Spinal Dynamic Stabilization Rods Having Interior Bumpers

1 . A dynamic stabilization device comprising:

a) a first hollow cylinder having an open end, an intermediate annular portion and a closed end, the closed end defining an inner surface, the intermediate annular portion defining an outer annular surface and a first inner annular surface,

b) a first rod having an outer diameter, a first end having a first end surface, and a second end, the first end of the first rod being slidably received within the inner annular surface of the first hollow cylinder, and

c) a first elastomeric bumper having a first end and a second end,

wherein the first end of the first elastomeric bumper is attached to the inner surface of the closed surface of the first hollow cylinder, and

wherein the second end of the first elastomeric bumper is attached to the first end surface of the first end of the first rod.

2 . The device of claim 1 wherein the first elastomeric bumper has an hourglass shape in an unloaded condition.

3 . The device of claim 2 wherein the first elastomeric bumper substantially contacts the inner annular surface of the first hollow cylinder in extension.

4 . The device of claim 1 wherein the rod is curved to provide lordosis.

5 . The device of claim 4 wherein the curved rod has a length to span at least two levels of a spine.

6 . The device of claim 4 wherein the curved rod has an intermediate portion between the first end and a second end, wherein the intermediate portion is substantially straight.

7 . The device of claim 6 wherein the curved rod has a first curve between the first end and the intermediate portion, and a second curve between the second end and the intermediate portion.

8 . The device of claim 6 further comprising d) a second hollow cylinder having open ends, wherein the straight intermediate portion of the first rod is slidably disposed within the second hollow cylinder.

9 . The device of claim 8 , wherein the straight intermediate portion of the first rod is slidably disposed within the second hollow cylinder.

10 . The device of claim 8 , wherein the straight intermediate portion of the first rod is fixedly disposed within the second hollow cylinder.

11 . The polyaxial dynamic stabilization device of claim 1 further comprising:

d) a second hollow cylinder having an open end, an annular portion and a closed end, the closed end defining an inner surface, the annular portion defining an outer annular surface and an inner annular surface,

e) a second elastomeric bumper having a first end and a second end,

wherein the second end of the rod is slidably received within the inner annular surface of the second hollow cylinder,

wherein the first end of the second elastomeric bumper is attached to the inner surface of the closed surface of the second hollow cylinder, and

wherein the second end of the second elastomeric bumper is attached to the second end surface of the second end of the rod.

12 . The device of claim 1 further comprising:

d) an extension/compression stop.

13 . The device of claim 12 wherein the extension/compression stop comprises i) a slot disposed through the annular portion of the hollow cylinder, and ii) a pin extending from the outer diameter of the rod,

wherein the pin extends through and is slidably received in the slot.

14 . The device of claim 1 wherein the second end of the first rod forms a blind recess having an blind recess surface bore defining a second inner annular surface.

15 . The device of claim 14 further comprising:

d) a second rod having a first end having a first end surface, and a second end, the first end of the second rod being slidably received within the second inner annular surface of the first rod,

16 . The device of claim 15 further comprising:

e) a second elastomeric bumper having a first end and a second end,

wherein the first end of the second elastomeric bumper is attached to the blind recess surface, and

wherein the second end of the second elastomeric bumper is attached to the first end surface of the first end of the second rod.

17 . The device of claim 1 having first and second bone anchors attached thereto.

18 . The device of claim 1 wherein at least one of the hollow cylinder and the first rod has a predetermined geometry that increases its mechanical interlock with the bumper.

19 . The device of claim 18 wherein at least one of the inner surface of the closed surface of the first hollow cylinder and the first end surface of the first end of the first rod has a ribbed post extending therefrom.

20 . The device of claim 19 wherein the post has at least one circumferential groove to increase mechanical interlock with the bumper.

21 . The device of claim 1 further comprising d) a hose clamp, wherein the hose clamp is attached to i) at least one of the hollow cylinder and the first rod, and ii) at least one end of the bumper.

22 . A posterior dynamic spinal stabilization system for use in a human spine, comprising:

a) first and second bone anchors, each anchor having a recess for receiving a rod,

b) a first hollow cylinder having an open end, an intermediate annular portion and a closed end, the closed end defining an inner surface, the intermediate annular portion defining an outer annular surface and a first inner annular surface,

c) a first rod having an outer diameter, a first end having a first end surface, and a second end, the first end of the first rod being slidably received within the inner annular surface of the first hollow cylinder, and

d) a first elastomeric bumper having a first end and a second end,

wherein the first end of the first elastomeric bumper is attached to the inner surface of the closed surface of the first hollow cylinder, and

wherein the second end of the first elastomeric bumper is attached to the first end surface of the first end of the first rod.

wherein the outer annular surface of the first hollow cylinder is received in the recess of the first bone anchor,

wherein the second end of the first rod is received in the recess of the second bone anchor.

23 . The system of claim 22 wherein the elastomer bumper is located at least partially within one of the recesses of the bone anchors.

24 . A method of implanting a posterior dynamic spinal stabilization system, comprising the steps of:

a) inserting two bone anchors into adjacent pedicles within a functional spinal unit of a patient, each bone anchor having a recess for receiving a rod,

b) providing a polyaxial dynamic stabilization device comprising:

i) a first hollow cylinder having an open end, an intermediate annular portion and a closed end, the closed end defining an inner surface, the intermediate annular portion defining an outer annular surface and a first inner annular surface,

ii) a first rod having an outer diameter, a first end having a first end surface, and a second end, the first end of the first rod being slidably received within the inner annular surface of the first hollow cylinder, and

iii) a first elastomeric bumper having a first end and a second end,

wherein the first end of the first elastomeric bumper is attached to the inner surface of the closed surface of the first hollow cylinder, and

wherein the second end of the first elastomeric bumper is attached to the first end surface of the first end of the first rod,

c) fastening the outer annular surface of the first hollow cylinder into the recess of the first bone anchor, and

d) fastening the second end of the first rod into the recess of the second bone anchor.

25 . A dynamic stabilization device comprising:

a) a first hollow cylinder having an open end, an intermediate annular portion and a closed end, the closed end defining an inner surface, the intermediate annular portion defining an outer annular surface and a first inner annular surface,

b) a first rod having an outer diameter, a first end having a first end surface, and a second end, the first end of the first rod being slidably received within the inner annular surface of the first hollow cylinder, and

c) a first elastomeric bumper having a first end and a second end,

wherein the first end of the first elastomeric bumper faces the inner surface of the closed surface of the first hollow cylinder, but is unattached thereto, and

wherein the second end of the first elastomeric bumper is attached to the first end surface of the first end of the first rod.

26 . A dynamic stabilization device comprising:

a) a first hollow cylinder having an open end, an intermediate annular portion and a closed end, the closed end defining an inner surface, the intermediate annular portion defining an outer annular surface and a first inner annular surface,

b) a first rod having an outer diameter, a first end having a first end surface, and a second end, the first end of the first rod being slidably received within the inner annular surface of the first hollow cylinder, and

c) a first elastomeric bumper having a first end and a second end,

wherein the first end of the first elastomeric bumper is attached to the inner surface of the closed surface of the first hollow cylinder, and

wherein the second end of the first elastomeric bumper faces the first end surface of the first end of the first rod, but is unattached thereto

27 . A dynamic stabilization device comprising:

a) a first hollow cylinder having an open end, an intermediate annular portion and a closed end, the closed end defining an inner surface, the intermediate annular portion defining an outer annular surface and a first inner annular surface,

b) a first rod having an outer diameter, a first end having a first end surface, and a second end, the first end of the first rod being slidably received within the inner annular surface of the first hollow cylinder, and

c) a first elastomeric bumper having a first end and a second end,

wherein the first end of the first elastomeric bumper faces the inner surface of the closed surface of the first hollow cylinder, but is unattached thereto, and

wherein the second end of the first elastomeric bumper faces the first end surface of the first end of the first rod, but is unattached thereto.