Implantable skeletal traction device

Abstract

An implantable bone traction device includes an inductive power transfer circuit at least partially located within one of an outer tube and an inner tube. A shape memory alloy actuator includes a shape memory alloy element powered by the inductive power transfer circuit and configured to transition from a first phase to a second phase in response to threshold resistance heating and having a corresponding shape change. A force transmission arrangement includes a locking clutch connected to the shape memory alloy actuator and slidably connected to the other of the outer tube and the inner tube. The locking clutch converts the shape change of the shape memory alloy element into extension of the inner tube from within the outer tube by transitioning from one of the first phase and the second phase to the other of the first phase and the second phase and prevents retraction of the inner tube into the outer tube when the shape memory alloy element transitions oppositely.

Description

Technical Field

[0001] This disclosure relates to limb extension devices and associated surgical procedures used on the human body to extend limbs (such as legs or arms). Background Technology

[0002] It is a widely accepted consensus that limb lengthening surgery is associated with a considerable number of complications. However, surgery is considered a valuable treatment option with successful outcomes. Therefore, limb length discrepancy and short stature can be treated with a variety of surgical bone lengthening techniques.

[0003] External fixation for bone lengthening was invented in the 1950s and remains the global gold standard. However, the use of external fixators for lengthening is associated with complications such as pain, pin tract infections, joint stiffness due to limited rehabilitation, and refracture due to early removal of the frame. External fixation also leads to poor cosmetic results, and the frame is impractical for patients' daily lives.

[0004] To overcome the problems of external fixation, limb lengthening surgery with intramedullary lengthening nails was developed and has become more widespread in the past decade. Although internal lengthening is more convenient for patients and can overcome the problems listed above, device-related complications and technical issues still exist. The problems reported in this series are (i) implant corrosion and release of abrasive particles (e.g., NuVasive's PRECICE (“Precice”) and Orthofix's FITBONE (“Fitbone”)), (ii) mechanical breakage of the nail (Precice), (iii) poor control of elongation rate (Intramedullary Bone Dynamic Traction Device (“ISKD”)), (iv) breakage of the detached antenna (Fitbone), (v) tissue irritation due to the antenna being placed in soft tissue (Fitbone), (vi) strong magnets causing danger to the home environment (Precice), (vii) elongation rate depending on the thickness of the soft tissue (Precice), (viii) bulky home care appliances that are difficult for patients to position correctly (Precice), (ix) impossibility of remotely monitoring patient compliance (all), and (x) limitations on rehabilitation due to strict weight-bearing restrictions (all). Summary of the Invention

[0005] Some embodiments of this disclosure relate to an implantable bone traction device comprising an outer tube, an inner tube at least partially disposed within the outer tube, an inductive power transmission circuit, a shape memory alloy actuator, and a force transmission device. The inductive power transmission circuit is connected to one of the outer and inner tubes and is at least partially located within one of the outer and inner tubes, and is configured to receive power via inductive coupling to an external power coil. The shape memory alloy actuator is connected to one of the outer and inner tubes and is at least partially located within one of the outer and inner tubes. The shape memory alloy actuator includes a shape memory alloy element electrically connected to be powered by the inductive power transmission circuit. The shape memory alloy element is configured to transition from a first phase to a second phase in response to threshold resistance heating and has a corresponding shape change. The force transmission device includes a one-way linear movement locking clutch connected to the shape memory alloy actuator and slidably connected to the other of the outer and inner tubes. A one-way linear movement locking clutch is configured to convert the shape change of the shape memory alloy element into an extension of the inner tube from the outer tube by switching from one of the first phase and the second phase to the other, and to prevent the inner tube from retracting into the outer tube when the shape memory alloy element switches from the other of the first phase and the second phase to the first phase and the second phase. In other embodiments, a ratchet mechanism may be used for switching from one of the first phase and the second phase to the other.

[0006] Some other embodiments relate to a bone traction system comprising an inductive power unit or home care unit and an implantable bone traction device. The inductive power unit includes at least one processor and a power source configured to be controlled by the at least one processor to provide a controlled current level to an inductive power coil. The implantable bone traction device includes an outer tube, an inner tube at least partially disposed within the outer tube, an inductive power transmission circuit, a shape memory alloy actuator, and a force transmission device. The inductive power transmission circuit is connected to and at least partially located within one of the outer and inner tubes and is configured to receive power via an inductively coupled transmitting coil or inductive power coil of the inductive power unit. The shape memory alloy actuator is connected to and at least partially located within one of the outer and inner tubes. The shape memory alloy actuator includes a shape memory alloy element electrically connected to be powered by the inductive power transmission circuit. The shape memory alloy element is configured to transition from a first phase to a second phase in response to threshold resistance heating and has a corresponding shape change. The force transmission device includes a one-way linear movement locking clutch connected to a shape memory alloy actuator and slidably connected to the other of the outer and inner tubes. The one-way linear movement locking clutch is configured to convert the shape change of the shape memory alloy element into an extension of the inner tube from the outer tube by switching from one of the first and second phases to the other, and to prevent the inner tube from retracting into the outer tube when the shape memory alloy element switches from the other of the first and second phases to the first and second phases.

[0007] Some other embodiments relate to a method comprising operating an inductive power transmission circuit to receive power from a transmitting coil via inductive coupling, wherein the inductive power transmission circuit is connected to and at least partially disposed within an inner tube, both of the outer and inner tubes. The method further comprises providing a shape memory alloy actuator connected to and at least partially disposed within one of the outer and inner tubes, wherein the shape memory alloy actuator includes a shape memory alloy element electrically connected to be powered by the inductive power transmission circuit. The shape memory alloy element is configured to transition from a first phase to a second phase in response to threshold resistance heating and has a corresponding shape change. The method further comprises providing a force transmission device including a one-way linear movement locking clutch connected to the shape memory alloy actuator and slidably connected to the other of the outer and inner tubes. The one-way linear moving locking clutch is configured to convert the shape change of the shape memory alloy element into the extension of the inner tube from the outer tube by switching from one of the first phase and the second phase to the other of the first phase and the second phase, and to prevent the inner tube from retracting into the outer tube when the shape memory alloy element switches from the other of the first phase and the second phase to the first phase and the second phase.

[0008] Other implantable bone traction devices, systems, and methods according to embodiments of the subject matter of the present invention will become apparent to those skilled in the art upon viewing the following figures and detailed description. All such additional implantable bone traction devices, systems, and methods are intended to be included in this specification, within the scope of the subject matter of the invention, and are protected by the appended claims. Furthermore, all embodiments disclosed herein are intended to be implementable individually or in any manner and / or in combination. Attached Figure Description

[0009] Various aspects of this disclosure are illustrated by way of example and are not limited to the accompanying drawings. In the drawings:

[0010] Figure 1 The illustration shows a nickel-titanium nail femoral lengthening implant configured according to some implementation schemes, which is implanted into the femur and fixed with locking screws;

[0011] Figure 2 The illustration shows tools for a surgical kit according to some implementation schemes, which can be used with other tools available in an orthopedic operating room to implant a femoral lengthening implant into the femur and secure locking screws.

[0012] Figure 3 The illustration shows a home care unit with a control transmitting coil positioned adjacent to the inductive power transmission unit of a nickel-titanium nail implant, according to some embodiments.

[0013] Figure 4 The diagram illustrates a block diagram of components of a nickel-titanium nail system according to some embodiments;

[0014] Figure 5 The diagram illustrates four main components of a nickel-titanium nail implant that, when operated according to some implementation schemes, results in an elongated implant.

[0015] Figure 6 The diagram illustrates a receiving antenna, including secondary and tertiary circuitry with inductive links, according to some implementation schemes.

[0016] Figure 7 The illustration shows a portion of a locking screw configured according to one implementation scheme;

[0017] Figure 8 The diagram illustrates a home care unit and a connected transmitting coil according to some embodiments, the transmitting coil being used to transmit power to the inductive power transmission circuit of the nickel-titanium nail implant;

[0018] Figure 9 The diagram illustrates a simplified structural diagram of a nickel-titanium alloy actuator according to some embodiments, shown in a non-activated expansion state (left) and an activated contraction state (right).

[0019] Figure 10 The figure illustrates the effect of hysteresis on the transformation temperature of nickel-titanium alloy materials used in some embodiments of this disclosure;

[0020] Figure 11 The illustration shows a cross-sectional view of a unidirectional linear movement locking clutch of a force transmission device configured according to some embodiments;

[0021] Figure 12 The illustration shows a side view of a one-way linear movement locking clutch configured according to some embodiments, the one-way linear movement locking clutch having a roller that moves along a corner ring to engage a square bar, allowing movement in the free direction while preventing movement in the locking direction;

[0022] Figure 13 The illustration shows two views of another nickel-titanium nail femoral lengthening implant configured according to some implementation schemes;

[0023] Figure 14 The diagram illustrates the configuration based on some implementation schemes. Figure 13 Two longitudinal sectional views of a nickel-titanium nail implant;

[0024] Figure 15 The diagram shows... Figure 14 An enlarged view of a nickel-titanium alloy actuator shown in the figure and configured according to some embodiments;

[0025] Figure 16 The illustration shows a cross-sectional view of an inductive power transmission circuit configured according to some implementation schemes;

[0026] Figure 17A illustrates an isometric view of a unidirectional linear movement locking clutch of a force transmission device configured according to some embodiments;

[0027] Figure 17B illustrates a cross-sectional view of the one-way linear movement locking clutch of Figure 17A configured according to some embodiments; and

[0028] Figure 18 The diagram illustrates a circuit diagram of a wireless power transfer function according to some implementation schemes. Detailed Implementation

[0029] The following discussion is provided to enable those skilled in the art to implement and use embodiments of this disclosure. Various modifications to the illustrated embodiments will be apparent to those skilled in the art, and the principles herein can be applied to other embodiments and applications without departing from the embodiments of this disclosure. Therefore, embodiments are not intended to be limited to those shown, but should have the broadest scope consistent with the principles and features disclosed herein. Refer to the accompanying drawings, in which similar elements have similar reference numerals. The drawings are not necessarily drawn to scale, depict selected embodiments, and are not intended to limit the scope of embodiments. Those skilled in the art will recognize that the examples provided herein have many useful alternative forms and fall within the scope of embodiments.

[0030] It should be understood that this disclosure, in its application, is not limited to the construction details and component arrangements shown in the description or accompanying drawings herein. The teachings of this disclosure may be used and practiced in other embodiments and in various ways. Furthermore, it should be understood that the wording and terminology used herein are for descriptive purposes and should not be considered limiting. The use of “comprising,” “including,” or “having,” and variations thereof herein means to include items listed herein and their equivalents, as well as additional items. Unless otherwise specified or limited, the terms “mounted,” “connected,” “supported,” and “coupled,” and variations thereof are used extensively and include direct and indirect mounting, connection, support, and coupling. Furthermore, “connection” and “linkage” are not limited to physical or mechanical connections or linkages.

[0031] To overcome the various problems of external fixation, limb lengthening surgery using intramedullary lengthening nails was developed and has become popular in the past decade. Although internal lengthening is more convenient for patients and can overcome the various problems mentioned above, device-related complications and technical issues still exist. Reported problems may include (i) implant corrosion and abrasive particle release (Precice and Fitbone), (ii) mechanical breakage of the nail (Precice), (iii) poor control of the lengthening rate (ISKD), (iv) breakage of the independent antenna (Fitbone), (v) tissue irritation due to the antenna being placed in soft tissue (Fitbone), (vi) dangers posed by strong magnets in the home environment (Precice), (vii) the lengthening rate depending on the thickness of the soft tissue (Precice), (viii) bulky home care appliances that are difficult for patients to position correctly (Precice), (ix) inability to remotely monitor patient compliance (all), and (x) limitations on rehabilitation due to strict weight-bearing restrictions (all).

[0032] Embodiments of this disclosure relate to limb lengthening systems and devices that can overcome one or more problems associated with other internal lengthening nails. Some embodiments are described in the context of SYNOSTE's nickel-titanium nail systems, SYNOSTE being part of Globus Medical, Inc., although these and other embodiments are not limited to the exemplary nickel-titanium nail system and device configurations disclosed herein.

[0033] Nickel-titanium nail systems can be used to lengthen the femur, tibia, and / or other bones to, for example, compensate for limb length differences caused by traumatic shortening, congenital malformations, and tumor resection.

[0034] The nickel-titanium screw system may include five sub-components: 1) a nickel-titanium screw implant that operates as a telescopic traction screw; 2) a locking screw, which is a bone screw used to fix the nickel-titanium screw implant to the bone; 3) a surgical kit, which is a set of specific surgical instruments for implantation and explantation; 4) a home care unit, which is a remote control for wireless activation of the nickel-titanium screw implant extension; and 5) extension protocol software 40 ( Figure 4 The software supports establishing a prescribed activation schedule for the patient's home care use of the device during the traction phase.

[0035] Figure 1 The illustration shows a nickel-titanium nail femoral lengthening implant 10 (“nickel-titanium nail implant” or “implant”), which is shown implanted in the femur 14 and secured with locking screws 12, and configured according to some embodiments. Figure 2The illustration shows the tools of a surgical kit 20 according to some embodiments, which can be used with other tools available in an orthopedic operating room to implant a femoral lengthening implant 10 into the femur 14 and secure the locking screw 12. Figure 3 The illustration shows a home care unit 32 that controls a transmitting coil positioned adjacent to the inductive power transmission unit of the nickel-titanium nail implant 10. While various implementations of the implant are illustrated in the context of femoral lengthening, they can also be used to lengthen the arm and other skeletal structures.

[0036] The home care unit 32 is an electronic device that can be used in hospitals and patients' homes to activate the extension mechanism of the nickel-titanium nail implant 10. During implantation, the unit 32 can also be used in the operating room to confirm implant function and perform initial extension of the nickel-titanium nail implant 10. The nickel-titanium nail implant 10 is activated via resonant inductive power transmission by placing a transmitting coil 30 around the treated leg or arm and aligning it with the receiving antenna of the nickel-titanium nail implant 10. Resonant inductive transmission can be performed via near-field wireless transmission of electrical energy between magnetically coupled coils tuned to resonate at the same frequency or any selected frequency. As will be explained below, the transmitting coil 30 is briefly operated to inductively power a force transmission device of the femoral lengthening implant 10, which applies a predetermined level of internal axial force to the femur 14 and causes it to lengthen at a predetermined rate. Repeated operation of the implant 10 each day of a series of predetermined days can provide the desired lengthening of the femur or other limb.

[0037] Home care unit 32 can be configured to transmit data to a networked server via wireless (e.g., WiFi, Bluetooth, 4G / 5G / NR cellular, etc.) and / or wired connections (e.g., Ethernet) and wide area networks (e.g., the Internet) for monitoring by patients, caregivers, and / or healthcare professionals. This data may include timestamps of usage, location information, the geographic location of home care unit 32, and patient-reported outcome measures such as pain levels. The surgeon may also prescribe new treatments for home care unit 32, extending the schedule to control the movement of the nitinol implant 10. This data may include information measured or determined from the nitinol implant 10, such as the force acting on the implant 10 or the implant length. For example, both home care unit 32 and nitinol implant 10 may include wireless communication circuitry providing a telemetry link between them to enable the measurement of certain implant parameters (e.g., length, load sharing, impedance measurements, quality of regenerated bone), allowing the surgeon to control long-term treatment and potentially improve outcomes.

[0038] Figure 4The diagram illustrates a block diagram of components of a nickel-titanium nail system according to some embodiments, including a surgical kit 20, a nickel-titanium nail femoral lengthening implant 10 (also referred to as a "nickel-titanium nail" or "nickel-titanium nail implant" for simplicity), a locking screw 12, a home care unit 32, and Syndex lengthening protocol software 40 (also referred to as "Syndex software" for simplicity), which is executed by at least one processor of at least one computing platform to perform operations. For example, some operations of the lengthening protocol software 40 may be performed by the processor of the home care unit 32, while others may be performed by a networked computer that provides a robust interface for medical professionals to monitor and control the operation of the nickel-titanium nail implant 10 and the progress of the patient's lengthening process.

[0039] In both hospital and home care settings, activation of the extension mechanism for the nickel-titanium nail implant 10 is performed using a home care unit 32. The software is used to control the extension by providing the patient with an activation schedule to be completed in the form of a patient diary.

[0040] The nitinol implant 10 is configured as an intramedullary nail. In one embodiment, the intramedullary nail may have a maximum outer diameter of 14 mm and varying starting length and elongation capability based on configuration variations, such as: one variation having an elongation capability of 50 mm starting from a starting length of 305 mm; and another variation having an elongation capability of 70 mm starting from a starting length of 325 mm. The function of the nitinol implant 10 is based on the use of nitinol, the precise coupling of the phase change shape of nitinol with mechanical movement, and the activation of energy transfer of nitinol via inductive energy transfer from the transmitting coil 30. Figure 5 The illustration shows some of the main components of a nickel-titanium nail implant 10 for causing mechanical extension according to some embodiments.

[0041] refer to Figure 5 The four main components of the nickel-titanium nail implant 10 are:

[0042] 1) Inductive power transmission circuit 54, which includes an antenna configured to receive power from transmitting coil 30 via inductive coupling (inductive power transmission), and the inductive power transmission circuit is used to convert the power of the alternating magnetic field into alternating current (AC).

[0043] 2) A nickel-titanium alloy actuator 52 having a nickel-titanium element that operates with a bidirectional phase change shape memory effect activated by resistive heating of the nickel-titanium element in response to AC current from an inductive power transmission circuit 54.

[0044] 3) A force transmission device 50 that forms a friction-based unidirectional linear movement locking clutch. In one embodiment, the clutch includes friction-based locking stacks that are connected by a nail frame 56 to move through the shape change of a nitinol element and provide force transmission, which causes telescopic extension of the implant 10 in a manner similar to a stepper motor; and

[0045] 4) Screw fasteners through paired screw holes 58 ( Figure 1 The screws 12 are not shown in the figure). These screw holes extend through the spaced-apart end regions of the nitinol nail implant 10 to be attached to the demineralized bone gap and transmit the nail extension to the demineralized bone gap.

[0046] The functions of the different components of the nitinol nail implant 10 will be elaborated in more detail in the following sections. The inductive power transmission circuit 54 converts the electromagnetic field received from the transmitting coil 30 into an AC current that flows through the nitinol alloy actuator 52 to heat and change the shape of the nitinol element through the phase change of the nitinol material therein. The nitinol material is a metallic alloy of nickel and titanium, and the two elements can be present in approximately equal atomic percentages. The shape memory property depends on the specific atomic composition of the metallic alloy. The two-way phase change shape memory effect is a reversible phenomenon, also known as the two-way shape memory effect (TWSME), which is caused by the nitinol transformation between the martensite and austenite phases. During the memory effect phase transformation from martensite to austenite, nitinol is capable of generating movement, which is used by the nitinol nail implant 10 as the working energy to extend its length. The phase transformation from martensite to austenite begins at a defined temperature As and finishes at a defined temperature Af. The reverse transformation from austenite to martensite begins at a defined temperature Ms and finishes at a defined temperature Mf. The phase transformation exhibits hysteretic behavior, and the relationship with temperature is: Mf < As < Ms < Af. The power transmitted by the transmitting coil 30 is controlled by the home care unit 32 to cause resistive heating of the nitinol element and trigger its phase change, which triggers the defined traction rate target of the nitinol nail implant 10.

[0047] Although some embodiments of the present disclosure discuss the use of nitinol alloy actuators, other embodiments are not limited to the use of nitinol materials because other shape memory alloys (SMAs) that change shape in response to heating can be used, and the heating can be obtained by the power provided by inductive coupling as described herein.

[0048] The amount of TWSME movement generated by the alloy is affected by the following factors: 1) prestress, 2) the load applied to the alloy during the phase transformation, and 3) the degree of transformation at the end of the transformation. Prestress is the stress applied to the nitinol alloy in the martensite phase before the phase transformation to austenite to assist the transformation from austenite to martensite.

[0049] The transmitting coil 30 and the home care unit 32 can be configured to convert 50Hz-60Hz, 100V-240V power from a conventional power outlet or battery-powered power into an RF energy transfer signal with a frequency of 258kHz, for example, within a tolerance of + / -4kHz. During energy transfer, the transmitting coil 30 is aligned with the receiving antenna of the inductive power transfer circuit 54. In practice, this means placing the transmitting coil 30 around the patient's thigh near the knee. The energy transfer signal is transmitted via the transmitting coil 30.

[0050] Figure 6 The diagram illustrates a circuit diagram of a receiving antenna, including an inductively linked secondary circuit and a tertiary circuit, according to some embodiments. Its function is to receive power transmitted by the transmitting coil 30 and transmit it to the tertiary circuit. A secondary winding 62, which may be made of copper stranded wire, is wound around the top of the coil frame. A ferrite rod is inserted inside the coil frame to focus the magnetic field through the winding 62. The ferrite rod may also form at least a portion of the coil frame. A capacitor 60 is attached in series with the winding 62 to the end of the coil frame. The entire secondary circuit is encapsulated within a leak-free, seamless glass package. A three-wire (three parallel wires) tertiary winding 64 is wound directly around the top of the glass package. Through coupling with the secondary circuit, the induced current is guided via a biocompatible conductor to the nickel-titanium element (Rt) 66 of the nickel-titanium actuator 52. The tertiary winding 64 may be made of biocompatible silver wire insulated with poly(ethylene ether carbamate). The secondary and tertiary windings, coaxially wound on the ferrite rod, essentially function as a transformer. The current in a three-stage circuit can be specified as a maximum value, such as 14.75A. Therefore, in Figure 6 In this context, the term Cs 60 represents the secondary circuit series resonant slot capacitor, the term Ls represents the secondary circuit winding, the term Lt represents the tertiary winding, and the term Rt represents the resistive load of the nickel-titanium element of the nickel-titanium alloy actuator 52.

[0051] Refer again Figure 5 The nickel-titanium alloy actuator 52 functions by being repeatedly activated in a controlled manner (by heating with an electric current) through nickel-titanium elements. Heating of the nickel-titanium elements causes a change in their shape, which is configured to generate stroke in the axial direction of the nickel-titanium nail implant 10. The nickel-titanium elements (nickel-titanium wires) are heated by conducting current through them for a period of time (e.g., 4 seconds). In one embodiment, a group of nickel-titanium wires are crimped together to form a coordinated active element. These wires are mechanically and electrically parallel in the bundle, resulting in increased actuation performance and reduced resistance compared to a single wire. In another embodiment, the bundle has 7 wires with a diameter of 0.381 mm, with a 20 mm distance between the crimps.

[0052] By heating nickel-titanium above its transformation temperature (approximately 70°C–120°C, depending on the opposite load), a martensitic-to-austenitic phase transformation occurs in the nickel-titanium element, causing the element to contract and generate high forces. The nickel-titanium alloy actuator 52 converts this contraction into radial travel along the nickel-titanium nail implant 10. The contraction of the nickel-titanium element and the resulting travel depend on the opposite load and vary, for example, between 1% and 7% of the linear length. This travel directly pushes the rods of the nickel-titanium nail implant 10 apart via a friction-based unidirectional linear moving locking clutch of the force transmission device 50. When the nickel-titanium cools back to its initial temperature, for example, below the transformation temperature, it returns to the martensitic phase and prepares for another actuation or travel.

[0053] The nickel-titanium element is thermally insulated from the nail frame 56 by, for example, a polymer tube or an air gap, to reduce or prevent direct heat conduction to the implant surface. Shortly after actuation, some degree of localized surface warming occurs near the nickel-titanium element. However, the thermal mass of the nickel-titanium nail implant 10 is sufficient to keep the heating within acceptable limits.

[0054] Figure 5 The force transmission device 50 is used to convert and transmit the repetitive stroke of the nitinol actuator 52 into a step-by-step unidirectional axial extension of the nitinol implant 10. The force transmission device 50 also carries the axial loads applied to the nitinol implant 10. The force transmission includes two friction-based unidirectional linear moving locking clutches (one movable and one fixed) and a square rod. The two locking clutches and the rod form an inchworm-type actuator actuated by the stroke of the nitinol actuator 52. The nitinol actuator 52 is attached to the movable locking clutch. The fixed clutch is attached to the inner tube of the nail frame 56. The square rod is attached to the outer tube of the nail frame 56. When the nitinol actuator 52 is actuated, it forces the movable locking clutch forward, clamps (“locks”) the square rod, and forces it to move through the fixed locking clutch, resulting in the extension of the telescopic nitinol implant 10. Therefore, the nitinol implant 10 extends by a one-minute step distance. In one embodiment, the locking clutch is configured as a stack of 10 identical locking levers, which allows the square rod to move in one direction but prevents movement in the other direction, wherein a small roller is wedged between the surface of the rod and the inclined wall of the locking lever.

[0055] The nail frame 56 includes an inner tube and an outer tube and is used to bear bending and torsional loads (in conjunction with the force transmission device 50) applied to the nitinol nail implant 10, securing it to the treated bone and protecting other implant components from fluid infiltration. The nail frame 56 serves as the outer surface of the nitinol nail implant 10. The nail frame 56 shown has a telescopic outer tube 59A and an inner tube 59B. The nail frame 56 may be formed from a cobalt-chromium alloy, MP35N, ASTM F 562, which is less prone to crevice corrosion. Two locking screws 12 are inserted into the proximal and distal ends of the nitinol nail implant 10 with a centrally lateral orientation. The construction of the locking screws 12 allows for the establishment of stable fixation. The screw fixation is responsible for transmitting the extension of the nitinol nail implant 10 to the separation of the osteotomy space. The portions of the nail frame 56 serve as a housing for the remaining portions of the nitinol nail implant 10 and protect them from fluid infiltration by means of, for example, lip seals or O-rings.

[0056] Figure 7 The illustration shows a portion of a locking screw 12 configured according to one embodiment. The locking screw 12 includes a self-tapping thread for proximal cortex, a hexagonal socket (e.g., 3.5 mm), and internal threads for attachment to a screwdriver to facilitate insertion and external implantation. The locking screw 12 may be made of grade 5 titanium or a cobalt-chromium alloy.

[0057] Figure 8 The diagram illustrates a circuit of a home care unit 32 and a connected transmitting coil 30 according to some embodiments, the transmitting coil being used to transmit power to the inductive power transmission circuit 54 of the nickel-titanium nail implant 10. Reference Figure 8 Wireless power transfer from the transmitting coil 30 to the inductive power transfer circuit 54 is based on resonant inductive power transfer. To achieve power transfer to the nitinol implant 10, the transmitting coil 30 has an AC current (I_pri)w, which in turn generates an AC magnetic field, further enabling wireless power transfer to the nitinol implant 10. The circuit is characterized by the adjustment of power transmission, ensuring that the correct amount of power is transferred to the nitinol implant 10 as long as the implant 10 remains in the area where treatment is possible (this can be indicated to the user by selectively activated LEDs or other visual and / or auditory devices in the transmitting coil 30) and the transmitting coil 30 operates under specified operating conditions, regardless of the position of the nitinol implant 10 within the transmitting coil 30. The position of the receiving antenna of the nitinol implant 10 relative to the transmitting antenna of the transmitting coil 30 can be determined by sensing changes in the impedance of the primary coil of the transmitting coil 30. The magnetic field generated by the transmitting coil 30 is coupled to the receiving antenna of the inductive power transfer circuit 54 and provides the necessary power for the function of the nitinol actuator 52.

[0058] The home care unit 32 includes at least one processor circuit (“processor”) that executes program instructions from at least one memory, and may also include a removable memory module port (e.g., an SD card slot) that can be used to provide instructions to the processor to switch the device between surgeon mode and patient mode. Differences between modes may include: patient mode having time limits, such as 20 minutes between activations; and surgeon mode having time limits, such as 10 minutes between activations. The daily limit for activations may be, for example, 10 times in patient mode and, for example, 30 times in surgeon mode. The surgeon mode is intended to facilitate more efficient use in operating rooms and hospital settings.

[0059] The extension protocol software 40 can be a web-based application designed for planning and tracking traction osteogenesis treatments using a nickel-titanium nail system. The software 40 is used by orthopedic surgeons in conjunction with the nickel-titanium nail system for traction osteogenesis treatments. Additionally, the software includes management modes where the user (surgeon) and the implant can be managed. In one embodiment, there is no direct interface between the software 40 and other parts of the nickel-titanium nail system. However, the software 40 receives critical implant information required for algorithmic operation, as well as other key information such as expiration dates. Key information includes individually measured performance characteristics and the maximum extension amount for each nickel-titanium nail implant. Furthermore, the software 40 allows for the assignment of implants to specific surgeons, minimizing the risk of selecting the wrong nickel-titanium nail implant.

[0060] In various implementations, the software 40 can operate to generate periodic traction plans to meet the surgeon's target traction rate (mm / day). The software 40 uses patient tags in the patient diary as input, taking into account the extensions performed (measured from X-rays or other measuring devices within the nickel-titanium nail implant 10) and the number of activations performed in the previous control cycle. Based on this information, along with information provided by the surgeon, the software 40 calculates the treatment plan for the next cycle (typically one week), targeting the surgeon-provided target traction rate. Additionally, the software 40 provides a printable patient diary automatically created based on the calculated plan, providing patients with an easy means of following prescriptions and tracking performed activations. The entire treatment, with all events, is saved to the software 40, allowing the surgeon to review treatment progress and edit incorrect data. Once treatment is complete, a summary table including all key information from the treatment can be printed and stored in the patient record. The software 40 can provide a surgeon mode that allows for the planning and control of treatment, as well as a management mode that allows for the addition of surgeon, implant, and other management functions. The algorithm logic of software 40 can be used to adjust the number of activations per day based on previous extension measurements, which can be measured by X-ray analysis.

[0061] Therefore, in some embodiments, the processor is configured to control the power supply of the home care unit 32 to provide a controlled current level to the transmitting coil 30 (inductive power coil). In another embodiment, the processor is configured to control the power supply via a power conversion unit to provide a controlled current level to the transmitting coil 30 for a first defined duration sufficient to transition the shape memory alloy element from a first phase to a second phase with a corresponding shape change, and thereafter prevent the power supply from providing the controlled current level to the transmitting coil 30 for at least a second defined duration sufficient to transition the shape memory alloy element from the second phase to the first phase with a corresponding inverted shape change. In another embodiment, the home care unit 32 includes a network interface configured to communicate via a communication network. The processor is configured to generate a patient treatment diary that tracks the time of day each time the power supply is controlled to transition the shape memory alloy element from the first phase to the second phase with a corresponding shape change, and to transmit the patient treatment diary via the network interface to a remote network server, such as one monitored by a surgeon. In yet another implementation, the processor is configured to receive a predetermined activation schedule via a network interface and control the power supply to provide a controlled current level to the transmitting coil 30 according to the predetermined activation schedule.

[0062] Exemplary configurations of various components of the nickel-titanium nail implant 10 are now described according to some implementation schemes.

[0063] As described above and referenced Figure 3 and Figure 5 The transmitting coil 30 is powered to provide wireless power transfer to the inductive power transfer circuit 54 via inductive coupling. The inductive power transfer circuit 54 provides current through the nitinol actuator 52 to resistively heat the nitinol element. Heating causes the nitinol element to generate a TWSME (Transient Wound Scale), and the TWSME actuates a lever (“push rod”) to move the clutch and force transmission device 50, thereby moving the telescopic outer tube 59A relative to the telescopic inner tube 59B. If the nitinol element is allowed to cool sufficiently, continuous inductive activation will cause the push rod to move back and forth repeatedly.

[0064] The force transmission device 50 includes a one-way linear movement locking clutch connected to the nitinol actuator 52 via a push rod of the nail frame 56. The TWSME movement of the nitinol actuator 52 causes the one-way linear movement locking clutch to move. In some embodiments, when the clutch moves, it engages a square rod. This results in a certain amount of elastic recoil, which depends on the external load and reduces the actuation amount achievable by the telescopic stepper motor function of the nitinol actuator 52. The square rod, in turn, moves via another linear one-way linear movement locking clutch fixed to the frame of the force transmission device 50. The square rod is attached to the outer tube and the clutch. The forward and backward movement of the TWSME movement of the nitinol actuator 52 causes the telescopic portion to move and increase its length. When the TWSME movement of the nitinol actuator 52 reverses during cooling to shorten it, the one-way linear movement locking clutch engages in the locking direction, preventing the nitinol nail implant 10 from shortening, except for elastic recoil due to loading.

[0065] Figure 9 The diagram illustrates a simplified structural representation of a nickel-titanium alloy actuator 52 according to some embodiments. Based on the original shape memory of the shape memory alloy, the actuator is in an inactive expanded state (left) and an active contracted state (right), or vice versa. As described above, the nickel-titanium alloy actuator 52 operates via a TWSME transformation of a nickel-titanium element 94. The nickel-titanium element 94 is configured to undergo a TWSME transformation when excited by a transmitting coil 30 via a current supplied by an inductive power transmission circuit 54. When the actuator 52 is inactive, the nickel-titanium element 94 is in the martensitic (cold) phase and expands in this phase. While in the martensitic phase, a prestressed spring 96 is used to apply prestress to the nickel-titanium element 94, for example, to aid in the expansion (elongation) of the element 94. The purpose of the prestress is to increase the actuating properties of the nickel-titanium alloy material of the nickel-titanium element 94 and to assist in the transformation from the austenitic (hot) phase back to the martensitic phase. Heating nickel-titanium alloys above the austenite initiation temperature (As) triggers a transformation from martensite to austenite. Once the austenite termination temperature (Af) is reached, the nickel-titanium alloy is entirely in austenitic form, and the nickel-titanium alloy element 94 is in a contracted state. Figure 9 (Right side) or vice versa, depending on the original shape memory of the shape memory alloy. When the nickel-titanium alloy material begins to cool and reaches the martensite initiation (Ms) temperature, it begins to transform back into the martensite phase. This transformation is completed at the martensite termination (Mf) temperature, whereby the nickel-titanium element 94 is in an expanded state ( Figure 9 (Left side), or vice versa, depending on the original shape memory of the shape memory alloy.

[0066] exist Figure 9 In this configuration, the nitinol element 94 can be at least one bundle of individual wires or rods made of nitinol or any other shape memory alloy. The bundles of individual wires or rods are electrically connected in series or in parallel and mechanically arranged in parallel, thereby providing the sum of the contractile forces of each individual wire or rod through the contractile force of its phase change.

[0067] Figure 10 The figure illustrates the effect of hysteresis on the transformation temperature of nickel-titanium alloy materials used in some embodiments of this disclosure. Nickel-titanium alloy materials exhibit hysteresis at transformation temperature, meaning that the material must be cooled further than the austenite initiation temperature to fully transform back to martensite. This can be an important design factor when selecting the correct nickel-titanium composition to achieve good operation inside the human body, where the minimum normal operating temperature is approximately 37 degrees Celsius.

[0068] The transformation from martensitic to austenitic phase results in a decrease in the length of the nitinol wire used in the nitinol element 94, or vice versa, to increase its length, depending on its original shape memory. This increased length is used to generate the output stroke of the actuator 52, such as... Figure 9 The length variation Δ-L is shown. Elements 90 and 91 are fixed structures that can be connected to the telescopic outer tube 59A or the inner tube, and are connected to the telescopic actuator component 59B. Element 92 is a movable structure that causes the push rod 98 to move through the alternation of phases, via the expansion and contraction of the nitinol element 94. The push rod 98 is connected to a force transmission device 50 including a one-way linear movement locking clutch. The repeated expansion and contraction of the nitinol element 94 causes the outer tube 59A to gradually extend away from the inner tube 59B. When the nitinol element 94 expands after actuation during cooling, the one-way linear movement locking clutch of the force transmission device 50 substantially prevents the contraction movement of the outer tube 59A relative to the inner tube 59B.

[0069] The nitinol wires in the nitinol element 94 are heated to their transformation temperature by an electric current within seconds. Afterward, the wires are allowed to cool down and return to the martensitic state with the aid of a prestressed spring. During length changes, the nitinol element 94 is also capable of generating a force proportional to the surface area of ​​the element 94. The nitinol actuates against external loads regardless of load size. However, the size of the load affects the output stroke of the nitinol. Figure 9 The Δ-L and fatigue life are related. Generally speaking, the higher the external load and the shorter the stroke, the shorter the maximum cycle life. At a load level of 170MPa, the cycle life can be several million cycles (depending on the design), while when using a load level of 400MPa-500MPa, the cycle life drops to several thousand cycles.

[0070] The prestress level caused by the prestressed spring 96 affects the transition temperature, output stroke, and fatigue life. Generally, higher prestress results in higher transition temperature and output stroke, but a slight decrease in fatigue life. Commercial NiTiNO actuator alloy manufacturers generally recommend a prestress level of 50MPa-70MPa as the criterion for optimal performance. The effective output force of the actuator can be calculated as follows:

[0071] F(sma_act_out) = F(design_stress) - F(prestress) = P(design) * AP(prestress) * A

[0072] Figure 11 The illustration shows a cross-sectional view of a unidirectional linear movement locking clutch of a force transmission device 50 configured according to some embodiments. (Reference) Figure 11 The one-way linear movement locking clutch uses friction-based operation to allow only unidirectional movement of the square rod 110, which is connected by push rod 98. Figure 9 Movement. The one-way linear movement locking clutch can be operated with different locking levers. Figure 11 In the image, moving the square lever 110 upwards allows it to move freely with a certain amount of friction. In stark contrast, pushing the square lever 110 downwards causes the clutch to lock and generates a backlash. Pushing the locking lever 112 downwards allows it to move freely with a certain amount of friction, while pulling the locking lever 112 upwards causes the clutch to lock and generates a backlash.

[0073] According to some implementations, a friction-based unidirectional linear movement locking clutch is a device comprising at least three components that generate a locking action based on friction-driven wedging. Figure 12The diagram illustrates a side view of a one-way linear movement locking clutch having a roller 114 that moves along an angle ring 120 to engage a square rod, allowing movement in the free direction while preventing movement in the locking direction, and configured according to several embodiments. The components of the one-way linear movement locking clutch include an angle ring 120 with an inclined surface, roller 114, and square rod 110. A flat spring may be used to hold roller 114 in contact with square rod 110 and angle ring 120 (in all cases) and a roller baffle 122 to prevent system blockage.

[0074] Therefore, in some embodiments, the one-way linear movement locking clutch of the force transmission device 50 includes a lever (e.g., Figure 9 92 and 98 in Figure 11 (e.g., 110 in the example), the rod is connected to the shape memory alloy actuator 52. At least one ring device includes a corner ring and a roller, the corner ring surrounding the square rod and a portion of the corner ring having an inclined surface facing the rod, the roller being positioned between the inclined surface and the rod. When the shape memory alloy element transitions from one phase to another, it causes the inner tube 59B to retract into the outer tube 59A, and friction causes the roller to roll on the slab surface, thereby wedging itself between the slab surface and the rod and preventing the inner tube 59B from retracting into the outer tube 59A.

[0075] Key material parameters for limiting recoil are the material's hardness and elastic modulus. To prevent damage under high external loads, the material's yield strength and hardness are also important parameters. Additionally, increasing the contact surface area between components can reduce recoil and increase maximum load-bearing capacity. This can be achieved, for example, by increasing the number of locking levers used.

[0076] In principle, the recoil is reduced by 1 / N, where N is the number of locking levers in the system. Increasing the length of roller 114 in the system produces a similar effect and is affected by the non-idealities caused by the non-uniform contact surfaces between roller 114, corner ring 120, and square bar 110. When the number of locking levers is increased, the load-bearing capacity of the system increases approximately by N times.

[0077] Furthermore, the chosen locking angle affects recoil. A larger locking angle α results in less recoil. However, increasing the angle too high will cause the system to slip in the locking direction instead of locking completely. Environmental factors must also be considered when selecting the locking angle, as factors that may alter the coefficient of friction in the system will also change the required locking angle. An angle value of 8-12 degrees is typically used. When the square rod 110 moves in the free direction ( Figure 11 Upward, and Figure 12(From center to right), roller 114 disengages from the wedge position, and square rod 110 can move freely. Friction is generated in this situation, primarily due to the normal force generated on the roller as the planar spring holds roller 114 in contact with the corner ring.

[0078] The higher the spring force, the higher the friction. From a recoil perspective, a high spring force is beneficial because it increases the load on roller 114 against the two opposing surfaces. Without load, roller 114 forms line contact with each opposing surface, and as the load increases, the contact area increases rapidly, thus the recoil behavior is not linear. The initial loading step generates the greatest recoil, and this can be partially offset by the preload caused by the planar spring.

[0079] As described above, when the nitinol element 94 retracts to generate the output stroke of the push rod 98, the telescopic stepper motor function of the nitinol actuator 52 is actuated. Actuation of the push rod 98 pushes the clutch, which moves the square rod 110. Once the stroke of the nitinol actuator 52 is complete, the unidirectional linear moving locking clutch slides relative to the square rod 110 and the moving clutch returns to its original position pulled by the nitinol actuator 52. During actuation, for the duration of the output stroke generated by the nitinol actuator 52, the external load is initially transferred from the stationary clutch to the moving clutch. Once the stroke is complete and the nitinol actuator 52 begins to retract, the external load is transferred back to the stationary clutch.

[0080] The step size of the nickel-titanium alloy actuator 52 is given by the following equation: ΔL = ΔL(SMA_act) - L(recoil), where L(recoil) = the sum of the recoil of the moving and stationary clutches, which is approximately twice the recoil of a single clutch in the case of two identical clutches.

[0081] The generated force output is given by the following equation: F(out) = F(sma_act_out) - F(friction force), where F(friction force) = the sum of the friction forces of the clutch and other sliding structures of the telescopic stepper motor. After initial actuation, the system is ready to actuate again after a proper cooling time, which allows the nickel-titanium alloy actuator 52 to reset.

[0082] Post-actuation extension is an operation that allows the telescopic stepper motor function of the nickel-titanium alloy actuator 52 to retain its length after actuation. This is due to the elastic property of recoil in the friction-based one-way clutch. If the external load on the telescopic stepper motor decreases after actuation, the recoil of the stationary clutch will decrease, and the telescopic stepper motor will retain the same length. The maximum length retained is due to the complete recoil caused by the external load.

[0083] The actuation of the stepper motor depends not only on the external load but also on the loading history of that load. The first actuation performed after increasing the external load from zero to a desired load is called a ramp actuation. The second activation under the same load is called a dwell activation. Dwell actuation is shorter (smaller actuation step size) than ramp actuation, and all subsequent actuations after the first dwell actuation have the same size if actuation continues under the same external load without additional loading or unloading steps. The variation in actuation length is due to the complex combination of loading / unloading of the friction-based unidirectional linear moving locking clutches and the external load transmitted through them to the nickel-titanium alloy actuator 52. The difference between ramp and dwell actuation becomes larger as the external load increases.

[0084] A third actuation category, clinical performance actuation, has been defined, and the history of the most likely load scenarios in clinical use is presented. This load scenario simulates variations in external load caused by the load on the treated leg and the contraction and relaxation of muscles between actuations. This is defined as 1) initially increasing the compressive load to 300N higher than the desired actuation force, 2) then reaching a lower compressive force of 100N, 3) then returning to a higher compressive load of 300N, and 4) finally reaching the desired actuation external load and actuating the stepper motor. Clinical performance actuation lies between dwell actuation and ramp actuation.

[0085] The actuation length of a stepper motor decays during its use. This is due to TWSME fatigue of the nitinol in the nitinol actuator 52. Fatigue depends on the external load, prestress, number of actuations, and actuation temperature of the nitinol. Fatigue must be considered when constructing a stepper motor to meet requirements. Cyclic external loads on a stepper motor cause a slight backlash (shortening). Backlash is a function of load cycles and is attributed to elastic and plastic deformation in the friction-based unidirectional linear movement locking clutch and other components of the stepper motor structure.

[0086] Figure 13 Two views of another nickel-titanium screw femoral lengthening implant 130 configured according to some embodiments are illustrated. The top view of the nickel-titanium screw implant 130 corresponds to the nominal initial length before extension of the inner tube 132 from within the outer tube 134 is performed via alternating activation and deactivation. The bottom view of the nickel-titanium screw implant 130 corresponds to the maximum length of extension after extension of the inner tube 132 from within the outer tube 134 is performed via alternating activation and deactivation. The lengthening capacity of the nickel-titanium screw implant 130 is illustrated as the difference between the maximum length (bottom view) and the nominal initial length (top view). Although various embodiments are illustrated and described in the context of the inner tube 132 and outer tube 134 having circular cross-sections, these and other embodiments are not limited thereto and may have any cross-sectional shape, such as elliptical, rectangular, square, etc.

[0087] Figure 14 The diagram illustrates a construction based on some implementation schemes. Figure 13 Two longitudinal sectional views of the nickel-titanium nail implant 130. (Reference) Figure 14 The top view shows a longitudinal sectional view of the entire nickel-titanium nail implant 130. The bottom view shows an enlarged view between points B and C, with the housing (frame) removed to allow viewing of the components of the nickel-titanium nail implant 130. These components include a force transmission device 140, a nickel-titanium alloy actuator 142, and an inductive power transmission circuit 144.

[0088] Depend on Figure 14 The nickel-titanium nail implant 130 offers potential advantages, including, for example, that the curved axis of the outer tube 134 can more easily conform to a hollow opening formed in curved bone, such as the femur. In some embodiments, the inner tube 132 and the outer tube 134 are curved along their length to closely conform to an opening formed in the bone for implantation. For example, as Figure 5 As shown, when compared to using another implant with a straight bar, a curved bar can therefore allow an implant with a larger nominal diameter to be inserted into the curved bone. Alternatively or additionally, when compared to using another implant with a straight bar, a curved bar can allow less bone to be hollowed out to receive the implant.

[0089] refer to Figure 14 An inductive power transmission circuit 144 is connected to one of the outer tube and the inner tube, and is at least partially located within one of the outer tube and the inner tube (e.g., illustrated as located within the inner tube 132), and is configured to receive power via inductive coupling to a transmitting coil 30 (e.g., an external power coil). A nitinol actuator 142 (e.g., or other shape memory alloy actuator) is connected to one of the outer tube and the inner tube, and is at least partially located within one of the outer tube and the inner tube (e.g., illustrated as located within the inner tube 132). The nitinol actuator 142 includes a nitinol element 148 (e.g., or other shape memory alloy element) electrically connected to be powered by the inductive power transmission circuit 144. The nitinol actuator 142 is configured to respond to threshold resistance heating (e.g., as... Figure 10(As shown) the transformation from a first phase to a second phase with a corresponding shape change (e.g., from austenitic to martensitic phase). The force transmission device 140 includes a one-way linear movement locking clutch 170 connected to the nickel-titanium alloy actuator 142 and slidably connected to the other of the outer and inner tubes (e.g., illustrated as outer tube 134). The one-way linear movement locking clutch 170 is configured to convert the shape change of the nickel-titanium alloy element 148 into the extension of the inner tube 132 from within the outer tube 134 by the transformation from one of the first and second phases to the other (e.g., from austenitic to martensitic or vice versa), and to prevent the inner tube 132 from retracting into the outer tube 134 when the nickel-titanium alloy element 148 transforms from the other of the first and second phases to the first and second phases (e.g., from martensitic to austenitic or vice versa).

[0090] exist Figure 14 and Figure 15 In the illustrated embodiment, a prestressed spring 146 is attached between a nickel-titanium alloy element 148 and a force transmission device 140, and is configured to apply tension to the nickel-titanium alloy element 148 to facilitate the elongation of the nickel-titanium alloy element 148 when the element transforms from one of the first and second phases to the other (e.g., from a martensitic phase to an austenitic phase or vice versa).

[0091] Figure 17A illustrates an isometric view of a component 172 forming part of a one-way linear movement locking clutch 170 configured according to some embodiments. Figure 17B illustrates a cross-sectional view of a pair of assembled components 172 forming a one-way linear movement locking clutch 170 configured according to some embodiments. In the illustrated embodiments, each component 172 of the one-way linear movement locking clutch 170 includes a set of stacked corner rings 120 and associated rollers, balls, spheres, or cylinders 114, for example, 10.

[0092] In one embodiment, the one-way linear movement locking clutch 170 of the force transmission device 140 includes at least one ring assembly comprising an angle ring 120 and a roller 114. At least a portion of the angle ring 120 has an inclined surface facing the inner surface of the other of the outer and inner tubes (e.g., illustrated as outer tube 134), and the roller is positioned between the inclined surface and the inner surface of the other of the outer and inner tubes (e.g., outer tube 134). When the nickel-titanium alloy element 148 transforms from one of the first and second phases to one of the first and second phases (e.g., from martensitic phase to austenitic phase or vice versa), this causes a forward-pushing clutch to contract, clamping the inner surface of the outer tube and then extending the sleeve. In the illustrated embodiment, the one-way linear movement locking clutch 170 includes a plurality of ring assemblies and a rod 176 extending through a central opening of the angle ring 120 of the plurality of ring assemblies to arrange the angle ring 120 along the long axis of one of the outer and inner tubes. Rod 176 is attached to nickel-titanium alloy actuator 142.

[0093] In the embodiment shown in FIG17A, the ring device includes a plurality of surface recesses 174 in the corner ring 120, the surface recesses being circumferentially spaced around the corner ring 120 and having inclined surfaces, and a plurality of rollers 120 being positioned in different surface recesses of the surface recesses 174.

[0094] The roller can be a spherical, cylindrical, or other shape that can be moved by friction to provide the unidirectional linear movement locking clutch described herein.

[0095] The one-way linear movement locking clutch 170 is configured to convert the shape change of the nickel-titanium alloy element 148 (e.g., a shape memory alloy element) into the extension of the inner tube 132 from the outer tube 134 by the transition from the first phase to the second phase (e.g., when the transition is from the austenitic phase to the martensite phase or vice versa) and to prevent the inner tube 132 from retracting into the outer tube 134 when the nickel-titanium alloy element 148 transitions from the second phase to the first phase (e.g., when the transition is from the martensite phase to the austenitic phase or vice versa).

[0096] The surface of the corner ring 120 is inclined relative to the outer tube 134, thereby pushing the rod 176 in the locking direction (movement of rod 176 to the left in Figure 17B) to cause the roller 114 to wedge between the inner surfaces of the corner ring 120 and the outer tube 134. The angle value required to lock the roller 114 is based on the coefficient of friction between the materials used in the structure. When locking occurs, the external force applied to the rod 176 generates recoil in the system. The recoil is caused by the elastic properties of the materials.

[0097] Figure 15 Provided Figure 14 An enlarged view of a nickel-titanium alloy actuator 142 shown in the figure and configured according to some embodiments. (See reference...) Figure 14 The nickel-titanium alloy actuator 142 includes a nickel-titanium alloy element 148 and a prestressed spring 146.

[0098] The nickel-titanium alloy actuator 142 includes a plurality of nickel-titanium alloy rods 150 (e.g., or other rod-shaped shape memory alloy elements) extending between a first member 149A and a spaced-apart second member 149B. The first member 149B is connected to and at least partially located within one of the outer and inner tubes (e.g., illustrated as being within the inner tube 132). The rods may have a circular cross-section, an elliptical cross-section, a square cross-section, or other shapes. The second member 149A is connected to a one-way linear movement locking clutch 170 of a force transmission device 140, for example, the force transmission device being connected to the clutch via a rod extending through a prestressed spring. Figure 14 and Figure 15 As shown, the prestressed spring is supported by the abutment tube 149.

[0099] The nickel-titanium alloy rod 150 comprises a nickel-titanium alloy of nickel and titanium. The nickel-titanium alloy actuator 142 may include a plurality of resilient rods 152 extending between a first member 149A and a second member 149B, such as a metal or other elastic material of sufficient strength. The resilient rods 152 may be arranged alternately with the nickel-titanium alloy rod 150. The first member 149A and the second member 149B may include clamps with openings configured to receive and securely clamp to the opposite ends of the resilient rods 152 and the nickel-titanium alloy rod 150.

[0100] The prestressed spring 146 may be attached between the second member 149B and the force transmission device 140 and is configured to apply tension to the nickel-titanium alloy rod 150 to promote the elongation of the nickel-titanium alloy rod 150 during the transition from the second phase to the first phase (e.g., when the transition is from the martensitic phase to the austenitic phase or vice versa).

[0101] As mentioned above, wireless power transfer in the nickel-titanium nail system is based on resonant inductive power transfer. Figure 18 The diagram illustrates a circuit diagram of wireless power transfer functionality according to some implementation schemes. See also... Figure 18An AC signal is fed into the primary LC circuit (L_pri and C_pri). At the resonant frequency, the reactive components of C_pri and L_pri cancel each other out, essentially reducing the impedance of the primary circuit to R_pri. The current in the inductor L_pri induces an AC magnetic field at the resonant frequency of the LC circuit. The generated magnetic field couples to the secondary circuit (k_12), which consists of a resonant circuit tuned to a specific frequency. This coupling induces a current, which further generates a magnetic field opposite to the one generated by the primary circuit. The secondary circuit is further coupled to the tertiary circuit (k_23) via the generated magnetic field, thereby inducing a current in the tertiary circuit. The induced current in the tertiary circuit causes the nickel-titanium wire (R_nickel-titanium) to heat up. The primary magnetic field is also directly coupled to the tertiary circuit (k13) and the metal casing (k_14) of the nickel-titanium nail implant 10. The coupling with the metal casing causes eddy currents in the metal tube of the implant 10, which leads to an increase in its temperature (loss).

[0102] The performance of a power transmission system largely depends on selecting the correct values ​​for each component. Furthermore, deviations from nominal values ​​can significantly impact overall performance. Therefore, specific parameters in the control circuitry are necessary. Assuming some inherent variations in all components, overall system performance optimization includes 1) performance optimization (efficiency P_tert / P_pri) and 2) robustness optimization. The latter involves designing the circuitry so that the system's performance is insensitive to specific individual parameters. Additionally, this design needs to consider limitations imposed by factors such as patient safety settings (high voltage, magnetic field strength, etc.), component limitations (rated voltage and current of C_sec, etc.), and physical size constraints.

[0103] The selection of components in the primary winding essentially determines the operating frequency of the entire power transfer system. The inductance of the primary winding (L_pri) and the current I_pri flowing within it correspondingly determine the strength of the generated magnetic field. The number of turns and cross-sectional area of ​​the primary winding are also important design parameters. Furthermore, the value of R_pri determines the resistive losses in the primary winding and, together with L_pri, determines the Q value of the primary circuit.

[0104] The combination of the secondary and tertiary stages needs to be designed so that it resonates at a meaningful frequency relative to the primary magnetic field. This frequency is not necessarily exactly equal to the operating frequency of the primary stage. In the receiving circuit (secondary and tertiary stages), losses (excluding the expected losses in NiTi) are mainly caused by resistive losses in the secondary stage (R_sec), resistive losses in the tertiary stage (R_wire), eddy current losses in the tube, and losses in the ferrite. To control the losses in NiTi, these losses also need to be controlled.

[0105] The positions between the primary and secondary windings are not fixed. Therefore, the coupling k_12 changes significantly as the NiTi implant 10 (i.e., the inductive power transfer circuit 54) moves within the primary coil of the transmitting coil 30. Generally, better coupling is achieved near the edges of the primary coil. Correspondingly, worse coupling is achieved at the center of the coil. Without compensation, the changing coupling results in significantly different currents across the three stages. The home care unit 32 can observe the coupling k_12 as a change in the ratio of V_DC, I_DC, and R_DC. Higher coupling increases the load on the buck converter, and correspondingly, lower coupling reduces the load. Minimal R_drop is observed when there is no load in the primary winding. The relationship between coupling and R_drop can be used to compensate for the current transferred to the NiTi load. At the highest coupling (high R_drop), I_drop can be reduced, while at the lowest coupling, I_drop can be increased to achieve a current close to the nominal value in the NiTi load.

[0106] Figure 16 The illustration shows a cross-sectional view of an inductive power transmission circuit 142 constructed according to some embodiments. The inductive power transmission circuit 142 includes a secondary coil 160 and a tertiary coil 162 wound around a ferrite rod 164 and further inductively coupled through the ferrite rod. These components are encapsulated in a sealed or other type of leak-proof capsule 166 to prevent contamination of the inductive power transmission circuit 142 by bodily fluids.

[0107] Further definitions and implementation plans:

[0108] In the above description of various embodiments of the inventive concept, it should be understood that the terminology used herein is for describing particular embodiments only and is not intended to limit the inventive concept. Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which the inventive concept pertains. It should also be understood that terms such as those defined in common dictionaries should be interpreted as having the meaning consistent with their meaning in the context of this specification and the relevant field, and should not be interpreted in an idealized or overly formal sense unless expressly defined herein.

[0109] When an element is referred to as “connection,” “link,” “response,” or a variation thereof to another element, the element may be directly connected, linked, or responsive to the other element, or an intermediary element may be present. Conversely, when an element is referred to as “direct connection,” “direct link,” “direct response,” or a variation thereof to another element, no intermediary element is present. Throughout this document, the same numbers refer to the same elements. Furthermore, as used herein, “connection,” “link,” “response,” or variations thereof may include wireless connections, links, or responses. As used herein, the singular forms “a,” “an,” and “the” are intended to also include the plural forms unless the context clearly indicates otherwise. For the sake of brevity and / or clarity, well-known functions or constructions may not be described in detail. The term “and / or” includes any and all combinations of one or more of the associated listed items.

[0110] It should be understood that although the terms "first," "second," "third," etc., may be used herein to describe various elements / operations, these elements / operations should not be limited by these terms. These terms are only used to distinguish one element / operation from another. Therefore, without departing from the teachings of the inventive concept, a first element / operation in some embodiments may be referred to as a second element / operation in other embodiments. Throughout the specification, the same reference numerals or the same reference indicators denote the same or similar elements.

[0111] As used herein, the terms “comprising,” “including,” “having,” or variations thereof are open-ended and include one or more of the stated features, integers, elements, steps, components, or functions, but do not exclude the presence or addition of one or more other features, integers, elements, steps, components, functions, or groups thereof. Furthermore, as used herein, the common abbreviation “eg,” derived from the Latin phrase “exempli gratia,” may be used to introduce or specify one or more general examples of previously mentioned items and is not intended to limit such items. The common abbreviation “ie,” derived from the Latin phrase “id est,” may be used to specify a particular item from a more general description.

[0112] This document describes exemplary embodiments with reference to block diagrams and / or flowcharts illustrating computer-implemented methods, apparatus (systems and / or devices), and / or computer program products. It should be understood that the blocks in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented by computer program instructions executable by one or more computer circuits. These computer program instructions can be provided to processor circuits of general-purpose computer circuits, special-purpose computer circuits, and / or other programmable data processing circuits to produce a machine such that instructions executed via a computer and / or other programmable data processing apparatus transform and control transistors, values ​​stored in memory locations, and other hardware components within such circuits to implement the functions / actions specified in the block diagrams and / or one or more flowchart blocks, thereby creating means (functions) and / or structures for implementing the functions / actions specified in the block diagrams and / or flowchart blocks.

[0113] These computer program instructions can also be stored in a tangible computer-readable medium, which can instruct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable medium produce an article of writing containing instructions that implement the functions / actions specified in block diagrams and / or one or more flowchart blocks. Therefore, embodiments of the inventive concept can be embodied in hardware and / or software (including firmware, resident software, microcode, etc.) that runs on a processor such as a digital signal processor, which can be collectively referred to as a "circuit," a "module," or variations thereof.

[0114] It should also be noted that in some alternative embodiments, the functions / actions indicated in the boxes may not occur in the order shown in the flowchart. For example, two boxes shown consecutively may actually be executed substantially simultaneously, or these boxes may sometimes be executed in reverse order, depending on the functions / actions involved. Furthermore, the function of a given box in the flowchart and / or block diagram may be divided into multiple boxes, and / or the functions of two or more boxes in the flowchart and / or block diagram may be at least partially integrated. Finally, without departing from the scope of the inventive concept, other boxes may be added / inserted between the shown boxes, and / or boxes / actions may be omitted. Moreover, although some illustrations include arrows on communication paths to indicate the main communication direction, it should be understood that communication may occur in the direction opposite to the depicted arrows.

[0115] Many variations and modifications may be made to the embodiments without substantially departing from the principles of the inventive concept. All such variations and modifications are intended to be included within the scope of the inventive concept herein. Therefore, the subject matter disclosed above should be considered illustrative rather than restrictive, and the appended examples of embodiments are intended to cover all such modifications, enhancements, and other embodiments that fall within the spirit and scope of the inventive concept. Thus, to the fullest extent permitted by law, the scope of the inventive concept will be determined by the broadest permissible interpretation of this disclosure, including the following examples of embodiments and their equivalents, and should not be limited or restricted by the foregoing detailed description.

Claims

1. An implantable bone traction device, comprising: outer tube; An inner tube, which is at least partially disposed within the outer tube; An inductive power transmission circuit is connected to one of the outer tube and the inner tube, and is at least partially located within one of the outer tube and the inner tube, and is configured to receive power via inductive coupling to an external power coil; A shape memory alloy actuator, the shape memory alloy actuator being connected to one of the outer tube and the inner tube and being at least partially located within one of the outer tube and the inner tube, the shape memory alloy actuator including a shape memory alloy element electrically connected to be powered by the inductive power transmission circuit, the shape memory alloy element being configured to transition from a first phase to a second phase in response to threshold resistance heating and having a corresponding shape change; as well as A force transmission device includes a one-way linear movement locking clutch connected to the shape memory alloy actuator and slidably connected to another of the outer tube and the inner tube. The one-way linear movement locking clutch is configured to convert a shape change of the shape memory alloy element into an extension of the inner tube from within the outer tube by transitioning from one of the first phase and the second phase to the other, and to prevent the inner tube from retracting into the outer tube when the shape memory alloy element transitions from the other of the first phase and the second phase to the first of the first phase and the second phase. The one-way linear movement locking clutch of the force transmission device includes: A plurality of ring devices, each of the ring devices including an angle ring and a roller, at least a portion of the angle ring having an inclined surface relative to and facing the inner surface of the other of the outer tube and the inner tube, the roller being positioned between the inclined surface and the inner surface of the other of the outer tube and the inner tube; and A rod extending through the central opening of the corner ring of the plurality of ring devices, arranging the corner ring along the long axis of one of the outer and inner tubes, the rod being attached to the shape memory alloy actuator. When the shape memory alloy element transforms from one of the first phase and the second phase to one of the first phase and the second phase, it causes the inner tube to retract into the outer tube, and friction causes the roller to roll on the inclined surface, thereby wedging between the inclined surface and the inner surface of the other of the outer tube and the inner tube and preventing the inner tube from retracting into the outer tube.

2. The implantable bone traction device of claim 1, wherein the unidirectional linear movement locking clutch is configured to convert the shape change of the shape memory alloy element into the extension of the inner tube from the outer tube by the transition from the first phase to the second phase, and to prevent the inner tube from retracting into the outer tube when the shape memory alloy element transitions from the second phase to the first phase.

3. The implantable bone traction device according to claim 1, wherein the shape memory alloy actuator further comprises: A prestressed spring, coupled between the shape memory alloy element and the force transmission device, and configured to apply tension to the shape memory alloy element to facilitate the elongation of the shape memory alloy element during transition from the other of the first phase and the second phase to the first of the first phase and the second phase.

4. The implantable bone traction device of claim 1, wherein the ring device includes a plurality of surface recesses located in the corner ring, the plurality of surface recesses being circumferentially spaced around the corner ring and having the inclined surface, and a plurality of rollers positioned in different surface recesses of the surface recesses.

5. The implantable bone traction device according to claim 1, wherein the roller comprises: One of a sphere and a cylinder.

6. The implantable bone traction device according to claim 1, wherein the unidirectional linear movement locking clutch of the force transmission device comprises: A first rod, which is connected to the shape memory alloy actuator; as well as At least one ring device, the at least one ring device comprising an angle ring and a roller, the angle ring surrounding a second rod and a portion of the angle ring having an inclined surface facing the rod, the roller being positioned between the inclined surface and the rod. When the shape memory alloy element changes from one of the first phase and the second phase to one of the first phase and the second phase, this causes the locking clutch to engage with the first rod, thereby causing the implantable bone traction device to move and extend.

7. The implantable bone traction device according to claim 1, wherein the shape memory alloy actuator comprises: A plurality of rod-shaped shape memory alloy elements extend between a first member and a spaced-apart second member, the first member being connected to one of the outer tube and the inner tube and at least partially located within one of the outer tube and the inner tube, and the second member being connected to the unidirectional linear movement locking clutch of the force transmission device.

8. The implantable bone traction device according to claim 7, wherein the rod-shaped shape memory alloy element comprises a nickel-titanium alloy.

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