Powered improved intramedullary nail for bone lengthening or transport

Abstract

An intramedullary nail (1) for bone lengthening or transport, comprising: a first tubular portion (2) extending along the main axis of the nail (1); a second rod-shaped portion (3) sliding in itself and axially within the first tubular portion (2); an electric motor device (4) for driving the rod-shaped portion (3), inserted within the first tubular portion (2) and comprising electric terminals (48, 49) accessible through a proximal portion of the nail (1); a covering element (9) for covering and protecting the electric terminals (48, 49), through which respective ends (24, 26) of electric wires (18, 19) pass; a spacer (8) for supporting the covering element (9) at a preset distance from the electric terminals.

Description

Technical Field

[0001] This disclosure relates to the general technical field of orthopedics. More specifically, it relates to an electrically powered intramedullary nail for bone lengthening or transport of long bones.

[0002] For example, intramedullary nails allow for limb lengthening without the use of external fixators; in addition, they can be used for optimal transport and alignment of bone segments, and even for joint locking required for post-traumatic or therapeutic purposes. Background Technology

[0003] In this particular technical field, a type of electrically powered intramedullary nail is known that allows for the lengthening of long limbs. For example, one called Fitbone... TM Such systems have been known for many years and were originally developed by the world-renowned expert Professor Rainer Baumgart.

[0004] This system is primarily used for unilateral limb lengthening that requires intervention due to trauma or congenital malformation, or for limb lengthening in cases where the limb is not fully developed.

[0005] Furthermore, with proper preoperative planning, the previously described type of intramedullary nail allows for axial and torsional correction during limb lengthening.

[0006] These nails are configured with a first portion that can be defined as a fixed part and a second portion that can slide and extend telescopically into the first fixed part; an electromechanical drive is provided to control the extension of the sliding part by an externally applied control signal.

[0007] For example, prior art document WO2021032823 (A1) relates to an intramedullary nail for lengthening long bones, which includes a first tubular body and a second tubular body inserted into and sliding therein, and connected by gears to a small electric motor, allowing it to be axially translated relative to the first tubular body.

[0008] Despite their advantages in several aspects, these known bone lengthening nails have some structural defects, especially when it is necessary to manufacture intertrochanteric nails of the femur with angular proximal portions, as will be clarified below.

[0009] First, the small electric motor nested inside the nail must be powered by current, and the wires carrying the corresponding voltage are a necessary component that must be provided near the end of the nail.

[0010] Currently, known solutions provide a single channel obtained at the proximal end of the nail to accommodate two wires on the same side, as shown in Figure 1.

[0011] However, the volume of this channel can cause misalignment of the proximal hole used for tilting trochanter screws. Trochanter screws are larger than the stabilizing or fixing bone screws used in straight screws; furthermore, they must be positioned in the center of the screw so that they can be inserted into the center of the trochanter neck of the left or right limb.

[0012] Therefore, the rotor screw holes must not be offset. Furthermore, the size of the rotor screws does not allow for a single groove to pass through the control line.

[0013] In fact, the transverse misalignment holes used for rotor screws weaken the proximal structure of the screw, which makes one side more vulnerable than the other and forces the implantation of intramedullary rotor screws to ensure that the “weak side” always faces the anterior plane. This actually forces surgeons to use right-side and left-side screws, or more complex instrument sets, which in either case limits the surgeon’s maneuverability.

[0014] For example, documents FR 2 847 153 A1 and US 6,245,075 B1 illustrate electric nails according to the prior art.

[0015] The technical problem upon which this disclosure is based is to provide a novel structure for an intramedullary electromechanical rotor nail that has structural and functional features that overcome the previously highlighted disadvantages, and also allows for faster assembly of the nail's electromechanical components. Summary of the Invention

[0016] The solution concept upon which this invention is based is to separate the two wires of the electric motor connected to the electric drive device for driving the active part of the nail, so that they pass through substantially against the inner wall of the proximal portion of the nail, located on opposite sides of the transverse hole of the rotor screw, and to provide a cover element for covering the motor terminal, which insulates, protects and separates the ends of the wires connected to the motor terminal and passing through the cover element.

[0017] Based on this solution concept, this disclosure relates to an electrically powered modified intramedullary nail for bone lengthening or transport as described in claim 1.

[0018] More specifically, the nail of this disclosure is rotor type, with its proximal portion having a centrally located, laterally inclined hole for a centrally located rotor screw.

[0019] In addition, two corresponding grooves or two tubular housings are provided to accommodate the corresponding wires in the opposite portion near the proximal inner wall of the nail and relative to the transverse holes for the rotor screw obtained at the center of the proximal portion of the nail as described above.

[0020] It is worth noting that the aforementioned spacer is a partition plate that separates electrical terminals. It acts as a support wall for the covering portion that supports the terminals. A through hole is provided in the covering portion at the electrical terminals for the passage of the corresponding connection end of the wire.

[0021] The spacers and covering elements that act as partitions are made of electrically insulating materials.

[0022] The electric motor for driving the rod-shaped portion is contained in a housing or capsule having a bottom or distal wall from which electrical terminals extend, and a partition rising from the bottom wall to support the covering element, maintaining a predetermined spacing relationship between it and the bottom wall.

[0023] The capsule, spacer, and cover element can be integrally molded and made of synthetic plastic material that can provide electrical insulation.

[0024] It is also worth noting that each end of the wire connected to the electrical terminal passes through a through-hole obtained at the electrical terminal in the covering element.

[0025] The features and advantages of the electrically powered intramedullary nail according to this disclosure will become clear from the following description of indicative and non-limiting embodiments with reference to the accompanying drawings. Attached Figure Description

[0026] Figure 1 shows a front view of the proximal portion of a known type of intramedullary nail;

[0027] Figure 2 A three-dimensional schematic diagram of a rotor intramedullary nail according to the present disclosure is shown;

[0028] Figure 3A Show Figure 2 A front-view transparent schematic diagram showing details of the proximal portion of the nail;

[0029] Figure 3B Showing with Figure 3A A side-view transparent diagram showing the same proximal details;

[0030] Figure 4 Show Figure 2 A schematic diagram of the assembly steps for the nail components;

[0031] Figure 5 Shown at completion Figure 4 After the component insertion step, Figure 2 A transparent schematic diagram showing details of the proximal portion of the nail;

[0032] Figure 6 A partially transparent schematic diagram showing the connection steps of connecting the gear motor to the power cord;

[0033] Figure 7 Show Figure 2 A magnified three-dimensional diagram of a gear motor with a protective cover contained in a nail;

[0034] Figure 8 Show Figure 7Enlarged view of the components in detail;

[0035] Figure 9 Show Figure 7 A three-dimensional schematic diagram of the component inserted through the proximal portion of the nail of this disclosure;

[0036] Figure 10 Showing the result after insertion Figure 7 A three-dimensional schematic diagram of a covered gear motor. Detailed Implementation

[0037] Refer to these accompanying figures, especially Figure 2 As an example, reference numeral 1 schematically illustrates a preferred embodiment of an improved intramedullary nail 1 according to the present disclosure for performing bone lengthening of long bones as needed. For this purpose, the nail 1 is essentially an extendable nail and, as will be seen below, can be extended by activating an electromechanical drive mechanism inserted into the nail itself.

[0038] Screw 1 is a rotor type, which means it is particularly suitable for the femur and can have a proximal portion that is slightly inclined relative to the main longitudinal axis of the screw itself.

[0039] As described below, the intramedullary nail 1 can be coupled to an electromechanical actuator or geared motor equipped with a signal receiver and connected via a bipolar power line to receive power. External control electronics and a transmitter may also be provided. Commands required for the nail extension process are transmitted via the transmitter to the receiver implanted under the skin, thus there is no contact between the implanted intramedullary nail 1 and the body surface (skin). Power is supplied via an electrical connection through bipolar wires.

[0040] The intramedullary nail 1 actually includes a first tubular portion 2, which can be defined as a fixation portion, extending along the axial direction of the nail itself. Preferably, this portion may have a circular cross-section and includes a proximal portion 10, as previously described, which is slightly inclined relative to the main longitudinal axis of the nail 1.

[0041] The terms “axial” and “radial” must be understood here in relation to the longitudinal axis of the intramedullary nail 1; that is, the axis extending along the greater length of the intramedullary nail 1, or in any case, the axis along the direction of the maximum spatial extension of the intramedullary nail 1.

[0042] More specifically, axial direction refers to the direction aligned with or parallel to the longitudinal axis of the intramedullary nail 1; while radial direction refers to the direction perpendicular to the longitudinal axis.

[0043] However, it should be noted that the longitudinal axis of the intramedullary nail 1 has a slightly inclined portion; for example, the slight curvature of the proximal portion 10 helps in the correct positioning of the transverse trochanter screws, which must penetrate the femur, while the trochanter neck is inclined at approximately 30° relative to the mid-lateral plane.

[0044] Typically, the tubular portion 2 is made of metal or a metal alloy, particularly a biocompatible metal or a biocompatible metal alloy. Other components of the intramedullary nail 1 are made of synthetic plastic materials, such as epoxy resin, silicone resin, or thermoplastic resin.

[0045] The tubular portion 2 includes a hollow cylindrical shell, in which a second rod-shaped portion 3 is slidably and telescopically mounted, the rod-shaped portion itself also being tubular. The rod-shaped portion 3 can also be made of multiple interconnected stages.

[0046] The rod-shaped portion 3 includes a first hole 11 at its distal end, which is transverse to the axial direction and configured to receive a bone screw. Alternatively, the hole 11 may be threaded to receive a guide screw, preventing rotation of the rod-shaped portion 3 relative to the tubular portion 2.

[0047] A second hole 12 is also provided, which is transverse to the axial direction and can be parallel to or inclined to the first hole 11, depending on the need for fixing the rod-shaped portion 3.

[0048] Advantageously, an electric and electrically driven electromechanical device 4 is provided for translating the drive rod-shaped portion 3 within the tubular portion 2.

[0049] Essentially, the intramedullary nail 1 includes an electric device 4 configured to axially move the rod-shaped portion 3 within the tubular portion 2 with millimeter-level precision. Preferably, the device 4 includes an electric motor or geared motor 41 and a lead screw drive 42.

[0050] The electric motor 41 is adapted to drive the lead screw drive 42, which in turn couples with and acts on the rod-shaped portion 3 to achieve its reversible movement.

[0051] The electric device 4 is housed within a protective housing or capsule 15, which also contains an electronic control unit (not shown) for the electric motor 41 and inserts the proximal portion 10 of the nail 1 after inserting the rod-shaped portion 3. The capsule 15 has a bottom or proximal wall 7 from which electrical terminals 48, 49 connected to the electric motor 41 protrude.

[0052] Generally, once implanted, the intramedullary nail 1 is powered by an external controller associated with an electronic control device via an antenna, which transmits electrical pulses to the subcutaneous tissue. Electrical energy is transmitted to the electric geared motor 41 of the intramedullary nail 1 via a bipolar power line 33 exposed outside the proximal portion 10 of the nail 1. The electric motor 41, preferably via a reduction gear system, provides rotational motion to a worm gear 42, which is coupled to a rod-shaped portion 3 to achieve reversible displacement of the rod-shaped portion 3.

[0053] An electric motor 41 is housed in a capsule 15, with its power terminals 48, 49 extending outside the capsule 15 via a base or bottom wall 7 facing the bipolar power line 33. The bipolar power line 33 apparently comprises two wires 18, 19 with corresponding ends 24, 26 for connection to the terminals 48, 49.

[0054] A separation and support partition 8 is provided between these terminals 48 and 49 for covering element 9, which also functions to protect terminals 48 and 49 themselves. The partition 8 also serves as a spacer for supporting covering element 9, maintaining a predetermined spacing relationship with the base wall 7 of capsule 15.

[0055] Considering the proximal portion of capsule 15 as independent, we can say that the base 7 from which terminals 48 and 49 protrude is covered by a top cover represented by a covering element 9 and centrally supported by a partition 8 that also separates the two terminals 48, 49 from each other, much like a dividing partition. The partition 8 has a lateral dimension occupying the same lateral space as capsule 15, while the generally circular covering element 9 has the same overall dimension as the bottom wall 7 of capsule 15.

[0056] The partition and support plate 8 and the covering element 9 are made of electrically insulating material.

[0057] Even capsule 15 is made of insulating material, and the rear and proximal walls 7 of capsule 15 can be integrally molded with the same insulating material as septum 8 and cover element 9.

[0058] Furthermore, components 7, 8, and 9 of capsule 15 as described herein can also be integrally molded together and made into a single unit, so that once capsule 15 containing electric device 4 is inserted into the proximal portion 10 of nail 1, terminals 48 and 49 are located in their respective independent protective spaces.

[0059] like Figure 6 As shown, when the capsule 15 of the electric device 4 is inserted into the proximal portion 10 of the nail 1, the two terminals 48 and 49 are actually enclosed between the inner walls of the proximal portion 10 of the nail 1 and surrounded by the defined space and the partition 8, which actually occupies the inner diameter of the proximal portion 10 of the nail 1, walls 7 and 9.

[0060] Two terminals 48 and 49 are accessible at the terminal ends 24 and 26 of the bipolar wire 33, which are covered by corresponding electrically insulating washers 31 and 32. Each of the two ends passes through a corresponding through-hole 28 and 29 obtained in the thickness of the covering element 9, precisely at the terminals 48 and 49.

[0061] Thus, the corresponding ends 24, 26 of the wires 18 and 19 of the bipolar conductor 33 can be constrained to the corresponding terminals 48, 49 during the assembly step of the capsule 15 containing the electric device 4.

[0062] Advantageously, wires 18 and 19 are each housed in a corresponding longitudinal groove or tubular housing 16, 17, which is located near the inner wall 20 and partially within the proximal portion 10 of the nail 1.

[0063] These longitudinal grooves 16, 17 can be provided in the inner wall 20 itself, or made into receiving sheaths for the wires 18, 19. Alternatively, the actual tubular housing can be made into the longitudinal inner wall 20 near the proximal portion of the nail 1.

[0064] Therefore, guide wires 18 and 19 pass through the inner wall 20 substantially flush with it and are located on opposite sides of the proximal transverse holes 14, which are angled but centered and are typically provided in these types of trochanter screws to accommodate trochanter screws fixed in the femoral neck. This solution has the significant advantage of allowing the manufacture of universal trochanter screws (both left and right). In fact, due to the anatomy of the femur, in order to have a single left or right lateral screw, the trochanter screw must pass through the center of the screw.

[0065] The corresponding grooves, or the arrangement of the two tubular housings 16, 17, are precisely for accommodating the corresponding wires 18, 19 of the connector 33 near the inner wall 20 of the proximal portion 10 of the nail 1.

[0066] Thus, the volume caused by the passage of each wire 18, 19 is indeed very small and does not actually interfere with the need to obtain the central transverse hole 14 in the proximal part of nail 1 due to the passage of the transverse rotor screw.

[0067] In this way, relatively small diameter rotor nails can also be manufactured, provided that the transverse hole 14 for the rotor screw passes through the center in the proximal portion 10.

[0068] The capsule 15 described earlier can be assembled before it is inserted through the proximal portion 10 of the nail 1. The capsule 15 as a whole represents a separately operable component, which can be defined as a motor-wire connector assembled at the proximal end of the nail 1.

[0069] This component allows for easier assembly of the elements constituting the electric motor 4, thereby avoiding axial positioning errors that could be introduced into these elements, while also providing protection for the soldered areas between the ends 24, 26 of the wires 18, 19 and the terminals 48, 49 of the electric motor.

[0070] Figure 9 and Figure 10 The operational steps for achieving the rapid assembly of the nails disclosed herein are illustrated, thanks to the pre-assembly of the electric motor 4 and its connection to the connector 33 prior to nail insertion. All components are designed with minimal clearance, the assembly is unique, and there is no possibility of assembly error in terms of the axial position of the various parts.

[0071] Furthermore, the interconnection between the terminals of the electric motor and the main power line is achieved in a simple, safe, and reliable manner.

[0072] All components are easy to manufacture and have a particularly low cost. Claims (as amended under Article 19 of the Treaty) 1. An electrically powered intramedullary nail (1) for bone lengthening or transport, comprising: The first tubular portion (2) extends along the main axis of the intramedullary nail (1); The second rod-shaped portion (3) slides within the first tubular portion (2) along the axial direction; An electric motor device (4) for driving the rod-shaped portion (3) is inserted into the first tubular portion (2) and includes electrical terminals (48, 49) accessible through the proximal portion of the nail (1). Wires (18, 19) are connected to the electrical terminals (48, 49); and A covering element (9) is used to cover and protect the electrical terminals (48, 49), through which the corresponding ends (24, 26) of the wires (18, 19) pass; Spacer (8) is used to support the cover element (9) at a preset distance from the electrical terminal. Its features are: The spacer (8) is incompressible; The spacer (8) and the cover element (9) are made of electrically insulating material. 2. The intramedullary nail (1) according to claim 1, wherein the nail (1) is rotor type and its proximal portion (10) has a centrally located transversely inclined hole (14) for a rotor screw. 3. The intramedullary nail (1) according to claim 1, wherein two corresponding grooves or two tubular shells (16, 17) are provided to accommodate corresponding wires (18, 19) near the proximal inner wall (20) of the nail. 4. The intramedullary nail (1) according to claim 3, wherein the groove or tubular shell (16, 17) is located at a diameter-opposite position relative to the proximal transverse hole (14). 5. The intramedullary nail (1) according to claim 1, wherein the spacer (8) is a partition separating the electrical terminals (48, 49), configured as a support wall of a cover element (9) supporting the terminals, and a through hole (28, 29) is provided in the cover element (9) at the electrical terminals (48, 49) for the corresponding connecting ends (24, 26) of the wires (18, 19) to pass through. 6. The intramedullary nail (1) according to claim 1, wherein the electric motor (4) for driving the rod-shaped portion (3) is contained in a housing (15) or capsule having a bottom or distal wall (7) from which the electrical terminals (48, 49) extend, and the spacer (8) rises from the bottom wall (7) to support the covering element (9) such that the covering element and the bottom wall (7) maintain a predetermined spacing relationship. 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 isolation. 8. The intramedullary nail (1) according to claim 1, wherein the wires (18, 19) connected to the electrical terminals (48, 49) pass through substantially against the inner wall (20) of the proximal portion of the nail (1) and are located on the opposite side relative to 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 wire (18, 19) connected to the electrical terminals (48, 49) passes through a corresponding through hole (28, 29) obtained in the covering element (9) at the electrical terminals (48, 49).

Claims

1. An electrically powered intramedullary nail (1) for bone lengthening or transport, comprising: The first tubular portion (2) extends along the main axis of the intramedullary nail (1); The second rod-shaped portion (3) slides within the first tubular portion (2) along the axial direction; An electric motor device (4) for driving the rod-shaped portion (3) is inserted into the first tubular portion (2) and includes electrical terminals (48, 49) accessible through the proximal portion of the nail (1). Wires (18, 19); as well as A covering element (9) is used to cover and protect the electrical terminals (48, 49), through which the corresponding ends (24, 26) of the wires (18, 19) pass; Spacer (8) is used to support the cover element (9) at a preset distance from the electrical terminal. Its features are: The spacer (8) is incompressible; The spacer (8) and the cover element (9) are made of electrically insulating material.

2. The intramedullary nail (1) according to claim 1, wherein, The nail (1) is rotor type, with its proximal portion (10) having a centrally located transversely inclined hole (14) for the rotor screw.

3. The intramedullary nail (1) according to claim 1, wherein, Two corresponding recesses or two tubular housings (16, 17) are provided to accommodate corresponding wires (18, 19) near the proximal inner wall (20) of the nail.

4. The intramedullary nail (1) according to claim 3, wherein, The groove or tubular housing (16, 17) is located at a diameter-opposite position to the proximal transverse hole (14).

5. The intramedullary nail (1) according to claim 1, wherein, The spacer (8) is a partition that separates the electrical terminals (48, 49) and is configured as a support wall for the cover element (9) that supports the terminals. The cover element (9) has through holes (28, 29) at the electrical terminals (48, 49) for the corresponding connecting ends (24, 26) of the wires (18, 19) to pass through.

6. The intramedullary nail (1) according to claim 1, wherein, The electric motor (4) for driving the rod-shaped part (3) is contained in a box (15) or capsule having a bottom or distal wall (7) from which the electrical terminals (48, 49) extend, and the spacer (8) rises from the bottom wall (7) to support the cover element (9) so that the cover element and the bottom wall (7) maintain a predetermined spacing relationship.

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

8. The intramedullary nail (1) according to claim 1, wherein, The wires (18, 19) connected to the electrical terminals (48, 49) pass through substantially against the inner wall (20) of the proximal portion of the nail (1) and are located on the opposite side relative to the proximal transverse hole (14) for the rotor bone screw.

9. The intramedullary nail (1) according to claim 1, wherein, Each end (24, 26) of the wires (18, 19) connected to the electrical terminals (48, 49) passes through a corresponding through hole (28, 29) obtained in the cover element (9) at the electrical terminals (48, 49).

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