METHOD AND APPARATUS FOR POSITIONING A BONE PROSTHESIS USING A LOCALIZATION SYSTEM
First Claim
1. A method of using a surgical navigation system for positioning in a femur a femoral prosthetic component of a hip joint replacement prosthesis, said method comprising the steps of:
- acquiring a pelvic frame of reference;
acquiring a center of rotation of said hip joint in said pelvic frame of reference;
acquiring a first femoral point substantially fixed with respect to said femur in said pelvic frame of reference while said hip joint is intact;
calculating a length of a first line between said first acquired femoral point and said center of rotation of said hip joint;
implanting a prosthetic cup component of said hip joint replacement prosthesis in said pelvis;
acquiring a position of a center of rotation of said implanted prosthetic cup component in said pelvic frame of reference;
calculating a first difference in position between said center of rotation of said hip joint and said center of rotation of said implanted prosthetic cup component in said pelvic frame of reference;
forming a hole in said femur for accepting said femoral prosthetic component;
rigidly mounting a marker in said hole, said marker having a known position relative to a position of a center of rotation of a prosthetic femoral head of a femoral prosthetic component if implanted in said hole;
calculating a position of a center of rotation of said prosthetic femoral head if implanted in said hole as a function of said position of said marker mounted in said hole;
while said marker is mounted in said hole, re-acquiring said first femoral point relative to said position of said marker mounted in said hole;
calculating a length of a second line between said re-acquired first femoral point and said center of rotation of said prosthetic femoral head;
calculating a second difference in length of said first line and said second line; and
displaying leg length data as a function of said first and second differences.
2 Assignments
0 Petitions
Accused Products
Abstract
Methods and apparatus using a surgical navigation system to position the femoral component of a prosthetic hip during hip joint replacement surgery without separately affixing a marker to the femur. The navigation system acquires the center of rotation of the hip joint as well as at least one point on the femur in the pelvic frame of reference. From these two points, the navigation system calculates the position and length of a first line between the center of rotation of the hip joint and the point on the femur. Optionally, a second point on the femur that is not on the first line is palpated. The system can calculate the position and length of a second line that is perpendicular to the first line and that runs from the first line to the second palpated point on the femur. The prosthetic cup is implanted and its center of rotation is recorded. A tool for forming the bore within which the stem of the femoral implant component will be placed is tracked by the navigation system. While the tool is fixed to the femur, the surgeon re-palpates the same point(s) on the femur that were previously palpated. The navigation system calculates the position and length of a first line between the center of rotation of the prosthetic cup and the re-palpated first point. If a second point on the femur was re-palpated, the navigation system also calculates the position and length of a perpendicular line between the first line and the second point. The surgical navigation system uses this information to calculate and display to the surgeon relevant information about the surgery, such as change in the patient'"'"'s leg length and/or medialization/lateralization of the joint.
281 Citations
37 Claims
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1. A method of using a surgical navigation system for positioning in a femur a femoral prosthetic component of a hip joint replacement prosthesis, said method comprising the steps of:
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acquiring a pelvic frame of reference; acquiring a center of rotation of said hip joint in said pelvic frame of reference; acquiring a first femoral point substantially fixed with respect to said femur in said pelvic frame of reference while said hip joint is intact; calculating a length of a first line between said first acquired femoral point and said center of rotation of said hip joint; implanting a prosthetic cup component of said hip joint replacement prosthesis in said pelvis; acquiring a position of a center of rotation of said implanted prosthetic cup component in said pelvic frame of reference; calculating a first difference in position between said center of rotation of said hip joint and said center of rotation of said implanted prosthetic cup component in said pelvic frame of reference; forming a hole in said femur for accepting said femoral prosthetic component; rigidly mounting a marker in said hole, said marker having a known position relative to a position of a center of rotation of a prosthetic femoral head of a femoral prosthetic component if implanted in said hole; calculating a position of a center of rotation of said prosthetic femoral head if implanted in said hole as a function of said position of said marker mounted in said hole; while said marker is mounted in said hole, re-acquiring said first femoral point relative to said position of said marker mounted in said hole; calculating a length of a second line between said re-acquired first femoral point and said center of rotation of said prosthetic femoral head; calculating a second difference in length of said first line and said second line; and displaying leg length data as a function of said first and second differences. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 27, 28)
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26. The method of 1 wherein a leg of said patient is maintained in about the same amount of flexure during performance of said method.
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29. A computer readable product embodied on computer readable media readable by a computing device for generating a display for a surgical navigation system to be used for positioning in a femur a femoral prosthetic component of a hip joint replacement prosthesis, the product comprising:
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first computer executable instructions for acquiring a pelvic frame of reference; second computer executable instructions for acquiring a center of rotation of said hip joint in said pelvic frame of reference; third computer executable instructions for acquiring a first femoral point substantially fixed with respect to said femur in said pelvic frame of reference; fourth computer executable instructions for calculating a length of a first line between said first acquired femoral point and said center of rotation of said hip joint; fifth computer executable instructions for acquiring a position of a center of rotation of said implanted prosthetic cup component in said pelvic frame of reference; sixth computer executable instructions for calculating a first difference in position between said center of rotation of said hip joint and said center of rotation of said implanted prosthetic cup component; seventh computer executable instructions for calculating a position of a center of rotation of a prosthetic femoral head of a femoral prosthetic implant if implanted in said hole as a function of said position of said marker mounted in said hole; eighth computer executable instructions for re-acquiring said first femoral point relative to said position of said marker mounted in said hole while said marker is mounted in said hole; ninth computer executable instructions for calculating a length of a line between said re-acquired first femoral point and said center of rotation of said prosthetic femoral head; tenth computer executable instructions for calculating a second difference in length of said first line and said second line; and eleventh computer executable instructions for displaying leg length data as a function of said first and second differences. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37)
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Specification