Method of determining the position of the articular point of a joint
First Claim
1. A method of obtaining preoperative information determining the position of an articular point of a central joint for guiding orthopaedic surgery performed on said central joint, said central joint being between two substantially rigid bodies, the central joint being located between first and second outer joints located at the ends of said first and second rigid bodies distal to said central joint, respectively, said method comprising the steps of:
- identifying the position of a first point on said first rigid body located substantially at said central joint;
determining the position of a first articular point of said first rigid body at said first outer joint;
defining a first axis between said first articular point and said first point;
identifying the respective positions of a second and a third point on said first rigid body on opposite sides of said central joint;
defining a plane substantially perpendicular to said first axis and at substantially equal respective rectangular distances to said second and third points, the intersection of said plane and said first axis being an initial estimate of said articular point of said central joint;
determining the position of a second articular point of said second rigid body at said second outer joint;
defining a region in said plane having a predetermined size, said region including said initial estimate of said articular point of said central joint;
moving said second articular point relatively to said first rigid body by rotating said second rigid body about said central joint;
identifying a multiplicity of different positions of said second articular point during said rotation of said second rigid body;
determining one point among a multiplicity of points within said region for which the position is substantially invariant for each of said positions of said second articular point, said one point being said articular point of said central joint; and
using the position of said articular point to guide an orthopaedic surgical procedure.
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0 Petitions
Accused Products
Abstract
A non-invasive method for determining the articular point of a joint is disclosed. The method uses a surgical navigation system having a stereoscopic cameras which tracks the positions of infrared emitting or reflecting markers attached to appendages on either side of the joint. A movable marker is used to palpate known landmarks on the appendages to determine their positions. The appendages are moved to determine the trajectories of the landmarks relative to the joint. Positional information from the cameras is fed to a data processing system with resident software which uses the positional information and trajectories to mathematically determine the position of the joint articular point according to the laws of kinematics.
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Citations
14 Claims
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1. A method of obtaining preoperative information determining the position of an articular point of a central joint for guiding orthopaedic surgery performed on said central joint, said central joint being between two substantially rigid bodies, the central joint being located between first and second outer joints located at the ends of said first and second rigid bodies distal to said central joint, respectively, said method comprising the steps of:
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identifying the position of a first point on said first rigid body located substantially at said central joint; determining the position of a first articular point of said first rigid body at said first outer joint; defining a first axis between said first articular point and said first point; identifying the respective positions of a second and a third point on said first rigid body on opposite sides of said central joint; defining a plane substantially perpendicular to said first axis and at substantially equal respective rectangular distances to said second and third points, the intersection of said plane and said first axis being an initial estimate of said articular point of said central joint; determining the position of a second articular point of said second rigid body at said second outer joint; defining a region in said plane having a predetermined size, said region including said initial estimate of said articular point of said central joint; moving said second articular point relatively to said first rigid body by rotating said second rigid body about said central joint; identifying a multiplicity of different positions of said second articular point during said rotation of said second rigid body; determining one point among a multiplicity of points within said region for which the position is substantially invariant for each of said positions of said second articular point, said one point being said articular point of said central joint; and using the position of said articular point to guide an orthopaedic surgical procedure. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of obtaining preoperative information determining the position of an articular point of a knee joint for guiding orthopaedic surgery performed on said central joint, said central joint being between the femur and the tibia, the knee joint comprising a patella and medial and lateral epicondyles and being located between a hip joint and an ankle joint located at respective ends of said femur and said tibia distal to said knee joint, said method comprising the steps of:
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identifying the position of said patella; determining the position of an articular point of said femur at said hip joint; defining a femoral axis extending between said femur articular point and said patella; identifying the positions of said medial and lateral epicondyles; defining a plane substantially perpendicular to said femoral axis and at substantially equal respective rectangular distances to said positions of said medial and lateral epicondyles, the intersection of said plane and said femoral axis being an initial estimate of said articular point of said knee joint; defining a region in said plane having a predetermined size, said region including said initial estimate of said articular point of said knee joint; determining the position of an articular point of said tibia at said ankle joint; moving said tibia articular point relatively to said femur by rotating said tibia about said knee joint; identifying a multiplicity of different positions of said tibia articular point during said rotation of said tibia; determining one point among a multiplicity of points within said region for which the position is substantially invariant for each of said positions of said tibia articular point, said one point being said articular point of said knee joint; and using the position of said articular point of said knee joint to guide an orthopaedic surgical procedure. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification