Bone transport and lengthening system

• US 5,626,579 A
• Filed: 06/28/1995
• Issued: 05/06/1997
• Est. Priority Date: 02/12/1993
• Status: Expired due to Term

• Current Assignee: Cleveland Clinic Foundation
• Original Assignee: Cleveland Clinic Foundation
• Inventors: Kotschi, Helmuth, Muschler, George F., Smith, William A.
• Primary Examiner(s): Brown, Michael A.
• Application Number:
  US08/495,924
• Time in Patent Office: 678 Days
• Field of Search: 606/60-68, 606/72-79, 606/86, 606/87, 606/88, 606/102
• US Class Current: 606/60
• CPC Class Codes: A61B 17/66 Alignment, compression or distraction mechanisms
• CPC Class Codes: A61B 17/7216 for bone lengthening or compression A61B17/7258 takes precedence
• CPC Class Codes: A61B 2017/00137 Details of operation mode
• CPC Class Codes: A61B 2017/00867 shape memory effect for prostheses A61F2210/0014
• CPC Class Codes: A61F 2/0077 Special surfaces of prostheses, e.g. for improving ingrowth A61F2/30767 takes precedence

Abstract

A surgically implantable cable apparatus has a means for securing (32) a first bone segment (12) and a second bone segment (13). A flexible cable (17) is attached at one end relative to one bone segment (25). A flexible non-compressible sheath (15) has a bore (16) for slidably receiving the cable (17). The non-compressible sheath (15) is secured to the securing means (32) at point (40) and transmits a counter-compression force to the bone segment (25). An implantable actuator (36) is connected to the second end (19) of the flexible cable (17) and to the second end of the sheath (15). The implantable actuator (36) is fully implantable subcutaneously. The implantable actuator (36) is responsive to a transcutaneous energy signal and pulls the flexible cable (17) through the sheath (15) in an axial direction. The cable movement is applied to the bone segment (25), either directly or transmitted through an internal fixation device and the bone segment (25) moves a predetermined distance. Art energy source (42) generates the transcutaneous energy signal which activates the implantable actuator (36) through an intact skin layer (44). The transcutaneous energy signal is a magnetic field or induced electrical current.

Claims

1. A surgically implantable cable apparatus for post-operative, gradual in vivo bone transport of a first bone segment between a second bone segment and a third bone segment comprising:

a means for securing the second bone segment and the third bone segment a fixed distance from one another;

a flexible cable having a first end portion for attaching to the first bone segment, and a second end portion;

an implantable prosthetic flexible, non-compressible sheath having a bore for accepting the cable, the sheath having a first end, a second end, and a means for securing the first end to the second bone segment, the sheath being adapted to transmit a counter-compression force to the second bone segment;

an implantable actuator connected to the second end portion of the flexible cable and to the second end of the sheath, and in response to a transcutaneous energy signal, the implantable actuator moves the flexible cable relative to the sheath; and

,

an energy source for generating the transcutaneous energy signal, the transcutaneous energy signal being capable of activating the implantable actuator through an intact skin layer.

2. The surgically implantable cable apparatus as set forth in claim 1 wherein the means for securing the second bone segment and the third bone segment includes an intramedullary rod having a locking element in each of the second bone segment and the third bone segment.

3. The surgically implantable cable apparatus as set forth in claim 2 wherein the locking element includes a transverse bone screw.

4. The surgically implantable cable apparatus as set forth in claim 1 wherein the implantable actuator includes a tensioning assembly connected to the second end portion of the flexible cable for applying tension to the flexible cable.

5. The surgically implantable cable apparatus as set forth in claim 4 wherein the tensioning assembly includes a cable take-up spool, the second end portion of the flexible cable being connected to the cable take-up spool.

6. The surgically implantable cable apparatus as set forth in claim 1 wherein the implantable actuator includes a means for selectively restricting motion of the flexible cable.

7. The surgically implantable cable apparatus as set forth in claim 1 wherein the implantable actuator includes a gear stage for moving the flexible cable relative to the sheath.

8. The surgically implantable cable apparatus as set forth in claim 7 wherein the gear stage has a planocentric configuration.

9. The surgically implantable cable apparatus as set forth in claim 1 wherein the implantable actuator includes a racheting means for moving the flexible cable relative to the sheath.

10. The surgically implantable cable apparatus as set forth in claim 1 wherein the actuator includes magnetically sensitive elements;

and

wherein the energy source includes means for generating a magnetic field as the transcutaneous energy signal.

11. The surgically implantable cable apparatus as set forth in claim 10 wherein the magnetically sensitive elements include magnets, and

wherein the means for generating a magnetic field include magnets.

12. The surgically implantable cable apparatus as set forth in claim 10 wherein the implantable actuator includes a gear stage connected between the magnetically sensitive elements and the cable.

13. The surgically implantable cable apparatus as set forth in claim 10 further including a means to limit the acceleration of the magnetically sensitive elements as the energy source and the magnetically sensitive elements are approximated to each other.

14. The surgically implantable cable apparatus as set forth in claim 13 wherein the means to limit acceleration includes one of a damper, a cam, and a screw mechanism.

15. The surgically implantable cable apparatus as set forth in claim 1 wherein the actuator is electrically powered;

and,

the energy source includes means for transcutaneously activating the electrically powered actuator.

16. The surgically implantable cable apparatus as set forth in claim 15 wherein the implantable actuator further includes a receiving coil electrically connected to cable driving elements, the receiving coil generating a current in response to an external field from the energy source.

17. The surgically implantable cable apparatus as set forth in claim 1 wherein the implantable actuator includes thermally sensitive elements;

and,

wherein the energy source includes means for heating the thermally sensitive elements.

18. The surgically implantable cable apparatus as set forth in claim 17 wherein the thermally sensitive elements are made from a shape memory alloy, the thermally sensitive elements having a shape which changes as the transcutaneous energy signal from the energy source heats the temperature sensitive elements, the shape change moving the cable relative to the sheath.

19. The surgically implantable cable apparatus as set forth in claim 17 wherein the implantable actuator further includes a receiving coil electrically connected to the thermally sensitive elements, the receiving coil generating a current in response to an external field from the energy source.

20. The surgically implantable cable apparatus as set forth in claim 19 wherein the energy source includes an external coil, and during activation of in vivo bone transport, the external coil generating an electric field when activated and is positioned over the receiving coil separated by the intact skin layer.

21. The surgically implantable cable apparatus as set forth in claim 1 further including a means for detecting motion of the bone segment.

22. The surgically implantable cable apparatus as set forth in claim 21 wherein the means for detecting motion includes a transducer responsive to motion of the flexible cable.

23. The surgically implantable cable apparatus as set forth in claim 1 further including a means for measuring force applied to the bone segment.

24. The surgically implantable cable apparatus as set forth in claim 1 further including a sheath seal for reducing fluid communication to an interior of the sheath.

25. The surgically implantable cable apparatus as set forth in claim 1 further including an actuator seal for reducing fluid communication to an interior of the implantable actuator.

26. A surgically implantable apparatus for in vivo production of relative motion between a plurality of bone segments of a bone, comprising:

an implanted actuator for producing a force, the actuator being remotely located relative to the bone incorporating the plurality of bone segments;

means for energizing said actuator, while maintaining the skin layer intact; and

,

means for transmitting the force from the actuator to the bone including a flexible, non-compressible sheath.

27. The surgically implanted apparatus as set forth in claim 26 wherein the means for transmitting the force includes a flexible cable being slidably received axially through the flexible, non-compressible sheath, the flexible cable having a first end portion attached to one of the plurality of bone segments, and a second end portion attached to the actuator.

28. The surgically implantable apparatus as set forth in claim 27 wherein the flexible, non-compressible sheath includes a first end with means for securing the flexible, non-compressible sheath to the bone, and a second end portion for attaching to the actuator, the sheath being adapted to transmit a counter-force between the bone and the actuator.

29. The surgically implantable apparatus as set forth in claim 27 wherein the flexible cable is adapted to transmit force along its length.

30. The surgically implantable apparatus as set forth in claim 27 wherein the implanted actuator includes a force multiplying means connected to the flexible cable for moving the flexible cable relative to the flexible, non-compressible sheath.

31. The surgically implantable apparatus as set forth in claim 30 wherein the force multiplying means is a gear stage.

32. The surgically implantable apparatus as set forth in claim 26, the means for energizing the actuator including an implanted power source connected to the actuator by a switch, the switch being responsive to a transcutaneous signal.

33. The surgically implantable apparatus as set forth in claim 26, the means for energizing the actuator including means external to the skin for radiating energy, and means under the skin for receiving the energy and conducting the energy to the actuator.

34. The surgically implantable apparatus as set forth in claim 33, further including an external transmitting antenna for producing an electric field in response to a high frequency electrical current, and an internal antenna outputting an electrical current induced by the radiated electrical field.

35. The surgically implantable apparatus as set forth in claim 26 wherein the actuator includes a set of magnetically sensitive elements, responsive to a magnetic field produced outside the body.

36. The surgically implantable apparatus as set forth in claim 26 further including a means for defining an initial positional relationship between the plurality of bone segments of the bone.

37. The surgically implantable apparatus as set forth in claim 36 wherein the means for defining an initial positional relationship includes an intramedullary rod.

38. The surgically implantable apparatus as set forth in claim 26 further including a means for defining a fixed positional relationship between a plurality of bone segments of the bone.

39. The surgically implantable apparatus as set forth in claim 26 wherein the implanted actuator is electrically powered.

40. The surgically implantable apparatus as set forth in claim 26 wherein the implanted actuator includes thermally sensitive elements for producing motion in response to a change in temperature.

41. The surgically implantable apparatus as set forth in claim 26 further including a transducer for monitoring a system status of the surgically implantable apparatus.

42. The surgically implantable apparatus as set forth in claim 26 further including a transducer for measuring the force produced by the implanted actuator.

43. The surgically implantable apparatus as set forth in claim 26 further including a transducer for measuring a displacement of the plurality of bone segments.

44. A surgically implantable apparatus for in vivo displacement of a bone segment, comprising:

a flexible cable having a first end portion with means for attaching the cable to the bone segment to which a motion is applied;

an implantable, flexible, non-compressible sheath having a bore for accepting the cable;

an implanted, remotely located actuator for moving the bone segment by pulling the cable through the sheath; and

,

means for activating the actuator while maintaining an intact skin layer.

45. The surgically implantable apparatus as set forth in claim 44 further including a means to establish a positional relationship of a plurality of bone segments in at least one dimension.

46. The surgically implantable apparatus as set forth in claim 44 wherein the flexible cable is adapted to transmit force along its length.

47. The surgically implantable apparatus as set forth in claim 44 further including a means for providing a feedback signal indicating a system operation.

48. The surgically implantable apparatus as set forth in claim 47 further including a telemetry means for delivering the feedback signal outside of the patient.

49. A method for surgically treating by distraction a selected bone of a patient, comprising the steps of:

affixing an implant to the selected bone;

severing the selected bone into a plurality of bone segments;

affixing the implant to the plurality of bone segments;

gradually moving at least one bone segment of the plurality of bone segments relative to one another a selected dimension per unit of time in response to a transcutaneous energy signal; and

,

wherein in the step of gradually moving, a flexible force transmitting member extends from the implant to a remote site where force is applied thereto.

50. The method as set forth in claim 49 wherein the remote site is subcutaneous within the patient.

51. The method as set forth in claim 49 wherein in the step of affixing the implant to the selected bone, the implant is placed in an intramedullary canal of the selected bone.

52. The method as set forth in claim 49 wherein the gradually moving step includes rotating a force transmitting member to move the at least one bone segment.

53. The method as set forth in claim 49 further including, before the gradually moving step, inserting a flexible cable axially through the flexible force transmitting member;

and

fixing the flexible cable to the selected bone.

54. The method as set forth in claim 49 wherein the gradually moving step includes transporting the at least one bone segment across an intermediate gap between ends of the selected bone.

55. The method as set forth in claim 49 wherein the gradually moving step includes producing relative motion between ends of the selected bone.

56. A surgically implantable cable apparatus for in vivo bone displacement of a first bone segment that is spaced from a second bone segment comprising:

a) a flexible cable having first and second end portions, the first end portion including means for attaching the cable to the first bone segment to which force is to be applied;

b) an implantable prosthetic flexible, non-compressible sheath having a bore for accepting the cable, and through which a counter-compression force is transmitted to the second bone segment, the sheath having a first end and second end;

c) means for mechanically linking the first end of the sheath and the second bone segment; and

d) a subcutaneous actuator, attached to the second end of the sheath and the second end portion of the cable, for moving the cable through the sheath to move the first and second bone segments relative to each other over a period of time after surgical implantation when the cable is manipulated to move within the sheath in response to a transcutaneous signal.