Improved motorized intramedullary nail for bone lengthening or bone movement

Abstract

An electrically operated intramedullary nail (1) for bone lengthening or bone movement, comprising: a first tubular portion (2) extending in the main axial direction of the intramedullary nail (1); a second rod-shaped portion (3) sliding in an extendable and retractable manner along its own axial direction inside the first tubular portion (2); an electrically operated electromechanical means (4) for driving the rod-shaped portion (3), the electromechanical means (4) being inserted inside the first tubular portion (2) and having electrical terminals (48, 49) accessible through the proximal portion of the intramedullary nail (1); a covering element (9) for covering and protecting the electrical terminals (48, 49) through which the respective ends (24, 26) of the electrical conductors (18, 19) pass; and a spacer (8) supporting the covering element (9) at a predetermined distance from the electrical terminals.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the general technical field of orthopedics. More specifically, the present disclosure relates to a motor-driven intramedullary nail for bone lengthening or bone transport of long bones.

[0002] For example, intramedullary nails make it possible to perform limb lengthening without using an external fixator. Furthermore, it may also be used for optimal movement and alignment of bone segments, or for desired arthrodesis for post-traumatic treatment or therapeutic procedures. BACKGROUND ART

[0003] In this particular technical field, a type of motor-driven intramedullary nail that enables long limb lengthening is already known. For example, this type of system called Fitbone® has been known for many years and was originally developed by the world-renowned expert Professor Rainer Baumgart.

[0004] This system is primarily intended for lengthening of one limb that requires intervention due to trauma or congenital malformation, or lengthening of a limb that has not developed sufficient length.

[0005] Furthermore, with appropriate preoperative planning, intramedullary nails of the type indicated above make it possible to provide axial and torsional corrections as part of limb lengthening.

[0006] These intramedullary nails are composed of a first portion, which may be defined as a fixed side, and a second portion that telescopically slides and extends inside the first fixed portion. Electromechanical drive means are provided for controlling the extension of the sliding portion by a control signal applied from the outside.

[0007] For example, the prior art document, International Publication No. 2021 / 032823, relates to an intramedullary nail for extending a long bone, comprising a first tubular body and a second tubular body inserted into the first tubular body and sliding within it, and connected by gears to a small electric motor that enables axial translation relative to the first tubular body.

[0008] While these known bone lengthening nails have advantages in some respects, they also have several structural drawbacks. As will become apparent later herein, these drawbacks are particularly pronounced when it is necessary to fabricate intramedullary nails of the femoral trochanter with an angled proximal portion.

[0009] Firstly, the small electric motor housed inside the intramedullary nail needs to be powered by electric current, and the conductive cable that carries the corresponding voltage must be placed proximal to the intramedullary nail, which imposes a structural burden.

[0010] Currently, a known solution is to provide a single channel in the proximal part of the intramedullary nail, as shown in Figure 1, to house both conductors on the same side.

[0011] However, the bulkiness of this channel can lead to misalignment of the proximal foramen for inclined trochanteric screws. However, trochanteric screws are larger than the stabilizing or fixing bone screws used for straight intramedullary nails. Furthermore, trochanteric screws need to be centrally positioned in the intramedullary nail so that they can be inserted into the center of the trochanteric neck of the right or left limb.

[0012] Therefore, the trochanter screw hole cannot be offset. Furthermore, the size of the trochanter screw cannot maintain a single groove for passing the control wire.

[0013] In fact, if the hole for the trochanteric screw is misaligned laterally, it weakens the proximal structure of the intramedullary nail, resulting in one side being weaker than the other. Consequently, when implanting a trochanteric intramedullary nail, the "weaker side" must always face forward, effectively forcing surgeons to prepare separate nails for the right and left sides, or to prepare a more complex set of instruments, in either case limiting the surgeon's surgical freedom.

[0014] Prior art electric intramedullary nails are described, for example, in French Patent Application Publication No. 2847153 and U.S. Patent No. 6,245,075. [Overview of the project] [Problems that the invention aims to solve]

[0015] The technical problem underlying this disclosure is to provide a novel structure for an electrically operated intramedullary nail for the trochanter that has structural and functional features capable of overcoming the shortcomings mentioned above, and furthermore, to enable faster assembly of the electromechanical components of this electrically operated intramedullary nail. [Means for solving the problem]

[0016] The fundamental idea of ​​the present invention is to separate two conductors connected to an electric motor of an electric drive means for driving the movable part of an intramedullary nail, to pass them substantially along the inner wall of the proximal part of the intramedullary nail on both sides of the transverse hole of the trochanteric screw, and to provide a covering element for covering the motor terminals, thereby insulating, protecting, and separating the ends of the conductors connected to the motor terminals and passing through such covering element.

[0017] According to the idea of ​​this solution, the present disclosure relates to an improved motorized intramedullary nail for bone lengthening or bone movement as described in claim 1.

[0018] More specifically, the intramedullary nail of this disclosure is for use in the trochanter and has a proximal portion in which an inclined transverse hole for a trochanteric screw is formed in the center.

[0019] Further, two separate grooves or two tubular housings are provided adjacent to the proximal inner wall of the intramedullary nail, on both sides of a transverse hole for a trochanteric screw formed in the center of the proximal portion of the intramedullary nail, for receiving the corresponding electrical conductors respectively.

[0020] It should be noted that the spacer is a separation partition that separates the electrical terminals, functions as a support wall for supporting the covered portion of the terminals, and a through hole is provided in the covered portion at the position of the electrical terminals for allowing the respective connection ends of the conductors to pass therethrough.

[0021] The spacer and the covering element functioning as the separation partition are made of an electrically insulating material.

[0022] The motorized electromechanical means for driving the rod-shaped portion is accommodated in a cartridge or capsule having a bottom wall or a distal wall from which the electrical terminals protrude, and the separation partition rises from the bottom wall and supports the covering element while being spaced apart from the bottom wall by a predetermined distance.

[0023] The capsule, the spacer and the covering element may be integrally formed, and may be made of a synthetic plastic material capable of exhibiting an electrical insulation function.

[0024] It should also be noted that each end of the electrical conductor connected to the electrical terminal passes through a through hole provided in the covering element at the position of the electrical terminal.

[0025] The features and advantages of the motorized intramedullary nail according to the present disclosure will become apparent from the following description of embodiments, given by way of illustrative and non-limiting example, with reference to the accompanying drawings. [Brief Description of the Drawings]

[0026] [Figure 1] It is a schematic front view showing the proximal portion of a known type of intramedullary nail. [Figure 2] It is a schematic perspective view showing the trochanteric intramedullary nail according to the present disclosure. [Figure 3A] It is a schematic front perspective view showing details of the proximal portion of the intramedullary nail of FIG. 2. [Figure 3B] It is a schematic perspective view seen from the side, showing details of the same proximal portion as in FIG. 3A. [Figure 4] It is a schematic view showing the process of assembling the constituent elements of the intramedullary nail of FIG. 2. [Figure 5] It is a schematic perspective view showing details of the proximal portion of the intramedullary nail of FIG. 2 after the step of inserting the constituent elements of FIG. 4. [Figure 6] It is a schematic partial perspective view showing the step of connecting the gear motor to a power cable. [Figure 7] It is an enlarged schematic perspective view showing the gear motor with a protective cover incorporated into the intramedullary nail of FIG. 2. [Figure 8] It is an enlarged view showing details of the constituent elements of FIG. 7. [Figure 9] It is a schematic perspective view showing the insertion of the constituent elements of FIG. 7 through the proximal portion of the intramedullary nail of the present disclosure. [Figure 10] It is a schematic perspective view showing the covered gear motor of FIG. 7 after insertion is completed. [Mode for Carrying Out the Invention]

[0027] With reference to these drawings, particularly the example of FIG. 2, reference numeral 1 generally and schematically indicates a preferred embodiment of the improved intramedullary nail 1 according to the present disclosure for performing bone lengthening of long bones as needed. For these purposes, the intramedullary nail 1 is a substantially extendable intramedullary nail, which is extendable by actuating electromechanical drive means incorporated inside the intramedullary nail, as will be described later.

[0028] The intramedullary nail 1 is for the trochanteric region in that it is particularly suitable for use in the femur, and may have a proximal portion slightly inclined with respect to the main longitudinal axis of the intramedullary nail itself.

[0029] As described later in this specification, the intramedullary nail 1 may be coupled to an electromechanical actuator or gear motor equipped with a signal receiver, which may be connected via a bipolar power line to receive power. External control electronics and a transmitter may also be provided. Commands required for the bone lengthening process are transmitted via the transmitter to a subcutaneously implanted receiver, so there is no contact between the implanted intramedullary nail 1 and the body surface (skin). Power is supplied by an electrical connection via a bipolar conductor.

[0030] The intramedullary nail 1 actually comprises a first tubular portion 2 which can be defined as the fixation side, and this first tubular portion 2 extends in the axial direction of the intramedullary nail itself. Preferably, this tubular portion may have a circular cross-section and comprises a proximal portion 10 that is slightly inclined with respect to the main longitudinal axis of the intramedullary nail 1, as described above.

[0031] In this specification, the terms “axial” and “radial” should be intended to refer to the longitudinal axis of the intramedullary nail 1, that is, the axis extending along the main length of the intramedullary nail 1, or the axis extending in the direction in which the spatial extension of the intramedullary nail 1 is maximized.

[0032] More specifically, the axial direction refers to a direction that coincides with or is parallel to the longitudinal axis of the intramedullary nail 1, while the radial direction refers to a direction perpendicular to the longitudinal axis.

[0033] However, it should be noted that the longitudinal axis of the intramedullary nail 1 has a slightly inclined portion. For example, the proximal portion 10 is slightly curved, and this curvature facilitates the precise positioning of the lateral trochanteric screw that needs to penetrate the femur, which has a trochanteric neck that is inclined at approximately 30° to the medial and lateral surfaces.

[0034] Typically, the tubular portion 2 is made from a metal or metal alloy, particularly a biocompatible metal or metal alloy. On the other hand, the other elements of the intramedullary nail 1 are made from synthetic plastic materials such as epoxy resin, silicone, or thermoplastic resin.

[0035] The tubular portion 2 comprises a hollow cylindrical shell, and a second rod-shaped portion 3, which may also be tubular, is slidably and extendably mounted inside it. This rod-shaped portion 3 may also consist of multiple interconnected sections.

[0036] The rod-shaped portion 3 has a first hole 11 at its distal end that extends laterally with respect to the axial direction and is configured to accommodate a bone screw. Alternatively, the hole 11 may be threaded to accommodate a guide screw for preventing the rod-shaped portion 3 from rotating relative to the tubular portion 2.

[0037] A second hole 12 is also provided, which extends laterally with respect to the axial direction. Depending on the fixing needs of the rod-shaped portion 3, this second hole 12 may be parallel to the first hole 11 or may be inclined with respect to the first hole 11.

[0038] Advantageously, an electrically powered and power-supplied electromechanical means 4 is provided to translate the rod-shaped portion 3 within the tubular portion 2.

[0039] In essence, the intramedullary nail 1 is equipped with an electric means 4 configured to move the rod-shaped portion 3 axially within the tubular portion 2 with millimeter precision. Preferably, the electric mechanical means 4 comprises an electric motor or gear motor 41 and a screw transmission mechanism 42.

[0040] The electric motor 41 is configured to drive the screw transmission mechanism 42, which is coupled to the rod-shaped portion 3 and acts on the rod-shaped portion 3, causing the rod-shaped portion 3 to move reversibly.

[0041] The electric motor 4 is housed in a protective cartridge or capsule 15, which also houses the electronic control means (not shown) for the motor 41, and is inserted into the proximal portion 10 of the intramedullary nail 1 after the rod portion 3 is inserted. The cartridge 15 has a bottom wall or proximal wall 7, and electrical terminals 48 and 49 that connect to the motor 41 protrude from the bottom wall or proximal wall 7.

[0042] Generally, after implantation, the intramedullary nail 1 is actuated by an external controller that transmits electrical impulses subcutaneously via an antenna associated with electronic control means. The electrical energy is transmitted to the electric gear motor 41 of the intramedullary nail 1 via a bipolar power cable 33 that protrudes to the outside through the proximal portion 10 of the intramedullary nail 1. The electric motor 41, preferably through a reduction system, brings rotational motion to a worm screw 42 coupled to the rod portion 3, causing the rod portion 3 to reversibly displace.

[0043] The electric motor 41 is housed within the capsule 15, with its power terminals 48, 49 protruding outside the capsule 15 through the base wall or bottom wall 7 on the side facing the bipolar power cable 33. The bipolar cable 33 naturally comprises two electrical conductors 18, 19, each having ends 24, 26 for connecting to the terminals 48, 49.

[0044] Between these terminals 48 and terminal 49, a separation support partition wall 8 for the covering element 9 is provided, which also serves to protect the terminals 48 and 49 themselves. The partition wall 8 also acts as a spacer for supporting the covering element 9, keeping the covering element 9 separated from the base wall 7 of the capsule 15 by a predetermined distance.

[0045] If we consider the proximal portion of the capsule 15 as an independent structure, the base 7 from which terminals 48 and 49 protrude is covered by a roof formed by a covering element 9 and is supported in the center by a partition wall 8 that similarly separates the two terminals 48 and 49 from each other, as if it were a separating partition wall. The partition wall 8 has lateral dimensions that occupy the same lateral space as the capsule 15, and the substantially circular covering element 9 has the same overall dimensions as the bottom wall 7 of the capsule 15.

[0046] The separation support partition wall 8 and the covering element 9 are made from an electrical insulating material.

[0047] The capsule 15 is also made of insulating material, and the rear proximal wall 7 of the capsule 15 may be a single component made of the same insulating material as the partition wall 8 and the covering element 9.

[0048] Furthermore, the components 7, 8, and 9 of the capsule 15 referred to herein may also be integral with each other and may be configured as a single part. This ensures that when the capsule 15 housing the motor means 4 is inserted into the proximal portion 10 of the intramedullary nail 1, the terminals 48 and 49 protrude into separate protective spaces.

[0049] As clearly shown in Figure 6, when the capsule 15 of the motorized means 4 is inserted into the proximal portion 10 of the intramedullary nail 1, the two terminals 48 and 49 are positioned between the inner walls of the proximal portion 10 of the intramedullary nail 1 and are substantially confined within the space defined by the walls 7 and 9 and the partition wall 8 (which actually occupies the inner diameter of the proximal portion 10 of the intramedullary nail 1).

[0050] The two terminals 48 and 49 are accessible at the terminal-side ends 24 and 26 that connect the bipolar cable 33, and these terminal-side ends 24 and 26 are covered by corresponding electrical insulating gaskets 31 and 32, respectively. Each of the two ends passes through the respective through holes 28 and 29, which are provided with a thickness of the covering element 9 corresponding to the positions of the terminals 48 and 49.

[0051] In this way, the respective ends 24 and 26 of the conductors 18 and 19 of the bipolar conductor 33 can be fixed to the corresponding terminals 48 and 49, respectively, during the assembly process of the capsule 15 that houses the motor means 4.

[0052] Advantageously, the conductors 18 and 19 are provided in corresponding longitudinal grooves or near the inner wall 20, and are housed in tubular housings 16 and 17 provided in a portion of the proximal portion 10 of the intramedullary nail 1.

[0053] These longitudinal grooves 16, 17 may be provided in the inner wall 20 itself, or they may be formed as housing sheaths for the conductors 18, 19. Alternatively, the actual tubular housing is formed close to the longitudinal inner wall 20 of the proximal portion of the intramedullary nail 1.

[0054] Therefore, conductors 18 and 19 pass substantially along such an inner wall 20 and on either side of a central inclined proximal transverse hole 14, which is typically provided in these trochanteric intramedullary nails to receive a trochanteric screw for fixation to the femoral neck. This solution has the great advantage of making it possible to obtain a versatile trochanteric intramedullary nail that can be used on both the left and right sides. In fact, due to the anatomical structure of the femur, in order to realize a single intramedullary nail common to both the right and left sides, the trochanteric screw must pass through the center of the intramedullary nail.

[0055] Each groove, or alternatively, each of the two tubular housings 16, 17, is precisely positioned in close proximity to the inner wall 20 of the proximal portion 10 of the intramedullary nail 1, to accommodate the respective electrical conductors 18, 19 of the connector 33.

[0056] In this way, the bulkiness caused by the passage of each conductor 18, 19 is reduced to an extremely small degree, and does not substantially prevent the provision of a central transverse hole 14 located proximal to the intramedullary nail 1 for the passage of the lateral trochanter screw.

[0057] In this way, when the transverse hole 14 for the trochanteric screw passes through the center of the proximal portion 10, it is possible to fabricate an intramedullary trochanteric nail with a relatively small diameter.

[0058] The aforementioned capsule 15 may be assembled before being inserted through the proximal portion 10 of the intramedullary nail 1. The capsule 15 as a whole represents individually handleable components and can be defined as a motor wire connector assembled at the proximal end of the intramedullary nail 1.

[0059] Such components allow for easier assembly of the elements constituting the electric electromechanical means 4, thereby avoiding axial positioning errors of such elements, while protecting the welding area between the ends 24, 26 of the cables 18, 19 and the terminals 48, 49 of the electric means.

[0060] Figures 9 and 10 illustrate the operational steps that enable rapid assembly of the intramedullary nail of this disclosure. This rapid assembly is supported by the fact that the electrically operated electromechanical means 4 is pre-assembled and connected to the connector 33 before being inserted into the intramedullary nail. Since all components are designed with minimal clearance, the assembly is unique and no assembly errors can occur with respect to the axial position of the various parts.

[0061] Furthermore, the interconnection between the electric motor terminals and the main power cable is achieved in a simple, safe, and reliable manner.

[0062] All components are easy to manufacture, especially at low cost.

Claims

1. A motorized intramedullary nail (1) for bone lengthening or bone movement, - The first tubular portion (2) extending in the main axial direction of the intramedullary nail (1), - A second rod-shaped portion (3) slides inside the first tubular portion (2) in a manner that allows it to expand and contract along the axial direction, - An electric electromechanical means (4) for driving the rod-shaped portion (3), the electric electromechanical means (4) being inserted into the first tubular portion (2) and having electrical terminals (48, 49) accessible via the proximal portion of the intramedullary nail (1), - Electrical conductors (18, 19) connected to the aforementioned electrical terminals (48, 49), - Covering elements (9) for covering and protecting the electrical terminals (48, 49) through which each end (24, 26) of the electrical conductors (18, 19) passes, - A spacer (8) that supports the covering element (9) at a predetermined distance from the electrical terminal, Equipped with, The spacer (8) is incompressible, The intramedullary nail (1) is characterized in that the spacer (8) and the covering element (9) are made of an electrical insulating material.

2. The intramedullary nail (1) according to claim 1, wherein the intramedullary nail (1) is for use in the trochanter and has a proximal portion (10) in which an inclined transverse hole (14) for a trochanter screw is formed in the center.

3. The intramedullary nail (1) according to claim 1, wherein two separate grooves or two tubular housings (16, 17) are provided adjacent to the proximal inner wall (20) of the intramedullary nail for housing corresponding electrical conductors (18, 19), respectively.

4. The intramedullary nail (1) according to claim 3, wherein the grooves or tubular housings (16, 17) are arranged on both sides of the proximal transverse bore (14) at positions facing each other in the diametrical direction.

5. The intramedullary nail (1) according to claim 1, wherein the spacer (8) is a separation partition wall separating the electrical terminals (48, 49), and is configured as a support wall supporting the covering element (9) of the electrical terminals, and through holes (28, 29) are provided in the covering element (9) at the positions of the electrical terminals (48, 49) to allow the respective connection ends (24, 26) of the electrical conductors (18, 19) to pass through.

6. The intramedullary nail (1) according to claim 1, wherein the electric electromechanical means (4) for driving the rod-shaped portion (3) is housed in a cartridge (15) or capsule having a bottom wall or distal wall (7) from which the electrical terminals (48, 49) protrude, and the spacer (8) rises from the bottom wall (7) and supports the covering element (9) at a predetermined distance from the bottom wall (7).

7. The intramedullary nail (1) according to claim 6, wherein the capsule (15), the spacer (8), and the covering element (9) are integrally formed and made of a synthetic plastic material capable of providing electrical insulation.

8. The intramedullary nail (1) according to claim 1, wherein the electrical conductors (18, 19) connected to the electrical terminals (48, 49) substantially follow the inner wall (20) of the proximal part of the intramedullary nail (1) and pass on both sides of the proximal transverse hole (14) for the trochanteric bone screw.

9. The intramedullary nail (1) according to claim 1, wherein each end (24, 26) of the electrical conductor (18, 19) connected to the electrical terminals (48, 49) passes through the respective through holes (28, 29) provided in the covering element (9) at the positions of the electrical terminals (48, 49).

Images