BE1026129B1 - Method of manufacturing prosthetic implants and kit of parts obtained by the method - Google Patents

Abstract

Method of manufacturing a prosthetic implant (40) for the replacement of a damaged or diseased part of a bone structure (9), comprising obtaining a digital model of the bone structure and manufacturing a model bone structure material on the basis of the digital model, the manufacture of a resection guide (30) defining a resection line (32) of the bone structure, and the manufacture of the prosthetic implant. The resection guide includes a guide surface (33) configured to support a surgical resection tool in a predetermined orientation along the resection line. The resection guide is validated on the hardware model, including performing a resection in the hardware model following the guide surface and in the predetermined orientation. The prosthetic implant is made on the basis of a geometry of the resection performed in the material model. Kit of parts obtained by the process.

Description

The present invention relates to a method of manufacturing a prosthetic implant to replace a damaged or diseased part of a bone structure (of a bone) in a human or animal body. The method can also be adapted for planning and preoperative simulation on a hardware model.

Some patients have damaged bone structure, notably due to an accident, or are struck by a disease affecting the bone structure, in particular tumors. In these cases, it is desirable to resect, i.e. cut out, the damaged / affected part of the bone structure and replace it with an implant, which may be made of a biocompatible polymer or metal. This is particularly the case with parts of the craniofacial bone structure, for example, in the case of reconstructive repair of a damaged part of the bone structure of the head.

One problem encountered during surgery is that the implants generally have standard dimensions, and must be adjusted in the operating room during the surgical procedure. This takes time, and the result is that the implant does not adapt properly to the resected part of the bone structure. WO 98/12995 by Peckitt, April 2, 1998, describes a method of manufacturing a prosthetic implant to replace a damaged or diseased bone. A digital representation of the bone structure of interest is used to create a replica of the bone structure by stereolithography and to produce the implant by CNC machining. The replica and the implant are then used to perfect the surgical intervention in the workshop under non-surgical and non-sterile conditions by cutting and experimentally mounting the implant on the model skull. During this stage, the shape of the machined implant can also be improved to better fit the anatomical edges. During the perfecting procedure, it is possible to produce cutting templates which are placed in relation to well-defined points on the skull and which constitute a guide to allow the surgeon to cut the bone precisely.

A drawback always present in the above procedure is that the implant machined by CNC very often requires subsequent machining during the improvement procedure, which must be carried out in a mechanical workshop and takes time.

BE2018 / 5200 [0006] WO 2016/086049, The Johns Hopkins University, June 2, 2016, describes a method of manufacturing an implant with a self-contained manufacturing device. A digital reconstruction of a patient's bone structure is compared to a digital reconstruction of an implant to produce a plot from a point cloud. The implant is manufactured with an additive and / or subtractive manufacturing device on the basis of the layout, and is usually a few millimeters larger than the size of the defect. A traceable cutting guide is designed based on the digital model of the patient's anatomy. When the cutting guide is placed on the patient and the desired cutting lines are made, a drawing of the defect limits is carried out, for example, by means of an optical digitizer, and the drawing of the defect limits is returned to the implant. Cut lines that correspond to a size offset between the implant and the defect are then drawn on the implant. The tracing can be used to precisely reduce the oversized implant.

This method suffers from the same drawback as indicated above, namely that the oversized implant will very often require additional machining and improvement, which takes time and in particular lengthens the duration of the intervention on the patient. .

The present invention aims to provide a method for overcoming the above problems. The present invention aims in particular to provide a process for the production of a prosthetic implant which offers a perfect fit with the resected part of the bone structure. The present invention further aims to provide a method of producing a prosthetic implant which reduces the intervention time on the patient.

The present invention also aims to provide an implant as it can be obtained from the above methods.

According to a first aspect of the invention, there is therefore provided a method for manufacturing a prosthetic implant, as set out in the appended claims. A digital model of the bone structure is obtained. A material model of the bone structure is produced on the basis of the digital model. A resection guide is produced by defining a line for resection of the bone structure. A prosthetic implant is produced.

In another aspect, the resection guide includes a guide surface configured to support a surgical resection tool in a predetermined orientation along the line of resection. According to another aspect, the resection guide is validated on the hardware model, the validation step comprising performing a resection in the hardware model. The prosthetic implant is

BE2018 / 5200 only manufactured after validation of the resection guide, and is advantageously manufactured on the basis of a geometry of the resection carried out in the material model. According to another aspect, when performing the resection in the material model, a cutting tool follows the guide surface in the predetermined orientation. The different aspects above can be incorporated into the process mentioned in the previous paragraph independently of each other, or in combination.

Unlike the methods of the prior art which are based on the advance production of an oversized implant and the adjustment of its size during an improvement procedure before or during the surgical intervention, in the present disclosure, a resection guide or a cutting guide is firstly manufactured and can be validated advantageously on a material model of the bone structure, for example, by making cutting lines on the model. The implant is then produced on the basis of the resection guide and / or the shape of the resection obtained on the model, in particular during the resection carried out on the material model of the bone structure.

In order to obtain an implant of the correct size which does not require adjustment during the surgical intervention, a guide surface is provided on the resection guide in order to guide the cutting tool used to perform the resection. . The guide surface ensures that the cutting tool is supported in the correct orientation during resection, which corresponds to the geometry of the implant. The guide surface further ensures that the resection performed on the model will match the resection performed on the patient, so that the implant will adapt without requiring further adjustment.

According to another aspect of the invention, a kit of parts is provided, as set out in the appended claims. The parts kit includes a resection guide defining a resection line and a prosthetic implant comprising a shape corresponding to the resection line. In another aspect, the resection guide includes a guide surface configured to support a surgical resection tool in a predetermined orientation, preferably along the line of resection. In another aspect, the prosthetic implant includes a perimeter corresponding to the resection line and a surface extending from the perimeter and having an orientation corresponding to the guide surface.

Other features, details and advantages of the invention will emerge from the description and examples given below, without limitation and with reference to the accompanying drawings.

BE2018 / 5200 [0016] FIG. 1 represents a flow diagram of a method for manufacturing a prosthetic implant according to aspects of the present invention.

Figure 2 shows a more elaborate flowchart of a method for manufacturing a prosthetic implant according to aspects of the present invention.

Figure 3 shows a perspective view of a resection guide according to several aspects of the present invention.

Figure 4 shows a perspective view of a prosthetic implant according to several aspects of the present invention which adapts to the resection guide of Figure 3.

5 shows a sectional view of the resection guide of Figure 3 along the line of section AA, placed on the bone structure, in which has been illustrated a section of the resection in the bone structure made with guide. 6 shows a sectional view of the implant of Figure 4 along the section line B-B implanted in the resection made in the bone structure of Figure 5.

Referring to Figure 1, a method 10 of manufacturing a prosthetic implant according to several aspects of the present disclosure comprises a first step 11 comprising obtaining a digital model of the bone structure in which the prosthesis will be implanted. For example, a CT scan or an MRI scan or other suitable medical imaging technique can be used to conventionally determine a set of computer-readable data defining in three dimensions the bone part d interest, for example, the skull. The digital model can therefore be a point cloud or another digital representation of the bone structure.

In step 12, the digital model obtained in step 11 is used to make a full-scale material model of the bone structure, preferably by means of an additive manufacturing technique, such as a 3-D printing, stereolithography, selective laser sintering or any other suitable technique. The material model is advantageously made of a polymer material. The hardware model is used in several aspects of this disclosure to determine precise geometry for the prosthetic implant.

Unlike the methods of the prior art which would immediately start with the manufacture of the prosthetic implant, a resection guide (or cutting guide) is firstly manufactured in step 13. The guide resection guides a surgical resection tool (or cutting tool) so that it performs the desired cuts through the bone structure in a precise manner. In order to manufacture the

BE2018 / 5200 resection guide, the desired lines or cutting planes, along which the surgeon will cut the bone structure, are advantageously defined first, in particular during a preoperative planning stage. The definition of the desired cutting lines or planes can be carried out, for example, by a surgeon on the digital model, the hardware model or both.

In one aspect, the resection guide includes a guide surface which supports the cutting tool with which the resection is performed in a predetermined orientation. Therefore, the guide surface not only defines a cutting line, but also allows you to define the angular orientation of the cutting tool, and therefore the angle at which the tool cuts the bone structure. The guide surface is advantageously inclined relative to a surface of the bone structure. This can increase an interface area between the bone structure and the prosthetic implant, facilitate attachment, for example by means of screws and a flush mounting of the implant. The resection guide may further include a cutting edge which defines the cutting lines. The cutting edge is advantageously a continuous edge and advantageously forms a closed curve.

The resection guide is made with a support which advantageously corresponds to a surface of the digital model and / or material. The support can form a lower surface of the resection guide. Advantageously, the bottom surface (support surface) of the resection guide corresponds to an anatomical surface of the patient. This ensures that the resection guide fits over the bone structure in a single position, thereby avoiding any possible placement errors during surgery.

It should be noted that steps 12 and 13 can be carried out in parallel and for example, that the resection guide is first of all modeled numerically, for example, by computer, on the basis of the digital model obtained at l 'step 11.

Once the resection guide or at least a prototype of the resection guide has been manufactured, it is advantageously validated on the digital model and / or hardware in step 14. In step 14, the guide resection is placed on the material model and the surgical intervention is simulated on the material model. Resection is in particular carried out along the cutting edge in the material model. Resection in the material model obtained in step 14 is used in step 15 to produce the prosthetic implant. The prosthetic implant is manufactured to adapt to the geometry of the resection in the material model. Therefore, the prosthetic implant is manufactured directly on the basis of correct dimensions which

BE2018 / 5200 can be determined from the dimensions of the resection guide. The dimensions will therefore be of repeatable precision, so that a perfect adequacy will be ensured even during the actual surgical intervention. No improvement of the prosthetic implant is required after manufacture.

The methods of the present invention therefore make it possible to manufacture prosthetic implants directly or in the operating room under sterile conditions, for example, by molding of polymer resins. Alternatively, the implants can be made of metal or ceramic in the workshop beforehand and sterilized when brought to the operating room. No further machining is necessary after manufacture, since the geometry of the resection and of the implant is defined by the geometry of the resection guide and therefore a perfect fit is ensured.

Referring to Figure 2, the method 20 according to certain aspects of the present disclosure comprises steps 11 and 12 as described above. In step 23, a prototype resection guide is made. This can be a full-scale hardware model of the resection guide. The prototype can be manufactured by planning a cutting line and / or a cutting surface of the bone structure on the digital model, on the material model of the bone structure, or both. The prototype resection guide may include a guide surface which corresponds to the planned cutting lines and the predetermined orientation of the cutting tool, or which corresponds to the cutting surface. Cut lines designate an intersection of the cut surface with an external surface of the bone structure or a model of that structure. The guide surface defines an orientation of the cutting tool along the cutting line and therefore defines a cutting surface through the bone structure. Advantageously, the guide surface is inclined relative to the anatomical surface, making it possible to control the cutting slope. Advantageously, the prototype resection guide can first be produced digitally, for example, as a set of data readable by computer, after which a material prototype can be produced, in particular by additive manufacturing techniques. The prototype is advantageously made of a polymer material.

In step 24, the prototype resection guide is validated on the material model of the bone structure, for example, by simulating the surgical intervention. The prototype resection guide can be placed on the hardware model in the desired location. The resection guide may include a support which defines a position of the resection guide in a well-defined and unique manner with respect to the

BE2018 / 5200 bone structure. The material model is cut with the cutting tool following the guide surface of the resection guide, and in the orientation defined by the guide surface. This validates the geometry of the resection which is or will be performed on the bone structure.

In step 25, a prototype of the prosthetic implant is manufactured, which can be a real-scale hardware model of the prosthetic implant. According to aspects of this disclosure, the implant prototype is fabricated based on the resection geometry obtained in step 24, which corresponds to the shape of the resection guide prototype. In particular, the implant prototype comprises a perimeter which corresponds to the cutting line and is therefore defined by a projection of the guide surface of the prototype resection guide on (a surface of) the bone structure. By manufacturing the implant prototype following the manufacturing of the resection guide prototype, we ensure that the geometry of the implant will correspond to the region of cutting of the bone structure and that no other improvement of the implant will be required. The implant can therefore be manufactured directly with the correct dimensions. An important feature in this regard is that the guide surface provided on the resection guide defines an orientation of the cutting surface in a precise and reproducible manner. Advantageously, the implant prototype can firstly be produced digitally, for example, in the form of a set of data readable by computer, by digitization of the resection carried out in the material model of the bone structure. The computer-readable dataset can then be used to build a hardware prototype, for example, by additive manufacturing techniques. The implant prototype is advantageously made of a polymer material. In an optional step 26, the implant prototype is validated on the hardware model. This step could be particularly useful in order to check whether the implant can be fixed correctly to the remaining bone structure, for example by means of osteosynthesis screws. As a variant, the validation of the implant fixation can be carried out during step 24, on the basis of the geometry obtained from the resection of the material model. Some or all of steps 12 to 26 can be repeated or iterated if the implant needs to be redefined.

In step 27, the final resection guide and the implant are fabricated.

These are the elements that will be used during the actual surgery. This step can include making molds from validated and possibly improved prototypes of the implant and the resection guide. These molds usually include recesses which are a negative of the geometry of the resection guide and the prosthetic implant. The molds can be cast with a

BE2018 / 5200 moldable material, in particular a biocompatible material, which can be a polymer. Alternatively, ceramic or metallic material can be used. The final resection guide and implant obtained from the molds can be used in the surgical procedure and do not require further development. Items made of metal or ceramic may need to be sterilized before use in the operating room. Elements made of polymeric materials can be poured under sterile conditions in the operating room and can be used directly afterwards.

It should be noted that in steps 23 and 25, instead of manufacturing prototypes, it is possible to manufacture the final elements if no iteration is necessary.

The actual surgery is performed with the final resection guide and implant obtained from the above methods, and can be performed in a conventional manner. The resection guide is used first to perform the resection, after which it is removed and the implant is placed and fixed.

Referring to Figures 3 to 6, the resection guide 30 and the prosthetic implant 40 are now described in more detail based on an illustrative example of resection in the craniofacial part, in particular the skull and forehead. Referring to FIG. 5, the resection guide 30 comprises a first part, called the external part 31 configured to engage with an (external) surface 91 of the bone structure 9. The external part 31 advantageously comprises a so-called lower surface 310 which complements the surface 91 of the bone structure 9 which surrounds the area 92 which must be resected in a complementary manner. The surface 310 is advantageously arranged so that the resection guide 30 adapts to the surface 91 in a unique position and in a unique orientation, thus making it possible to avoid any incorrect placement of the resection guide. To this end, the lower surface 310 advantageously engages with the surface 91 along an advantageously closed curve which advantageously completely surrounds a cutting edge 32 of the resection guide 30. This lower surface 310, and more generally , the resection guide 30, essentially has the shape of a ring.

The cutting edge 32 advantageously forms a curve defining the cutting line on the surface 91 of the bone structure. The cutting edge 32 is advantageously an internal edge of the lower surface 310 of the resection guide. The resection guide 30 further comprises an upper surface 34 arranged opposite the lower surface 310, an internal surface 33 and an external lateral surface 35. The internal surface 33 and the external lateral surface 35 are arranged

BE2018 / 5200 opposite one another and extend between the lower surface 310 and the upper surface 34. In the example of FIG. 5, the internal surface 33 can be considered to form a wall of a through hole of the resection guide, extending between the upper surface 34 and the lower surface 310, and the cutting edge 32 forming an edge of the through hole.

According to aspects of this disclosure, the internal surface 33 is a guide surface configured to support a surgical cutting tool, such as a surgical saw which will cut the bone. The guide surface 33 supports the surgical cutting tool in a predefined orientation, advantageously making it possible to perform a bias cut through the bone of the structure 9. The guide surface 33 can extend from the cutting edge 32 in a direction away from the lower surface 310, for example, to the upper surface 34. The cutting edge 32 may therefore form the edge between the lower surface 310 and the guide surface 33. The surface of guide 33 advantageously has an appropriate height H in order to provide suitable support for the surgical cutting tool. By way of example, the surface 33 can be wide enough so that a surgical cutting tool can be held precisely against the surface 33 at a predetermined angle. The height H is advantageously at least 5 mm, advantageously at least 10 mm and is advantageously at least 15 mm as measured in a plane perpendicular to the cutting edge 32 in a direction perpendicular to the lower surface 310. This height H may correspond to the thickness of the resection guide 30, as measured between the surfaces 310 and 34. Advantageously, the line of intersection between the surface 33 and a plane perpendicular to the cutting edge 32 is a straight line.

The guide surface 33 is advantageously an inclined surface relative to the surface 91 of the bone structure. The angle of inclination a of the guide surface 33 in a plane perpendicular to the cutting edge 32 and with respect to a normal 94 to the surface 91, or as the case may be, to the surface 310, is advantageously between 15 ° and 60 °, advantageously between 20 ° and 55 °, advantageously between 25 ° and 50 °. The angle of inclination may depend on the size of the bone part that needs to be resected. For larger implants, an angle of approximately 45 ° may be more appropriate, while for smaller implants, an angle of approximately 30 ° may be chosen.

When a cutting tool is held against the guide surface 33 and swept along it, a resection 92 can be performed through the bone structure 9. The resection 92 will have a cutting surface 93 having a slope

BE2018 / 5200 which corresponds to the slope (of angle a) of the guide surface. Depending on the thickness of the cutting tool, and the possible offset between the guide surface 33 and the cutting edge 32, the surface 93 can be offset relative to the surface 33 and / or to the edge 32 of the guide. resection 30.

Referring to Figures 3 and 5, the resection guide 30 advantageously comprises an inner part 37 positioned on the inner side of the outer part 31, in opposition to the guide surface 33 and / or to the cutting edge 32. The outer part 31 and inner part 37 are spaced a certain distance apart so as to form a groove 38 between the two outer parts 31 and inner 37. The groove 38 advantageously extends completely through the thickness of the parts 31 and 37. The outer side of the groove forming the guide surface 33, the groove 38, is designed to receive the cutting tool. The inner part advantageously helps to keep the cutting tool in its position.

Advantageously, one or more bridges 381 connecting the outer 31 and inner 37 parts can be provided. It is also possible to provide in the groove 38 a bottom connecting the outer 31 and inner 37 parts. In the latter case, the groove 38 does not extend completely through the thickness of the parts 31 and 37. The bridge (s) (s) 381 and the groove bottom can also be combined and are advantageously cut when the cutting tool passes. In this case, provision should be made for the prior production of a casting or injection mold. This mold makes it possible to manufacture the final resection guide to be used during the intervention on the patient following the validation step on the material model.

To allow the cutting tool to sink into the bone structure, a starting hole 39 is advantageously provided. The hole 39 has larger dimensions than, for example, the width of the groove 38, and is advantageously located between the outer 31 and inner 37 parts and communicates with the groove 38.

Referring again to Figure 3, the resection guide 30 may further include fixing means, such as holes 36, for fixing the resection guide to the bone structure 9, for example, through of osteosynthesis screws.

Referring to Figures 4 and 6, the prosthetic implant 40 comprises an upper surface 41, an opposite lower surface 42 and a lateral contour surface 43 extending between the upper surface 41 and the lower surface 42. The surface of lateral contour 43 is configured to form an interface with the bone structure 9, that is to say to provide the interface with the cut surface 93,

BE2018 / 5200 and advantageously forms a closed contour. The intersection between the upper surface 41 and the lateral contour surface 43 forms a perimeter 44 which advantageously corresponds to the cutting line on the surface 91, which can in turn be defined by the cutting edge 32 and / or the surface guide 33 of the resection guide 30. In order to offer a perfect match between the implant 40 and the resected part 92 of the bone structure 9, the lateral contour surface 43 is oriented in a complementary manner to the guide surface 33, namely with the same angle of inclination a relative to normal 94 when viewed in a plane perpendicular to the perimeter curve 44. Advantageously, the line of intersection between the lateral contour surface 43 and a plane perpendicular to the perimeter curve 44 is a straight line.

The prosthetic implant 40 may also include fixing means (not shown) for fixing the implant to the bone structure 9, for example, by means of known fixing means such as osteosynthesis screws.

An advantage of the implants 40 according to several aspects of the present disclosure is that the surface 93 which is cut from the bone structure 9 based on the resection guide 30 closely corresponds to the lateral contour surface 43 of the implant 40. Therefore, a perfect match between the implant 40 and the bone structure is ensured, allowing the implant to be fixed through the interface formed by the lateral contour surface 43. This means that the upper surface 41 can be flush with the external surface 91 of the bone structure 9, improving the visual appearance of the reconstructed structure after the surgical intervention.

Claims (20)

1. Method (10, 20) of manufacturing a prosthetic implant (40) for the replacement of a damaged or diseased part of a bone structure (9), comprising: obtaining a digital model of the bone structure and manufacturing a material model of the bone structure based on the digital model, manufacturing a resection guide (30) defining a resection line (32) of the bone structure, and the manufacture of the prosthetic implant, characterized in that: the resection guide includes a guide surface (33) configured to support a surgical resection tool in a predetermined orientation along the resection line, the resection guide is validated on the material model, comprising performing a resection in the material model by following the guide surface and in the predetermined orientation, and the prosthetic implant is produced on the basis of a geometry of the resection carried out in the material model. 2. Method according to claim 1, in which the guide surface is a surface inclined with respect to a surface (91) of the bone structure. 3. Method according to claim 1 or 2, wherein the guide surface is designed to orient the surgical resection tool to achieve a cutting angle (a), as measured in a plane perpendicular to the line of resection, between 20 ° and 55 ° relative to a normal (94) to a surface of the bone structure. 4. Method according to any one of the preceding claims, in which the resection guide comprises an outer part (31) and an inner part (37) spaced apart by a groove (38), the guide surface (33) constituting a side of the groove. 5. Method according to claim 4, comprising positioning the resection guide on the material model, in which a lower surface (310) of the external part (31) complements the surface of the bone structure in a complementary manner. 6. Method according to claim 4 or 5, wherein the groove (38) comprises a bottom connecting the outer part (31) and the inner part (37), the step BE2018 / 5200 of resection in the material model including the cutting of the bottom so as to separate the external part from the internal part. 7. Method according to any one of claims 4 to 6, comprising a step of manufacturing a mold for the resection guide prior to or during the step of validation on the material model and a step of manufacturing a guide. final resection using the mold following the resection step in the material model. 8. Method according to any one of the preceding claims, in which the guide surface supports the surgical resection tool along a height (H) of at least 5 mm measured in a direction perpendicular to a surface of the bone structure at the level of the resection line. 9. Method according to any one of the preceding claims, in which the prosthetic implant is a craniofacial implant. 10. Method according to any one of the preceding claims, in which the resection guide is in the form of a ring. 11. Method according to any one of the preceding claims, comprising obtaining computer-readable data representative of a geometry of the resection carried out in the material model and the manufacture of the prosthetic implant on the basis of the computer-readable data. . 12. The method of claim 11, comprising manufacturing a mold for the prosthetic implant on the basis of the computer readable data and pouring a material into the mold for manufacturing the prosthetic implant. 13. Kit of parts (30, 40), comprising: a resection guide (30) defining a resection line (32) on a surface (91) of a bone structure (9), and a prosthetic implant (40) comprising a perimeter (44) corresponding to the resection line, characterized in that the resection guide includes a guide surface (33) configured to support a surgical resection tool in a predetermined orientation along the resection line, and in that the prosthetic implant comprises a surface (43) extending from the perimeter and having an orientation corresponding to the guide surface. 14. Kit of parts according to claim 13, further comprising a model of the bone structure, and the resection guide comprising a support surface (310) adapting to a surface of the model surrounding the resection line. BE2018 / 5200 15. Kit of parts according to claim 14, in which a line of intersection of the guide surface with a plane perpendicular to the resection line forms an angle (a) with respect to a direction normal to the support surface between 20 ° and 55 °. 16. Kit of parts according to any one of claims 13 to 15, wherein the resection line extends over a thickness of the resection guide of at least 5 mm. 17. Kit of parts according to any one of claims 13 to 16, in which the resection guide (30) comprises an outer part (31) and an inner part (37) spaced apart by a groove (38), the guide surface (33) constituting one side of the groove provided on the part exterior. 18. Kit of parts according to claim 17, in which the external part (31) and the internal part (37) are connected by means of an element chosen from the group consisting of at least one bridge (381), and a bottom. of the groove (38). 19. Kit of parts according to claim 17 or 18, wherein the resection guide comprises a starting hole (39) communicating with the groove (38) and located between the outer part (31) and the inner part (37). 20. Kit of parts according to any one of claims 13 to 19, obtained according to the method of any one of claims 1 to 12.