Automated implantable bone distractor for incremental bone adjustment

• US 6,033,412 A
• Filed: 04/03/1998
• Issued: 03/07/2000
• Est. Priority Date: 04/03/1997
• Status: Expired due to Fees

• Current Assignee: David Bartholomew Smith, Gerald G. Cano, Losken H. Wolfgang, Richard J. Arnott, Thomas G. Loebig
• Original Assignee: David Bartholomew Smith, Gerald G. Cano, Losken H. Wolfgang, Richard J. Arnott, Thomas G. Loebig
• Inventors: Loebig, Thomas G., Cano, Gerald G., Smith, David W., Losken, H. Wolfgang, Arnott, Richard J.
• Primary Examiner(s): Buiz, Michael
• Assistant Examiner(s): Reip, David O.
• Application Number:
  US09/054,657
• Time in Patent Office: 704 Days
• Field of Search: 606/78, 606/76, 606/71, 606/70, 606/69, 606/62, 606/63, 606/64, 606/57, 606/58, 606/73
• US Class Current: 606/105
• CPC Class Codes: A61B 17/663 for jaw bones, e.g. subcutaneous distractors with external access periodontal bone regeneration A61C8/0006
• CPC Class Codes: A61B 17/7216 for bone lengthening or compression A61B17/7258 takes precedence
• CPC Class Codes: A61B 2017/00867 shape memory effect

Abstract

An implantable distractor that provides controlled forceful movement either to facing bone ends created by osteotomy or across cranial sutures for the purpose of fostering bone deposition to support bone growth (distraction osteogenesis). The improved Distractor adjusts separation of such through precise, forceful, incremental movements. The mechanism has an actuator powered by intermittent electrical current flow through a shape-memory-effect (SME) actuation component. The SME component deforms forcefully. This force is amplified to result in incremental separation of two plates affixed to bone on either side of the osteotomy or suture.

Claims

1. An implantable bone distractor having a longitudinal length extending generally along the direction of distraction, said distractor comprising:

a first base member adapted to be attached to the bone to be distracted;

a second base member adapted to be attached to the bone to be distracted at a position spaced across a separation in the bone from the attachment site of the first base member;

a moving means movably coupling said first base member and said second base member for incremental movement of said second base member relative to said first base member; and

An actuating means within said moving means, said actuating means including a shape-memory-effect alloy wire extending substantially along said longitudinal length of said distractor.

2. The distractor of claim 1 wherein said shape-memory-effect alloy wire undergoes Martensitic to Austenitic transformation when electrically energized so that said shape memory-effect alloy wire decreases in length, said decrease in length producing a pulling force that operates said moving means;

and said actuating means including a reset spring which applies a bias force to said shape-memory effect alloy to reset said shape-memory-effect alloy wire to its original length during and after Austenitic to Martensitic transformation.

3. The distractor of claim 1 further including connectors attached to said shape-memory-effect alloy wire, wherein said connectors electrically connect said shape-memory-effect alloy wire to electrical leads and said connectors mechanically restrain said shape-memory-effect alloy wire within said distractor.

4. The distractor of claim 1 wherein said moving means includes a ratchet.

5. The distractor of claim 1 wherein said shape-memory-effect alloy wire is an alloy of nickel and titanium.

6. The distractor of claim 1 wherein said actuating means includes a drive spring which is compressed by said shape-memory-effect alloy wire when said shape-memory-effect alloy wire is energized, said drive spring moving said moving means.

7. The distractor of claim 1 further including a rotational adjustment mechanism to rotationally adjust the orientation of said moving means relative to at least one of said base members.

8. The distractor of claim 1 wherein said moving mean is an electromechanical screw comprising:

a) a shaft and screw means;

b) a motion/force transmission means, said motion/force transmission means engaging with said shaft and screw means to impart one-way rotational motion to said shaft and screw means; and

c) a housing that contains said motion/force transmission means, said actuating means and a portion of said shaft and screw means.

9. The distractor of claim 8 wherein said motion/force transmission means converts linear motion imparted to it by said actuating means into one-way rotational motion of said shaft and screw means.

10. The distractor means of claim 8 comprising:

a) at least one pin mounted on shaft and screw means within said housing perpendicular to the length of said shaft and screw means;

b) a cylindrical cam that slidably engages said at least one pin mounted on shaft and screw means, said cylindrical cam, when angularly secured, causing said shaft and screw means to rotate; and

c) a clutch that angularly secures said cylindrical cam during rotation of said shaft and screw means, and allows said cylindrical cam to angularly reset after rotation of said shaft and screw means.

11. The distractor of claim 1 wherein said actuating means includes an electromechanical actuator means comprising:

a) a telescoping housing comprised of a first section and a second section;

b) at least one rack fixed to said first section; and

c) a gear train of at least two gears fixed to said second section, said gear train engaged by said at least one rack.

12. The distractor of claim 1 wherein said first base member and said second base member each include bilateral multihole plates, wherein said plates are adapted to be modified by cutting and bending to conform to the contour of the bone at the attachment site.

13. An implantable bone distractor having a length extending generally along the direction of distraction, said distractor comprising:

a first base member adapted to be attached to the bone to be distracted;

a second base member adapted to be attached to the bone to be distracted at a position spaced across a separation in the bone from the attaching site of said first base member;

a moving means movably coupling said first base member and said second base member for incremental movement of said second base member relative to said first base member; and

an actuating means within said moving means, said actuating means including a shape-memory-effect alloy wire at least partially extending along said length of said distractor, wherein said moving means includes at least one sealed chamber of constant volume that contains said actuating means.

14. The distractor of claim 13 further including connectors attached to said shape-memory-effect alloy wire, wherein said connectors electrically connect said shape-memory-effect alloy wire to electrical leads and said connectors mechanically restrain said shape-memory-effect alloy wire within said distractor.

15. The distractor of claim 13 wherein said moving means includes a clutch.

16. The distractor of claim 13 further including a rotational adjustment mechanism to rotationally adjust the orientation of said moving means relative to at least one of said base members.

17. An implantable bone distractor having a length extending generally along the direction of distraction, said distractor comprising:

a first base member adapted to be attached to the bone to be distracted;

a second base member adapted to be attached to the bone to be distracted at a position spaced across a separation in the bone from the attaching site of said first base member;

a moving means movably coupling said first base member and said second base member for incremental movement of said second base member relative to said first base member; and

an actuating means within said moving means, said actuating means including a shape-memory-effect alloy wire at least partially extending along said length of said distractor, wherein said moving means includes at least one sealed chamber of constant volume having a hollow lumen extending generally along the direction of distraction, wherein said shape-memory-effect alloy wire extends at least partially within said hollow lumen.

18. An implantable bone distractor comprising:

a first base member adapted to be attached to the bone to be distracted;

a second base member adapted to be attached to the bone to be distracted at a position spaced across a separation in the bone from the attachment site of said first base member;

a moving means movably coupling said first base member and said second base member for incremental movement of said second base member relative to said first base member; and

an actuating means within said moving means, said actuating means including an electrically energized shape-memory-effect alloy wire and connectors attached to said shape-memory-effect alloy wire, wherein said connectors electrically connect said shape-memory-effect alloy wire to electrical leads and said connectors mechanically secure said shape-memory-effect alloy wire within said distractor.

19. The distractor of claim 18 wherein said connectors are selected from the group consisting of crimps and screw down connectors.

20. The distractor of claim 18 wherein said moving means includes at least one sealed chamber of constant volume that contains said actuating means.

21. The distractor of claim 20 wherein said first base member and said second base member each include bilateral multihole plates, wherein said plates are adapted to be modified by cutting and bending to conform to the contour of the bone at the attachment site.