Dynamic knee balancer with pressure sensing

• US 20050177170A1
• Filed: 10/25/2004
• Published: 08/11/2005
• Est. Priority Date: 02/06/2004
• Status: Active Grant

• Current Assignee: Synvasive Technology Incorporated (Zimmer Biomet Holdings, Inc.)
• Original Assignee: Synvasive Technology Incorporated (Zimmer Biomet Holdings, Inc.)
• Inventors: Howard, Michael, Cordes, Kevin, Fisher, Michael G., Hedley, Anthony K., Katsuya, Toshinobu
• Granted Patent: US 7,578,821 B2
• Time in Patent Office: Days
• US Class Current: 606/88
• CPC Class Codes: A61B 17/02 for holding wounds open; Tractors specula A61B1/32 ; drainage appliances for wounds A61M27/00
• CPC Class Codes: A61B 17/025 Joint distractors
• CPC Class Codes: A61B 17/155 Cutting femur
• CPC Class Codes: A61B 2017/0268 for the knee
• CPC Class Codes: A61B 2090/064 for measuring force, pressure or mechanical tension
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/4657 Measuring instruments used for implanting artificial joints for surgical instruments A61B90/06
• CPC Class Codes: A61F 2/4684 Trial or dummy prostheses
• CPC Class Codes: A61F 2002/30092 using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2002/30428 made by inserting a protrusion into a slot
• CPC Class Codes: A61F 2002/30507 using a threaded locking member, e.g. a locking screw or a set screw
• CPC Class Codes: A61F 2002/30538 for adjusting angular orientation
• CPC Class Codes: A61F 2002/30553 for adjusting a position by translation along an axis
• CPC Class Codes: A61F 2002/30566 Helical springs
• CPC Class Codes: A61F 2210/0014 using shape memory or superelastic materials, e.g. nitinol
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2250/0006 for adjusting angular orientation
• CPC Class Codes: A61F 2250/0008 for adjusting a position by translation along an axis or two perpendicular axes

Abstract

A device for performing a surgical procedure on a knee includes an adjustable femoral portion, a tibial portion and at least one sensor coupled with the femoral and/or tibial portions to sense pressure exerted by the femoral and tibial portions against one another. The femoral portion is adapted for removably coupling with a distal end of a femur to adjust tension in soft tissue adjacent the knee and has at least one positioning feature adapted to move relative to the distal end of the femur as the femoral portion is adjusted, thus helping position a femoral prosthetic on the distal end of the femur. The sensor(s) may be adapted to sense pressure at medial and lateral sides of the knee, and relative pressures may be displayed as data on a visual display. Adjustments to the femoral member may be made to balance pressure at flexion and extension of the knee.

Claims

1. A device for performing a surgical procedure on a knee, the device comprising:

an adjustable femoral portion for removably coupling with a distal end of a femur to adjust tension in soft tissue adjacent the knee, the femoral portion having at least one positioning feature adapted to move relative to the distal end of the femur as the femoral portion is adjusted and thus help position a femoral prosthetic on the distal end of the femur;

a tibial portion for removably coupling with a proximal end of a tibia and movably coupling with the femoral portion to allow the knee to be moved through a range of motion without removing the femoral and tibial portions from the knee; and

at least one sensor coupled with at least one of the femoral and tibial portions to sense pressure exerted by the femoral and tibial portions against one another.

2. A device as in claim 1, wherein the pressure exerted by the femoral and tibial portions against one another is caused by soft tissues adjacent the knee.

3. A device as in claim 2, wherein the pressure may be increased or decreased on one or both lateral sides of the knee by adjusting the femoral portion of the device.

4. A device as in claim 1, wherein the at least one sensor is coupled with the tibial portion.

5. A device as in claim 1, wherein the at least one sensor is coupled with the femoral portion.

6. A device as in claim 1, wherein the at least one sensor comprises at least two sensors disposed on laterally opposite sides of the device.

7. A device as in claim 1, wherein the at least one sensor comprises a layer of pressure sensing material disposed along a surface of the femoral portion or the tibial portion to contact the distal femur or proximal tibia.

8. A device as in claim 1, further comprising a sensor housing plate coupled with the femoral or tibial portion and adapted to house the at least one sensor.

9. A device as in claim 8, wherein the sensor housing plate is removably coupled with the femoral portion or the tibial portion.

10. A device as in claim 8, further comprising a connector plate for coupling the sensor housing plate with the femoral portion or the tibial portion.

11. A device as in claim 8, wherein the sensor housing plate is adapted to contact the femur or tibia.

12. A device as in claim 1, wherein the at least one sensor is selected from the group consisting of piezoelectric sensors, force sensing resistors, strain gauges, load cells, other pressure sensors and other force sensors.

13. A device as in claim 1, further comprising a processor coupled with the at least one sensor for processing sensed pressure data into usable data for providing to a user.

14. A device as in claim 13, further comprising a visual display coupled with the processor for displaying the usable data.

15. A device as in claim 14, wherein the visual display comprises a digital display for providing at least one of alpha and numerical data to the user, the device further comprising an analog to digital converter.

16. A device as in claim 14, wherein the visual display separately displays usable data representing pressure on a lateral side and a medial side of the knee.

17. A device as in claim 14, further comprising at least one connector for connecting the sensor(s) with the visual display.

18. A device as in claim 17, wherein the connector is selected from the group consisting of electrical cable, wireless infrared, electromagnetic and optical connectors.

19. A device as in claim 17, wherein the visual display is directly attached to the femoral portion or the tibial portion.

20. A device as in claim 17, wherein the visual display is removably couplable with a leg of a patient, below the knee.

21. A device as in claim 17, wherein the visual display is removably couplable with a thigh of a patient, above the knee.

22. A device as in claim 1, further comprising at least one pressure selection member coupled with the sensor(s) and the femoral portion, the pressure selection member adapted to allow a user to select a desired amount of pressure exerted between the femoral and tibial portions and to automatically adjust the femoral portion to achieve the selected amount of pressure.

23. A device as in claim 22, wherein the pressure selection member is adapted to allow the user to separately select desired pressures exerted between the femoral and tibial portions at medial and lateral sides of the knee.

24. A device as in claim 1, wherein the femoral portion comprises:

a stationary femoral member for removably attaching in a fixed position to the distal end of the femur; and

a mobile femoral member movably coupled with the stationary femoral member to adjust the tension in the soft tissue adjacent the knee.

25. A device as in claim 24, wherein the mobile femoral member is separately adjustable on laterally opposite sides of the femoral portion.

26. A device as in claim 25, wherein adjusting on one lateral side relative to the opposite side causes the mobile femoral member to rotate relative to the distal femur.

27. A device as in claim 1, wherein the at least one positioning feature of the adjustable femoral member is selected from the group consisting of apertures, drill bit guides, surface markers, surface features, measurement devices, embedded markers, fiducials, transponders, transceivers and sensors.

28. A device as in claim 27, wherein the at least one positioning feature facilitates at least one of placing a cutting guide on the distal femur for making bone cuts, making one or more bone cuts on the distal femur, and positioning a prosthetic femoral component on the distal femur.

29. A device as in claim 1, wherein the tibial portion comprises at least one shim, paddle, plate, bar, platform or rod.

30. A device as in claim 29, wherein the tibial portion comprises a plurality of tibial shims having different thicknesses or heights, wherein any one of the plurality of shims may be selected for engaging with the proximal end of the tibia to provide a desired amount of tension in soft tissue adjacent the knee.

31. A device as in claim 1, wherein the femoral and tibial portions are movably coupled via force provided by the soft tissue adjacent the knee.

32. A device as in claim 1, wherein the femoral and tibial portions are adapted to reside primarily within a joint space between the distal end of the femur and the proximal end of the tibia.

33. A device as in claim 32, wherein a patella of the knee remains approximately in its anatomical position while the femoral and tibial portions are engaged and the knee is moved through the range of motion.

34. A device for performing a surgical procedure on a knee, the device comprising:

a femoral portion for removably coupling with a distal end of a femur;

a tibial portion for removably coupling with a proximal end of a tibia and movably coupling with the femoral portion to allow the knee to be moved through a range of motion without removing the femoral and tibial portions from the knee;

means for adjusting the position of the femoral portion relative to the tibial portion to adjust tension in soft tissue adjacent the knee; and

at least one sensor coupled with at least one of the femoral and tibial portions to sense pressure exerted by the femoral and tibial portions against one another.

35. A system for performing a surgical procedure on a knee, the system comprising:

a knee adjustment device comprising;

an adjustable femoral portion for removably coupling with a distal end of a femur to adjust tension in soft tissue adjacent the knee, the femoral portion having at least one positioning feature adapted to move relative to the distal end of the femur as the femoral portion is adjusted and thus help position a femoral prosthetic on the distal end of the femur; and

a tibial portion for removably coupling with a proximal end of a tibia and movably coupling with the femoral portion to allow the knee to be moved through a range of motion without removing the femoral and tibial portions from the knee; and

a sensor device coupled with the femoral or tibial portion, the sensor device comprising;

at least one sensor coupled with the femoral or tibial portion to sense pressure exerted by the femoral and tibial portions against one another;

a processor coupled with the sensor(s) for processing sensed pressure data into usable data for providing to a user; and

a visual display coupled with the processor for displaying the usable data.

36. A system as in claim 35, wherein the pressure exerted by the femoral and tibial portions against one another is caused by soft tissues adjacent the knee.

37. A system as in claim 36, wherein the pressure may be increased or decreased on one or both lateral sides of the knee by adjusting the femoral portion.

38. A system as in claim 35, wherein the at least one sensor is coupled with the tibial portion.

39. A system as in claim 35, wherein the at least one sensor is coupled with the femoral portion.

40. A system as in claim 35, wherein the at least one sensor comprises at least two sensors disposed on laterally opposite sides of the device.

41. A system as in claim 35, wherein the at least one sensor comprises a layer of pressure sensing material disposed along a surface of the femoral portion or the tibial portion to contact the distal femur or proximal tibia.

42. A system as in claim 35, further comprising a sensor housing plate coupled with the femoral or tibial portion and adapted to house the at least one sensor.

43. A system as in claim 42, wherein the sensor housing plate is removably coupled with the femoral portion or the tibial portion.

44. A system as in claim 42, further comprising a connector plate for coupling the sensor housing plate with the femoral portion or the tibial portion.

45. A system as in claim 42, wherein the sensor housing plate is adapted to contact the femur or tibia.

46. A system as in claim 35, wherein the at least one sensor is selected from the group consisting of piezoelectric sensors, force sensing resistors, strain gauges, load cells, other pressure sensors and other force sensors.

47. A system as in claim 35, wherein the visual display comprises a digital display for providing at least one of alpha and numerical data to the user, the device further comprising an analog to digital converter.

48. A system as in claim 35, wherein the visual display separately displays usable data representing pressure on a lateral side and a medial side of the knee.

49. A system as in claim 35, further comprising at least one connector for connecting the sensor(s) with the visual display.

50. A system as in claim 49, wherein the connector is selected from the group consisting of electrical cable, wireless infrared, electromagnetic and optical connectors.

51. A system as in claim 49, wherein the visual display is directly attached to the femoral portion or the tibial portion.

52. A system as in claim 49, wherein the visual display is removably couplable with a leg of a patient, below the knee.

53. A system as in claim 49, wherein the visual display is removably couplable with a thigh of a patient, above the knee.

54. A system as in claim 35, further comprising at least one pressure selection member coupled with the sensor(s) and the femoral portion, the pressure selection member adapted to allow a user to select a desired amount of pressure exerted between the femoral and tibial portions and to automatically adjust the femoral portion to achieve the selected amount of pressure.

55. A system as in claim 54, wherein the pressure selection member is adapted to allow the user to separately select desired pressures exerted between the femoral and tibial portions at medial and lateral sides of the knee.

56. A method for sensing pressure in a knee during a surgical procedure on the knee, the method comprising:

engaging femoral and tibial portions of a knee adjustment device with the knee;

sensing pressure exerted by the femoral and tibial portions against one another, using at least one sensor coupled with the femoral or tibial portion;

displaying data describing the sensed pressure; and

moving the knee through a range of motion while the knee adjustment device remains engaged with the knee.

57. A method as in claim 56, further comprising adjusting the femoral portion of the knee adjustment device to adjust tension in soft tissue adjacent the knee, wherein adjusting the tension affects the pressure exerted by the femoral and tibial portions against one another.

58. A method as in claim 57, wherein the adjusting step is performed before the moving step.

59. A method as in claim 57, wherein the adjusting step is performed after the moving step.

60. A method as in claim 57, wherein the adjusting step is performed before and after the moving step.

61. A method as in claim 57, wherein the adjusting step is performed one or more times to balance pressure data displayed while the knee is flexed with pressure data displayed while the knee is extended.

62. A method as in claim 57, wherein the adjusted femoral portion provides positional data for helping position at least part of a prosthetic knee.

63. A method as in claim 56, further comprising inserting and removing multiple, differently-sized tibial portions to adjust tension in soft tissue adjacent the knee, wherein adjusting the tension affects the pressure exerted by the femoral and tibial portions against one another.

64. A method as in claim 63, wherein the inserting and removing steps are performed before the moving step.

65. A method as in claim 63, wherein the inserting and removing steps are performed after the moving step.

66. A method as in claim 63, wherein the inserting and removing steps are performed before and after the moving step.

67. A method as in claim 63, wherein the inserting and removing steps are performed one or more times to balance pressure data displayed while the knee is flexed with pressure data displayed while the knee is extended.

68. A method as in claim 56, further comprising processing the sensed pressure into the data describing the pressure.

69. A method as in claim 68, wherein processing comprises converting analog data to digital data.

70. A method as in claim 56, wherein sensing the pressure comprises:

transmitting a voltage to the at least one sensor;

measuring the voltage after it has passed through the sensor(s);

determining a percentage of the voltage passed through the sensor(s) relative to the voltage transmitted to the sensors; and

deriving the pressure from the percentage.

71. A method as in claim 56, wherein sensing the pressure comprises sensing with at least one sensor selected from the group consisting of piezoelectric sensors, force sensing resistors, strain gauges, load cells, other pressure sensors and other force sensors.

72. A method as in claim 56, wherein displaying the data comprises:

displaying at least a first number representing the pressure in a medial portion of the adjustment device; and

displaying at least a second number representing pressure in a lateral portion of the adjustment device.

73. A method as in claim 72, wherein the first and second numbers represent relative amounts of pressure as compared to one another or to pressure(s) measured with different positioning of the knee.

74. A method as in claim 72, wherein the first and second numbers represent absolute amounts of pressure.

75. A method as in claim 56, further comprising:

receiving an input from a user of a desired amount of pressure to be exerted by the femoral and tibial members against one another; and

automatically adjusting the femoral portion of the adjustment device to achieve the desired amount of pressure.

76. A method as in claim 75, wherein receiving the input comprises receiving a first amount of desired pressure for a medial side of the knee and a second amount of desired pressure for a lateral side of the knee.

77. A method as in claim 56, further comprising automatically adjusting the adjustment device to balance the pressure exerted by the femoral and tibial members against one another while the knee is flexed with pressure exerted while the knee is extended.