Impulsive percussion instruments for endplate preparation

Abstract

A hand-held instrument, with a rotary power input to a camshaft, has cam and follower arrangement to provide a reciprocating shaft output. A cutter is provided on the output shaft. In one example, rotating cam percussion is transmitted to the cutter by engaging the cutter with the tissue to be cut, and pushing the instrument forward toward the cutter. In another example, rotating cam percussion is transmitted to the cutter by engaging the cutter with the tissue to be cut, and pulling the instrument back toward the user while maintaining engagement of the cutter with the tissue. In both examples, the cutter remains in idle condition until an axially directed load, forward in the one example, or backward on the other example, is placed on the cutter by moving the instrument forward or backward, respectively, while the camshaft is rotating. A distractor with frame is used to spread and maintain space between vertebral bodies, enabling entrance of the cutter.

1 .- 34 . (canceled) 
   
   
       35 . A surgical method for treating vertebral endplates, comprising:
 selecting an elongate disc space keeper frame having two side members and front, intermediate and rear cross members;   engaging with the frame a distractor having a wedge portion, head portion, handle portion and a hook;   receiving the front cross member of the frame in a groove defined in a front tip of the wedge portion of the distractor;   receiving the intermediate cross member of the frame in the hook on the distractor; and   inserting the frame into the intervertebral disc space from an anterior approach by displacing the distractor.   
   
   
       36 . The method of  claim 35  and further comprising:
 removing the distractor from the frame while leaving the distractor front cross member and portions of the side members in the disc space to maintain the disc space for insertion of cutter instruments adapted for the preparation of vertebral endplates for receipt of an interbody fusion device.   
   
   
       37 . A combination distractor and disc space keeper for use in spinal surgery, comprising:
 an elongate frame having two side members and front, intermediate and rear cross members; and   a distractor having a wedge portion, head portion, handle portion and a forward facing hook;   the wedge portion of the distractor having a tip at the front of the wedge portion and having a forward facing groove in the tip; and   the front cross member of the frame being received in the groove in the tip of the wedge portion, and the intermediate cross member of the frame being received in the hook of the distractor.   
   
   
       38 . The combination of  claim 37  and wherein:
 the wedge portion of the distractor is located between the frame side members.   
   
   
       39 . The combination of  claim 38  and wherein:
 the head portion of the distractor is located between portions of the side members of the frame.   
   
   
       40 . The combination of  claim 38  and wherein:
 portions of the wedge portion are adjacent frontal portions of the side members and diverge vertically in a rearward direction from a rounded tip to a shoulder at the head portion.   
   
   
       41 . The combination of  claim 40  and wherein:
 the frontal portions of the side members of the frame adjacent the wedge portion diverge in a manner similar to the wedge portion from the front cross member rearward.   
   
   
       42 . The combination of  claim 41  and wherein:
 the handle portion and wedge portion and front cross member lie in a first plane; and   the side members have portions intermediate the frontal portions and extending rearward from the frontal portions and away from the first plane to the rear cross member in a second plane offset from the first plane to admit a powered instrument to the space between the planes upon separation of the distractor from the frame.   
   
   
       43 . The combination of  claim 42  and wherein:
 the departure of the intermediate portions of the side members from the first plane to the second plane is sufficient to admit a cutter instrument into the space between the planes.   
   
   
       44 . A combination distractor and disc space keeper for use in spinal surgery, comprising:
 a distractor extending along a longitudinal axis and including a wedge portion, an elongate shaft portion, and a forward facing engagement portion, the wedge portion having a distal tip and upper and lower surfaces that diverge away from one another from the distal tip in a rearward direction toward the shaft portion;   an elongate frame having two side members laterally offset from one another to define a housing space therebetween, the frame including a transverse cross member between the side members; and   wherein the distractor and the frame are removably assembled together with the wedge portion of the distractor positioned within the housing space between the side members of the frame and with the forward facing engagement portion of the distractor engaged with the transverse cross member of the frame.   
   
   
       45 . The combination of  claim 44 , wherein the frame includes a front transverse cross member and a rear transverse cross member each extending between the side members. 
   
   
       46 . The combination of  claim 44 , wherein the distal tip of the wedge portion of the distractor has a forward facing transverse groove; and
 wherein the frame includes a front transverse cross member extending between the side members; and   wherein the front transverse cross member of the frame is received in the transverse groove in the distal tip of the wedge portion when the wedge portion is positioned within the housing space between the side members of the frame.   
   
   
       47 . The combination of  claim 44 , wherein the forward facing engagement portion of the distractor comprises a forward facing hook; and
 wherein the transverse cross member of the frame comprises a transverse pin; and   wherein the transverse pin is received in the forward facing hook when the wedge portion of the distractor is positioned within the housing space between the side members of the frame.   
   
   
       48 . The combination of  claim 47 , wherein the forward facing hook of the distractor extends transversely from the shaft portion of the distractor. 
   
   
       49 . The combination of  claim 44 , wherein the distractor further includes a head portion between the wedge portion and the shaft portion, the distractor defining abutment shoulders at the transition from the wedge portion to the head portion and extending outward from the upper and lower surfaces of the wedge portion, respectively. 
   
   
       50 . The combination of  claim 49 , wherein the abutment shoulders have an arcuate shape. 
   
   
       51 . The combination of  claim 44 , further comprising a cutter instrument having a cutting head sized for insertion into the housing space between the side members of the frame and adapted for preparation of vertebral endplates. 
   
   
       52 . The combination of  claim 44 , wherein the wedge portion is positioned adjacent frontal portions of the side members of the frame; and
 wherein the frontal portions of the side members include upper and lower frame surfaces that diverge in a manner similar to the upper and lower surfaces of the wedge portion in the rearward direction.   
   
   
       53 . The combination of  claim 44 , wherein the side members have frontal portions positioned adjacent the wedge portion of the distractor and lying in a first plane, intermediate portions extending rearward from the frontal portions away from the first plate, and rear portions extending rearward from the intermediate portions and lying in a second plane offset from the first plane, the first and second planes spaced apart to admit a cutter instrument in a space between the first and second planes upon removal of the distractor from the frame. 
   
   
       54 . The combination of  claim 53 , wherein the transverse cross member of the frame is offset from the first plane.