FR2979817A1 - Manufacturing bone prosthesis for filling gaps of all/part of bone of patient, comprises digitalizing patient using three-dimensional medical acquisition device by magnetic resonance, defining prosthesis, and manufacturing the prosthesis - Google Patents

Abstract

The method comprises digitalizing the patient using a three-dimensional medical acquisition device such as a scanner or an imagery device by magnetic resonance during establishing a file such as osseous representative of remaining osseous volumes of the patient, defining the prosthesis during defining a file such as prosthesis, representative of the shape of the final prosthesis, according to which the final prosthesis comprises a part of replacement of the bone gaps of the patient, and manufacturing the prosthesis during transfer of the prosthesis file towards the rapid prototyping machine. The method comprises digitalizing the patient using a three-dimensional medical acquisition device such as a scanner or an imagery device by magnetic resonance during establishing a file such as osseous representative of remaining osseous volumes of the patient, defining the prosthesis during defining a file such as prosthesis, representative of the shape of the final prosthesis, according to which the final prosthesis comprises a part of replacement of the bone gaps of the patient, manufacturing the prosthesis during transfer of the prosthesis file towards the rapid prototyping machine comprising a laser gun that is guided in response to information of the prosthesis file in a prototype powder layer to operate a fusion with the selective laser part of each layer so as to manufacture a section of a support and/or a section of prosthesis, and performing finishing step. The part is obtained from the bone file of the patient by symmetry of bone parts corresponding to the patient and/or from the bone file of an intact model by transposition of the bone parts of the models. The file comprises a support for manufacturing the prosthesis to realize a succession of the cross-sections thickness whose stack determines the shape of the prosthesis, and instructions series for a laser beam of rapid prototyping machine intended to allow the manufacturing of the support and prosthesis. In the manufacturing step, synthetic prototyping powder is used and has an increased rigidity. Recesses are filled by a three-dimensional grid forming an alveolate structure intended to allow colonization of the grid by bone cells of the patient. An independent claim is included for a bone prosthesis.

Description

The invention relates to a method of manufacturing a prosthesis by rapid prototyping.

The invention more particularly relates to a method of manufacturing a bone prosthesis intended to fill the bone deficiencies of all or part of a bone of a patient, of the type which comprises at least: a first step of digitizing said patient to using a three-dimensional medical acquisition device, in particular a scanner or a magnetic resonance imaging device, during which a so-called "bone" file representing the remaining bone volumes of the patient is established, at least a second step of defining the prosthesis during which a so-called "prosthesis" file, representative of the shape of the definitive prosthesis, is defined according to which the definitive prosthesis comprises at least one part of replacement of the bone deficiencies of the patient, said part being obtained from the bone file of the patient by symmetry of intact corresponding bone parts of the patient and / or from the bone file of a model the intact by transposition of the bone parts of said model, said file comprising one by a succession of sections, the stack of which determines the shape of at least one support for manufacturing the prosthesis to be produced, a succession of sections of the same thickness of which the stack determines the shape of the prosthesis to be produced, and a series of displacement instructions for a rapid prototyping machine laser beam intended to allow the manufacture of the support and the prosthesis, - at least a third stage of manufacture of the prosthesis during which the prosthesis file is transferred to a rapid prototyping machine comprising a laser cannon which is guided in response to the prosthesis file information in successive layers of a prototyping powder in order to effect a fusion at laser of a portion of each layer so as simultaneously to manufacture a section of at least one manufacturing support and section of said prosthesis, the layers being fed successively by a powder dispenser until the stack of sections made corresponds to the prosthesis, - at least a fourth finishing step during which the prosthesis is removed from any manufacturing support and any roughness. Many examples of such processes are known. The document EP-A1-2.110.079 describes and represents a method of manufacturing a mask or a prosthesis which comprises a first step in the course of which anatomical and / or pathological structures are deduced from a device of FIG. medical acquisition. Imaging data obtained by the acquisition device is used to create a surface contour and is transmitted to a compatible fast prototyping apparatus which can establish a positive or negative surface pattern such as a fixture, mask or prosthesis or other instruments for medical purposes. In this document, as in the other known devices, the production of a prototyping-based prosthesis is approached only briefly without taking into account the medical requirements that allow its grafting. Among these imperatives, it is necessary to mention the surface state of the prosthesis, the fidelity of the prosthesis with respect to the bone part which it must replace, in particular to allow its implantation in an existing environment, the weight, and the capacities of bone colonization. The invention overcomes these drawbacks by proposing a method of the type described above implementing a prototyping step laser power, only manufacturing method allowing a precision of execution to obtain a surface state of the prosthesis satisfactory, a high fidelity of the prosthesis in relation to the bone part it must replace, in particular to allow its implantation in an existing environment, reduced weight and high capacity for bone colonization. For this purpose, the invention proposes a method of the type described above, characterized in that during the third step of manufacturing the prosthesis is used a laser gun laser power type, to obtain a prosthesis of reduced roughness and high accuracy relative to the intact corresponding bone parts of the patient or model used. According to other characteristics of the process: - during the third manufacturing stage, a synthetic prototyping powder with a high rigidity is used after the melting, - during the third stage of manufacture, a prototyping powder based on cobalt / chromium, or titanium, or aluminum, - during the second step of definition of the prosthesis is defined a file called "prosthesis", representative of the shape of the prosthesis definitive, according to which the definitive prosthesis consists solely of a replacement part of the patient's bone deficiencies whose volume and dimensions are limited to the strict restoration of the anatomical functions of the patient, in particular to lighten the weight of the prosthesis, of the second step of definition of the prosthesis is defined a file called "prosthesis", representative of the shape of the final prosthesis, according to which the prosthesis final is an outer volume and dimensions substantially corresponding to the external volume and dimensions of the intact bones of the patient or model used, and comprises - at least one solid part, the actual volume and dimensions of which are limited to the strict restoration of the anatomical functions of the patient, - at least one recess for lightening the weight of the prosthesis, - during the second stage of definition of the prosthesis, the prosthesis file is defined according to a ratio of the volumes of the solid part and the recess which depends in particular on the prototyping powder used and the location of the prosthesis in the bone in question, and which makes it possible to guarantee a high stiffness of the solid part and a high flexibility of the entire prosthesis, - during of the second step of defining the prosthesis, the prosthesis file is defined so that each recess is filled by a sorting mesh. dimensional forming a honeycomb structure for allowing the colonization of said mesh by bone cells of the patient. The invention also relates to a bone prosthesis for filling the bone deficiencies of all or part of a bone of a patient, obtained at least by rapid prototyping in a rapid prototyping machine comprising a laser cannon which is guided in response to the information of a prosthesis file in successive layers of a prototyping powder in order to effect a selective laser melting of a portion of each layer so as to manufacture at least one section of said prosthesis, characterized in that is obtained by rapid prototyping in a rapid prototyping machine comprising a laser laser of the power laser type. According to other characteristics of the prosthesis: the bone prosthesis is made from a synthetic prototyping powder of high rigidity, the bone prosthesis is made based on a cobalt / chromium prototyping powder, or titanium, or aluminum, or any other implantable metal material in the body of a patient, - the bone prosthesis is only a replacement part of the patient's bone deficiencies whose volume and dimensions are limited to the strict restoration of the anatomical functions of the patient, the bone prosthesis is of an external volume and of dimensions substantially corresponding to the external volume and dimensions of the intact corresponding bony parts of the patient or of the model used, and comprises at least one solid part, of which the actual volume and dimensions are limited to the strict restoration of the anatomical functions of the patient,. at least one recess to lighten its weight. each recess is filled by a three-dimensional mesh forming a honeycomb structure intended to allow colonization of said mesh by bone cells of the patient. Other characteristics and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference will be made to the appended drawings in which: FIGS. 1A to 1C are successive views illustrating the second step of FIG. a method of manufacturing a prosthesis according to the invention; FIG. 2A is a view illustrating the third step of a method of manufacturing a prosthesis according to the invention; FIG. 2B is a perspective view of a maxillofacial prosthesis and its manufacturing supports. FIG. 3 is a perspective view of a maxillofacial prosthesis according to a first embodiment of the invention; FIG. 4 is a perspective view of the implantation on the skull of a patient of the prosthesis of FIG. 3; FIG. 5 is a perspective view of a maxillofacial prosthesis according to a second embodiment of the invention; - Figure 6 is a perspective view of the implantation on the skull of a patient of the prosthesis of Figure 5. In the following description, identical reference numerals designate parts identical or having similar functions. FIG. 1 shows a second step of a method of manufacturing a bone prosthesis intended to fill the bone deficiencies of all or part of a bone of a patient, here a cranial box. As known, such a method comprises at least a first step of digitizing said patient using a three-dimensional medical acquisition device, in particular a scanner or a magnetic resonance imaging device, during which one establish a file called "bone" representative of the remaining bone volumes of the patient. In the context of the invention, this first step known per se of the state of the art comprises in particular the export of the three-dimensional file generated by the medical acquisition device in three dimensions to a software allowing to rework this file. In this case, in this case, and in a nonlimiting manner 25 of the invention, three-dimensional file is exported in the form of an STL type file obtained using software of the "DICOM VIEWER" type. "to convert a file from a medical acquisition device into a file type STL or IGES. Such software of the "DICOM VIEWER" type is for example provided by MATERIALISE. Then during a second step of defining the prosthesis during which we define a so-called "prosthesis" file, representative of the shape of the final prosthesis.

To do this, one uses the previously created STL file and modifies it for example using MAGICS software from MATERIALISE, or any other similar software. This second step involves first cleaning the STL file by removing the scanning errors and smoothing out the edges of the resulting image. Then we define a file called "prosthesis", representative of the shape of the final prosthesis. As illustrated in FIG. 1A, which represents the cranial box 10 of a patient, which lacks a part corresponding to a bone deficiency 12, during this second stage the definitive prosthesis 14, called epithesis in this type, is defined. maxillofacial reconstruction, as comprising at least a replacement part of the patient's bone deficiencies. For this purpose, as shown in FIG. 1B, from the patient's bone file, an intact bone part 16 is isolated from the cranial box of the patient and a symmetrical image 18 of this part 16 is defined, which will make it possible to elaborate the final prosthesis 14 which can be adjusted to the skull of the patient, as shown in Figure 1C. Alternatively (not shown) of this first step, it is possible to define the final prosthesis 14, isolating and then transposing the bone parts of an intact model. Once the design is done, the prosthesis 14 to be produced is transferred to a preparation area of the MAGICS software in the position where it will be constructed. The software calculates manufacturing supports 26 which will be intended to support the prosthesis 14 during its manufacture, as represented in FIG. 2B. The supports 26 are then decomposed into sections to be made by melting successive layers of prototyping powder. The cutting of the supports in sections or "slicing" is carried out according to varying thicknesses of layers, typically of the order of 25, 30, 50 or 75 microns. The different slices of the supports 26 are then stored. Once the data relating to the media 26 has been recorded, a similar decomposition is made for the prosthesis 14. To do this, the software REALIZER from the company REALIZER or VISCAM from the company MARCAM is used. The prosthesis 14 is then also decomposed into sections to be made by fusing successive layers of prototyping powder to form a succession of sections, the stack of which determines the shape of the prosthesis to be produced, keeping for each layer the same thickness of The software finally establishes a fusion strategy, that is to say the set of displacement instructions that will be given to the laser beam to produce the supports 26 and the prosthesis 14. As shown in FIG. 2A, the method comprises in known manner at least a third step of manufacturing the prosthesis in which the prosthesis file is transferred to a rapid prototyping machine 20 comprising a laser gun 22 which is guided in response to the information of the prosthesis file in successive layers of a prototyping powder 24 to perform a selective laser fusion of a portion of each layer so as to manufacture a section of at least one support 26 of manufacture and / or a section 28 of said prosthesis. The layers of powder are fed successively by a powder distributor (not shown) until the stack of the sections made corresponds to the prosthesis 14. At the end of the exposure of each layer to the laser beam, a scraper 23 spreads the layers of powder to distribute the prototyping powder in a homogeneous layer, prior to the next exposure of said layer to the laser beam. The result is an assembly as shown in FIG. 2B, comprising the prosthesis 14 and the supports 26.

Finally, the method according to the invention comprises at least a fourth finishing step (not shown) during which the prosthesis 14 is cleared of any manufacturing support 26 and any roughness.

This step may involve a milling operation or any equivalent manual finishing operation, including a manual finish on a microtour. This known method of the state of the art has hitherto been used unsatisfactorily using laser prototyping machines operating with the aid of electron beam lasers, carrying out the melting of titanium powder. exclusively under vacuum. This technology does not allow the restoration of the patient's bone characteristics with sufficient precision to allow reimplantation of the prosthesis in the body. The invention overcomes this disadvantage by using a laser and materials capable of obtaining sufficient accuracy. For this purpose, the invention proposes a method of the type described above, characterized in that during the third step of manufacturing the prosthesis is used a laser gun 22 of the power laser type, to obtain a reduced roughness prosthesis and high precision with respect to the intact, intact bone portions of the patient or model used. The use of a laser gun 22 of power allows for example to obtain a precision compared to the original dimensions of the models within a range of 801.1m, and thus define a prosthesis with a roughness Ra equal to 5 after finishing. According to a first embodiment of the third step, a synthetic prototyping powder having a high rigidity at the end of the melting is used. This powder makes it possible to obtain a light prosthesis 14. According to a second embodiment of the third step, during the third manufacturing step, a metal prototyping powder is used. This is preferably a powder based on cobalt / chromium, or titanium, or aluminum. More generally it is any type of implantable metal powder in the body without side effects on the health of the patient. According to a preferred embodiment of the invention, the prosthesis 14 is designed to be lighter than the prostheses known from the state of the art.

Thus, according to a first embodiment of the second step which has been previously described, during the second step of defining the prosthesis is defined a so-called "prosthesis" file, representative of the shape of the final prosthesis, according to which the final prosthesis is of an external volume and of dimensions substantially corresponding to the external volume and dimensions of the intact corresponding bony parts of the patient or of the model used, and comprises - at least one solid part 30, whose actual volume and dimensions are limited the strict restoration of the anatomical functions of the patient, - at least one recess 32 to lighten the weight of the prosthesis. Such a prosthesis or epithesis has been shown in FIG. 3 and its implantation on the skull 10 of the patient has been represented in FIG. 4. More particularly, during the second step of defining the prosthesis, the prosthesis file can be defined according to a ratio of the volumes of the solid portion 30 and of the recess portion 32 which depends in particular on the prototyping powder used and on the location of the prosthesis 14 in the bone in question, and which ensures a high rigidity of the solid part 30 and high flexibility of the entire prosthesis 14.

The method can be further improved by maintaining the principle of a prosthesis 14 provided with recess portion 14, but by designing these parts in a honeycomb structure. Thus, according to this variant of the manufacturing method according to the invention, the prosthesis file is defined so that each recess 32 is filled by a three-dimensional mesh 34 forming a honeycomb structure. This honeycomb structure is intended to confer more rigidity to the prosthesis while allowing the colonization of said mesh 34 by bone cells of the patient during his convalescence. The prosthesis 14 can thus gradually integrate into the bone tissue of the patient. As a variant, as illustrated in FIGS. 5 and 6, during the second step of defining the prosthesis, a so-called "prosthesis" file, representative of the shape of the definitive prosthesis, is defined according to which the definitive prosthesis 14 is consisting only of a replacement portion of the patient's bone deficiencies whose volume and dimensions are limited to the strict restoration of the anatomical functions of the patient, in particular to lighten the weight of the prosthesis 14. Such a prosthesis has been shown in FIG. 5, and its integration with the cranial box 10 of the patient has been shown in Figure 6. It will be noted for this purpose that the prosthesis 14 may have at its free ends 36 holes 38 for the passage of screws intended to be referred in the The invention therefore proposes an innovative method that makes it possible in particular to reconstruct the bone of a patient who has been severely affected. t by the manufacture of a prosthesis functionally identical to the missing parts of the bone element to be repaired.

Claims (13)

REVENDICATIONS1. A method of manufacturing a bone prosthesis (14) intended to fill the bone gaps (12) of all or part of a bone (10) of a patient, of the type which comprises at least: a first digitization step of said a patient using a three-dimensional medical acquisition device, in particular a scanner or a magnetic resonance imaging device, during which a "bone" file representing the remaining bone volumes of the patient is established, at least a second step of defining the prosthesis in the course of which a "prosthesis" file, representative of the shape of the definitive prosthesis, is defined according to which the definitive prosthesis (14) comprises at least a portion (18, 19) for replacing the bone deficiencies (12) of the patient, said part being obtained from the patient's bone file by symmetry of intact corresponding bone parts (16) of the patient and / or from the bone file of an intac model. t by transposition of the bone parts of said model, said file comprising on the one hand a succession of sections, the stack of which determines the shape of at least one support (26) for manufacturing the prosthesis to be produced, a succession of sections of the same thickness, the stack of which determines the shape of the prosthesis (14) to be produced, and a series of displacement instructions for a rapid prototyping machine laser beam intended to allow the manufacture of the support and the prosthesis, - at least one third step of manufacturing the prosthesis during which the prosthesis file is transferred to a rapid prototyping machine (20) comprising a laser gun (22) which is guided in response to the information of the prosthesis file in successive layers of a prototyping powder (24) for selectively laser fusing a portion of each layer to produce a section of at least one fabric support (26) ion and / or a section deladite prosthesis (14), the layers being fed successively by a powder dispenser until the stack of sections made corresponds to the prosthesis (14), - at least a fourth stage of finishing at during which the prosthesis (14) is removed from any support (26) for manufacturing and any roughness, characterized in that during the third step of manufacturing the prosthesis a laser-type laser cannon (22) is used of power, to obtain a prosthesis (14) of reduced roughness and high accuracy relative to the bones parts (16) intact intact patient or the model used. 2. Manufacturing process according to the preceding claim, characterized in that during the third manufacturing step, using a synthetic prototyping powder (24) having a high rigidity after the melting. 3. Manufacturing process according to claim 1, characterized in that during the third manufacturing step, using a prototyping powder (24) based on cobalt / chromium, or titanium, or aluminum or any other implantable metallic material in the body of a patient. 4. Manufacturing method according to one of the preceding claims, characterized in that during the second step of defining the prosthesis is defined a file called "prosthesis", representative of the shape of the prosthesis (14) final , according to which the definitive prosthesis consists solely of a replacement part (30) of the patient's bone deficiencies whose volume and dimensions are limited to the strict restoration of the anatomical functions of the patient, in particular to lighten the weight of the prosthesis (14). ). 5. Manufacturing method according to one of claims 1 to 3, characterized in that during the second step of defining the prosthesis defines a file called "prosthesis", representative of the shape of the prosthesis (14). ) according to which the final prosthesis (14) is of an external volume and dimensions corresponding substantially to the external volume and dimensions of the intact corresponding bone parts (18) of the patient or of the model used, and comprises - at least one solid part ( 30), the actual volume and dimensions of which are limited to the strict restoration of anatomical functions of the patient, - at least one recess (32) for lightening the weight of the prosthesis. 6. Manufacturing method according to the preceding claim, characterized in that during the second step of defining the prosthesis is defined the prosthesis file in a ratio of the volumes of the solid part (30) and recess (32). ) which depends in particular on the powder (14) used prototyping and the location of the prosthesis (14) in the bone (10) considered, and which ensures a high rigidity of the solid part (30) and a high flexibility of the entire prosthesis (14). 7. The manufacturing method according to the preceding claim, characterized in that during the second step of defining the prosthesis is defined the prosthesis file so that each recess is filled by a three-dimensional mesh forming a honeycomb structure intended to allow the colonization of said mesh by bone cells of the patient. 8. A bone prosthesis (14) intended to fill the bone deficiencies of all or part of a bone (10) of a patient, obtained by the manufacturing method according to any one of claims 1 to 7, in particular at least by rapid prototyping in a rapid prototyping machine comprising a laser cannon which is guided in response to information from a prosthesis file in successive layers of a prototyping powder in order to perform a selective laser fusion of a portion of each layer in order to manufacture at least one section of said prosthesis, characterized in that it is obtained by rapid prototyping in a rapid prototyping machine comprising a laser laser of the power laser type, 9. bone prosthesis (14) according to the preceding claim, characterized in that it is made from a synthetic prototyping powder of high rigidity. 10. bone prosthesis (14) according to claim 8, characterized in that it is made based on a prototyping powder based on cobalt / chromium, or titanium, or aluminum, or any other implantable metalllic powder in the human body. 11. bone prosthesis (14) according to one of claims 8 15 to 10, characterized in that it consists solely of a replacement part of the patient's lack of bone (12) whose volume and dimensions are limited to strict restoration of the anatomical functions of the patient. 12. bone prosthesis (14) according to one of claims 8 to 10, characterized in that it is of an external volume and dimensions corresponding substantially to the external volume and dimensions of the corresponding parts of the bones (12) intact patient or of the model used, and comprises - at least one solid part (30), the actual volume and dimensions of which are limited to the strict restoration of the anatomical functions of the patient, - at least one recess (32) for lightening its weight. 13. Bone prosthesis (14) according to the preceding claim, characterized in that each recess (32) is filled by a three-dimensional mesh (34) forming a honeycomb structure intended to allow colonization of said mesh by bone cells of the patient .