Method for producing a surgical navigation module

Abstract

The invention relates to a method for producing a surgical navigation module (1), the method comprising the following steps: - providing a navigation marker (2) comprising a retroreflective lens; - producing a shell (3) by moulding a rigid thermoplastic material, wherein the shell defines an interior cavity and has at least one coupling member for attachment to a rigid navigation support; - placing the navigation marker in the interior cavity of the shell while maintaining an interstitial space between the shell and the navigation marker; and - forming an intermediate cap (4) by moulding an elastomeric thermoplastic material at least in the interstitial space, such that the intermediate cap is moulded within the interior cavity and partially overmoulds the navigation marker, between the shell and the navigation marker.

Description

[0001] DESCRIPTION

[0002] TITLE: Manufacturing process of a surgical navigation module

[0003] [Technical field]

[0004] The invention relates to a method of manufacturing a surgical navigation module, used in the field of surgical navigation and in particular in orthopedic surgery.

[0005] It relates more particularly to a method of manufacturing a surgical navigation module comprising a reflective navigation marker and a coupling part shaped to be mounted on a rigid navigation support.

[0006] [State of the art]

[0007] As is known, surgical navigation implements a video capture system, particularly in the infrared range, which tracks reflective navigation markers mounted on a rigid navigation support, itself fixed to a surgical instrument, an implant or a part of the patient's body. Thus, the position of these reflective navigation markers is tracked by the video capture system in the surgical unit, in order to track the position and orientation in space of the surgical instrument, the implant or the part of the patient's body concerned.

[0008] A first reflective navigation marker is in the form of a spherical marker with an opaque and reflective surface and which is single-use. An orifice is provided in the spherical marker, allowing mounting on a stud of the rigid navigation support which is itself reusable, which makes it possible to limit costs and waste to only spherical markers. Thus, the surgeon can remove the spherical markers from their sterile bags and then easily mount them on the studs of the rigid navigation support.

[0009] During surgery, these spherical markers can be subjected to projections of fluid (especially blood) and particles (such as bone debris), thus reducing their visibility and tracking by the video capture system and thus inducing errors in the measurement of their positions. In addition, the opaque and reflective surfaces of these spherical markers are fragile and prevent them from being wiped. To remedy this when performing operations causing projections, surgeons replace the spherical markers each time they are stained (thus generating waste and additional costs) or place transparent protections on these spherical markers (thus partially altering their tracking by the video capture system).This attention that surgeons must pay to the cleanliness of spherical markers therefore makes their use difficult, particularly for guiding a surgical instrument (such as a cutting instrument) while projections are being emitted.

[0010] To address this issue, a second design of reflective navigation marker has been developed in the form of a retro-reflective lens, which is generally spherical in shape and is secured to an annular collar; where the retro-reflective lens has a transparent and smooth surface, generally made of plastic, which allows it to be wiped clean and makes it less susceptible to contamination by fluid splashes and particles. A reference for this type of retro-reflective lens is, for example, the Radix™ module from Northern Digital Inc.

[0011] However, the integration of such a retro-reflective lens on a rigid navigation support presents difficulties, in particular because the retro-reflective lens is not suitable for withstanding a sterilization operation and is therefore single-use. However, it is customary to glue the annular collar inside a receiving orifice provided for this purpose on the rigid navigation support, thus securing the retro-reflective lens to the rigid navigation support. This securing therefore involves making the rigid navigation support itself single-use, which induces an additional cost (because the rigid navigation support will not be reusable) and which also generates a greater quantity of waste. Furthermore, such gluing is a source of inaccuracy in the mounting of the retro-reflective lens on the rigid navigation support, thus harming the accuracy of tracking by the video capture system.

[0012] [Summary of the invention]

[0013] The subject matter of the present invention relates to a method for manufacturing a surgical navigation module comprising a retro-reflective lens and a coupling part provided for coupling to a rigid navigation support, which is adapted to be able to reuse the rigid navigation support.

[0014] Another object of the invention is to improve the precision of the mounting of the retro-reflective lens on the rigid navigation support.

[0015] To this end, the invention proposes a method for manufacturing a surgical navigation module, comprising the following steps:

[0016] - provide a navigation marker comprising a retro-reflective lens;

[0017] - producing a hull by molding a rigid thermoplastic material, said hull defining an interior cavity and having at least one coupling member to allow coupling of the hull to a rigid navigation support;

[0018] - placing the navigation marker in the interior cavity of the hull while maintaining an interstitial space between the hull and the navigation marker; and

[0019] - producing an intermediate cap by molding an elastomeric thermoplastic material at least in the interstitial space, so that the intermediate cap is molded inside the interior cavity and partially overmolds the navigation marker, between the hull and the navigation marker.

[0020] Thus, the invention proposes to produce the coupling part in the form of a two-material part composed of the shell and the intermediate cap which are made of separate thermoplastic materials. Once the shell is produced, the navigation marker is placed in the interior cavity of the shell, and the elastomeric thermoplastic material is poured between the shell and the navigation marker, which promotes the centering of the navigation marker by freeing itself from the precision of the molding tool.

[0021] Thus, the surgical navigation module, as supplied to the surgeon, is presented in the form of this assembly of the bi-material part overmolded around the navigation marker. A first advantage is that the surface of the retro-reflective lens is protected by the rigid shell during transport.

[0022] Furthermore, the invention proposes two distinct thermoplastic materials, because the intermediate cap and the shell do not have the same function:

[0023] - the function of the intermediate cap is to receive, center and maintain the navigation marker which is, as a reminder, a fragile part, so that the elastomeric nature of its material is particularly advantageous in order to avoid the risk of damaging the surface of the retro-reflective lens thanks to its flexibility, and moreover a thermoplastic elastomeric material has a sufficiently low and well-adapted melting temperature so as not to damage this surface of the retro-reflective lens which is sensitive to temperature, and

[0024] - the function of the hull is to ensure coupling and maintenance on the rigid navigation support, so that the rigid nature of its material is particularly advantageous because such coupling requires improved mechanical strength such as can be offered by a rigid thermoplastic material which couples with a rigid support.

[0025] Working with two superimposed, bi-material moldings therefore improves the maintenance and centering of the navigation marker on the rigid navigation support. Advantageously, the rigid thermoplastic material is a semi-crystalline rigid thermoplastic material.

[0026] According to one characteristic, the rigid thermoplastic material is chosen from rigid thermoplastic materials of the polypropylene or polyethylene type.

[0027] According to one possibility, the thermoplastic elastomer material is selected from materials such as thermoplastic polyurethane elastomer (TPU), thermoplastic styrenic elastomer (TPS), thermoplastic copolyester elastomer (TPC), thermoplastic copolyamide elastomer (TPA), unvulcanized thermoplastic olefin elastomer (TPO) and vulcanized thermoplastic olefin elastomer (TPV).

[0028] Alternatively, the elastomeric thermoplastic material has a melting temperature of less than or equal to 150°C.

[0029] Indeed, this low melting temperature is advantageous for preserving the surface of the retro-reflective lens which is sensitive to temperature, so as to ensure that the contact temperature between the elastomeric thermoplastic material and the retro-reflective lens is lower than 150°C and therefore that the coating of the retro-reflective lens is not damaged during molding with the elastomeric thermoplastic material.

[0030] According to another characteristic, the thermoplastic elastomer material has a Shore A hardness between 40 and 70, and for example between 50 and 60, which favors the role of shock absorber during molding and during use of the surgical navigation module.

[0031] According to another characteristic, the at least one coupling member of the outer part is a snap-fastening member.

[0032] In a particular embodiment, this coupling member comprises a projecting latching hook secured to a gripping tab.

[0033] Variants are possible, such as a screw thread type coupling member, for screw coupling.

[0034] In a particular embodiment, the shell has a peripheral edge surrounding the interior cavity and in which notches are formed, so that the elastomeric thermoplastic material at least partially fills said notches when producing the intermediate cap.

[0035] This conformation with notches is advantageous for a solid assembly of the intermediate cap inside the shell, and therefore to ultimately have a compact and mechanically robust module for good centering and good support. Advantageously, the shell has a peripheral wall in which at least one orifice is provided which opens into the interior cavity, in order to introduce the thermoplastic elastomer material through this at least one orifice during the production of the intermediate cap.

[0036] Preferably, the rigid thermoplastic material and the elastomeric thermoplastic material are medical grade materials.

[0037] Advantageously, the rigid thermoplastic material and the elastomeric thermoplastic material are materials resistant to gamma sterilization.

[0038] The invention also relates to a surgical navigation module obtained by the manufacturing method as described above, this surgical navigation module comprising:

[0039] - an intermediate cap made of an elastomeric thermoplastic material partially overmolding a navigation marker comprising a retro-reflective lens; and

[0040] - a hull made of a rigid thermoplastic material and having at least one coupling member to allow coupling of the hull to a rigid navigation support, said hull defining an interior cavity inside which the intermediate cap is assembled, said intermediate cap thus being arranged between the hull and the navigation marker.

[0041] Of course, all the characteristics relating to the manufacturing process apply to the surgical navigation module, particularly with regard to the rigid thermoplastic material and the elastomeric thermoplastic material.

[0042] The invention also relates to a surgical navigation assembly comprising:

[0043] - a rigid navigation support comprising at least one housing; and

[0044] - at least one surgical navigation module as described above; wherein the shell of the at least one surgical navigation module is mounted in the at least one housing and is held by a coupling of the at least one coupling member with at least one complementary coupling member disposed on the at least one housing.

[0045] According to one variant, the rigid navigation support comprises at least two arms, and the at least one housing comprises at least two housings provided on the at least two respective arms, such that the at least one surgical navigation module comprises at least two surgical navigation modules mounted in the at least two respective housings. [Brief description of the figures]

[0046] Other characteristics and advantages of the present invention will appear on reading the detailed description below, of a non-limiting example of implementation, made with reference to the appended figures in which:

[0047] Figure 1 is a schematic perspective view of a shell obtained by molding a rigid thermoplastic material;

[0048] Figure 2 is a schematic perspective view of a placement of a navigation marker in the interior cavity of the hull of Figure 1, prior to molding of the intermediate cap;

[0049] Figure 3 is a schematic perspective and axial sectional view of a surgical navigation module obtained after molding the intermediate cap between the shell and the navigation marker;

[0050] Figure 4 is a schematic exploded perspective view of the surgical navigation module of Figure 3;

[0051] Figure 5 is a schematic perspective view of a surgical navigation assembly comprising a rigid navigation support provided with four arms receiving four surgical navigation modules of Figure 4;

[0052] Figure 6 is a schematic view of the surgical navigation assembly of Figure 5, in which the rigid navigation support is attached to a surgical instrument.

[0053] [Detailed description of an embodiment of the invention]

[0054] The following description relates to a method of manufacturing a surgical navigation module 1, implementing the provision of a navigation marker 2 (visible in Figure 2) comprising a retro-reflective lens 20 of generally hemispherical shape and surrounded by an annular collar 21.

[0055] With reference to Figure 1, one step of this method consists of producing a shell 3 by molding in a mold 30 a rigid thermoplastic material, and in particular a semi-crystalline rigid thermoplastic material, such as polypropylene or polyethylene, preferably a medical grade material and resistant to gamma sterilization.

[0056] This shell 3 has a peripheral wall 31 defining or delimiting an interior cavity 32, and this peripheral wall 31 of the shell 3 has a peripheral edge 33 surrounding the interior cavity 32 and in which notches 34 are provided; in the example illustrated, there are three notches 34. At least one orifice 35 is provided in the peripheral wall 31 to open into the interior cavity 32. The shell 3 also has a solid bottom wall 39, which forms the bottom of the interior cavity 32; the interior cavity 32 thus extending from this bottom wall 39 to the peripheral edge 33.

[0057] This hull 3 also has coupling members 36 to allow coupling of the hull 3 to a rigid navigation support 5 described later. These coupling members 36 are here two in number and are arranged diametrically opposite. Each of the coupling members 36 is in the form of a latching member which comprises a projecting latching hook 37 secured to a gripping tab 38, in order to allow mounting by latching on the rigid navigation support 5.

[0058] Then, the navigation marker 2 is placed in the interior cavity 32 of the hull 3 while maintaining an interstitial space between the hull 3 and the navigation marker 2. The annular collar 21 rests on several contact points provided for this purpose in the interior cavity 32.

[0059] Finally, an elastomeric thermoplastic material is poured into the interstitial space, through the orifice 35, in order to produce an intermediate cap 4 by molding this elastomeric thermoplastic material, so that the intermediate cap 4 is molded inside the interior cavity and partially overmolds the navigation marker 2, between the shell 3 and the navigation marker 2. The intermediate cap 4 at least partially overmolds the annular collar 21 at the periphery, and therefore provides the assembly of the navigation marker 2 with the shell 3. Thus, the navigation marker 2 is secured to a coupling part which is a bi-material part formed from the shell 3 and the intermediate cap 4.

[0060] The thermoplastic elastomer material is selected from materials of the polyurethane elastomer thermoplastic (TPU), styrenic elastomer thermoplastic (TPS), copolyester elastomer thermoplastic (TPC), copolyamide elastomer thermoplastic (TPA), unvulcanized olefinic elastomer thermoplastic (TPO) and vulcanized olefinic elastomer thermoplastic (TPV); and this elastomer thermoplastic material has a melting temperature of less than or equal to 150°C, and for example less than or equal to 120°C.

[0061] This thermoplastic elastomer material is preferably a medical grade material and resistant to gamma sterilization, with a Shore A hardness between 40 and 70, and for example between 50 and 60.

[0062] At the end of this manufacturing process, the surgical navigation module 1 obtained comprises:

[0063] - navigation marker 2;

[0064] - the intermediate cap 4 partially overmolding the navigation marker and made of the elastomer thermoplastic material; and

[0065] - the shell 3 made of the rigid thermoplastic material and defining the interior cavity 32 inside which the intermediate cap 4 is assembled, this intermediate cap 4 thus being arranged between the shell 3 and the navigation marker 2.

[0066] Also, as explained, the navigation marker 2 is overmolded by a two-material part formed from the shell 3 and the intermediate cap 4.

[0067] With reference to Figures 5 and 6, a surgical navigation assembly 6 comprises the rigid navigation support 5 which may comprise several arms 50 (four in the illustrated example), where each of the arms 50 has a free end provided with a housing 51 suitable for receiving a surgical navigation module 1. The surgical navigation assembly 6 therefore also comprises as many surgical navigation modules 1 as there are housings 51 in the rigid navigation support 5.

[0068] In each housing 51, the shell 3 is mounted inside the housing 51 and is held in place by snap-fastening, by a coupling of these coupling members 36 with complementary coupling members arranged on the housing 51.

[0069] As seen in Figure 6, the rigid navigation support 5 can then be fixed to a surgical instrument 7, and the position of the navigation markers 2 can be tracked by the video capture system in the surgery unit, in order to track the position and orientation in space of the surgical instrument 7. The rigid navigation support 5 can also be fixed to an implant or to a part of the patient's body, in order to track the position and orientation in space of this implant or of this part of the patient's body concerned.

Claims

CLAIMS 1. Method for manufacturing a surgical navigation module (1), comprising the following steps: - providing a navigation marker (2) comprising a retro-reflective lens (20); - producing a hull (3) by molding a rigid thermoplastic material, said hull (3) defining an interior cavity (32) and having at least one coupling member (36) to allow coupling of the hull (3) to a rigid navigation support (5); - placing the navigation marker (2) in the interior cavity (32) of the hull (3) while maintaining an interstitial space between the hull (3) and the navigation marker (2); and - producing an intermediate cap (4) by molding an elastomeric thermoplastic material at least in the interstitial space, so that the intermediate cap (4) is molded inside the interior cavity (32) and partially overmolds the navigation marker (2), between the shell (3) and the navigation marker (2).

2. A manufacturing method according to claim 1, wherein the rigid thermoplastic material is a semi-crystalline rigid thermoplastic material.

3. Manufacturing method according to claim 2, in which the rigid thermoplastic material is chosen from rigid thermoplastic materials of the polypropylene or polyethylene type.

4. Manufacturing method according to any one of claims 1 to 3, in which the thermoplastic elastomer material is chosen from materials of the type thermoplastic polyurethane elastomer (TPU), thermoplastic styrenic elastomer (TPS), thermoplastic copolyester elastomer (TPC), thermoplastic copolyamide elastomer (TPA), unvulcanized thermoplastic olefin elastomer (TPO) and vulcanized thermoplastic olefin elastomer (TPV).

5. Manufacturing method according to any one of claims 1 to 4, in which the elastomeric thermoplastic material has a melting temperature of less than or equal to 150°C.

6. Manufacturing method according to any one of claims 1 to 5, in which the thermoplastic elastomer material has a Shore A hardness of between 40 and 70, and for example between 50 and 60.

7. Manufacturing method according to any one of claims 1 to 6, in which the at least one coupling member (36) of the shell (3) is a snap-fastening member.

8. Manufacturing method according to claim 7, in which the coupling member comprises a projecting latching hook (37) secured to a gripping tab (38).

9. Manufacturing method according to any one of claims 1 to 8, in which the shell (3) has a peripheral edge (33) surrounding the interior cavity (32) and in which notches (34) are formed, so that the elastomeric thermoplastic material at least partially fills said notches (34) during the production of the intermediate cap.

10. Manufacturing method according to any one of claims 1 to 9, in which the shell (3) has a peripheral wall (31) in which at least one orifice (35) is provided which opens into the interior cavity (32), in order to introduce the thermoplastic elastomer material through this at least one orifice (35) during the production of the intermediate cap (4).

11. Manufacturing method according to any one of claims 1 to 10, wherein the rigid thermoplastic material and the elastomeric thermoplastic material are medical grade materials.

12. Manufacturing method according to any one of claims 1 to 11, wherein the rigid thermoplastic material and the elastomeric thermoplastic material are materials resistant to gamma sterilization.

13. Surgical navigation module (1) obtained by the manufacturing method according to any one of the preceding claims, said surgical navigation module (1) comprising: - an intermediate cap (4) made of an elastomeric thermoplastic material partially overmolding a navigation marker (2) comprising a retro-reflective lens (20); and - a shell (3) made of a rigid thermoplastic material and having at least one coupling member (36) to allow coupling of the shell (3) to a rigid navigation support (5), said shell (3) defining an interior cavity (32) inside which the intermediate cap (4) is assembled, said intermediate cap (4) thus being arranged between the shell (3) and the navigation marker (2).

14. Surgical navigation assembly (6) comprising: - a rigid navigation support (5) comprising at least one housing (51); and - at least one surgical navigation module (1) according to claim 13; wherein the shell (3) of the at least one surgical navigation module (1) is mounted in the at least one housing (51) and is held by a coupling of the at least one coupling member (36) with at least one complementary coupling member arranged on the at least one housing (51).

15. Surgical navigation assembly (6) according to claim 14, wherein the rigid navigation support (5) comprises at least two arms (50), and the at least one housing (51) comprises at least two housings (51) provided on the at least two respective arms (50), so that the at least one surgical navigation module (1) comprises at least two surgical navigation modules (1) mounted in the at least two respective housings (51).

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