Motorized and improved intramedullary nail for bone lengthening or transport

Abstract

A motorized intramedullary nail (1) for bone lengthening or transport, of the type comprising: - a first tubular portion (2) extending in a prevalent axial direction of the intramedullary nail (1); - a second rod-shaped portion (3) telescopically sliding inside the first tubular portion (2) and along the axial direction itself; - motorized electro-mechanical means (4) for driving the rod-shaped portion (3) inserted inside the first tubular portion (2) and comprising electrical terminals (48, 49) accessible through the proximal part of the nail (1); - a covering element (9) for covering and protecting the electrical terminals (48, 49) which is passed through by respective ends (24, 26) of electrical conductors (18, 19); - a spacer (8) to support the covering element (9) at a preset distance from the electrical terminals.

Description

[0001] Title: Motorized and improved intramedullary nail for bone lengthening or transport

[0002] DESCRIPTION

[0003] Field of application

[0004] The present disclosure relates to the general technical field of orthopedics. More particularly, it relates to a motorized intramedullary nail for bone lengthening or transport of long bones.

[0005] For instance an intramedullary nail allows performing a lengthening of a limb without the use of external fixators; moreover, it may also be used for an optimal transport and alignment of bone segments or even for a desired blocking of a joint for the purposes of post-traumatic or therapeutic treatment.

[0006] Prior art

[0007] In this specific technical field, a type of motorized intramedullary nails is already known, which allow for the lengthening of long limbs. For instance, a system of this type called Fitbone™ has been known for many years and was initially developed by Prof. Rainer Baumgart, a world-famous specialist.

[0008] This system is mainly intended for the lengthening of single limbs that require intervention due to trauma or congenital malformations, or for the lengthening of limbs that are not fully developed in length.

[0009] Moreover, with proper preoperative planning, an intramedullary nail of the type previously indicated allows providing axial and torsional corrections as part of limb lengthening.

[0010] These nails are configured with a first portion that could be defined as fixed and a second portion that slides and extends telescopically into the first fixed portion; electro-mechanical driving means are provided to control the extension of the sliding portion by means of externally applied control signals.

[0011] For instance, a prior art document, no. WO2021032823 (Al), relates to an medullary nail for lengthening a long bone comprising a first tubular body and a second tubular body inserted in the first tubular body and sliding therein, as well as connected by means of gears to a small electric motor that allows an axial translation thereof relative to the first tubular body.

[0012] Though advantageous under several aspects, these known nails for bone lengthening have some structural drawbacks, in particular when it is necessary to make trochanteric femoral nails with an angled proximal portion, as it will become clear herein after.

[0013] First of all, the small electric motor nested inside the nail must be powered by electric current and the conductive cables that carry the relative voltage are a necessary encumbrance to be provided in the proximal part of the nail.

[0014] Currently, the known solutions provide a single channel obtained in the proximal part of the nail to house both the conductors on a same side, as shown in Figure 1.

[0015] However, the bulk of this channel would lead to a possible misalignment of the proximal holes for the inclined trochanteric screws. But the trochanteric screws are larger than the stabilization or fixing bone screws used in straight nails; moreover, they must be placed in the center of the nail so that they can be inserted in the center of the trochanteric neck for the right or left limb.

[0016] It follows that a trochanteric screw hole cannot be offset. Moreover, the size of the trochanteric screws does not allow for maintaining single groove to pass the control wire.

[0017] Indeed, transverse misaligned holes for the trochanteric screws would weaken the proximal structure of the nail, which would result in one side being weaker than the other and would force the implantation of an intramedullary trochanteric nail, making sure that the “weak side” is always facing the front plane, effectively forcing the surgeon to have a right-sided nail and a left-sided nail, or a more complex instrument set, in any case limiting the surgeon’s ability to operate.

[0018] Motorized nails according to the prior art are shown for instance in documents FR 2 847 153 Al and US 6,245,075 Bl.

[0019] The technical problem underlying the present disclosure is to provide a new structure of an intramedullary and motorized trochanteric nail having structural and functional features able to overcome the previously highlighted drawbacks, moreover allowing speeding up the assembly operations of the electro-mechanical components of the nail.

[0020] Summary of the invention

[0021] The solution idea underlying the invention is to separate the two conductors connected to the electric motor of the motorized driving means for driving the moving portion of the nail, making them pass substantial adhering to the inner walls of the proximal portion of the nail, on opposite sides with respect to the transverse holes of the trochanteric screws, and to provide a covering element for covering the motor terminals that insulates, protects and separates the ends of the conductors connected to the motor terminals and passing through such covering element.

[0022] According to this solution idea, the present disclosure relates to a motorized and improved intramedullary nail for bone lengthening or transport, according to claim 1.

[0023] More particularly, the nail of the present disclosure is of the trochanteric type with a proximal part having centrally obtained transverse inclined holes for trochanteric screws obtained centrally. Moreover, two respective grooves or two tubular housings are provided to receive a respective electrical conductor close to the proximal inner wall of the nail and on opposite parts with respect to the above transverse holes for trochanteric screws, which are obtained centrally in the proximal part of the nail.

[0024] It is worth noting that the above spacer is a separation partition separating the electrical terminals which acts as a support wall supporting the covering portion of said terminals, through-holes being provided in said covering portion at said electrical terminals for the passage of a respective connecting end of said conductors.

[0025] The spacer acting as separation partition and the covering element are made of an electrically insulating material.

[0026] The motorized electro-mechanical means for driving the rod-shaped portion are contained in a cartridge or capsule having a bottom or distal wall from which the electrical terminals emerge and said separation partition rises from said bottom wall to support said covering element in a preset spaced-apart relationship from said bottom wall.

[0027] The capsule, the spacer and the covering element may be made in one piece and of a synthetic-plastic material capable of carrying out a function of electrical isolation.

[0028] It is also worth noting that each end of the electric conductors connected to the electrical terminals passes through a through-hole obtained in the covering element at said electrical terminals.

[0029] The features and advantages of the motorized intramedullary nail according to the present disclosure will become clear from the following description of an embodiment given by way of indicative and nonlimiting example with reference to the appended drawings.

[0030] Brief description of the drawings Figure 1 shows a front schematic view of a proximal portion of an intramedullary nail of the known type;

[0031] Figure 2 shows a perspective and schematic view of a trochanteric and intramedullary nail according to the present disclosure;

[0032] Figure 3A shows a front schematic and transparent view of a detail of the proximal part of the nail of Figure 2;

[0033] Figure 3B shows a schematic and transparent view of the same proximal detail of Figure 3A but from a side view;

[0034] Figure 4 shows a schematic view of an assembly step of a component of the nail of Figure 2;

[0035] Figure 5 shows a schematic and transparent view of a detail of the proximal part of the nail of Figure 2 after the insertion step of the component of Figure 4;

[0036] Figure 6 shows a schematic and partially transparent view of a connecting step of a gearmotor to power cables;

[0037] Figure 7 shows a perspective and schematic view, on an enlarged scale, of a gearmotor with protecting cover incorporated in the nail of Figure 2;

[0038] Figure 8 shows an enlargement of a detail of the component of Figure 7;

[0039] Figure 9 a perspective and schematic view of the insertion of the component of Figure 7 through the proximal part of the nail of the present disclosure;

[0040] Figure 10 shows a perspective and schematic view of the gearmotor with covering of Figure 7 once the insertion has been completed.

[0041] Detailed description With reference to these figures, and in particular to the example of Figure 2, reference number 1 globally and schematically illustrates a preferred embodiment of the improved intramedullary nail 1 according to the present disclosure to carry out bone lengthening of a long bone as needed. For these purposes the nail 1 is substantially an extendable nail and, as it will be seen, is extendable by activating electromechanical driving means inserted in the nail itself.

[0042] The nail 1 is of the trochanteric type, in the sense that it is particularly suitable for femoral use and may have a proximal part that is slightly inclined with respect to the prevalent longitudinal axis of the nail itself.

[0043] As it will be described herein after, the intramedullary nail 1 may be coupled to an electro-mechanical actuator or gearmotor equipped with a signal receiver and connected via a bipolar power line to receive electrical power. External control electronics and a transmitter may also be provided. Commands necessary for the nail lengthening process are transmitted to the receiver implanted under the skin via the transmitter, so that there is no contact between the implanted intramedullary nail 1 and the surface (skin) of the body. The power supply instead comes from an electrical connection via a bipolar conductor.

[0044] The intramedullary nail 1 actually comprises a first tubular portion 2 which can be defined as fixed and which extends in an axial direction of the nail itself. Preferably this portion may have a circular section and comprises a proximal part 10 which, as said, is slightly inclined with respect to the prevailing longitudinal axis of the nail 1.

[0045] The terms “axial” and “radial” must be intended herein with respect to the longitudinal axis of the intramedullary nail 1; that is, an axis that extends according to the prevailing length of the intramedullary nail 1 or anyway in the direction of maximum spatial expansion of the intramedullary nail 1. More particularly, axial direction indicates a direction that is aligned or parallel to the longitudinal axis of the intramedullary nail 1; whereas, radial direction indicates a direction that is perpendicular to the longitudinal axis.

[0046] However, it should be noted that the longitudinal axis of the intramedullary nail 1 has a slightly inclined portion; for instance, a slight curvature of the proximal part 10 that promotes the correct positioning of transverse trochanteric screws that must penetrate a femoral bone with a trochanteric neck inclined by approximately 30° with respect to the medio-lateral plane.

[0047] Typically, the tubular portion 2 is made of metal or of a metal alloy, in particular a biocompatible metal or a biocompatible metal alloy. Instead, other elements of the intramedullary nail 1 are made of a synthetic-plastic material, for instance epoxy resin, silicone or thermoplastic resin.

[0048] The tubular portion 2 comprises a hollow cylindrical shell inside which a second rod-shaped portion 3, which may be in turn tubular, is slidingly and telescopically mounted. This rod-shaped portion 3 may also be made with multiple interconnected stages.

[0049] The rod-shaped portion 3 comprises, in distal position, a first hole 11 that is transverse to the axial direction and configured to house a bone screw. Alternatively, the hole 11 may be threaded to house a guide screw to prevent the rotation of the rod-shaped portion 3 with respect to the tubular portion 2.

[0050] A second hole 12 that is transverse to the axial direction and that can be parallel to the first hole 11 or inclined, depending on the fixing needs of the rod-shaped portion 3, is also provided.

[0051] Advantageously, motorized electro-mechanical means 4 and electrically powered are provided to drive in translation the rod-shaped portion 3 inside the tubular portion 2. Substantially, the intramedullary nail 1 comprises motorized means 4 configured to move the rod-shaped portion 3 inside the tubular portion 2 axially and with millimetric precision. Preferably, the above means 4 comprise an electric motor or gearmotor 41 and a screw transmission 42.

[0052] The electric motor 41 is adapted to drive the screw transmission 42, which in turn is coupled and acts on the rod-shaped portion 3 for a reversible shift thereof.

[0053] The motorized means 4 are housed inside a protecting cartridge or capsule 15 which also encloses electronic control means (not represented) of the motor 41 and which is inserted into the proximal part 10 of the nail 1 after the insertion of the rod-shaped portion 3. This cartridge 15 has a bottom or proximal wall 7 from which electrical terminals 48, 49 connecting to the motor 41 emerge.

[0054] In general, once implanted, the intramedullary nail 1 is powered by an external controller that transfers the electrical impulses under the skin through an antenna associated with the electronic control means. Electrical energy is transferred to the electric gearmotor 41 of the intramedullary nail 1 via the bipolar power cable 33 emerging externally through the proximal part 10 of the nail 1. The electric motor 41, preferably through a reduction system, provides rotary movement to a worm screw 42 coupled to the rod-shaped portion 3 for reversible displacement of such a rod-shaped portion 3.

[0055] The electric motor 41 is housed in the capsule 15 with the electrical power terminals 48, 49 emerging outside the capsule 15 through a base or bottom wall 7 on the side facing the bipolar electrical power cable 33. The bipolar cable 33 obviously comprises two electrical conductors 18, 19 having respective ends 24, 26 for connection to the terminals 48, 49.

[0056] A separating and support partition 8 for a covering element 9 which also performs the function of protecting the terminals 48, 49 themselves is provided between these terminals 48 and 49. The partition 8 is also a spacer for supporting the covering element 9 which keeps it in a preset spaced-apart relationship with the base wall 7 of the capsule 15.

[0057] Considering the proximal portion of the capsule 15 as if it were standalone, we could say that the base 7 from which the terminals 48 and 49 emerge is covered by a roof represented by the covering element 9 and centrally supported by the partition 8 which also separates the two terminals 48, 49 from each other, as if it were a separating partition. The partition 8 has lateral dimensions such as to occupy the same lateral space as the capsule 15, whereas the covering element 9, substantially circular, has the same overall dimensions as the bottom wall 7 of the capsule 15.

[0058] The separation and support partition 8 and the covering element 9 are made of an electrically insulating material.

[0059] Even the capsule 15 is made of an insulating material and the rear and proximal wall 7 of the capsule 15 may be in a single piece made of the same insulating material as the partition 8 and the covering element 9.

[0060] Moreover, the components 7, 8, and 9 of the capsule 15 herein cited may also be integral with each other and made as a single piece, so that the terminals 48 and 49 emerge in respective and independent protective spaces once the capsule 15 containing the motorized means 4 has been inserted into the proximal part 10 of the nail 1.

[0061] As well shown in Figure 6, when the capsule 15 of the motorized means 4 is inserted into the proximal part 10 of the nail 1, the two terminals 48 and 49 actually remain enclosed between the inner walls of the proximal part 10 of the nail 1 and by a delimited space, as well as by the walls 7 and 9, by the partition 8 that actually occupies the dimension of the inner diameter of the proximal part 10 of the nail 1.

[0062] The two terminals 48 and 49 are accessible at the terminal ends 24, 26 connecting the bipolar cable 33, which are covered by respective electrical insulation gaskets 31, 32. Each of the two ends passes through a respective through-hole 28, 29 obtained in the thickness of the covering element 9 precisely at the terminals 48, 49.

[0063] In this way, the respective ends 24, 26 of the cables 18 and 19 of the bipolar conductor 33 are constrainable to the respective terminals 48, 49 in the assembly step of the capsule 15 that encloses the motorized means 4.

[0064] Advantageously, the conductors 18 and 19 are housed each in a corresponding longitudinal groove or in a tubular housing 16, 17 provided close to the inner wall 20 and for a portion thereof in the proximal part 10 of the nail 1.

[0065] These longitudinal grooves 16, 17 may be provided in the inner wall 20 itself or made as housing sheaths for the conductors 18, 19. Alternatively, actual tubular housings are made close to the longitudinal inner wall 20 of the proximal part of the nail 1.

[0066] Therefore, the conductors 18 and 19 pass substantially adhering to such an inner wall 20 and on opposite sides with respect to the proximal transverse holes 14, inclined but central, normally provided in these types of trochanteric nails to receive trochanteric screws for fixing in the femoral neck. This solution has the great advantage of allowing obtaining a universal trochanteric nail, both on the right and left sides. Indeed, due to the anatomy of the femur, in order to have a single right and left nail, the trochanteric screws must pass through the center of the nail.

[0067] The respective grooves or, alternatively, the two tubular housings 16, 17 are provided precisely to receive a respective electric conductor 18, 19 of the connector 33 close to the inner wall 20 of the proximal part 10 of the nail 1.

[0068] In this way, the bulk due to the passage of each conductor 18, 19 is truly minimal and does not actually interfere with the need to provide central and transverse holes 14 obtained in the proximal part of the nail 1 due to the passage of the transverse trochanteric screws.

[0069] In this way, it is possible to also make trochanteric nails of relatively small diameter, provided that the transverse holes 14 for the trochanteric screws pass centrally in the proximal part 10.

[0070] The previously described capsule 15 may be assembled prior to its insertion through the proximal part 10 of the nail 1. This capsule 15 represents as a whole an individually handable component that can be defined as a motor-wire connector which is assembled on the proximal end of the nail 1.

[0071] Such a component allows for easier assembly of the elements that make up the motorized electro-mechanical means 4, thus avoiding the introduction of axial positioning errors of such elements and meanwhile allowing for the provision of protection to the welding area between the ends 24, 26 of the cables 18, 19 and the terminals 48, 49 of the motorized means.

[0072] In Figures 9 and 10 the operational steps that lead to a quick assembly of the nail of the present disclosure are illustrated, which is supported by the fact that the motorized electro-mechanical means 4 are preassembled and connected to the connector 33 before insertion into the nail. With all components designed with a minimal clearance, the assembly is unique and there can be no assembly errors in terms of axial position of the various parts.

[0073] Moreover, the interconnection between the terminals of the electric motor and the main power cable is obtained in a simple, safe and secure way.

[0074] All components are easy to manufacture with particularly low costs.

Claims

AMENDED CLAIMS received by the International Bureau on 13 February 2025 (13.02.205)CLAIMS1. A motorized intramedullary nail (1) for bone lengthening or transport, of the type comprising:- a first tubular portion (2) extending in a prevalent axial direction of the intramedullary nail (1);- a second rod-shaped portion (3) telescopically sliding inside said first tubular portion (2) and along said axial direction;- motorized electro-mechanical means (4) for driving the rod-shaped portion (3) which are inserted inside said first tubular portion (2) and comprise electrical terminals (48, 49) accessible through the proximal part of the nail (1);- electrical conductors (18, 19) connected to the electrical terminals (48, 49); and- a covering element (9) for covering and protecting said electrical terminals (48, 49) which is passed through by respective ends (24, 26) of the electrical conductors (18, 19);- a spacer (8) to support said covering element (9) at a preset distance from said electrical terminals; characterized in that:- the spacer (8) is incompressible;- said spacer (8) and said covering element (9) are made of an electrically insulating material.

2. The intramedullary nail (1) according to claim 1, wherein the nail (1) is of trochanteric type with a proximal part (10) with centrally obtained transverse inclined holes (14) for trochanteric screws.AMENDED SHEET (ARTICLE 19)3. The intramedullary nail (1) according to claim 1, wherein two respective grooves or two tubular housings (16, 17) are provided to receive a respective electrical conductor (18, 19) close to the proximal inner wall (20) of the nail.

4. The intramedullary nail (1) according to claim 3, wherein said grooves or tubular housings (16, 17) are located in a diametrically opposite position on opposite sides with respect to proximal transverse holes (14).

5. The intramedullary nail (1) according to claim 1, wherein the aforementioned spacer (8) is a separation partition separating the electrical terminals (48, 49) that is configured as a support wall supporting the covering element (9) of said terminals, through-holes (28, 29) being provided in said covering element (9) at said electrical terminals (48, 49) for the passage of a respective connecting end (24, 26) of said electrical conductors (18, 19).

6. The intramedullary nail (1) according to claim 1, wherein the motorized electro-mechanical means (4) for driving the rod-shaped portion (3) are contained in a cartridge ( 15) or capsule having a bottom or distal wall (7) from which the electrical terminals (48, 49) emerge and said spacer (8) rises from said bottom wall (7) to support said covering element (9) in a preset spaced-apart relationship from said 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 made in one piece and of a synthetic-plastic material capable of carrying out a function of electrical isolation.

8. The intramedullary nail (1) according to claim 1, wherein the electrical conductors (18, 19) connected to the electrical terminals (48, 49) pass substantially adhering to the inner wall (20) of the proximal portion of the nail (1) and on opposite sides with respect to proximalAMENDED SHEET (ARTICLE 19)transverse holes (14) for trochanteric bone screws.

9. The intramedullary nail (1) according to claim 1, wherein each end (24, 26) of the electrical conductors (18, 19) connected to the electrical terminals (48, 49) passes through a respective through-hole (28, 29) obtained in the covering element (9) at said electrical terminals (48, 49).AMENDED SHEET (ARTICLE 19)STATEMENT UNDER ARTICLE 19.1 PCTThe claims have been modified based on the suggestions made by the Examiner under Item VIII of the Written Opinion of the International Search Authority, filed on December 23, 2024. Since the amendments address the only objections raised in the Written Opinion, which has also deemed the claims both new and inventive, no further defects are present, and the claims meet all validity requirements under the PCT Convention.

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