Method for manufacturing a surgical navigation module

Abstract

A method for manufacturing a surgical navigation module (1), comprising the following steps: - providing a navigation marker (2) having a retroreflective lens; - producing a shell (3) by molding a rigid thermoplastic material, said shell defining an internal cavity and having at least one coupling member for coupling to a rigid navigation support; - placing the navigation marker in the internal cavity of the shell, maintaining an interstitial space between the shell and the navigation marker; and - producing an intermediate cap (4) by molding at least one elastomeric thermoplastic material in the interstitial space, such that the intermediate cap is molded inside the internal cavity and partially overmold the navigation marker, between the shell and the navigation marker. Abstract figure: Figure 4

Description

Title of the invention: Method for manufacturing a surgical navigation module technical field

[0001] The invention relates to a method for manufacturing a surgical navigation module, used in the field of surgical navigation and in particular in orthopedic surgery.

[0002] It relates more particularly to a method for manufacturing a surgical navigation module comprising a reflective navigation marker and a coupling piece shaped to be mounted on a rigid navigation support. Prior art

[0003] Surgical navigation, as is known, employs a video capture system, particularly in the infrared range, which tracks reflective navigation markers mounted on a rigid navigation support, itself attached 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 operating room, in order to follow the position and orientation in space of the surgical instrument, implant, or the relevant patient body part.

[0004] A first reflective navigation marker is in the form of a spherical marker with an opaque and reflective surface and is for single use. An opening is provided in the spherical marker, allowing it to be mounted on a stud of the rigid navigation support, which is itself reusable. This limits costs and waste to just the spherical markers. Thus, the surgeon can remove the spherical markers from their sterile pouches and then easily mount them on the studs of the rigid navigation support.

[0005] During surgery, these spherical markers can be subjected to splashes of fluid (particularly blood) and particles (such as bone debris), thus reducing their visibility and tracking by the video capture system and leading to errors in measuring their positions. Furthermore, the opaque and reflective surfaces of these spherical markers are fragile and prevent them from being wiped clean. To address this when performing operations that cause splashes, surgeons replace the spherical markers each time they become soiled (thus generating waste and additional costs) or place transparent covers over them (partially impairing their tracking by the video capture system). This attention that surgeons must pay to the cleanliness of the spherical markers therefore makes their use difficult, particularly to guide a surgical instrument (such as a cutting instrument) while projections are emitted.

[0006] To address this problem, a second type of reflective navigation marker has been developed in the form of a retroreflective lens, which is generally spherical and attached to an annular collar; the retroreflective lens has a transparent and smooth surface, usually 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 retroreflective lens is, for example, the Radix™ module from Northern Digital Inc.

[0007] However, integrating such a retroreflective lens onto a rigid navigation support presents difficulties, particularly because the retroreflective lens is not designed to withstand sterilization and is therefore single-use. It is common practice to glue the annular collar inside a designated receiving hole on the rigid navigation support, thus securing the retroreflective lens to the support. This securing method makes the rigid navigation support itself single-use, resulting in additional costs (since the support cannot be reused) and generating more waste. Furthermore, this method of gluing introduces inaccuracies in mounting the retroreflective lens onto the rigid navigation support, thereby impairing the accuracy of tracking by the video capture system. Summary of the invention

[0008] The object of the present invention relates to a method for manufacturing a surgical navigation module comprising a retroreflective lens and a coupling piece intended for coupling to a rigid navigation support, which is adapted to be able to reuse the rigid navigation support.

[0009] Another object of the invention is to improve the accuracy of the mounting of the retroreflective lens on the rigid navigation support.

[0010] To this end, the invention proposes a method for manufacturing a surgical navigation module, comprising the following steps: - provide a navigation marker with a retroreflective lens; - to produce a hull by molding a rigid thermoplastic material, said hull defining an internal cavity and having at least one coupling element to allow coupling of the hull onto a rigid navigation support; - place the navigation marker in the internal cavity of the hull, maintaining an interstitial space between the hull and the navigation marker; and - to produce an intermediate cap by molding a thermoplastic elastomer material at least in the interstitial space, so that the intermediate cap is molded inside the inner cavity and partially overmolds the navigation marker, between the hull and the navigation marker.

[0011] Thus, the invention proposes to produce the coupling piece 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 inner cavity of the shell, and the elastomeric thermoplastic material is poured between the shell and the navigation marker, which facilitates the centering of the navigation marker by eliminating the need for precise molding tooling.

[0012] Thus, the surgical navigation module, as supplied to the surgeon, takes the form of this assembly of the bi-material part overmolded around the navigation marker. A primary advantage is that the surface of the retroreflective lens is protected by the rigid casing during transport.

[0013] Furthermore, the invention proposes two distinct thermoplastic materials, because the intermediate cap and the shell do not have the same function: - The function of the intermediate cap is to receive, center, and hold the navigation marker, which, as a reminder, is a fragile part. Therefore, the elastomeric nature of its material is particularly advantageous in preventing damage to the surface of the retroreflective lens thanks to its flexibility. Furthermore, a thermoplastic elastomeric material has a sufficiently low melting point, well-suited to avoid damaging this temperature-sensitive surface of the retroreflective lens. - the function of the hull is to ensure coupling and retention on the rigid navigation support, so the rigidity of its material is particularly advantageous because such coupling requires improved mechanical strength such as can be offered by a rigid thermoplastic material that couples with a rigid support.

[0014] The fact of working with two superimposed and bi-material moldings therefore improves the retention and centering of the navigation marker on the rigid navigation support.

[0015] Advantageously, the rigid thermoplastic material is a semi-crystalline rigid thermoplastic material.

[0016] According to a characteristic, the rigid thermoplastic material is chosen from among rigid thermoplastic materials of the polypropylene or polyethylene type.

[0017] According to one possibility, the thermoplastic elastomer material is chosen from among the thermoplastic elastomer type materials of polyurethane (TPU), thermoplastic styrenic elastomer (TPS), thermoplastic elastomer copolyester (TPC), thermoplastic elastomer copolyamide (TPA), thermoplastic olefinic elastomer non-vulcanized (TPO) and thermoplastic olefinic elastomer vulcanized (TPV).

[0018] According to another possibility, the thermoplastic elastomer material has a melting temperature less than or equal to 150 °C.

[0019] Indeed, this low melting temperature is advantageous for preserving the surface of the retroreflective lens which is sensitive to temperature, so as to ensure that the contact temperature between the thermoplastic elastomer material and the retroreflective lens is less than 150°C and therefore that the coating of the retroreflective lens is not damaged during molding with the thermoplastic elastomer material.

[0020] 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 promotes the role of shock absorber during molding and during the use of the surgical navigation module.

[0021] According to another feature, at least one coupling member of the outer part is a ratcheting member.

[0022] In a particular embodiment, this coupling member comprises a protruding snap hook integral with a gripping tab.

[0023] Variants are conceivable, such as for example a screw thread type coupling element, for a screw coupling.

[0024] In a particular embodiment, the shell has a peripheral edge surrounding the inner cavity and in which notches are provided, so that the thermoplastic elastomer material fills at least partially said notches when making the intermediate cap.

[0025] This notched conformation is advantageous for a solid assembly of the intermediate cap inside the shell, and therefore for ultimately having a compact and mechanically robust module for good centering and good support.

[0026] Advantageously, the shell has a peripheral wall in which at least one orifice is provided which opens into the internal cavity, in order to introduce the thermoplastic elastomer material through this at least one orifice during the making of the intermediate cap.

[0027] Preferably, the rigid thermoplastic material and the elastomeric thermoplastic material are medical grade materials.

[0028] Advantageously, the rigid thermoplastic material and the elastomeric thermoplastic material are materials resistant to gamma sterilization.

[0029] The invention also relates to a surgical navigation module obtained by the manufacturing process as described above, this surgical navigation module including: - an intermediate cap made of a thermoplastic elastomer material partially overmolded with a navigation marker incorporating a retroreflective lens; and - a hull made of a rigid thermoplastic material and having at least one coupling element to allow coupling of the hull onto a rigid navigation support, said hull defining an internal cavity inside which the intermediate cap is assembled, said intermediate cap being thus disposed between the hull and the navigation marker.

[0030] Of course, all the characteristics relating to the manufacturing process apply to the surgical navigation module, in particular with regard to the rigid thermoplastic material and the elastomeric thermoplastic material.

[0031] The invention also relates to a surgical navigation system comprising: - a rigid navigation support including at least one housing; and - at least one surgical navigation module as described above; in which the shell of at least one surgical navigation module is mounted in at least one housing and is held by a coupling of at least one coupling member with at least one complementary coupling member disposed on at least one housing.

[0032] 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, so 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 drawings

[0033] Other features and advantages of the present invention will become apparent from the following detailed description of a non-limiting example of implementation, made with reference to the accompanying figures in which:

[0034] [Fig-1] is a schematic perspective view of a shell obtained by molding a rigid thermoplastic material;

[0035] [Fig.2] is a schematic perspective view of a placement of a navigation marker in the inner cavity of the hull of the [Fig.1], before the molding of the intermediate cap;

[0036] [Fig.3] is a schematic perspective and axial section view of a surgical navigation module obtained after molding the intermediate cap between the hull and the navigation marker;

[0037] [Fig.4] is a schematic perspective and exploded view of the surgical navigation module of [Fig.3];

[0038] [Fig.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 the [Fig.4];

[0039] [Fig.6] is a schematic view of the surgical navigation assembly of [Fig.5], in which the rigid navigation support is fixed to a surgical instrument.

[0040] [Detailed description of an embodiment of the invention]

[0041] The following description relates to a method of manufacturing a surgical navigation module 1, implementing the provision of a navigation marker 2 (visible in [Fig.2]) comprising a retro-reflective lens 20 of generally hemispherical shape and surrounded by an annular collar 21.

[0042] With reference to [Fig. 1], one step of this process consists of producing a shell 3 by molding in a mold 30 of 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.

[0043] This shell 3 has a peripheral wall 31 defining or delimiting an internal cavity 32, and this peripheral wall 31 of the shell 3 has a peripheral edge 33 surrounding the internal cavity 32 and in which notches 34 are provided; in the illustrated example, there are three notches 34. At least one orifice 35 is provided in the peripheral wall 31 to open into the internal cavity 32. The shell 3 also has a solid bottom wall 39, which forms the bottom of the internal cavity 32; the internal cavity 32 thus extending from this bottom wall 39 to the peripheral edge 33.

[0044] This hull 3 also has coupling members 36 to allow the hull 3 to be coupled to a rigid navigation support 5 described later. There are two of these coupling members 36, arranged diametrically opposite each other. Each coupling member 36 is in the form of a snap-fit ​​member comprising a projecting snap hook 37 integral with a gripping tab 38, to allow snap-fit ​​mounting onto the rigid navigation support 5.

[0045] Next, the navigation marker 2 is placed in the inner cavity 32 of the hull 3, 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 inner cavity 32.

[0046] Finally, a thermoplastic elastomer material is cast in the space space in intermediate, through the orifice 35, in order to create an intermediate cap 4 by molding this thermoplastic elastomer material, so that the intermediate cap 4 is molded inside the inner cavity and partially overmolds the navigation marker 2, between the hull 3 and the navigation marker 2. The intermediate cap 4 overmolds at least partially the annular collar 21 at the periphery, and thus provides the assembly of the navigation marker 2 with the hull 3. Thus, the navigation marker 2 is secured to a coupling piece which is a bi-material piece formed from the hull 3 and the intermediate cap 4.

[0047] The thermoplastic elastomer material is selected from materials of the type thermoplastic polyurethane elastomer (TPU), thermoplastic styrene elastomer (TPS), thermoplastic copolyester elastomer (TPC), thermoplastic copolyamide elastomer (TPA), thermoplastic olefinic non-vulcanized elastomer (TPO) and thermoplastic olefinic vulcanized elastomer (TPV); and this thermoplastic elastomer material has a melting temperature less than or equal to 150 °C, and for example less than or equal to 120 °C.

[0048] 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.

[0049] At the end of this manufacturing process, the surgical navigation module 1 obtained comprises: - navigation marker 2; - the intermediate cap 4, partially overmolding the navigation marker and made of thermoplastic elastomer material; and - the hull 3 made of rigid thermoplastic material and defining the inner cavity 32 inside which the intermediate cap 4 is assembled, this intermediate cap 4 being thus arranged between the hull 3 and the navigation marker 2.

[0050] Also, as explained, the navigation marker 2 is overmolded by a bi-material part formed from the hull 3 and the intermediate cap 4.

[0051] With reference to Figures 5 and 6, a surgical navigation assembly 6 comprises the rigid navigation support 5 which may include several arms 50 (four in the illustrated example), where each of the arms 50 has a free termination provided with a housing 51 suitable for receiving a surgical navigation module 1. The surgical navigation assembly 6 therefore also includes as many surgical navigation modules 1 as there are housings 51 in the rigid navigation support 5.

[0052] In each housing 51, the shell 3 is mounted inside the housing 51 and is held in place by snap-fitting, by coupling these coupling members 36 with complementary coupling members arranged on the Apartment 51.

[0053] As seen in [Fig.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 operating room, in order to follow 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 follow the position and orientation in space of that implant or that part of the patient's body concerned.

Claims

Demands

1. A method for manufacturing a surgical navigation module (1), comprising the following steps: - providing a navigation marker (2) having a retroreflective lens (20); - producing a shell (3) by molding a rigid thermoplastic material, said shell (3) defining an internal cavity (32) and having at least one coupling member (36) to allow coupling of the shell (3) onto a rigid navigation support (5); - placing the navigation marker (2) in the internal cavity (32) of the shell (3) maintaining an interstitial space between the shell (3) and the navigation marker (2); and - producing an intermediate cap (4) by molding an elastomeric thermoplastic material at least in the interstitial space, such that the intermediate cap (4) is molded inside the internal cavity (32) and partially overmold 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. A manufacturing method according to claim 2, wherein the rigid thermoplastic material is selected from rigid thermoplastic materials of the polypropylene or polyethylene type.

4. A manufacturing method according to any one of claims 1 to 3, wherein the thermoplastic elastomer material is selected from materials of the type thermoplastic polyurethane elastomer (TPU), thermoplastic styrene elastomer (TPS), thermoplastic copolyester elastomer (TPC), thermoplastic copolyamide elastomer (TPA), thermoplastic unvulcanized olefinic elastomer (TPO) and thermoplastic vulcanized olefinic elastomer (TPV).

5. A manufacturing method according to any one of claims 1 to 4, wherein the thermoplastic elastomer material has a melting temperature less than or equal to 150 °C.

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

7. A manufacturing method according to any one of claims 1 to 6, in which at least one coupling member (36) of the hull (3) is a ratcheting member.

8. A manufacturing method according to claim 7, wherein the coupling member comprises a protruding snap hook (37) integral with a gripping tab (38).

9. A manufacturing method according to any one of claims 1 to 8, wherein the shell (3) has a peripheral edge (33) surrounding the inner cavity (32) and in which notches (34) are provided, such that the thermoplastic elastomer material at least partially fills said notches (34) during the making of the intermediate cap.

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

11. A 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. A 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 process according to any one of the preceding claims, said surgical navigation module (1) comprising: - an intermediate cap (4) made of a thermoplastic elastomer material partially overmolding a navigation marker (2) having a retroreflective 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 internal cavity (32) within which the intermediate cap (4) is assembled, said intermediate cap (4) being thus disposed 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 at least one surgical navigation module (1) is mounted in at least one housing (51) and is held by a coupling of at least one coupling member (36) with at least one complementary coupling member disposed on 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 respective at least two arms (50), so that the at least one surgical navigation module (1) comprises at least two surgical navigation modules (1) mounted in the respective at least two housings (51).

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