Systems and methods for determining the mechanical axis of a femur

Patent metadata

Field	Value
Publication number	US-9532788-B2
Application number	US-201514709722-A
Country	US
Kind code	B2
Filing date	May 12, 2015
Priority date	Dec 6, 2007
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

Abstract

A method positions a profile of a prosthetic component on the three-dimensional model of a limb. Patient-specific anatomical data of the limb is gathered. First and second anatomical landmarks are identified to determine a first spatial relationship. A third anatomical landmark is identified to determine a second spatial relationship with respect to the first spatial relationship. The profile of the prosthetic component is positioned in all but one degree of freedom. A fourth anatomical landmark is identified to position the profile of the prosthetic component in the one remaining degree of freedom.

First claim

What is claimed is:

1. A method comprising:
obtaining patient-specific anatomical data of a limb;
identifying a plurality of anatomical landmarks of the limb using the patient-specific anatomical data;
performing a series of computations to determine a three-dimensional mechanical axis of the limb based on the identified plurality of anatomical landmarks;
determining one or more planes for bone cuts on the limb based on the identified plurality of landmarks and the determined three-dimensional mechanical axis of the limb, at least one of the one or more planes having a predetermined orientation with respect to the determined three-dimensional mechanical axis of the limb; and
manufacturing a patient-specific surgical item based at least partially on the determined three-dimensional mechanical axis of the limb, the patient-specific surgical item including a portion that conforms to a corresponding portion of a bony surface of the limb such that the patient-specific surgical item is configured to engage the limb in a predetermined orientation, and the patient-specific surgical item is configured to indicate the determined one or more planes with respect to the limb when the patient-specific surgical item is engaged with the limb in the predetermined orientation.

2. The method of claim 1 , wherein performing a series of computations to determine the three-dimensional mechanical axis of the limb based on the identified plurality of anatomical landmarks comprises iteratively identifying spatial relationships or constraints to define the three-dimensional mechanical axis of the limb.

3. The method of claim 1 , wherein performing a series of computations to determine the three-dimensional mechanical axis of the limb based on the identified plurality of anatomical landmarks comprises performing multiple computations that are each based on locations of different anatomical landmarks of the plurality of anatomical landmarks.

4. The method of claim 1 , wherein determining the one or more planes for bone cuts on the limb comprises determining one or more planes for bone cuts to prepare the limb to receive a particular prosthetic component in a particular size.

5. The method of claim 1 , wherein determining the one or more planes for bone cuts on the limb comprises determining multiple planes for chamfered cuts on a femur.

6. The method of claim 1 , wherein determining the one or more planes for bone cuts on the limb comprises determining one or more planes for cuts on a tibia.

7. The method of claim 1 , further comprising determining a position for a prosthetic component with respect to a three-dimensional model of the limb such that the prosthetic component has a predetermined orientation with respect to the determined mechanical axis of the limb.

8. The method of claim 1 , wherein manufacturing the patient-specific surgical item comprises manufacturing a patient-specific cutting block having one or more guide elements configured to guide a resection along the determined one or more planes.

9. The method of claim 8 , wherein each of the one or more guide elements comprises a planar cutting surface or a cutting slot.

10. The method of claim 1 , wherein identifying the plurality of anatomical landmarks comprises identifying a tibial intercondylar eminence of the limb.

11. The method of claim 1 , wherein determining the one or more planes for bone cuts comprises:
establishing positions of the one or more planes in all but 2 degrees of freedom; and
after establishing the positions of the one or more planes in all but 2 degrees of freedom, further constraining the positions of the one or more planes to establish an appropriate flexion gap for a joint of the limb.

12. A method comprising:
obtaining patient-specific anatomical data of a limb;
identifying a plurality of anatomical landmarks of the limb using the patient-specific anatomical data;
determining, based on the identified plurality of anatomical landmarks, a position of a prosthetic component such that the prosthetic component has a predetermined orientation with respect to a mechanical axis of the limb; and
determining one or more planes for bone cuts on the limb based on the determined position of the prosthetic component, at least one of the one or more planes having a predetermined orientation with respect to the mechanical axis of the limb, wherein determining the one or more planes for bone cuts on the limb comprises iteratively changing positions of the one or more planes.

13. The method of claim 12 , wherein determining the position of the prosthetic component comprises adjusting a position of a profile of a three-dimensional computer model of the prosthetic component with respect to a three-dimensional computer model of the limb determined based on imaging data for the limb; and
wherein determining the one or more planes for bone cuts on the limb comprises determining one or more planes along the profile of the three-dimensional computer model of the prosthetic component after adjusting the position of the profile.

14. The method of claim 13 , wherein adjusting the position of the profile of the three-dimensional computer model of the prosthetic component comprises adjusting the position of the profile to adjust a flexion gap for a joint of the limb.

15. The method of claim 13 , wherein determining the position of the prosthetic component comprises determining an anterior-posterior positioning for the prosthetic component such that posterior-most portions of medial and lateral condylar bearing surfaces of a femoral implant are adjacent to or intersect posterior-most portions of natural bone of the limb.

16. A method comprising:
obtaining patient-specific anatomical data of a limb;
identifying a plurality of anatomical landmarks of the limb using the patient-specific anatomical data;
performing a series of computations to determine a three-dimensional mechanical axis of the limb based on the identified plurality of anatomical landmarks, wherein performing the series of computations comprises performing multiple computations that are each based on locations of different anatomical landmarks of the plurality of anatomical landmarks; and
determining one or more planes for bone cuts on the limb based on the identified plurality of landmarks and the determined three-dimensional mechanical axis of the limb, at least one of the one or more planes having a predetermined orientation with respect to the determined three-dimensional mechanical axis of the limb.

17. The method of claim 16 , wherein obtaining the patient-specific anatomical data comprises obtaining pre-operative imaging data for the limb that indicates contours of at least one bone of the limb;
wherein identifying the plurality of anatomical landmarks comprises identifying the plurality of anatomical landmarks with respect to a digital three-dimensional model of one or more bones of the limb generated based on pre-operative imaging data for the limb;
wherein determining the one or more planes for bone cuts on the limb comprises determining a position of a digital three-dimensional model of a prosthetic component with respect to the digital three-dimensional model of one or more bones of the limb and determining the one or more planes based on the determined position of the digital three-dimensional model of the prosthetic component; and
wherein the method further comprises manufacturing a patient-specific cutting guide including a portion that conforms to a corresponding portion of a bony surface of the limb such that the patient-specific surgical item is configur

Assignees

• Smith & Nephew Inc

Inventors

• Jordan Jason Sean
• Hughes Michael Dean
• Nadzadi Mark Ellsworth
• Mckinnon Brian William
• Crabtree Jr Paul Charles
• Mehl David Timothy

Classifications

• A61B2017/564

  Methods for bone or joint treatment · CPC title

• A61B17/157

  Cutting tibia · CPC title

• A61B17/1703

  using imaging means, e.g. by X-rays · CPC title

• A61B17/1725

  for applying transverse screws or pins through intramedullary nails or pins · CPC title

• A61B17/56

  Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor · CPC title