claim 5 , wherein the trajectory of the implant follows an at least partially curvilinear corridor within bone. 
   
   
       7 . A method as in  claim 5 , wherein the trajectory of the implant follows an at least partially straight corridor within bone. 
   
   
       8 . An anchor adapted for fixation onto a bone of a human or animal subject, comprising:
 a threaded bone screw having a curvilinear side partial defect that is adapted to form an implantation corridor for a second orthopedic implant.   
   
   
       9 . An anchor as in  claim 8  further comprising the second orthopedic implant, wherein the second orthopedic implant is rigidly securable onto the curvilinear side partial defect of the threaded bone screw. 
   
   
       10 . A device that is adapted to interconnect two anchors that are each implanted into a bone member of a human or animal subject comprising:
 a rod member that has a first bearing surface on one end, wherein the first bearing surface is contained within a second bearing surface, wherein the first and second bearing surfaces articulate with respect to one another in a manner that substantially permits rotational movement and limits translational movement;   wherein the second bearing surface is adapted to be retained by a bone anchor, such that in a first unlocked state of the bone anchor, the second bearing surface is freely movable relative to the bone anchor, and such that in a second locked state of the bone anchor, the second bearing surface is rigidly retained within the bone anchor but the first bearing surface is movable relative to the second bearing surface.   
   
   
       11 . A device as in  claim 10  wherein the first bearing surface on one end of the rod is contained within the second bearing surface and is maintained in a neutral position relative to the second bearing surface by the actions of a biasing member. 
   
   
       12 . An anchor adapted for fixation onto a bone of a human or animal subject, comprising:
 a screw member having a head and a shank;   a coupler that couples the head to a plate;   a locking member, wherein in a first state, the locking member permits the screw head to rotate relative to the coupler by virtue of a domed interface between the locking member and the coupler such that the screw can be freely rotated relative to the plate, and wherein in a second state the locking member is tightened against the coupler to lock against the coupler and fixate the coupler relative to the plate, and wherein the locking member is in the second state, the screw head can rotate at least slightly but is biased toward a neutral position.   
   
   
       13 . A method of linking a first dynamic bone screw connector to a second bone screw connector, comprising:
 removably attaching a modular connector of the first bone screw connector to a modular connector of the second bone screw connector, wherein the modular connectors are attached to one another in a manner that permits relative movement between the modular connectors.