Transforaminal intersomatic cage for an intervertebral fusion graft and an instrument for implanting the cage

Abstract

This present invention concerns a transforaminal intersomatic cage for an intervertebral fusion graft, and an instrument and method for implanting the cage, an embodiment of the cage having a body in the shape of a circular arc and comprising a lateral concave surface, a lateral convex surface, a straight upper surface, a straight lower surface and an end wall having at least one hole, called the end hole, designed to receive a rod of an instrument for implanting the cage between the vertebrae, wherein: the end hole has an orientation that is more or less tangential to the circular arc described by the body; the extremity opposite to the end wall of the body includes a return part extending the body toward the centre of the circle on which the circular arc described by the body lies.

1 - 17 . (canceled) 
     
     
         18 . An instrument for the implantation of an intersomatic cage for an intervertebral fusion graft comprising a body generally defining an arc, the body comprising a lateral concave surface; a lateral convex surface; a substantially transverse upper surface; a substantially transverse lower surface; an end wall at a first longitudinal extremity of the body, the end wall comprising an end hole oriented substantially tangential to the arc defined by the body; said instrument comprising:
 a rod comprising a retaining end configured for insertion in the end hole;   a gripping end for gripping the intersomatic cage, the gripping end comprising   a support spatula comprising a base and generally defining an arc complementary to the arc defined by the body,   a guide tube in which the rod is slidably disposed and to which the base of the support spatula is mounted, the guide tube comprising an opening through which the retaining end of the rod can transit for insertion in the end hole; and   a handling end for manipulating the instrument.   
     
     
         19 . An instrument according to  claim 18 , wherein the rod extends substantially to the vicinity of the handling end of the instrument. 
     
     
         20 . An instrument according to  claim 18 , wherein the instrument comprises a button attached to the rod and a groove through which the button projects, the button being configured for sliding the rod to adjust the position of the retaining end of the rod in relation to the opening in the guide tube. 
     
     
         21 . An instrument according to  claim 18 , wherein the guide tube comprises a pin configured to engage a recess disposed on the end wall of the intersomatic cage. 
     
     
         22 . An instrument according to  claim 18 , wherein the support spatula comprises an end portion distal from the base, the end portion configured for insertion into a return hole disposed on an incurvate return part of the intersomatic cage, which return hole is oriented substantially tangential to the arc defined by the body. 
     
     
         23 . An instrument according to  claim 22 , wherein the guide tube comprises a pin configured to engage a recess disposed on the end wall of the intersomatic cage, the retaining end of the rod, the pin, and the end portion of the implantation instrument being configured to cooperate with, respectively, the end hole, the recess, and the return hole, to secure a grip on the intersomatic cage by the implantation instrument, and to facilitate the withdrawal of the instrument following implantation of the intersomatic cage by removing the retaining end of the rod from the end hole. 
     
     
         24 . An instrument according to  claim 18 , further comprising an aiming tube that extends substantially to the vicinity of the handling end of the instrument, wherein the guide tube comprises a mobile portion that pivots in relation to the aiming tube at least in a primary pivot direction, the primary pivot direction lying substantially within a plane in which the arc defined by the support spatula lies, and the position of the mobile portion in relation to the aiming tube defining a pivot angle. 
     
     
         25 . An instrument according to  claim 24 , wherein one of the mobile portion or the aiming tube comprises a substantially spherical end, and the other of the mobile portion or the aiming tube comprises a recessed end having a shape and dimensions complementary to the shape and dimensions of the spherical end, the spherical end and the recessed end being configured, respectively, as a ball component and a socket component of a ball and socket connection. 
     
     
         26 . An instrument according to  claim 25 , wherein the socket component comprises opening edge portions, one of which portions is proximal to the support spatula and is configured to encompass the ball component less than the other opening edge portions to allow further pivoting of the mobile portion in relation to the aiming tube at least in the primary pivot direction. 
     
     
         27 . An instrument according to  claim 25 , wherein the rod is flexible and slidably transits the ball and socket connection through a channel located at the centre of the ball component and the socket component, the channel having a hollowed portion proximal to the support spatula, the hollowed portion configured to allow the rod to slide through the ball and socket connection even when the mobile portion is pivoted in relation to the aiming tube. 
     
     
         28 . An instrument according to  claim 24 , the instrument further comprising a lock slidably disposed along the aiming tube, the lock having a forward position and being configured to fix the mobile portion of the guide tube at a selected pivot angle when the lock is disposed in the forward position. 
     
     
         29 . An instrument according to  claim 28 , wherein the mobile portion comprises a serration configured to increase the maximum pivot angle at which the mobile portion of the guide tube can be fixed by the lock and to provide a pre-determined pivot angle. 
     
     
         30 . An instrument according to  claim 29 , wherein the serration is configured for engagement with the lock without disposing the lock in the forward position, said engagement establishing a pre-determined pivot angle and preventing pivoting of the mobile portion. 
     
     
         31 . An instrument according to  claim 18 , wherein the handling end of the instrument comprises a handle configured to allow the manipulation of the instrument and to facilitate the implantation of the intersomatic cage between the vertebrae. 
     
     
         32 . A method for implanting an intersomatic cage for an intervertebral fusion graft into the disc space between adjacent vertebrae of a vertebral column, said disc space comprising an annulus and a nucleus, said method comprising the steps of:
 providing an intersomatic cage for an intervertebral fusion graft comprising a body generally defining an arc, the body comprising:
 a lateral concave surface, 
 a lateral convex surface, 
 a substantially transverse upper surface, 
 a substantially transverse lower surface, 
 an end wall at a first longitudinal extremity of the body, the end wall comprising an end hole configured to receive a retaining end of a rod of an implantation instrument and oriented substantially tangential to the arc defined by the body, and 
 an incurvate return part at a second longitudinal extremity of the body opposite the end wall, the return part comprising a return hole oriented substantially tangential to the arc defined by the body and configured to receive an end portion of an implantation instrument; 
   providing an instrument comprising:
 a rod comprising a retaining end configured for insertion in the end hole, 
 a gripping end for gripping the intersomatic cage, the gripping end comprising a support spatula comprising a base and generally defining an arc complementary to the arc defined by the body, the support spatula comprising an end portion distal from the base configured for insertion into the return hole of the intersomatic cage, and 
 a guide tube in which the rod is slidably disposed and to which the base of the support spatula is mounted, the guide tube comprising an opening through which the retaining end of the rod can transit for insertion in the end hole, and 
 a handling end for manipulating the instrument; 
   making an incision to access the vertebral column;   incising the annulus and removing the nucleus from the disc space;   inserting the end portion of the spatula into the return hole of the intersomatic cage;   disposing the arc defined by the body proximal to the arc defined by the spatula;   fixing the intersomatic cage onto the instrument by inserting the retaining end of the rod into the end hole;   disposing the intersomatic cage in the disc space in an arcing movement;   releasing the intersomatic cage from the instrument by removing the retaining end of the rod from the end hole;   removing the instrument from the disc space; and   suturing the annulus and the skin.   
     
     
         33 . A method according to  claim 32 , wherein the step of disposing the intersomatic cage in the disc space is preceded or accompanied by a step of articulating a mobile portion of the instrument to a selected angle, said step of articulating the mobile portion being followed by a step of locking the mobile portion at the selected angle. 
     
     
         34 . A method according to  claim 32 , wherein the step of disposing the intersomatic cage in the disc space is followed by the steps of determining the position and orientation of the intersomatic cage in the disc space by detecting a radio-opaque marker comprised in the body of the intersomatic cage with x-rays and, if such position or orientation is improper, adjusting the position or orientation of the intersomatic cage in the disc space. 
     
     
         35 . A method according to  claim 32 , wherein the steps of inserting the end portion of the spatula into the return hole of the intersomatic cage and disposing the arc defined by the body proximal to the arc defined by the spatula are followed by, and the step of fixing the intersomatic cage onto the instrument by inserting the retaining end of the rod into the end hole is preceded by, a step of engaging a pin of the instrument with a recess disposed on the end wall of the intersomatic cage. 
     
     
         36 . A method according to  claim 32 , wherein the step of disposing the intersomatic cage in the disc space is preceded by a step of distraction of the adjacent vertebrae. 
     
     
         37 . An intersomatic cage for an intervertebral fusion graft comprising:
 an elongated, curved body with first and second ends; a lateral concave surface defining a lateral arc congruent with the lateral concave surface and extending past the first and second ends of the body, with the lateral concave surface configured to mate with a complementary support of an insertion instrument; a lateral convex surface; a substantially transverse upper surface; a substantially transverse lower surface; and an incurvate return part located at the second end of the body and protruding from the body across the lateral arc, with the incurvate return part disposed on the concave side of the lateral arc and the rest of the body lying on the convex side of the lateral arc.