GENERATING MRI IMAGES USABLE FOR THE CREATION OF 3D BONE MODELS EMPLOYED TO MAKE CUSTOMIZED ARTHROPLASTY JIGS

• US 20090138020A1
• Filed: 11/27/2007
• Published: 05/28/2009
• Est. Priority Date: 11/27/2007
• Status: Active Grant

• Current Assignee: Howmedica Osteonics Corp. (Stryker Corporation)
• Original Assignee: Otismed Corporation (Stryker Corporation)
• Inventors: Park, Ilwhan, Howell, Stephen M.
• Granted Patent: US 10,582,934 B2
• Time in Patent Office: Days
• US Class Current: 606/88
• CPC Class Codes: A61B 17/154 for preparing bone for knee prosthesis
• CPC Class Codes: A61B 17/155 Cutting femur
• CPC Class Codes: A61B 17/157 Cutting tibia
• CPC Class Codes: A61B 2034/105 Modelling of the patient, e.g. for ligaments or bones
• CPC Class Codes: A61B 2090/374 NMR or MRI
• CPC Class Codes: A61B 34/10 Computer-aided planning, simulation or modelling of surgical operations
• CPC Class Codes: A61B 5/055 involving electronic [EMR] or nuclear [NMR] magnetic resonance, e.g. magnetic resonance imaging
• CPC Class Codes: A61B 5/4528 Joints A61B5/4533, A61B5/4538 take precedence

Abstract

Disclosed herein is a method of creating a customized arthroplasty jig. The method may include: generating two-dimensional MRI images of a patient'"'"'s joint area to undergo arthroplasty; electronically orienting the two dimensional MRI image slices to account for the patient'"'"'s joint area being randomly physically oriented in a scanning area of a MRI machine; generating a three-dimensional bone image of at least a portion of a bone of the patient'"'"'s joint area from the generated two-dimensional MRI images; using the three-dimensional bone image to generate data pertaining to the customized arthroplasty jig, wherein the data includes bone surface information; providing the data to at least one manufacturing device; and employing the bone surface information to cause the at least one manufacturing device to create a surface on the arthroplasty jig configured to matingly receive a surface of the bone.

Claims

1. A method of creating a customized arthroplasty jig, the method comprising:

generating two-dimensional MRI images of a patient'"'"'s joint area to undergo arthroplasty, wherein the MRI images are between approximately 128×

128 to approximately 1024×

1024 resolution and between approximately 1 mm and approximately 4 mm slice spacing;

generating a three-dimensional bone image of at least a portion of a bone of the patient'"'"'s joint area from the generated two-dimensional MRI images;

using the three-dimensional bone image to generate data pertaining to the customized arthroplasty jig, wherein the data includes bone surface information;

providing the data to at least one manufacturing device; and

employing the bone surface information to cause the at least one manufacturing device to create a surface on the arthroplasty jig configured to matingly receive a surface of the bone.

2. The method of claim 1, wherein the slice spacing is between approximately 1.8 mm and approximately 2.2 mm.

3. The method of claim 1, wherein the slice spacing is the result of hardware spacing.

4. The method of claim 1, wherein the slice spacing is the result of software spacing.

5. The method of claim 1, wherein the slice spacing is approximately 2 mm.

6. The method of claim 5, wherein the slice spacing is obtained by combining at least two image slice runs, wherein the at least two image slice runs are spatially offset from each other and each have an image run slice spacing of 4 mm.

7. The method of claim 1, wherein the resolution is approximately 256×

256.

8. The method of claim 1, wherein the data further includes at least one of saw cut information and drill hole information and further comprising employing the at least one of saw cut information and drill hole information to cause the at least one manufacturing device to create at least one of a saw cut slot and a drill hole in the arthroplasty jig.

9. The method of claim 1, wherein the bone is at least one of a femur and a tibia.

10. The method of claim 1, wherein the bone is at least one of a humerus, radius and ulna.

11. The method of claim 1, further comprising electronically orienting the two-dimensional MRI image slices to account for the patient'"'"'s joint area being randomly physically oriented in a scanning area of a MRI machine.

12. The method of claim 1, further comprising electronically orienting the two-dimensional MRI image slices to account for the patient'"'"'s joint area being improperly physically oriented in a scanning area of a MRI machine.

13. The method of claim 1, further comprising electronically orienting the two-dimensional MRI image slices of the patient joint area to have a scan orientation that is different from a scan orientation that would result absent the electronic orientation.

14. A customized arthroplasty jig manufactured according to the method of claim 1.

15. The jig of claim 14, wherein the jig is a femur jig.

16. The jig of claim 14, wherein the jig is a tibia jig.

17. A method of creating a customized arthroplasty jig, the method comprising:

generating two-dimensional MRI images of a patient'"'"'s joint area to undergo arthroplasty;

electronically orienting the two-dimensional MRI image slices to account for the patient'"'"'s joint area being randomly physically oriented in a scanning area of a MRI machine;

generating a three-dimensional bone image of at least a portion of a bone of the patient'"'"'s joint area from the generated two-dimensional MRI images;

using the three-dimensional bone image to generate data pertaining to the customized arthroplasty jig, wherein the data includes bone surface information;

providing the data to at least one manufacturing device; and

employing the bone surface information to cause the at least one manufacturing device to create a surface on the arthroplasty jig configured to matingly receive a surface of the bone.

18. The method of claim 17, wherein the data further includes at least one of saw cut information and drill hole information and further comprising employing the at least one of saw cut information and drill hole information to cause the at least one manufacturing device to create at least one of a saw cut slot and a drill hole in the arthroplasty jig.

19. The method of claim 17, wherein the bone is at least one of a femur and a tibia.

20. The method of claim 17, wherein the two-dimensional MRI image slices are oriented to be generally perpendicular to a joint line of the patient'"'"'s joint area.

21. The method of claim 20, wherein the patient'"'"'s joint area is a knee.

22. The method of claim 17, wherein the two-dimensional MRI image slices are oriented to be generally parallel to a plane that is tangential a medial or lateral side of a femur condyle.

23. The method of claim 17, wherein the two-dimensional MRI image slices are oriented to be generally parallel to a plane that bilaterally divides the patient'"'"'s joint area into generally symmetrical medial and lateral portions.

24. The method of claim 17, wherein the two-dimensional MRI images are generated at a resolution of between approximately 128×

128 to approximately 1024×

1024 resolution.

25. The method of claim 17, wherein the two-dimensional MRI images are generated at a slice spacing of between approximately 1 mm and approximately 4 mm.

26. A customized arthroplasty jig manufactured according to the method of claim 17.

27. The jig of claim 26, wherein the jig is a femur jig.

28. The jig of claim 26, wherein the jig is a tibia jig.

29. A method of creating a customized arthroplasty jig, the method comprising:

generating a coronal MRI image of a knee joint area to undergo arthroplasty, wherein the coronal MRI image depicts a most distal point on a femur medial condyle and a most distal point on a femur lateral condyle;

extending a first tangent line to intersect the distal points;

generating an axial MRI image of the knee joint area, wherein the axial MRI image depicts a most posterior point on the femur medial condyle and a most posterior point on the femur lateral condyle;

generating two-dimensional MRI images of the knee joint area, wherein the two-dimensional MRI images are generally perpendicular to the first and second tangent lines;

generating a three-dimensional bone image of at least a portion of a bone of the patient'"'"'s joint area from the generated two-dimensional MRI images;

using the three-dimensional bone image to generate data pertaining to the customized arthroplasty jig;

providing the data to at least one manufacturing device; and

employing the data to cause the at least one manufacturing device to create the arthroplasty jig.

30. The method of claim 29, wherein the data includes bone surface information.

31. The method of claim 30, further comprising employing the bone surface information to cause the manufacturing device to create a surface on the arthroplasty jig configured to matingly receive a surface of the bone.

32. The method of claim 31, wherein the data further includes at least one of saw cut information and drill hole information and further comprising employing the at least one of saw cut information and drill hole information to cause the at least one manufacturing device to create at least one of a saw cut slot and a drill hole in the arthroplasty jig.

33. The method of claim 29, further comprising determining a first set of coordinates pertaining to a lateral condyle depicted in the two-dimensional MRI images, determining a second set of coordinates pertaining to a medial condyle depicted in the two-dimensional MRI images, and comparing the first and second set of coordinates.

34. The method of claim 31, further comprising rejecting the two-dimensional MRI images if the comparison indicates the two-dimensional MRI images are not sufficiently oriented for purposes of generating the three-dimensional bone image.

35. The method of claim 29, further comprising comparing a curvature of a femur condyle contour depicted in a first of the two-dimensional MRI images to a curvature of a femur condyle contour depicted in a second of the two-dimensional MRI images.

36. The method of claim 35, wherein the comparison of the curvatures includes comparing a slope change of a curvature of a femur condyle contour depicted in the first of the two-dimensional MRI images to a slope change of a curvature of a femur condyle contour depicted in the second of the two-dimensional MRI images.

37. The method of claim 36, further comprising rejecting the two-dimensional MRI images if the comparison indicates excessive patient movement occurred during the taking of the MRI images.

38. The method of claim 29, further comprising comparing a curvature of a femur condyle contour depicted in at least one two-dimensional MRI images to a curvature of an anatomically correct femur condyle contour.

39. The method of claim 29, wherein the two-dimensional MRI images are generated at a resolution of between approximately 128×

128 to approximately 1024×

1024 resolution.

40. The method of claim 29, wherein the two-dimensional MRI images are generated at a slice spacing of between approximately 1 mm and approximately 4 mm.

41. A customized arthroplasty jig manufactured according to the method of claim 29.

42. The jig of claim 41, wherein the jig is a femur jig.

43. The jig of claim 41, wherein the jig is a tibia jig.

44. A method of orienting MRI slice images of a bone, the method comprising:

generating a first MRI bone image;

causing a first reference line to intersect first and second points on the first MRI bone image; and

generating the MRI slice images to be generally perpendicular to the first reference line.

45. The method of claim 44, further comprising:

generating a second MRI bone image;

causing a second reference line to intersect third and fourth points on the second MRI bone image, wherein the MRI slice images are generated to be generally perpendicular to both the first and second reference lines.

46. The method of claim 45, wherein the first and second MRI bone images are generally perpendicular to each other.

47. The method of claim 45, wherein the first MRI bone image is a generally longitudinal view of the bone and the second MRI bone image is a generally axial view of the bone.

48. The method of claim 47, wherein the bone is a femur.

49. The method of claim 47, wherein the bone forms at least part of a knee or elbow.

50. The method of claim 49, wherein the first and second points are, respectively, a most distal point on a lateral femur condyle and a most distal point on a medial femur condyle.

51. The method of claim 50, wherein the third and fourth points are, respectively, a most posterior point on a lateral femur condyle and a most posterior point on a medial femur condyle.

52. The method of claim 45, wherein the first reference line includes a localizer line of a MRI imaging system.

53. The method of claim 45, wherein the first reference line is generally perpendicular to a longitudinal axis of the bone.

54. The method of claim 53, wherein the bone is a femur.

55. The method of claim 45, further comprising checking the MRI slice images to determine if excessive patient motion occurred when generating the MRI slice images.

56. The method of claim 55, wherein determining if excessive patient motion occurred includes comparing slopes of bone contours in a first MRI slice image to slopes of bone contours in a second MRI slice image.

57. The method of claim 55, wherein determining if excessive patient motion occurred includes comparing bone contours in at least one of the MRI slice images to anatomically correct bone contours.

58. The method of claim 55, further comprising determining whether the MRI slice images are adequately oriented by determining a first set of coordinates pertaining to a first feature depicted in the MRI slice images, determining a second set of coordinates pertaining to a second feature depicted in the MRI slice images, and comparing the first and second set of coordinates.

59. The method of claim 58, wherein the first and second features are, respectively, lateral and medial femur condyles.

60. A method of medically imaging a bone with a MRI machine, the method comprising:

generating two-dimensional MRI images of the bone;

electronically orienting the two-dimensional MRI images to account for the bone being randomly physically oriented in a scanning area of the MRI machine;

running an orientation check to determine if the two-dimensional MRI images have been adequately electronically oriented; and

running a motion check to determine if the excessive patient motion occurred during the generation of the two-dimensional MRI images.

61. The method of claim 60, wherein electronically orienting the two-dimensional MRI images includes causing the two-dimensional MRI images to be generally perpendicular to a reference line intersecting at least two points on the bone.

62. The method of claim 61, wherein the at least two points include a cortical/cancellous edge of the bone.

63. The method of claim 61, wherein the bone is a femur.

64. The method of claim 61, wherein the bone forms at least part of a knee or elbow.

65. The method of claim 60, wherein determining if excessive patient motion occurred includes comparing slopes of bone contours in a first two-dimensional MRI image to slopes of bone contours in a second two-dimensional MRI image.

66. The method of claim 60, wherein determining if excessive patient motion occurred includes comparing bone contours in at least one of the two-dimensional MRI images to anatomically correct bone contours.

67. The method of claim 60, wherein determining if the two-dimensional MRI images are adequately electronically oriented includes determining a first set of coordinates pertaining to a first feature depicted in the two-dimensional MRI slice images, determining a second set of coordinates pertaining to a second feature depicted in the two-dimensional MRI slice images, and comparing the first and second set of coordinates.