DEVICE FOR RESECTING SPINAL TISSUE

1 . A device for excising tissue, comprising:

an outer sleeve;

an inner tubular member slidingly received within the outer sleeve;

a cutting head on a distal end of the inner tubular;

wherein the cutting head comprises at least three arms extending axially from the inner tubular;

wherein the device has an open position in which the cutting head extends from the outer sleeve, and a closed position in which the cutting head is at least partially disposed within the sleeve; and

wherein the arms are biased away flom each other when the device is in the opened position.

2 . The device of claim 1 wherein the outer sleeve has an inner surface at a radius R 1 and at least one arm has an outer frustoconical surface that extends radially to a distance greater than the radius R 1 when the device is in the open position.

3 . The device of claim 2 wherein the inner surface of the outer sleeve engages a radially outermost portion of the frustoconical surface when the device is in the closed position.

4 . The device of claim 1 wherein each arm has a fixed end integral with the inner tubular and a free end.

5 . The device of claim 4 wherein the free end of at least one arm includes a tissue grasping member.

6 . The device of claim 5 wherein said tissue grasping member comprises a tooth extending radially inwards.

7 . The device of claim 5 wherein the free end of at least one arm comprises a cutter having a beveled edge adapted to slice tissue.

8 . The device of claim 6 wherein each arm has an axial length from the fixed end to the free end, and wherein the axial length of the at least one arm comprising the tooth is greater than the axial length of the other arms.

9 . The device of claim 1 wherein at least one arm has an inner surface that includes a textured surface feature.

10 . The device of claim 9 wherein the textured surface feature comprises ridges or knurling.

11 . The device of claim 1 wherein the at least three arms define a tissue receiving space that is contiguous with a through bore of the inner tubular.

12 . The device of claim 1 wherein each arm has a fixed end and a free end and wherein the free end of each arm engages the flee end of at least one other arm when the device is in the closed position.

13 . A method for treating stenosis in a spine of a patient having a median plane, the spine including a spinal canal having a posterior surface, a dural sac and an epidural space between the posterior surface and dural sac, the location of the stenosis determining a region of interest in the spine, comprising the steps of:

a) positioning a tissue excision device adjacent the region of interest, wherein the tissue excision device comprises:

an outer sleeve;

an inner tubular member slidingly received within the outer sleeve;

a cutting head connected to a distal end of the inner tubular;

wherein the cutting head comprises at least three arms extending axially from the inner tubular;

wherein the device has an open position in which the cutting head extends from the outer sleeve, and a closed position in which the cutting head is at least partially disposed within the sleeve.

b) opening the tissue excision device by extending the cutting head from the outer sleeve;

c) inserting the tissue excision device into tissue in the region of interest;

d) closing the tissue excision device by advancing the outer sleeve over the cutting head; and

e) retracting the tissue excision device from the tissue in the region of interest.

14 . The method of claim 13 wherein a portion of the patient's ligamentum flavum occupies the region of interest, and wherein step c) comprises inserting the tissue excision device into the ligamentum flavum in the region of interest, step d) comprises cutting at least a portion of the ligamentum flavum in the region of interest, and step e) comprises removing at least a portion of the cut ligamentum flavum.

15 . The method of claim 13 further comprising the steps of compressing the dural sac in the region of interest by injecting a fluid to form a safety zone and establish a working zone in the region of interest, the safety zone lying between the working zone and the dural sac.

16 . The method of claim 13 further comprising the step of emptying the cut tissue from the tissue excision device.

17 . A kit for performing a procedure on a spine, the spine including an epidural space containing a dural sac, the lit comprising:

an insertion member for accessing the epidural space;

a volume of a contrast medium adapted to be inserted into the epidural space by the insertion member and expanded so as to compress a portion of the thecal sac and provide a safety zone within the epidural space; and

a tissue excision device comprising:

an outer sleeve;

an inner tubular member slidingly received within the outer sleeve;

a cutting head connected to a distal end of the inner tubular;

wherein the cutting head comprises at least three arms extending axially from the inner tubular;

wherein the device has an open position in which the cutting head extends from the outer sleeve, and

a closed position in which the cutting head is at least partially disposed within the sleeve.