Modelling for surgery
First Claim
1. A method of modelling for use in surgical planning, the method comprising:
- (a) generating a bone model including a NURBS surface describing a first fitting surface of a bone to which a prosthesis component is to be fitted;
(b) providing a prosthesis shell model describing a prosthesis component, the prosthesis component including a second fitting surface;
(c) displaying superimposed representations of the bone model and the prosthesis model;
(d) translating and/or rotating one or both of the bone model and the prosthesis model to represent one fit of the prosthesis component to the bone;
(e) modifying the prosthesis or bone model by re-modelling at least one of the respective fitting surfaces;
(f) generating a modified bone or prosthesis model;
(g) passing the bone model to a surgical robot; and
(h) using the prosthesis shell model to generate a prosthesis component.
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Abstract
The invention in its various forms relates generally to surgical planning methods, and in particular to the planning of surgical operations to implant a prosthesis. In a first embodiment, the surgeon uses an interactive system to design both the shape of the prosthesis and the shape of the bone. In a second embodiment, a modified Marching Cubes algorithm is used to simulate cutting planes within bones. In a third embodiment, back-projection is used within a computer model to allow an integrated display of both bone and prosthesis. In a fourth embodiment, an interactive system is used to test the mobility of a proposed implant, prior to undertaking a surgical operation.
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Citations
44 Claims
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1. A method of modelling for use in surgical planning, the method comprising:
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(a) generating a bone model including a NURBS surface describing a first fitting surface of a bone to which a prosthesis component is to be fitted;
(b) providing a prosthesis shell model describing a prosthesis component, the prosthesis component including a second fitting surface;
(c) displaying superimposed representations of the bone model and the prosthesis model;
(d) translating and/or rotating one or both of the bone model and the prosthesis model to represent one fit of the prosthesis component to the bone;
(e) modifying the prosthesis or bone model by re-modelling at least one of the respective fitting surfaces;
(f) generating a modified bone or prosthesis model;
(g) passing the bone model to a surgical robot; and
(h) using the prosthesis shell model to generate a prosthesis component. - View Dependent Claims (2, 3, 4, 12)
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5. A method of modelling for use in surgical planning, the method comprising:
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(a) generating a bone model describing a first fitting surface of a bone to which a prosthesis component is to be fined;
(b) providing a prosthesis shell model describing a prosthesis component, the prosthesis component including a second fitting surface;
(c) displaying superimposed representations of the bone model and the prosthesis model;
(d) translating and/or rotating one or both of the bone model and the prosthesis model to represent one fit of the prosthesis component to the bone;
(e) modifying the prosthesis or bone model by re-modelling at least one of the respective fitting surfaces;
(f) generating a modified bone or prosthesis model;
(g) passing the bone model to a surgical robot; and
(h) outputting the prosthesis shell model for use in the generation of a prosthesis component. - View Dependent Claims (6, 7, 8)
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9. A surface modelling method for modelling a three-dimensional surface, comprising
(a) determining any polygon in one voxel and the voxels adjacent thereto of a surface to be modelled; -
(b) determining the polygon vertices of each determined polygon;
(c) encoding the polygon vertices as bit patterns, comprising, for each polygon vertex, the steps of;
(c1) encoding the polygon vertex as a bit pattern;
(c2) scanning a vertex list for the bit pattern;
(c3) including the bit pattern in the vertex list where the pattern is not in the vertex list; and
(c4) including an index of the bit pattern in a polygon table;
(d) repeating steps (a) to (c) for the other voxels of the surface to be modelled; and
(e) generating a vertex list and associated polygon table. - View Dependent Claims (10, 11, 13, 14, 19)
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15. A modelling method, comprising:
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(a) generating a bone model of a surface of a bone to which a prosthesis component is to be fitted by generating at least one polygon for each voxel on the surface of the bone as imaged;
(b) providing a prosthesis model describing a prosthesis component, the prosthesis component including a fitting surface;
(c) displaying superimposed representations of the bone model and the prosthesis model;
(d) translating and/or rotating one or both of the bone model and the prosthesis model to represent one fit of the prosthesis component to the bone;
(e) determining the relative translation and/or rotation of the fitting surface of the prosthesis component;
(f) generating a modified bone model by repositioning the vertices of the polygons of the bone model onto the fitting surface of the prosthesis component; and
(g) displaying the modified bone model. - View Dependent Claims (16, 17, 18)
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20. A method of enabling the optimization of the fit of first and second relatively-moveable prosthesis components, comprising:
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(a) positioning a prosthesis model of the first prosthesis component with respect to a first bone model, and a prosthesis model of the second prosthesis component with respect to a second bone model, to define respective first and second fitting models;
(b) simulating relative movement between the prosthesis components by moving one fitting model with respect to the other, subject to a constraint model;
(c) indicating any interference between the first and second fitting models;
(d) re-positioning the respective models of the first and second prostheses to define new first and second fitting models, and re-simulating movement;
(e) repeating (d) until a desired fit is achieved; and
(f) generating position data representative of the first and second fitting models for use in subsequent operation. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 36, 37, 38, 39)
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30. A method of enabling the optimization of the fit of a prosthesis component for a joint, comprising:
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(a) Defining a first fitting model including a model of the prosthesis and a second fitting model including a model of a further prosthesis or bone with which the prosthesis is to co-operate;
(b) simulating relative movement by moving one fitting model with respect to the other, subject to a constraint model;
(c) indicating any interference between the first and second fitting models;
(d) re-defining the first model and re-simulating movement; and
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(e) repeating (d) until a desired fit is achieved. - View Dependent Claims (31, 32, 33, 34, 35, 40, 41, 42, 43, 44)
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Specification