Ipsilateral approach to minimally invasive ligament decompression procedure

1. 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) generating at least one view of a portion of the spinal canal in the region of interest;

b) 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 generally between the working zone and the dural sac;

c) percutaneously accessing the region of interest on a first lateral side of the median plane via a tool trajectory that passes generally between a lamina of a superior first vertebra and a lamina of an inferior second vertebra and generally between the two superior articular processes of the inferior second vertebra, wherein the first and second vertebra are adjacent;

d) inserting a tissue removal tool into tissue in the working zone on the first lateral side of the median plane via the tool trajectory;

e) using the tissue removal tool to percutaneously reduce the stenosis on the first lateral side of the median plane; and

f) utilizing the at least one view to position the tissue removal tool during at least a part of step d) and at least part of step e).

2. The method of claim 1 wherein a portion of a ligamentum flavum occupies the working zone in the region of interest, and wherein step e) comprises inserting the tissue removal tool into the ligamentum flavum in the region of interest and removing at least a portion of the ligamentum flavum in the region of interest.

3. The method of claim 2 , wherein the ligamentum flavum in the region of interest has an anterior surface extending into the spinal canal and a posterior surface distal the spinal canal and wherein portions of the ligamentum flavum are first removed from the ligamentum flavum proximal to the anterior surface.

4. The method of claim 1 wherein said at least one view is a caudal-cranial posterior view.

5. The method of claim 1 wherein said at least one view is a caudal-cranial posterior-lateral view.

6. The method of claim 4 wherein the patient has an anterior front surface and a posterior back surface, and wherein the caudal-cranial posterior view is generated by positioning an imaging device at an angle Θ relative to the posterior back surface, wherein Θ is between 50 and 80 degrees.

7. The method of claim 5 wherein the patient has an anterior front surface and a posterior back surface, and wherein the caudal-cranial posterior-lateral view is generated by positioning an imaging device at an angle Θ relative to the posterior back surface and positioning the imaging device lateral to the spine, wherein Θ is between 50 and 80 degrees.

8. The method of claim 1 , further comprising utilizing a caudal-cranial posterior view and a caudal-cranial posterior-lateral view to perform at least part of steps d) and e).

9. A method of accessing a spinal location of a patient wherein the patient has a posterior back surface and wherein the method comprises:

a) positioning an instrument against the posterior back surface, wherein the instrument is positioned for insertion in a generally superior direction and is positioned at an initial angle relative to a generally longitudinal axis of the patient's spine, wherein the initial angle is less than about 20 degrees;

b) inserting the instrument into the posterior back surface of the patient generally toward a region of interest, wherein the region of interest includes a working zone;

c) advancing the instrument towards the region of interest along an ipsilateral trajectory that passes generally between a lamina of a superior first vertebra and a lamina of an inferior second vertebra and generally between the two superior articular processes of the inferior second vertebra, wherein the first and second vertebra are adjacent;

d) inserting the instrument into the working zone; and

e) removing tissue from the working zone.

10. The method of claim 9 wherein the instrument is initially inserted into the posterior back surface of the patient between about 5 and about 10 cm inferior to the region of interest.

11. The method of claim 9 wherein the instrument is adjustable to an angle .theta. that is between about 0 and about 90 degrees relative to the posterior back surface.

12. The method of claim 9 , wherein the instrument comprises a cannula having a central bore configured to receive a tissue removal tool.

13. The method of claim 9 , wherein the instrument is a tissue removal tool configured to remove tissue from the working zone.

14. The method of claim 1 wherein step e) comprises:

e1) engaging a tissue sample in the working zone with the tissue removal tool;

e2) excising the tissue sample with the tissue removal tool;

e3) removing the tissue sample from the working zone with the tissue removal tool; and

e4) repeating steps e1) through e3) until a desired amount of tissue has been removed.

15. The method of claim 14 wherein the tissue sample comprises tissue selected from the group consisting of the ligamentum flavum, fat, and bone.

16. The method of claim 14 wherein step e3 is carried out without repositioning the tissue removal tool in the tissue.

17. The method of claim 1 wherein the injected fluid includes a contrast medium.

18. The method of claim 1 wherein the injected fluid has a temperature-dependent viscosity and is more viscous at 37° C. than at 30° C.

19. The method of claim 9 , wherein fluoroscopic imaging is used during at least one of step c) and d).