Medical device employing a coaxial screw gear sleeve mechanism

1. A spinal implant extending along a longitudinal axis between a first region and a second region, the spinal implant comprising:

an upper body for contacting an upper vertebral body;

a lower body for contacting a lower vertebral body;

a first member located in the first region, the first member being translatable in a first direction with respect to cause the upper and lower bodies to move away from one another in at least the first region;

a second member located in the second region, the second member being translatable in a second direction to cause the upper and lower bodies to move away from one another in at least the second region;

a first actuator extending along a first axis and operably connected to the first member such that actuation of the first actuator causes the first member to translate in the first direction; and

a second actuator extending along a second axis and operably connected to the second member such that actuation of the second actuator causes the second member to translate in the second direction;

wherein the first and second actuators are actuatable independently of one another to independently move the upper and lower bodies away from one another in the respective first and second regions, and wherein the first and second axes of the respective first and second actuators are collinear with one another.

2. The spinal implant of claim 1 , wherein the first member is translatable in the first direction with respect to both of the upper and lower bodies, and wherein the second member is translatable in the second direction with respect to both of the upper and lower bodies.

3. The spinal implant of claim 1 , further comprising a connector for engaging a delivery system configured to position the spinal implant in an intervertebral space between the upper and lower vertebral bodies, wherein the longitudinal axis extends in a proximal-distal direction and the connector is disposed at a proximal end of the implant, such that the first region is positioned in a proximal portion of the implant and the second region is disposed in a distal portion of the implant.

4. The spinal implant of claim 3 , wherein the collinear first and second axes of the respective first and second actuators extend to the proximal end of the implant for actuation by a user.

5. The spinal implant of claim 3 , wherein at least a portion of the second actuator extending along the second axis is disposed within a portion of the first actuator extending along the first axis.

6. The spinal implant of claim 1 , wherein at least a portion of the second actuator extending along the second axis is disposed within a portion of the first actuator extending along the first axis.

7. The spinal implant of claim 1 , wherein the first and second members each include a respective outer surface having external threads thereon.

8. The spinal implant of claim 7 , wherein the external threads of the first and second members have gear teeth formed thereon.

9. The spinal implant of claim 7 , wherein the external threads of the first and second members engage respective threads formed in the lower body, such that the translation of the first member along the first direction is driven by advancement of the external threads of the first member along the respective threads formed in the lower body, and the translation of the second member along the second direction is driven by advancement of the external threads of the second member along the respective threads formed in the lower body.

10. The spinal implant of claim 1 , wherein the first and second actuators are operably connected with gear teeth on the respective first and second members.

11. The spinal implant of claim 1 , wherein each of the first and second members includes an opening having internal threads formed therein, wherein the internal threads of the first member are engaged with external threads of a first post member positioned within the opening of the first member, and wherein the internal threads of the second member are engaged with external threads of a second post member positioned within the opening of the second member.

12. The spinal implant of claim 11 , wherein the first and second post members are connected to the upper body.

13. The spinal implant of claim 12 , wherein the first post member is engaged with the first member such that the first post member telescopes out of the opening of the first member along the first direction while the first actuator causes the first member to translate in the first direction, and wherein the second post member is engaged with the second member such that the second post member telescopes out of the opening of the second member along the second direction while the second actuator causes the second member to translate in the second direction.

14. The spinal implant of claim 1 , wherein the first actuator is operably connected to the first member such that actuation of the first actuator causes the first member to rotate about a first axis, and wherein the second actuator is operably connected to the second member such that actuation of the second actuator causes the second member to rotate about a second axis.

15. The spinal implant of claim 14 , wherein the first axis extends along the first direction, and the second axis extends along the second direction.

16. The spinal implant of claim 14 , wherein the first actuator is a first worm operably connected to an outer surface of the first member, and wherein the second actuator is a second worm operably connected to an outer surface of the second member.

17. The spinal implant of claim 1 , wherein each of the first and second members includes an opening having internal threads formed therein, and wherein each of the openings extends entirely through the respective first and second member.

18. The spinal implant of claim 1 , wherein each of the first and second members has a respective helical raceway containing recirculating bearings.

19. The spinal implant of claim 1 , wherein the first direction of translation of the first member extends along the direction in which the upper and lower bodies move away from one another in the first region, and wherein the second direction of translation of the second member extends along the direction in which the upper and lower bodies move away from one another in the second region.

20. The spinal implant of claim 1 , wherein the first and second directions of translation of the respective first and second members extend orthogonal to the collinear first and second axes of the respective first and second actuators.

21. The spinal implant of claim 1 , wherein the first member is translatable in the first direction with respect to at least one of the upper and lower bodies, and wherein the second member is translatable in the second direction with respect to at least one of the upper and lower bodies.

22. The spinal implant of claim 1 , wherein at least one of the first and second members includes an opening having internal threads formed therein.