Patient Joint Simulation Process

Abstract

Method for simulating a patient's joint with a view to planning a surgical operation for implanting a joint prosthesis 20, consisting of - using an image 1 of the patient's joint to derive geometric information on the geometry of the bones 3, and at least part of the soft tissues 2 constituting it; - from this information, assigning geometric properties to the bones; - from this information, assigning connection points on the bones to the soft tissues, as well as connection forces estimated from the dimensions of these tissues; - numerically modeling the joint taking into account the geometric properties of the bones and the connection points of the soft tissues, as well as the maximum connection forces of the soft tissues; - integrating a numerical simulation of the joint prosthesis 20 into the numerical model;- animate the digital model obtained after integration of the prosthesis, to anticipate its effect on the operated patient. Figure for abstract: figure 5;

Description

Title of the invention: Method for simulating a patient's joint

[0001] The invention relates to the field of joint prosthesis implants.

[0002] More specifically, the invention relates to a method for simulating a patient's joint in order to plan a surgical operation for a joint prosthesis implant, for example a shoulder prosthesis.

[0003] It is already known, in the state of the art, to produce a personalized model of a part of the skeleton of a patient to receive a joint prosthesis from a scan carried out at the targeted joint. The model makes it possible to determine the geometry of the joint and to choose the prosthesis model most likely to restore the patient's movement capabilities once operated on. The authorized movements depend on the geometry of the skeleton and the mechanical connections put in place by the prosthesis.

[0004] A difficulty with the state-of-the-art method is that, despite the precautions taken by precise operative preparations, it is found that patients do not all benefit identically from the advantages of prostheses whose models are nevertheless identical. There are therefore other factors which influence the result of the implantation.

[0005] It has been put forward as a first hypothesis that diseases specific to each patient can create differences which influence the results of the implantation of the prosthesis.

[0006] The inventor has made and verified an additional hypothesis to explain this disparity in results between patients. Soft tissues such as ligaments, tendons, muscles, and cartilage, which are not taken into account in the simulation, have a significant influence on the success of the implantation. If they were taken into account, the simulation would result in potentially different choices of the prosthesis model and implantation of the prosthesis on the skeleton, for a more uniform result from one patient to another. This result has proven to be accurate following tests carried out by the inventor.

[0007] In the present description, the term "periosteal tissues" refers to all the soft tissues and cartilage which are in contact with the bones of a joint.

[0008] To this end, the invention relates to a method for simulating a patient's joint with a view to planning a surgical operation for implanting a joint prosthesis, the method consisting of: - obtain an image of the joint containing point clouds characteristic of the geometry not only of the patient's bones forming the joint, but also of at least part of the peri-osseous tissues constituting said joint, said periosteal tissues being constituted by soft tissues and / or cartilage which are in contact with the patient's bones forming the joint, subjecting the image containing the point clouds to shape recognition, by comparison with a database of anatomical parts including information relating to the insertion points on the bones and the binding forces of the muscles, and / or, using deep learning and artificial intelligence, to: identify the bones and peri-osseous tissues constituting the joint, and assign them properties relating to the insertion points on the bones and the bonding forces, create a so-called “segmented” digital model of the joint, taking into account the identified bones and peri-osseous tissues and their properties thus obtained, integrate a digital simulation of a joint prosthesis into the segmented digital model obtained during the previous step, replacing the anatomical parts to be replaced with the prosthesis, animate the digital model obtained after integration, to anticipate the effect of the presence of said prosthesis on the operated patient.

[0009] Advantageously, the peri-osseous tissues comprise at least one of the group consisting of muscles, tendons, ligaments and cartilage.

[0010] In a first embodiment of the invention, the image is obtained by scanning, then image processing highlighting the soft tissues which are not normally easily visible on a raw scanner image.

[0011] According to another embodiment, the image is obtained by MRI (magnetic resonance imaging), then image processing highlighting soft tissues which are not normally easily visible on a raw scanner image.

[0012] According to the invention, according to a first model, the digital modeling carried out from the image consists of identifying remarkable points of the image to to form point clouds and construct segments representing the components of the model. This step, which consists of transforming a point cloud into a solid, is called segmentation.

[0013] According to the invention, according to a second model, a finite element representation is used. Each bone and each peri-osseous tissue is represented by a mesh of elementary structures.

[0014] According to a particular embodiment of the invention, in the segmented digital model, each muscle is divided into a predetermined number of disjointed muscle fibers, each muscle fiber receiving a force value, which is a component of the overall strength of the muscle. This force value can vary throughout the cycle of movement of the joint.

[0015] According to a particular embodiment of the invention, the joint is a shoulder and the bones are the humerus, the scapula and the clavicle.

[0016] According to another particular embodiment, the joint is a hip or a knee.

[0017] According to a particular embodiment of the invention, the peri-osseous tissues taken into account in the segmented digital model are the muscles of the shoulder, namely the rotator cuff, i.e. supra and infra spinatus, subscapularis and teres minor, and the deltoid.

[0018] According to the invention, the insertion of the ligaments on the bones is taken into account in the segmented digital model in a precise manner, which makes it possible to very precisely simulate the force couples exerted by the muscles on the bones.

[0019] Advantageously, in the segmented digital model, each muscle is independent of the others.

[0020] Advantageously, in the segmented digital model, each fiber of a muscle is independent of the other fibers.

[0021] In a particular embodiment of the invention, a particular pathology of the patient is simulated in the segmented digital model by assigning to each fiber of a muscle and to each muscle a degraded maximum force value.

[0022] In a particular embodiment of the invention, the animation of the digital model after integration of the prosthesis consists of digitally contracting each muscle or muscle fiber, that is to say simulating the application of a force by each muscle or muscle fiber on the bones, and observing the theoretical movement of the bones in their degrees of freedom left by the simulated joint prosthesis.

[0023] The invention therefore makes it possible to predict, in a concrete and realistic manner, the future results of the implantation of the prosthesis on the patient.

[0024] In a particular embodiment, the method according to the invention also makes it possible to predict which muscles will require advantageous development for optimal functioning of the joint. Thus, the practitioner will be able to recommend to the patient muscle training movements adapted to develop certain muscles which will provide better operating efficiency to the joint equipped with the prosthesis. Such progress was not possible with the purely bone models of the state of the art.

[0025] The invention allows the surgeon to plan a surgical intervention in its entirety, taking into account not only the patient's local skeleton, but also the soft tissues. In the state of the art, knowledge of peri-osseous tissues is lacking and the surgeon only discovers at the start of the surgical intervention what is the environment of the patient's skeleton, made up of muscles, tendons, ligaments and cartilage. The surgeon must therefore adapt on the spot, that is to say without having been able to prepare for it, and possibly adjust the fixation of the joint.

[0026] According to the invention, the application of contractions on muscle models of the digital model aims to obtain simple movements such as: abduction adduction, flexion extension, internal or external rotation, convolutions.

[0027] According to a particular embodiment of the invention, the animation of the digital model is renewed under different hypotheses of muscular development of the patient, so as to anticipate the behavior of the prosthesis not only in the context of the state of muscular development of the patient before the operation, but also in evolving contexts of muscular development of the patient which would be recommended by the practitioner after the operation.

[0028] In a particular embodiment, the information from the database includes the density and / or bone quality of the bones. This consideration makes it possible to improve the durability of the prosthesis over time.

[0029] The invention also relates to the digital model of the local skeleton and the peri-osseous tissues surrounding the skeleton, obtained by implementing the method defined above.

[0030] The invention also relates to a method for selecting a prosthesis from a choice of different available prostheses, consisting of:

[0031] - successively test each of the prostheses of the choice of prostheses by implanting a digital model of the prosthesis and by animating the digital model of the local skeleton and the peri-osseous tissues surrounding the skeleton integrating said prosthesis according to a predetermined muscular force field,

[0032] - compare the results obtained,

[0033] - once all prosthesis models are tested, select the model providing the best results.

[0034] In a particularly advanced embodiment, the method consists of animating the digital model with several muscular force fields, each muscular force field representing a potential muscular development state of the patient, so as to select the joint prosthesis providing the best results in a given muscular force field. In this hypothesis, the patient will be recommended, after the operation, to follow muscular training allowing him to develop the muscular force field adapted to the prosthesis thus selected.

[0035] The invention also relates to a computer program product allowing surgical planning, comprising a series of instructions making it possible to implement at least one of the methods described above. Brief description of the figures

[0036] The invention will be better understood on reading the following description given solely by way of example and with reference to the appended drawings in which:

[0037] [Fig. 1] represents a flowchart illustrating a method according to the invention

[0038] [Fig.2] is a perspective and sectional scanned view of a patient's shoulder, in which a scapular implant is shown opposite the corresponding glenoid;

[0039] [Fig.3] is a view similar to that of [Fig.2], in which the soft tissues have been computer-removed and in which the scapular implant is shown implanted on the scapula;

[0040] [Fig.4] is a view illustrating a humeral implant, implanted in one end of a humerus; and,

[0041] [Fig.5] is a view similar to those of Figures 2 and 3, in which the scapular and humeral implants are shown in a functional relative position. Detailed description

[0042] In a first step 1, an image is produced of a joint area of ​​a patient, for example of their shoulder. The imaging device used in this example is a scanner.

[0043] In a second step 2, the images obtained are subjected to image processing which further reveals the geometry of the peri-osseous tissues surrounding the patient's local skeleton, so as to highlight point clouds characteristic of these peri-osseous tissues. This step is not necessarily required if the image obtained in step 1 is sufficiently precise to immediately reveal the point clouds characteristic of the bones and peri-osseous tissues.

[0044] An image combining data from a scanner or an MRI device can also be used.

[0045] In a following step 3, recognition of the anatomical elements present in the image is carried out using artificial intelligence, which compares the point clouds of the image with representations of bones and peri-osseous tissues present in a database containing geometric information on the anatomical parts and information on the insertion points on the bones and on the connecting forces of the muscles. A segmented digital model of the joint is thus obtained.

[0046] In a variant 3B of step 3, each muscle is replaced by ten independent muscle fibers, to which the same treatment is applied. In this case, the contraction of each muscle results in a contraction of each fiber, taking into account the individual properties of each fiber, the force of which, variable during the intended movement, may have been manually adjusted to take into account a disease of the patient.

[0047] In a following step 4, a digital model of a joint prosthesis is selected and this digital model is integrated into the segmented digital model of the joint, by digitally replacing the anatomical parts to be replaced by the joint prosthesis. This step 4 is illustrated by the images in Figures 2 to 5.

[0048] In a following step 5, the digital model is animated by applying forces to certain muscles to simulate their contractions and the movement thus produced on the skeleton linked by the joint prosthesis is observed.

[0049] In a subsequent step 6, the implantation of the joint prosthesis simulated in the previous step is modified until optimal behavior of the joint is obtained. Optimal movement is understood to mean a movement close to that of a patient of similar morphology in good health. Thus, the best location of the implant(s) and the best combination of implants are determined to obtain the best results. In addition, the necessary muscle building that the patient will have to develop after the operation is determined, to optimize his recovery.

[0050] The finite element model and the software resulting from the implementation of the method which has just been described can be produced by mobilizing the general knowledge of a person skilled in the art and will not be described here.

[0051] Figures 2 to 5 illustrate the installation according to the invention of a reverse prosthesis. In the example illustrated, this involves the installation of a prosthesis of the scapulohumeral joint.

[0052] [Fig. 2] illustrates a three-dimensional digital representation of the patient's left shoulder 1, in which the soft tissues, essentially muscle tissues 2, have been computer-removed to the right of a substantially vertical section plane S. Emerging from these soft tissues 2, emerging from the section plane S, are parts of the scapula 3, in particular: the glenoid 4, flush with the section plane S, the acromion 5 and the coracoid 6. [Fig. 2] also illustrates a digital model of a scapular implant 11, represented at a distance from the scapula 3. Hereinafter, the implant model is simply called an "implant".

[0053] As particularly illustrated in [Fig.3], the scapular implant 11 is intended to be implanted on the scapula, at the location of the glenoid 4.

[0054] In image 1 of [Fig.3], the soft tissues have been computer-generated entirely from the representation of the shoulder, so that only the scapula bone and the scapular implant attached to it are visible.

[0055] The scapular implant functionally replaces the glenoid, except that it comprises an articular surface 12 which is convex in shape. Thus, it is intended to form a reverse prosthesis 20, with a complementary humeral implant 13, a digital model of which is visible in Figures 4 and 5.

[0056] [Fig.4] illustrates a three-dimensional digital representation of the head 14 of the patient's left humerus 1, on which the soft tissues have been computer-removed. This figure also illustrates the implantation of the humeral implant 13, in the head 14 of the humerus. The implant 13 comprises a concave articular surface 16, complementary to the convex articular surface 12 of the glenoid. It is the sliding of the two surfaces 12, 16 which allows the joint 20 to function.

[0057] [Fig. 5] is a digital representation of the joint 20, once reduced, in the configuration and in the bone and muscle context that it is likely to take during its actual implantation in the patient's shoulder. The three-dimensional image of [Fig. 5] therefore constitutes a digital twin of the patient's shoulder equipped with the prosthesis, before the prosthesis is fitted.

[0058] The digital twin can be anatomically deformed so as to be able to model a dynamic operation of the prosthesis. It can be modified, for example by changing the shapes and dimensions of the implants, for example to choose those which are best suited, fit best into the anatomy and / or allow the greatest comfort of use for the patient.

[0059] This digital twin thus makes it possible to program the intervention. For example, it makes it possible to modify, before the surgical intervention, the shape of the scapular implant to avoid bone interference with certain parts of the scapula.

[0060] This process, thanks to the installation of a prosthesis better adapted, in shape and position, to the anatomy of the patient, allows for better rehabilitation and better recovery. It also allows for greater mobility to the joint.

[0061] Of course, the invention is not limited to the examples which have just been described. On the contrary, the invention is defined by the claims which follow.

[0062] It will indeed appear to those skilled in the art that various modifications can be made to the embodiments described above, in light of the teaching which has just been disclosed to them.

[0063] Thus, the method previously described with reference to a reverse prosthesis can be used for an anatomical prosthesis.

[0064] Also, the method can be used for any type of joint prosthesis, for which it is important to check the functionality of the prosthesis in each of the positions it can take, and also, in its movement. It can also be used for non-mobile prostheses to check and limit its interference with the patient's body.

Claims

Claims

1. A method for simulating a patient's joint for the purpose of planning a surgical operation for implanting a joint prosthesis, the method consisting of - obtaining an image (1) of the joint containing point clouds characteristic of the geometry not only of the patient's bones (3, 14) forming the joint, but also of at least part of the peri-osseous tissues constituting said joint, said peri-osseous tissues being constituted by soft tissues (2) and / or cartilage which are in contact with the patient's bones forming the joint, - subjecting the image containing the point clouds to shape recognition, by comparison with a database of anatomical parts comprising information relating to the insertion points on the bones and the muscle binding forces, and / or, using deep learning and artificial intelligence,to: - identify the bones and peri-osseous tissues constituting the joint; and, - assign them properties relating to the insertion points on the bones and to the connecting forces, - create a so-called "segmented" digital model of the joint taking into account the bones and peri-osseous tissues identified and their properties thus obtained, - integrate a digital simulation (20; 11, 13) of joint prosthesis into the segmented digital model obtained during the previous step, by replacing the anatomical parts to be replaced by the prosthesis, - animate the digital model obtained after integration, to anticipate the effect of the presence of said prosthesis on the operated patient.,

2. The method of claim 1, wherein the periosteal tissues comprise at least one of the group consisting of muscles, tendons, ligaments, cartilage

3. Method according to any one of the preceding claims, in which the image is obtained by scanner and / or MRI, then image processing highlighting the soft tissues.

4. A method according to any preceding claim, which comprises a segmentation step and wherein, in the model digitally segmented in this way, each muscle is divided into a predetermined number of disjointed muscle fibers, each muscle fiber receiving a maximum force value, which is a component of the overall maximum force of the muscle, which can vary during an animation cycle of said model.

5. Method according to any one of the preceding claims, characterized in that the digital model produced from the image consists of carrying out a segmentation, that is to say of identifying remarkable points of the image to form point clouds and of constructing segments representative of the constituents of the model.

6. A method according to claim 5, characterized in that each muscle is divided into a predetermined number of disjointed muscle fibers, each muscle fiber receiving a force value, which is a component of the overall force of the muscle, said force value being able to vary in the animation cycle of the model.

7. Method according to any one of claims 1 to 4, characterized in that the digital model is produced from a representation by finite elements, each bone and each peri-osseous tissue being represented by a mesh of elementary structures.

8. A method according to any preceding claim, wherein the joint is a shoulder and the bones are the humerus, scapula and clavicle.

9. A method according to any preceding claim, wherein the muscles are those of the shoulder, namely the rotator cuff, i.e. supra and infra spinatus, subscapularis and teres minor, and the deltoid.

10. Method according to any one of the preceding claims, in which a particular pathology of the patient is simulated in the digital model by attributing to each fiber of a muscle and where to each muscle a degraded maximum force value.

11. A method according to any one of the preceding claims, wherein the animation of the digital model after integration of the prosthesis consists of digitally contracting each muscle or muscle fiber, i.e. simulating the application of a force by each muscle or muscle fiber on the bones, and observing the theoretical movement of the bones in their degrees of freedom left by the simulated joint prosthesis (20).

12. Digital model for planning a chi- surgical procedure for implanting a joint prosthesis, obtained by implementing the method according to any one of the preceding claims.

13. Method for selecting a prosthesis from a choice of different available prostheses, consisting of: - successively testing each of the prostheses of the choice of prostheses by implanting a digital model of the prosthesis in a digital model according to claim 7 and by animating the digital model integrating said prosthesis according to a predetermined muscular force field, - comparing the results obtained, - once all the prosthesis models are tested, selecting, preferably automatically, preferably using artificial intelligence, the model providing the best results.

14. Method according to the preceding claim, in which the digital model is animated with several muscular force fields, each muscular force field representing a potential muscular development state of the patient, so as to select the joint prosthesis providing the best results in a given muscular force field.

15. Computer program product, executable by a computer, allowing surgical planning, comprising a series of instructions allowing at least one of the methods according to the preceding claims to be implemented.

Images