System and method for manufacturing implantable prostheses

Abstract

The present invention relates to a system and method for the laser printing of implantable bone prostheses, printed in 3D, more in particular scaffolds, which can be easily customized, that is modelled, based on real tomographic data obtained from the respective patients. The invention proposes the use of a new system for supporting and moving the prosthesis during the laser treatment process, which allows to implement at the same time both the functionalization of the surface of the prosthesis by implementing micro and nano-structured patterns, and the activation or improvement of antibacterial properties and osteogenesis, when the prosthesis comprises at least a layer of polymeric coating containing photo-absorbing material.

Description

[0001] TRANSLATION (RULE 12.3) 01 JUL. 2025 SIB BW1358R

[0002] SYSTEM AND METHOD FOR MANUFACTURING IMPLANTABLE PROSTHESES

[0003] DESCRIPTION

[0004] Technical field of the invention

[0005] The present invention relates to a system and method for the laser printing of implantable prostheses, printed in 3D, more in particular scaffolds, which can be easily customized, that is modelled, based on real tomographic data obtained from the patients the implant is intended to. Such prostheses are mainly intended to the use in implants for maxillo-facial bone regeneration.

[0006] The invention allows to implement at the same time the functionalization of the prosthesis surface, by means of the laser implementation of micro and nano-structured patterns, and the activation or improvement of antibacterial properties, as well as osteogenesis, when the prosthesis comprises at least a layer of polymeric coating containing photo-absorbing material.

[0007] Background

[0008] The need for obtaining high-performance technological solutions in the field of regenerative medicine is increasingly felt. In this context, for several years the attention has been particularly high on the implantable prostheses, and many efforts are concentrated on the improvement of the so-called ‘scaffolds’, that is implantable and reabsorbable artificial structures, configured to support the formation of three-dimensional organic tissue.

[0009] The scaffolds constitute an intersection element between medicine and tissue engineering, the latter focused on technique for regenerating organic tissues of the human body which involve seeding cells on a support, followed by their cultivation is suitable bioreactors until obtaining a new tissue to be - 2 - SIB BW1358R transplanted into the patient.

[0010] More extensively, within the present discussion, under the term ‘scaffolds’ any artificial implantable structure with micro or nanometric morphological features is designated, engineered so as to emulate the extracellular matrix to house the cell cultivations and support the proliferation thereof, with the purpose of regenerating a damaged tissue.

[0011] The scaffold, made of biodegradable or bio-absorbable materials, then plays a transitory role, but of crucial importance: it provides a physical support for the adhesion and cell growth. At the end of the process, it has to be wholly reabsorbed, giving way to the newly formed tissue. Ideally, the cells needed for seeding and colonization of scaffold should come from the patient, so that the newly formed tissue, once implanted, does not trigger an immune reaction of rejection.

[0012] Nowadays, the use of scaffolds in the clinical practice is still limited since the specific features required to achieve the regenerative result effectively can be obtained, when possible, by high-complex technological processes.

[0013] One of the crucial aspects of the scaffolds is the adhesion of cells to their surfaces, which fulfil the role of substrate. One of the most common techniques to obtain acceptable adhesion levels is the use of chemically modified substrates, functionalized with chemical groups or treated with ad hoc selected polymeric coatings. Other techniques include the use of electrical or magnetic fields to induce the adhesion of cells to the substrate, rather than the implementation of particular morphologies of its surface.

[0014] Summary of the invention

[0015] The technical problem placed and solved by the present invention is then to provide a simplified and effective solution to implement a predetermined morphology of the surface of an implantable prosthesis of which a three- dimensional model is available, which can be the same used for the 3D printing of the above-mentioned prosthesis, by obviating the drawbacks mentioned above with reference to the known art. - 3 - SIB BW1358R

[0016] Such problem is solved by a system according to claim 1 and a method according to claim 9.

[0017] Preferred features of the present invention are set forth in the depending claims.

[0018] The present invention relates to a system and a corresponding method for the laser finishing of the external surface of prosthesis, such as for example scaffolds, and more generally of surgical implants. Within the following discussion, for sake of simplicity - but not for limitative purposes - the prostheses only, or in particular the scaffolds, will be referred to.

[0019] The invention is particularly high-performing for the surface treatment of prostheses whereby a three-dimensional model (ex. CAD model) is already known, for example prostheses obtained by 3D printing, since it allows to determine and perform an effective movement of the prosthesis under the laser action by exploiting the same model with which its 3D printing was performed. According to this preferred aspect, the invention integrates laser printing with 3D printing.

[0020] The invention was born in response to the problem of inevitable wear and tear thereto the bone prostheses are subjected over time once implanted in a patient, requiring periodic replacements. Such problem can be solved or mitigated by increasing the osteointegration of prostheses. The proposed solution allows to implement prostheses with longer service life, as well as higher effectiveness, thanks to the implementation of a micro or nanostructured external surface, which indeed increases the osteogenesis proprieties. Moreover, if the prosthesis consists or comprises a layer of coating made of photo-absorbing material (ex. graphene oxide), or if a surface geometry with known antiadhesive properties is induced, such as the one of the shark skin or Cancer Pagurus carapace, the surface finishing pattern allows to increase the antibacterial effect of the scaffold.

[0021] According to an important aspect of the invention, the proposed system is configured to implement the laser printing by following operational logics allowing to optimize patterns on even very complex three-dimensional surfaces, - 4 - SIB BW1358R and they make it more agile with respect to the homologous systems of known type.

[0022] In particular, the system is configured to provide the laser ablative action at the external surface of a prosthesis housed in a new support device, moving the prosthesis according to a pattern of motions calculated thanks to the analysis of the three-dimensional model of the prosthesis itself, while the laser beam used for the treatment remains motionless. In this way, the system achieves at the same time both the implementation of the surface finishing by ablation and functional activation of the surface itself when made of materials reactive to the laser radiation, such as for example the graphene oxide, by obtaining surfaces with improved osteogenic and antibacterial features according to what already illustrated.

[0023] In summary, the main objectives of the shown solution are the implementation of customized prostheses, that is modelled based upon real data obtained from patients (ex. by tomography), and the functionalization of the prostheses’ surface by micro and nano-structured patterns, to provide longer in- vivo life to the prosthesis. The latter objective can be implemented by means of the above-mentioned laser activation process consisting in exposing the prosthetic surface to a pulsed laser beam having specific wavelength for the target material. The pulsed laser, then, activates the process of mechanical ablation and oxidation-reduction. It is demonstrated to the state of art that the creation of micro and nanometric roughness favours the cell adhesion with respect to the smooth surfaces. Moreover, if the activation takes place on surfaces containing graphene, even an antibacterial effect is obtained, due to a double mechanical and chemical action on the bacterial walls by the graphene sheets oriented by the laser.

[0024] By checking the action of the laser beam in terms of size (diameter) and intensity, it is possible to obtain optimal patterns for the bio-functionalization of the prosthetic surface. In particular, by adjusting the beam intensity, the size of its focus and the motion speed of the prosthesis, each time the features required for activating the surface depending the specific case can be obtained .

[0025] In wider terms, the invention solves the problem of exposing all surfaces of a - 5 - SIB BW1358R

[0026] 3D object having any - even complex - shape - to a laser beam performing ablative action and, then, to implement a predetermined pattern thanks to the partial removal of the more external material. To the above-mentioned object, it is crucial that the size of the laser beam incident on the surface keeps constant. In order to obtain this, the 3D printed prosthesis is subjected to laser ablation and, through a fine check of the motion point by point, the direction of the laser beam is kept perpendicular to the surface, as well as the focal distance.

[0027] Possible applications of the invention are in the medical field. The patterning of polymeric surfaces containing graphene or other photo-absorbers provides demonstrated biological advantages to medical devices such as implants, disposable devices (such as catheters and stents), surgical equipment, that is surgical robots, laboratory equipment and hospital surfaces. According to known statistics, when the laser activated graphene coating is present, the risk of infections is reduced by 10-30%. This contributes to decrease the use of antibiotics and the onset of antibiotic-resistant conditions in patients.

[0028] Other advantages, features and use modes of the present invention will result evident from the following detailed description of some embodiments, shown by way of example and not for limiting purposes.

[0029] Brief description of Figures

[0030] The Figures of the enclosed drawings will be referred to, wherein:

[0031] ■ Figure 1 shows a representative scheme of some important phases of the method for implementing a prosthesis in accordance with a preferred embodiment of the present invention;

[0032] ■ Figure 2 shows a schematic view of a preferred embodiment of a system according to the present invention;

[0033] ■ Figure 3 shows a front perspective view of a preferred embodiment of a support device of a prosthesis included in a system according to the present invention;

[0034] Figure 4 shows in detail a preferred embodiment of a mechanical arm - 6 - SIB BW1358R comprised in the support device of Figure 3;

[0035] ■ Figure 5 shows a block diagram representing a portion of a preferred embodiment of a method for checking a system according to the present invention;

[0036] ■ Figure 6 shows an example of mutual positioning of a unit of external surface of the prosthesis and of the laser beam implementable by means of a system according to the present invention;

[0037] ■ Figure 7 shows a block diagram representing an additional portion of a preferred embodiment of a method for checking a system according to the present invention;

[0038] ■ Figure 8 shows an example of scheme for moving a prosthesis while performing a laser ablation of its external surface in accordance with a preferred embodiment of a method according to the present invention.

[0039] The thicknesses and curvatures represented in the above introduced Figures are to be meant as purely exemplifying, they are generally magnified and are not necessarily shown in proportion.

[0040] Detailed description of preferred embodiments

[0041] Embodiments and variants of the invention will be described hereinafter, and this with reference to the above-illustrated Figures.

[0042] Analogous components are designated in the different Figures with the same numeral reference.

[0043] In the following detailed description, the different described embodiments and variants are likely to be used in combination, where compatible.

[0044] By firstly referring to Figure 1 , the invention provides an improved method for manufacturing an implantable prosthesis P, more in particular a synthetic scaffold. The proposed method uses a new laser ablation system 10 to implement a micro or nanostructured morphology of the external surface of such prosthesis P, with the purpose of increasing the osteo-regenerative and - 7 - SIB BW1358R antibacterial properties thereof. Within the present discussion, under the expression ‘prosthesis’ any type of implantable structure is meant, thereamong the structures of scaffold type.

[0045] The method allows to implement customized prostheses, that is modelled based on real data obtained from patients, and provided with functionalized surfaces by means of laser activation, that is exposure to a pulsed laser beam, having specific wavelength depending upon the prosthetic material to be treated.

[0046] The method first of all provides to acquire a three-dimensional representation of the bone structure of the patient in whom the prosthesis will be implanted, for example by tomography or other imaging techniques. For example, starting from tomography, a three-dimensional model of the prosthesis P to be implanted, such as a CAD 3D model, is implemented automatically.

[0047] Subsequently, the 3D printing of the three-dimensional model is implemented to obtain the prosthesis P intended to the implant. The material for the 3D printing, thereof the prosthesis is made, is selected depending upon the specific application and the features of the patient and preferably it contains a photoabsorbing material such as graphene.

[0048] The subsequent step provides a treatment of laser ablation or engraving of the external surface of the prosthesis P, with the result of producing a predetermined surface morphology and / or ‘activating’ such surface from the functional point of view.

[0049] The laser ablation of the prosthesis is performed by means of a new system 10, a concept model of which is shown in Figure 2 by way of example. The system 10 includes: a device 2 for supporting the prosthesis P, comprising a frame 1 and means for moving the prosthesis P with respect to the latter; a source 15 for emitting the laser beam; and a control unit 9 of the device 2. Preferably, the control unit 9 comprises, or consists of, a software interface for checking the movement means and a system for displaying the prosthesis P housed in the device 2 for the interaction with the operator.

[0050] As far as the laser source 15 is concerned, this can be configured to - 8 - SIB BW1358R dispense a nanosecond pulsed laser beam. Between the laser source 15 and the device 2 a lens L can be interposed to focus the pulsed laser. A beamsplitter (BS), if present, allows to send the image of the prosthesis P to an objective and a CCD camera which records the image thereof. A software interface written in Python can allow the control unit 9 to translate the same CAD model with which the prosthesis P was printed to be scanned with laser in a list of spatial coordinates, to move the prosthesis while keeping perpendicularity and focal distance of the laser beam. The displaying system, for example consisting of the above-mentioned objective and the CCD camera, allows the operator to observe in real time the laser scanning on the surface of the prosthesis.

[0051] Once the prosthesis P is housed in the laser ablation system 10, its three- dimensional model is loaded or acquired by the control unit 9, and the external surface S of the prosthesis P is divided in, or better represented by, a plurality of meshes defining single surface units, approximated or represented as planar surfaces. By way of example, Figure 6 shows the division into meshes of a polyhedron (miming the prosthesis) and with L the laser beam striking on a single surface unit is designated.

[0052] By means of interface means preferably comprised in the control unit 9, the operator in charge of the ablation selects a first surface unit s1 and the control unit 9 calculates a first spatial position which the prosthesis housed in the device 2 has to assume whereby said first surface unit s1 is exposed to the beam emitted by the laser source 15 in accordance with an orthogonal orientation and a focal distance predetermined by the operator, with respect to a three-dimensional reference system fixed to a frame 1 of the device 2.

[0053] With respect to such three-dimensional reference system, the control unit 9 then calculates automatically a succession of spatial positions of the prosthesis P, starting from the first spatial position, whereby each one of the surface units in which the three-dimensional model of the prosthesis P has been divided is exposed sequentially to the beam emitted by the laser source 15 in accordance with an orthogonal orientation and with the above-mentioned predetermined focal distance. In particular, it is noted that the system 10 allows to expose all - 9 - SIB BW1358R surfaces of the prosthesis P to the laser beam, so that the incidence angle and the spot size remain constant during the whole process of the laser irradiation of the surface.

[0054] The control unit 9 is further configured to control the device 2 to move the prosthesis P in accordance with the so-calculated position succession. The source 15 emitting the laser beam is activated in accordance with predetermined parameters, variable by means of the interface means, for example a software interface tool, or control software, which can be comprised in the control unit 9. In particular, the system 10 is configured in such a way that the laser beam acts on the prosthesis P exclusively during the pattern creation, and not during the motions of the prosthesis P which are useful to change the surface unit to be exposed to irradiation.

[0055] According to a preferred implementation, the laser beam emission can be locked by means of a control software acting on the source 15, or by controlling a mechanical chopper locking physically the beam and preventing it from reaching the prosthesis, or a trigger connected to the shutter of the laser source. The laser action on the prosthesis P has to be inhibited during all motions of the prosthesis P which are useful to change the surface unit to be exposed to the processing, while the irradiation has to be activated only during the pattern creation.

[0056] During irradiation, the laser beam is always kept in fixed position with respect to the frame 1 . Such laser beam direction can be kept constant even in case of motion of the source 15 thanks to the arrangement of irises or other type of diaphragms along the laser beam path, in order to be able to re-align it in accordance with the wished fixed direction. Preferably, the motion involves exclusively the device 2 housing the prosthesis P, while the laser source 15 remains always motionless, and then it is interchangeable even while performing the process.

[0057] More in particular, each spatial position of the prosthesis P is defined by a vector which includes coordinates expressed in the three-dimensional reference system fixed to the frame 1 of the support device 2. In accordance with a preferred variant of the invention, each position of the prosthesis P housed in - 10 - SIB BW1358R the system 10 can be expressed by means of a vector consisting of three Cartesian coordinates (X, Y, Z) and two angular coordinates (9, <p), as it will be examined closer hereinafter.

[0058] In accordance with such preferred aspect of the invention, the motion of the support device 2, and then of the herein housed prosthesis, can be articulated in accordance with five reference (three translational and two rotational) axes, then the prosthesis has five degrees of freedom when it is housed in the system 10.

[0059] In accordance with what described above the laser ablation and / or functional activation of the external surface of the prosthesis is performed, and the treatment is concluded. Preferably, laser micro-structuration techniques are used, whereby the laser beam engraves on the surface of the prosthesis and it creates surface structures at micro or nanometric level.

[0060] The antibacterial action of the prosthesis surfaces activated with laser in accordance with the herein proposed invention is obtained thanks to the implementation of a not uniform morphology, in particular by implementing raised scales with respect to a base external surface, preferably arranged to protrude vertically or better orthogonally therefrom. The scales are obtained by the laser ablation of a biopolymer present at the external surface of the prosthesis. The biopolymer can consist or comprise graphene, graphite or preferably graphene oxide, and the so-obtained scales can have a thickness of few atomic layers. It was demonstrated in the state or art that such scales arranged vertically with respect to the base external surface are effective in killing the prokaryotic cells, but they do not damage the eukaryotic cells.

[0061] With reference to the herein described laser processing technique, it is noted that it results to be applicable to any material capable of absorbing the light in the used wavelength range. Moreover, it is specified that antiadhesive motifs for bacteria of known type can be implemented.

[0062] Hereinafter, preferred embodiments of a laser processing system 10 in accordance with the invention will be described more in detail, with particular reference to Figures 2, 3 and 4. - 11 - SIB BW1358R

[0063] As anticipated, the system 10 comprises a device 2 for supporting the prosthesis P, which includes means for moving the latter and a fixed frame 1 .

[0064] With respect to such frame 1 , the already mentioned fixed three-dimensional reference system, which includes a horizontal direction X, vertical direction Y and a transversal direction Z, is defined.

[0065] With reference to Figure 3, the movement means is configured to move the prosthesis in accordance with translation and rotation motions with respect to the frame 1 , to allow facing orthogonally all faces of the prosthesis to the laser source. In particular, to this purpose the movement means includes first translation means 3 according to the transversal direction Z, second translation means 4 according to the vertical direction Y and third translation means 5 according to the horizontal direction X. Moreover, the movement means comprises first rotation means 6, configured to drag the prosthesis in rotation, or better to tilt it by angle 0, around the vertical direction Y, and second rotation means 7, configured to drag the prosthesis in rotation, or better to tilt it by an angle cp, around a variable rotation axis R, which keeps orthogonal to the vertical rotation axis Y. In particular, the second rotation means 7 is configured to keep the axis R orthogonal with respect to the second vertical direction Y during processing, however by allowing to vary its orientation with respect to the first horizontal direction X and to the third transversal direction Z, respectively. The translation means 3, 4, 5 can respectively include slides to allow the translation by sliding, for example shaped like a dovetail.

[0066] The translation means 3, 4, 5 includes actuators or motors controlled by the control unit 9, for example stepper motors. The rotation means 6, 7 comprises rotative actuators, for example still stepper motors, even controlled by the control unit 9.

[0067] According to a preferred variant of the invention shown in Figure 4, the support device 2 comprises a mechanical arm 20, configured to retain the prosthesis P. The arm 20 has a first extremal portion 21 and a second extremal portion 23, preferably arranged in mutually orthogonal way. The first extremal portion 21 comprises the first rotation means 6 and the second extremal portion 23 comprises the second rotation means 7. The first and second rotation means - 12 - SIB BW1358R

[0068] 6, 7 include rotative actuators having rotation axes arranged orthogonally to each other, as it is visible from the representation of Figure 4.

[0069] In accordance with such configuration, the translation means 3, 4, and 5 are configured to move the whole arm 20. The first rotation means 6 is configured to move the first extremal portion 21 of the arm 20, together with the prosthesis P. The translation slides comprised in the translation means 3, 4, 5 can be mechanically coupled to the arm 20 by means of screws, for example M6 screws. The extremal portion 23 of the arm 20 is integral with the translations in accordance with each one of the three axes X, Y, Z and the rotation around the axis Y, but it is not involved in the rotation around the axis R.

[0070] As anticipated, the first rotation means 6 do not affect the overall positioning / orientation of the arm 20. To this purpose, the first rotation means 6 comprises a mandrel 61 , configured for the coupling with the prosthesis P, the rotation axis thereof is the already mentioned axis R. Now it will be evident that the axis R of the mandrel 61 remains fixed with respect to the prosthesis P itself when it is housed in the device 2. The axis R then has variable direction, since it follows all applied translation and rotation motions in which the prosthesis P is dragged, while maintaining perpendicularity with respect to the axis of vertical rotation Y.

[0071] The first extremal portion 21 of the arm 20 can consist of the mandrel 61 . The mandrel 61 is preferably configured to engage the prosthesis P at anchoring means 62, preferably configured to be integral with the prosthesis P. Such anchoring means 62 can be 3D printed together with the prosthesis itself, thereof then it can be integrating portion. The anchoring means 62 is preferably configured like a stem, that is like an elongated element and with mainly rectilinear development, which is configured to be coupled integrally with the mandrel 61 at a first free terminal end. The configuration is so that, when the prosthesis P is engaged by the mandrel 61 , the anchoring stem 62 is arranged longitudinally in accordance with a direction coincident with the rotation axis R of the mandrel 61 . The anchoring stem 62 has a longitudinal development axis which coincides in use with the axis R of the mandrel 61 . The latter axis R is arranged perpendicularly to the rotation axis of the rotation means 6. In other - 13 - SIB BW1358R words, the rotation means 6 is configured to put in rotation the prosthesis P around the axis of the anchoring stem 62.

[0072] Preferably, the prosthesis P is connected to the device 2 by the anchoring means 62 only.

[0073] The laser source 15 is configured in such a way that the laser beam is always emitted in accordance with the transversal direction Z, for the whole processing duration. Therefore, by varying the position of the arm 20 along the transversal direction Z, the laser focal distance from the face of the prosthesis facing thereto is varied, while maintaining unaltered the (ex. orthogonal) orientation and the incidence angle.

[0074] According to a variant of the invention, the arm 20 comprised in the support device 2 is shaped like a ‘L’, wherein the two arms of the L consist of, or comprise, the first extremal portion 21 and the second extremal portion 23, respectively. According to an additional preferred variant, between the mainly rectilinear first extremal portion 21 and second extremal portion 23 a curved connection portion is interposed, to achieve an overall sickle-like shape of the arm 20, or a shape like a circle arc, or more generally bent, depending upon the extension of the extremal portions 21 and 23. The loop generated by the concavity of the arm 20 allows to position the prosthesis to be laser-engraved in axis with respect to both rotations (9, around the vertical direction Y, and cp, around the rotation axis R of the mandrel 61 ).

[0075] Preferably, the arm 20 is made in a single piece.

[0076] An example for implementing the above-illustrated method will be described in detail hereinafter, with reference to the actions performed by the software of the control unit 9.

[0077] The control unit 9 supports an interface, preferably written in Python, allowing to calculate the sequence of coordinates for moving the prosthesis in space, and more generally any three-dimensional object, so that each motion fulfils the perpendicularity and imposed focal distance condition with respect to the laser beam emitted by the source 15.

[0078] The strategy which can be used is that of dividing the CAD model of the - 14 - SIB BW1358R object, already known when the object has been produced by 3D printing, in a triangular mesh grid. For explanatory purposes, the scheme in Figure 6 shows the division into meshes of a polyhedron, wherein the arrow L represents the laser beam engraving the object.

[0079] An image of the type of that shown in Figure 6 is produced in an interactive way by the software, and it allows the operator to select a face among the plurality of triangular meshes, to initialize the calculation of the sequence of coordinates which the mechanical arm 20 will perform.

[0080] Starting from the first face selected by the operator, the software calculates:

[0081] - the sequence of the angular pairs (9, cp) to rotate the object kept by the arm 20 so as to expose the several facets in compliance with the condition of perpendicularity with the laser beam;

[0082] - the coordinate along the (fixed) direction Z of the laser beam, so as to keep constant the focal distance of the face after each rotation.

[0083] For each tern (6, cp, z) the coordinates (x, y) are calculated which correspond to the implementation of the pattern established on each face, by taking into consideration the specific shape of each face.

[0084] In particular, the steps to obtain the engraving / ablation of the 3D surface of the printed object (prosthesis) are the following, enlisted in sequence:

[0085] - a suitable subdivision of the external surface to be treated in a determined number of meshes , optimized based upon the resolution / implementation time relationship, is fixed;

[0086] - the operator selects the initial face from which scanning has to be started;

[0087] - starting from this face, the interface software calculates the tern of coordinates (6, cp, z) to expose sequentially all faces perpendicularly to the laser beam and at the same focal distance;

[0088] - for each tern of coordinates (6, cp, z), the coordinates of the motions along X, Y are calculated, so as to engrave / ablate each face in accordance with an established pattern, depending on the shape of the specific face. - 15 - SIB BW1358R

[0089] According to a preferred variant of the device 2, all translation and rotation means 3, 4, 5, 6 and 7 can include stepper motors and a computer can be connected - for example, by USB cables - to each stepper motor so that the control unit 9 calculates the correct sequence of motions.

[0090] An example of programming the software supported by the control unit 9 is described in detail hereinafter.

[0091] The software for controlling the setup can be wholly written in Python and it consists of two modules. The first module is managed by a desktop computer which, by using suitable libraries, calculates, starting from the file of the three- dimensional model representing the object (for example a file .stl), the sequence of motions which have to be performed by the motors (or actuators) of the mechanical arm in order to expose all surfaces of the herein housed prosthesis to the laser action.

[0092] The second module is managed by a Raspberry Pi which takes charge of the sequence of the motions calculated by the first module and checks the motors’ motions and the laser action to implement the ablation of the prosthetic surface.

[0093] Module 1

[0094] A flow chart representing the instructions performed by the first module is shown in Figure 5 and subsequently detailed.

[0095] Start

[0096] The software loads the file which was used for the 3D printing of the prosthesis (solid) to be exposed to the laser action.

[0097] Variation in number of faces (facets): the software allows to vary the number of facets in which the solid surface is divided so that the faceting allows acceptable processing periods of time and above all is compatible with the resolution of the translational slides. Once selected the suitable number of facets, the software calculates again, unanimously, the surface coordinates.

[0098] Variation in position of the meshes: once fixed the number of facets, the software allows to display (see Figure 6) the solid mesh to be processed in its own reference system of the file, and in such reference system also the vector - 16 - SIB BW1358R representing the direction of the laser beam in the setup is positioned. At this point, the operator intervenes in order to make the axes of the virtual reference system to coincide, that is the one with respect thereto the surface coordinates in the file are written, with those of the real setup. In order to do this, both the file and the real object assembled on the mechanical arm can be rotated and translated in accordance with the five degrees of freedom of the system, to implement the coincidence of the position of the virtual and real object with respect to the direction of the laser beam, acting as connecting element between the two reference systems.

[0099] Calculation of coordinates of the motions of the motors (or actuators): once implemented the coincidence between the virtual reference system and the real one, the software calculates the displacement sequences which have to be performed by the motors to expose all n facets of the surface of the prosthesis to the laser beam action so that each one is always at the same focal distance and is oriented perpendicularly to the beam.

[0100] Specifically, for each n-th facet the following coordinates are calculated:

[0101] - triplets (On, <pn, zn), where the first two coordinates are the rotation angles allowing to orient the facet perpendicularly to the laser beam, the translation yn along the beam direction allows to bring the facet back to the focal distance f after rotation.

[0102] - pairs (xni, yni), where n is the facet index and / are the indexes of the points on the plane xy, perpendicular to the beam, to be scanned on the single facet.

[0103] The sequence of the displacements to be performed by the motors is stored on a file which is sent to the Raspberry Pi, which controls the motors of the rotative arm.

[0104] Sending the list of coordinates to the Raspberry Pi: the Raspberry Pi receives from the PC calculator the coordinates to be sent to the motors under form of such list:

[0105] (0i,<pi,zi) xii,yii;xi2yi2;...;xiNiyiNifacet1

[0106] (02,(p2,z2): x2i,y2i;x22y22;...;x2N2y2N2facet2 - 17 - SIB BW1358R

[0107] (On, (pn,zn) xni,yni;xn2yn2; ...;xnNnynNn facetn

[0108] Once calculated the above-mentioned sequence, the file is sent to the Raspberri Pi which presides over the control of the motors and of the laser shutter as explained hereinafter.

[0109] Module 2

[0110] By way of example, the process is described hereinafter for obtaining a pattern consisting of a 250um-wide-row grating and a 500-um pitch on the surface of a mandibular defect printed by 3D printing in a material suitably purchased to implement bone prostheses, such as polylactic acid (PLA) added with 5% graphene oxide.

[0111] The irradiation conditions to obtain the optimal corrugation to amplify the osteo-inductive and antibacterial capabilities of the material were determined by performing ablation experiments on bidimensional samples with a Nd:YAG (Surelite Continuum) laser, which emits pulses lasting 4ns at the wavelength of 532 nm and repetition rate of 10 Hz.

[0112] The 250um strips with the best morphological features were obtained by focusing the laser beam with a lens with focal length f=50cm, peak power P=30mW and speed of motors xy equal to v=1.2 mm / s.

[0113] Once these parameters are set, the processing process starts. The maxillofacial defect to be subjected to laser ablation is assembled on the rotative arm thanks to the stem for anchoring to the rotary mechanical arm, suitably printed together with the defect, but not belonging to the file which is taken in charge by the Module 1 of the control software in accordance with what already described above.

[0114] The implementation of the stem for anchoring is constrained by the specific geometry of the object to be treated, for this the possibility of re-orienting also the file with respect to the assembly really implementable on the rotative arm is fundamental. - 18 - SIB BW1358R

[0115] Once the prosthesis is anchored to the mechanical arm, the operator interfaces with the control software by means of the Module 1 and all phases described in the flow diagram of Figure 5 are performed.

[0116] Once the sequence of motions is calculated, the Module 2 comes in action, which controls the motors for implementing the pattern according to the flow chart of Figure 7. For each facet, the grating pattern is implemented by moving the motors for the translation along the axes X and Y, according to the scheme shown in Figure 8. The continuous arrows (in this case along the direction X for sake of simplicity) represent the directions of the motors along which the laser beam action occurs (that is the shutter is set off by the Raspberry Pi). The dashed arrows represent the tracts along which the laser shutter locks the laser beam (shutter on), since these motions are useful to go to the subsequent ablation line. It is noted that the path is inside the facet, not to risk a double passage of the laser along the facet edges, which would cause a different morphological corrugation to the interface between two adjacent facets.

[0117] By still referring to Figure 8, an example is shown of how the prosthesis is moved so as to follow the grating pattern according to a sequence designated by the arrows. The arrows designate the direction, the adopted displacement scheme displacements and not the real thickness of the pattern lines.

Claims

- 19 - SIB BW1358RCLAIMS1. A laser treatment system (10) of a prosthesis (P) obtained by 3D printing of a respective three-dimensional model, comprising:- a laser source (15), configured so as to emit a laser beam that maintains a fixed direction with respect to a frame (1 );- a support device (2) of the prosthesis (P), comprising: said frame (1 ), fixed, with respect to which a three-dimensional reference system is defined including a first horizontal direction (X), a second vertical direction (Y) and a third transversal direction (Z), and movement means, movable with respect to said frame (1 ), which includes:• first translation means (3) according to said third transversal direction (Z);• second translation means (4) according to said second vertical direction (Y);• third translation means (5) according to said first horizontal direction (X);• first rotation means (6) around an axis (R), which axis (R) is orthogonal with respect to said second vertical direction (Y) but has variable orientation with respect to said first horizontal direction (X) and said third transversal direction (Z);• second rotation means (7) around said vertical direction (Y); wherein said support device (2) comprises an arm (20) which bears a first extremal portion (21 ) and a second extremal portion (23), wherein said first extremal portion (21 ) carries said first rotation means (6), and said second extremal portion (23) carries said second rotation means (7);- a control unit (9) configured to control the activation of said movement means in such a way that, if a subdivision of the external surface (S) of- 20 - SIB BW1358R the three-dimensional model of the prosthesis (P) housed in said support device (2) is provided in a plurality of surface units (s), wherein said surface units (s) are represented as planar surfaces, each one of said surface units (s) is exposed sequentially to the laser beam emitted by said laser source (15) in accordance with an orthogonal orientation and a constant focal distance.

2. The laser treatment system (10) according to the preceding claim, wherein said first, second and third translation means (3, 4, 5) and said second rotation means (7), are configured to move said arm (20) with respect to said frame (1 ).

3. The laser treatment system (10) according to any one of the preceding claims, wherein said arm (20) is shaped like a ‘L’.

4. The laser treatment system (10) according to any one of the preceding claims, wherein a curved connection portion is interposed between said first extremal portion (21 ) and said second extremal portion (23), to create an overall arched or sickle-shape conformation of said arm (20).

5. The laser treatment system (10) according to any one of the preceding claims, wherein said laser source (15) is configured so as to emit the laser beam in accordance with said third transversal direction (Z).

6. The laser treatment system (10) according to any one of the preceding claims, wherein said arm (20) is made in a single piece.

7. The laser treatment system (10) according to any one of the preceding claims, wherein said first rotation means (6) comprises a mandrel (61 ) capable of rotating around said axis (R) and configured to solidly engage in rotation an anchoring stem (62) fixed to the prosthesis (P), in such a way that a direction of longitudinal development of said anchoring stem (62) coincides with the rotation axis (R).

8. A method for laser treatment of a prosthesis (P) obtained by 3D printing of a respective three-dimensional model, comprising the following steps:- providing a laser treatment system (10) according to one of claims 1 to 7, comprising:- 21 - SIB BW1358R■ a fixed frame (1 ), with respect to which a three-dimensional reference system is defined including a first horizontal direction (X), a second vertical direction (Y) and a third transversal direction (Z);■ a laser source (15), configured so as to emit a laser beam that maintains a fixed direction with respect to said frame (1);■ a support device (2) of the prosthesis (P), comprising movement means which includes: o first translation means (3) according to said third transversal direction (Z); o second translation means (4) according to said second vertical direction (Y); o third translation means (5) according to said first horizontal direction (X); o first rotation means (6) around an axis (R) which is orthogonal with respect to said second vertical direction (Y) but it has variable orientation with respect to said first horizontal direction (X) and said third transversal direction (Z); o second rotation means (7) around said vertical direction (Y);■ a control unit (9) of said movement means;- housing the prosthesis (P) in said support device (2);- subdividing the external surface of said three-dimensional model in a plurality of surface units, approximated or represented as planar surfaces;- selecting a first surface unit (s1 ) from said plurality of surface units and controlling said movement means to arrange the prosthesis (P) in a first spatial position with respect to said three-dimensional reference system, wherein said first surface unit (s1 ) is exposed to the laser beam in accordance with an orthogonal orientation and a predetermined focal distance; calculating, with respect to said three-dimensional reference system, a- 22 - SIB BW1358R succession of spatial positions of the prosthesis (P) starting from said first spatial position, whereby each one of said surface units (s) is sequentially exposed to the laser beam in accordance with an orthogonal orientation and at said predetermined focal distance;- controlling said movement means to move the prosthesis (P) in said succession of spatial positions, starting from said first spatial position, while the laser beam is emitted, to achieve a laser ablation and / or functional activation of the external surface of the prosthesis (P).

9. The method for laser treatment according to the preceding claim, wherein each spatial position is defined by a vector which includes five coordinates in said three-dimensional reference system: position along first horizontal direction (X), position along said second vertical direction (Y); position along said third transversal direction (Z); angular position with respect to said second vertical direction (Y); and angular position with respect to said rotation axis (R).

10. A method for manufacturing a prosthesis (P), comprising the following steps:- acquiring a tomography of the patient’s bone structure in which the prosthesis will be implanted;- implementing a three-dimensional model of the prosthesis (P) starting from the tomography of the bone structure; printing the three-dimensional model in 3D and obtaining the prosthesis (P); carrying out the laser treatment of the external surface of the prosthesis (P) using the method according to claim 8 or 9.

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