Inertial sensor based surgical navigation system for knee replacement surgery

• US 9,706,948 B2
• Filed: 05/06/2010
• Issued: 07/18/2017
• Est. Priority Date: 05/06/2010
• Status: Active Grant

• Current Assignee: Sachin Bhandari
• Original Assignee: Sachin Bhandari
• Inventors: Bhandari, Sachin
• Primary Examiner(s): DOUGHERTY, SEAN PATRICK
• Application Number:
  US12/775,464
• Publication Number:
  US 20110275957A1
• Time in Patent Office: 2,630 Days
• Field of Search: 600595, 606102
• CPC Class Codes: A61B 2017/00725 Calibration or performance testing
• CPC Class Codes: A61B 2034/105 Modelling of the patient, e.g. for ligaments or bones
• CPC Class Codes: A61B 2034/108 Computer aided selection or customisation of medical implants or cutting guides
• CPC Class Codes: A61B 2034/2048 using an accelerometer or inertia sensor
• CPC Class Codes: A61B 2090/3983 Reference marker arrangements for use with image guided surgery
• CPC Class Codes: A61B 2090/3991 having specific anchoring means to fixate the marker to the tissue, e.g. hooks
• CPC Class Codes: A61B 2505/05 Surgical care
• CPC Class Codes: A61B 2562/0219 Inertial sensors, e.g. accelerometers, gyroscopes, tilt switches
• CPC Class Codes: A61B 34/20 Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
• CPC Class Codes: A61B 5/107 Measuring physical dimensions, e.g. size of the entire body or parts thereof
• CPC Class Codes: A61B 5/1114 Tracking parts of the body
• CPC Class Codes: A61B 5/6828 Leg
• CPC Class Codes: A61B 5/6829 Foot or ankle
• CPC Class Codes: A61B 5/725 using specific filters therefor, e.g. Kalman or adaptive filters A61B5/316 take precedence
• CPC Class Codes: G01C 25/005 initial alignment, calibration or starting-up of inertial devices
• CPC Class Codes: G01P 21/00 Testing or calibrating of apparatus or devices covered by the preceding groups
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

An inertial sensor based surgical navigation system for knee replacement surgery is disclosed. Inertial sensors composed of six-degree-of-freedom inertial chips, whose measurements are processed through a series of integration, quaternion, and kalman filter algorithms, are used to track the position and orientation of bones and surgical instruments. The system registers anatomically significant geometry, calculates joint centers and the mechanical axis of the knee, develops a visualization of the lower extremity that moves in real time, assists in the intra-operative planning of surgical cuts, determines the optimal cutting planes for cut guides and the optimal prosthesis position and orientation, and finally navigates the cut guides and the prosthesis to their optimal positions and orientations using a graphical user interface.

Claims

1. A surgical navigation system comprising:

a first inertial sensor that measures its own motion without an external reference and in response thereto provides data relating to a position and an orientation of said first inertial sensor, said first inertial sensor being configured to attach to a patient'"'"'s body;

a sensor processor that receives said data from said first inertial sensor and using said data calculates the position of said first inertial sensor and the orientation of said first inertial sensor in a common coordinate system that defines position and orientation coordinates relative to an initial position and an initial orientation of the first inertial sensor;

a mapping processor that stores in memory an initial location of a point on the patient'"'"'s body and determines a location of said point on the patient'"'"'s body in the common coordinate system based on the position and orientation of said first inertial sensor after the patient'"'"'s body has moved, wherein the mapping processor computes from the determined location of said point on the patient'"'"'s body, a point display element that represents a graphical depiction of the location of said point on the patient'"'"'s body in the common coordinate system; and

a display in communication with the mapping processor, the display comprising a graphical user interface that receives the point display element from the mapping processor and displays the point display element to provide a graphical depiction of the determined location of said point on the patient'"'"'s body relative to a planned surgical cut, thereby providing feedback as to an alignment of the patient'"'"'s body with the planned surgical cut.

2. The surgical navigation system as recited in claim 1, wherein said sensor processor processes said data with a Kalman filter.

3. The surgical navigation system as recited in claim 1, wherein said first inertial sensor comprises at least two inertial chips.

4. The surgical navigation system as recited in claim 1, wherein said first inertial sensor is configured to compensate for temperature fluctuations in said first inertial sensor.

5. The surgical navigation system as recited in claim 1, wherein the graphical user interface displays a graphical depiction of said patient'"'"'s body together with the point display element to represent a location of said first inertial sensor on said patient'"'"'s body.

6. The surgical navigation system as recited in claim 1, further comprising a pointer device comprising:

a housing that extends from a distal end to a proximal end;

a tip located at the proximal end of the housing; and

wherein the pointer device is configured to provide a position and an orientation of said pointer device to said mapping processor, said mapping processor being configured to calculate position and orientation coordinates of a location of said pointer device in the common coordinate system defined by the initial position and the initial orientation of said first inertial sensor.

7. The surgical navigation system as recited in claim 1, further comprising a second inertial sensor that measures its own motion without an external reference and in response thereto provides data relating to a position and an orientation of said second inertial sensor, said second inertial sensor being configured to attach to a surgical instrument.

8. The surgical navigation system as recited in claim 7, wherein:

said sensor processor receives said data from said second inertial sensor and calculates the position of said second inertial sensor and the orientation of said second inertial sensor in the common coordinate system;

said mapping processor is configured to determine a position and an orientation of said surgical instrument relative to a planned position and orientation of said surgical instrument based on the position and orientation of said first and second inertial sensors, wherein the position and orientation of said surgical instrument is determined in the common coordinate system and wherein the mapping processor computes from the determined position and orientation of said surgical instrument, a surgical instrument display element that represents a graphical depiction of the position and orientation of said surgical instrument; and

said display receives the surgical instrument display element from the mapping processor and displays the surgical instrument display element to provide a graphical depiction of the surgical instrument relative to the planned surgical cut, thereby providing feedback as to an alignment of the surgical instrument with the planned surgical cut.

9. The surgical navigation system as recited in claim 8, wherein the graphical user interface displays a graphical depiction of said patient'"'"'s body together with the surgical instrument display element to represent the position and orientation of the surgical instrument relative to said patient'"'"'s body.

10. The surgical navigation system as recited in claim 1, wherein said mapping processor determines a center of a hip joint by tracking the location of said point on the patient'"'"'s body when the patient'"'"'s body is moved and to calculate a common radius to the tracked locations of said point while the patient'"'"'s body was moved.

11. The surgical navigation system as recited in claim 1 further comprising a memory that is accessible by said mapping processor, said memory having stored thereon a geometry database containing geometrical information regarding human anatomy.

12. The surgical navigation system as recited in claim 1 further comprising a housing, wherein said first inertial sensor and said sensor processor are contained in the housing.

13. The surgical navigation system as recited in claim 1, further comprising an inertial sensor hub that communicates with said first inertial sensor and stores tracked locations of said first inertial sensor.

14. The surgical navigation system as recited in claim 1 further comprising a calibration device for calibrating said first inertial sensor and other inertial sensors relative to the common coordinate system prior to using said first inertial sensor, wherein the calibration device is configured to hold the first inertial sensor and the other inertial sensors at known positions and orientations relative to one another, such that the common coordinate system can be defined relative to the initial position and the initial orientation of the first inertial sensor so that positions and orientations of the first inertial sensor and the other inertial sensors are defined by the position and orientation coordinates in the common coordinate system.

15. The surgical navigation system as recited in claim 6, wherein said pointer device has coupled thereto an inertial sensor that measures its own motion without an external reference and in response thereto provides data relating to the position and the orientation of said pointer device to said mapping processor.

16. The surgical navigation system as recited in claim 2, wherein said first inertial sensor comprises at least two inertial chips that each measure the motion of the first inertial sensor by sensing their own motion in six degrees-of-freedom, and wherein the Kalman filter operates on redundant measurements obtained from the at least two inertial chips.

17. The surgical navigation system as recited in claim 16, wherein the at least two inertial chips comprise at least a first inertial chip having sensitive axes along which the first inertial chip senses its own motion in six degrees-of-freedom and a second inertial chip having sensitive axes along which the second inertial chip senses its own motion in six degrees-of-freedom, wherein the first inertial chip and the second inertial chip are arranged in the first inertial sensor such that the sensitive axes of the first inertial chip are parallel to respective ones of sensitive axes of the second inertial chip such that redundant measurements are obtained from the at least two inertial chips.

18. The surgical navigation system as recited in claim 8, wherein the surgical instrument is a cut guide and the planned surgical cut indicates a planned cutting plane.

19. The surgical navigation system as recited in claim 18, wherein the mapping processor tracks the position and orientation of the cut guide relative to the planned position and orientation of the cut guide and computes a cut guide display element that represents a graphical depiction of the tracked position and orientation of the cut guide so as to allow alignment of a cutting plane of the cut guide with a planned cutting plane.

20. The surgical navigation system as recited in claim 19, wherein the graphical user interface receives and displays body display element that represents a graphical depiction of said patient'"'"'s body and at least one of:

the cut guide display element to represent the position and orientation of the cut guide relative to said patient'"'"'s body;

a cutting plane display element that represents a graphical depiction of the position and orientation of the cutting plane relative to said patient'"'"'s body; and

a planned cutting plane display element that represents a graphical depiction of the position and orientation of the planned cutting plane relative to said patient'"'"'s body.

21. The surgical navigation system as recited in claim 11, wherein the geometry database stored on the memory also contains computer-aided design (CAD) data for a plurality of different surgical tools and implants.

46. The surgical navigation system as recited in claim 1, wherein the first inertial sensor further comprises a magnetometer that generates angular velocity data by measuring its orientation with respect to a magnetic axis of Earth, and wherein the sensor processor receives and uses the angular velocity data when calculating the position and orientation of said first inertial sensor in the common coordinate system.

22. A surgical navigation system, comprising:

at least one inertial sensor that measures its own motion without an external reference and is configured to be removably attached to an object, wherein the object is at least one of a portion of a patient'"'"'s anatomy and a surgical instrument;

a sensor processor in communication with the at least one inertial sensor to receive from the at least one inertial sensor, data indicative of a position and an orientation of the at least one inertial sensor in a common coordinate system that defines position and orientation coordinates relative to an initial position and an initial orientation of the at least one inertial sensor; and

a computer system in communication with the sensor processor to receive the data from the sensor processor;

compute, from the received data, a position and an orientation of the object in the common coordinate system; and

provide feedback to a user that indicates an alignment of the object to a planned surgical cut based on the computed position and orientation of the object.

23. The surgical navigation system as recited in claim 22, further comprising a display in communication with the computer system, and wherein the computer system computes an object display element from the computed position and orientation of the object in the common coordinate system and the display comprises a graphical user interface that receives the object display element from the computer system and displays the object display element to provide a graphical depiction of the position and orientation of the object and displays a planned surgical cut display element that provides a graphical depiction of a position and an orientation of the planned surgical cut, thereby providing the feedback to the user.

24. The surgical navigation system as recited in claim 23, wherein the planned surgical cut indicates a planned resection plane, and wherein the graphical user interface displays planned surgical cut display element and the object display element together to provide a graphical depiction of the position and orientation of the planned resection plane relative to the position and orientation of the object in the common coordinate system.

25. The surgical navigation system as recited in claim 23, wherein the computer system determines information associated with an alignment of the position and orientation of the planned surgical cut with the position and orientation of the object, and the display receives and displays the information associated with the alignment of the position and orientation of the planned surgical cut together with the object display element.

26. The surgical navigation system as recited in claim 23, wherein the object is a surgical instrument and the display displays the object display element together with the planned surgical cut display element to provide a graphical depiction of the position and orientation of the surgical instrument relative to the position and orientation of the planned surgical cut in the common coordinate system.

27. The surgical navigation system as recited in claim 26, wherein the display receives and displays a patient anatomy display element together with the object display element and the planned surgical cut display element to provide a graphical depiction of a position and orientation of a portion of the patient'"'"'s anatomy relative to the position and orientation of the planned surgical cut and the position and orientation of the surgical instrument in the common coordinate system.

28. The surgical navigation system as recited in claim 27, further comprising a second inertial sensor that measures its own motion without an external reference and is configured to be removably attached to the portion of the patient'"'"'s anatomy, and wherein the position and orientation of the portion of the patient'"'"'s anatomy is determined from data received from the second inertial sensor and the position and orientation of the portion of the patient'"'"'s anatomy is determined in the common coordinate system.

29. The surgical navigation system as recited in claim 23, wherein the object is a surgical implant and the graphical user interface displays the object display element together with a planned position display element that provides a graphical depiction of a planned position and orientation of the surgical implant, thereby providing the user feedback related to the position and orientation of the surgical implant relative to the planned position and orientation of the surgical implant in the common coordinate system.

30. The surgical navigation system as recited in claim 22, further comprising a pointer device comprising:

a housing that extends from a distal end to a proximal end;

a tip located at the proximal end of the housing; and

wherein the pointer device is in communication with the sensor processor to record a position and orientation of the tip of the pointer device as a reference point in the common coordinate system.

31. The surgical navigation system as recited in claim 30, wherein the reference point is an anatomical landmark recorded as a position and orientation of a point on a portion of the patient'"'"'s anatomy.

32. The surgical navigation system as recited in claim 30, wherein the pointer device further comprises at least one inertial sensor coupled to the pointer device and that measures its own motion without an external reference and in response thereto provides data relating to the position and orientation of the tip of the pointer device in the common coordinate system.

33. The surgical navigation system as recited in claim 30, further comprising a display in communication with the computer system, and wherein the computer system computes a reference point display element from the recorded reference point and an object display element from the computed position and orientation of the object in the common coordinate system, and wherein the display comprises a graphical user interface that receives and displays the reference point display element and the object display element to provide a graphical depiction of the position and orientation of the reference point relative to the position and orientation of the object in the common coordinate system.

34. The surgical navigation system as recited in claim 33, wherein the at least one reference point is associated with a point on a portion of the patient'"'"'s anatomy and the graphical user interface displays movement of the portion of the patient'"'"'s anatomy as movement of the at least one reference point relative to the position and orientation of the object.

35. The surgical navigation system as recited in claim 34, wherein the portion of the patient'"'"'s anatomy is a bone and the computer system computes a joint center from the position and orientation of the at least one reference point as the bone is moved.

36. The surgical navigation system as recited in claim 22, wherein the object is a portion of the patient'"'"'s anatomy and the computer system computes data associated with a difference between the position and orientation of the portion of the patient'"'"'s anatomy and a position and orientation of another point in the common coordinate system.

37. The surgical navigation system as recited in claim 36, wherein the position and orientation of the another point is provided in the common coordinate system by another inertial sensor in communication with the sensor processor.

38. The surgical navigation system as recited in claim 37, wherein the other inertial sensor measures its own motion without an external reference and is configured to be removably attached to a second object, wherein the second object is at least one of another portion of the patient'"'"'s anatomy and a surgical instrument.

39. A surgical navigation system, comprising:

a plurality of inertial sensors comprising at least one inertial sensor configured to be removably attached to a bone and at least one inertial sensor configured to be removably attached to a surgical instrument, wherein each of the plurality of inertial sensors measures its own motion without an external reference and in response thereto provides data relating to a position and an orientation of said inertial sensor;

a sensor processor in communication with the plurality of inertial sensors and configured to receive from the plurality of inertial sensors, data indicative of positions and orientations of the plurality of inertial sensors in a common coordinate system that defines position and orientation coordinates relative to an initial position and an initial orientation of one of the plurality of inertial sensors;

a computer system in communication with the sensor processor and configured to;

receive the data from the sensor processor;

compute from the received data, a position and an orientation of the bone in the common coordinate system;

compute from the received data, a position and an orientation of the surgical instrument in the common coordinate system;

compute from the position and orientation of the bone, a bone display element that represents a graphical depiction of the position and orientation of the bone in the common coordinate system;

compute from the position and orientation of the surgical instrument, a surgical instrument display element that represents a graphical depiction of the position and orientation of the surgical instrument in the common coordinate system; and

a display in communication with the computer system, the display comprising a graphical user interface that receives the bone display element and the surgical instrument display element from the computer system and displays the bone display element together with the surgical instrument display element to provide a graphical depiction of both the computed position and orientation of the bone and the computed position and orientation of the surgical instrument relative to each other in the common coordinate system, thereby providing feedback to a user as to an alignment of the surgical instrument with a location on the bone.

40. The surgical navigation system as recited in claim 39, wherein the surgical instrument is a cut guide.

41. The surgical navigation system as recited in claim 39, wherein the surgical instrument is a surgical implant.

42. The surgical navigation system as recited in claim 41, wherein the surgical implant is a prosthesis.

43. The surgical navigation system as recited in claim 42, wherein the computer system is configured to determine an optimal position and orientation of the prosthesis based on the computed position and orientation of the bone.

44. The surgical navigation system as recited in claim 39, wherein the computer system determines a planned cutting plane based on the computed position and orientation of the bone and computes a planned cutting plane display element from the determined cutting plane, and the graphical user interface also receives and displays the planned cutting plane display element to provide a graphical depiction of the planned cutting plane relative to the positions and orientations of the bone and the surgical instrument in the common coordinate system.

45. The surgical navigation system as recited in claim 39, wherein the computer system determines a joint center by tracking the computed position and orientation of the bone as the bone moves through a plurality of different positions and orientations.