Systems and methods for measuring parameters in joint replacement surgery

Patent metadata

Field	Value
Publication number	US-9456765-B2
Application number	US-201514863115-A
Country	US
Kind code	B2
Filing date	Sep 23, 2015
Priority date	Sep 16, 2011
Publication date	Oct 4, 2016
Grant date	Oct 4, 2016

Abstract

A computer-assisted surgery system includes a display, an input device configured to receive data input by a user, and a processor, coupled to the input device and the display. The processor is configured to establish a first position of a pre-operative center of rotation of a joint in a first coordinate space of a first bone and a second coordinate space of a second bone and establish a second position of the pre-operative center of rotation of the joint in the first coordinate space, wherein the second position is a projection into the first coordinate space of the position of the pre-operative center of rotation maintained in a constant position in the second coordinate space. The processor is further configured to determine a change in a parameter associated with the joint based on the first and second positions and output a result indicating the determined change to the display.

First claim

What is claimed is:

1. A computer-assisted surgery system comprising:
a display;
an input device configured to receive data input by a user;
a processor, operatively coupled to the input device and the display and configured to:
establish a first position of a pre-operative center of rotation of a joint in a first coordinate space of a first bone and a second coordinate space of a second bone;
establish a second position of the pre-operative center of rotation of the joint in the first coordinate space of the first bone, wherein the second position is a projection into the first coordinate space of the first bone of the position of the pre-operative center of rotation maintained in a constant position in the second coordinate space of the second bone; and
determine a change in a parameter associated with the joint based on the first and second positions; and
output a result indicative of the determined change in the parameter to the display.

2. The computer-assisted surgery system of claim 1 , wherein the processor is configured to establish the second position of the pre-operative center of rotation of the joint by:
estimating, by the processor after modification of the joint, a position of a center of rotation of the modified joint; and
positioning, by the processor in a virtual coordinate space, a virtual representation of the second bone in a predetermined pose based, at least in part, on the center of rotation of the modified joint.

3. The computer-assisted surgery system of claim 1 , wherein the joint is a hip joint, and wherein the first coordinate space is a pelvic space and the second coordinate space is a femoral space.

4. The computer-assisted surgery system of claim 3 , wherein the processor is configured to establish the second position of the pre-operative center of rotation of the joint by:
estimating, by the processor after modification of the hip joint, a position of a center of rotation of the modified hip joint; and
positioning, by the processor in a virtual coordinate space, a virtual representation of a femur in a predetermined pose based, at least in part, on the center of rotation of the modified hip joint.

5. The computer-assisted surgery system of claim 4 , wherein the processor is configured to position the virtual representation of the femur in the predetermined pose by:
establishing a first axis associated with the femur, the first axis comprising a virtual axis passing through the center of rotation of the modified hip joint and an estimated midpoint between epicondyles of the femur; and
establishing a second axis associated with the femur, the second axis comprising a virtual transverse axis passing through the epicondyles of the femur,
wherein the virtual representation of the femur is positioned in the virtual coordinate space so that the first axis is substantially parallel with a superior/inferior axis of the pelvis and the second axis is substantially parallel with a coronal plane of the pelvis.

6. The computer-assisted surgery system of claim 1 , further comprising a data storage device containing computed tomography (CT) data associated with the joint of a patient, wherein the processor is further configured to:
retrieve the CT data associated with the joint;
receive information indicative of a geometric feature of the joint; and
estimate the center of rotation of the joint based on the analysis of the geometric feature.

7. The computer-assisted surgery system of claim 6 , wherein the processor is further configured to:
generate a virtual representation of at least a part of the first bone, based on the obtained CT data associated with the joint;
capture positions of a plurality of anatomical landmarks associated with the first and second bones; and
electronically track a position of the virtual representation of the first bone based on the captured position.

8. The computer-assisted surgery system of claim 7 , wherein the processor is configured to establish the first position of the pre-operative center of rotation of the joint by:
defining the first position relative to the virtual representation of the second bone so that a change in the position of the virtual representation of the second bone relative to the first bone results in a corresponding change in position of the pre-operative center of rotation of the joint relative to the first bone, and
wherein establishing the second position of the pre-operative center of rotation of the joint comprises:
electronically tracking a position of the pre-operative center of rotation of the joint; and
determining, upon positioning of the second bone in the predetermined pose in the virtual coordinate space, the second position as the electronically-tracked position of the pre-operative center of rotation of the joint.

9. A computer-assisted surgery system for determining a change in a parameter associated with a joint caused by a modification of a portion of the joint, the method comprising:
a display;
an input device; and
a processor, operatively coupled to the input device and the display and configured to:
establish a first point of reference relative to a first bone of a joint, the first point of reference indicative of an estimated pre-operative center of rotation of the joint in pelvic space;
establish, after a modification of the joint, a second point of reference indicative of an estimated post-modification center of rotation of the joint;
position a virtual representation of the first bone in a predetermined pose based on the second point of reference and relative to a second bone;
approximate, based on the positioning of the virtual representation of the first bone in the predetermined pose, a third point of reference in pelvic space indicative of a position of the first point of reference maintained in a fixed relationship relative to the first bone;
estimate a change in a parameter associated with the joint based on a difference between the third point of reference and the first point of reference; and
output a result indicative of the estimated change in the parameter to the display.

10. The computer-assisted surgery system of claim 9 , wherein the joint is a hip joint, the first bone is a femur of the hip joint, and the second bone is a pelvis of the hip joint.

11. The computer-assisted surgery system of claim 10 , wherein the processor is configured to position the virtual representation of the first bone in a predetermined pose by:
establishing a first axis associated with the femur, the first axis comprising a virtual axis passing through the second point of reference and an estimated midpoint between epicondyles of the femur; and
establishing a second axis associated with the femur, the second axis comprising a virtual transverse axis passing through the epicondyles of the femur,
wherein the virtual representation of the femur is positioned in a virtual space so that the first axis is parallel with a superior/inferior axis of the pelvis and the second axis is parallel with the coronal plane of the pelvis.

12. The computer-assisted surgery system of claim 9 , wherein the processor is configured to establish the first point of reference by:
obtaining computed tomography (CT) data associated with the hip joint;
analyzing a geometric feature of the hip joint based on the CT data; and
estimating the center of rotation of the hip joint based on the analysis of the geometric feature.

13. The computer-assisted surgery system of claim 12 , wherein the processor is further configured to:
generate a virtual representation of at least a part of the first bone, based on the obtained CT data associated with the h

Assignees

• Mako Surgical Corp

Inventors

• Odermatt Daniel
• Thompson Matthew

Classifications

• A61B5/06 Primary

  Devices, other than using radiation, for detecting or locating foreign bodies {; Determining position of diagnostic devices within or on the body of the patient} · CPC title

• A61B5/4571

  Evaluating the hip · CPC title

• A61B5/4851

  Prosthesis assessment or monitoring · CPC title

• G06F19/3437

  Physics · mapped topic

• A61B5/4528

  Joints (A61B5/4533, A61B5/4538 take precedence) · CPC title