Impactor

Abstract

An orthopaedic impactor is disclosed that includes a strike assembly arranged to apply a force to an object; and a winding arranged to receive an electric current and thereby generate a magnetic field. The winding is arranged to interact with the strike assembly such that, in use, the magnetic field generated by the winding causes the strike assembly to move so as to apply a force to the object.

Description

[Technical field]

[0001] The present invention relates to impactors, particularly orthopedic impactors, and to methods of using and calibrating impactors. [Background technology]

[0002] There are many situations in which it is desirable to fasten two objects together. One way to do this is to use an impactor that induces a force on a first object to drive it into (or pull it out of) a second object. Such impactors can be used, for example, in orthopedic procedures, such as total hip arthroplasty (THA), which require an implant to be fastened to bone. Traditional THA procedures use a press fit to fasten an implant to a pelvic bone. Specifically, a cavity is created in the pelvic bone, the implant is placed into the cavity, and the implant is impacted such that the implant is forced into the bone. This process creates a hoop strain and generates friction at the implant-bone interface, which secures the implant.

[0003] Traditionally, the impact force is delivered using a hand-held mallet swung by the surgeon. Although this is a relatively simple process requiring only simple equipment, this method of delivering force can result in inconsistent forces being applied to the implant. As a result, each THA procedure performed using a mallet is likely to have a different implantation force, causing each implant to be fixed with different stability. This is undesirable, among other reasons, because if the implant is not impacted sufficiently by the surgeon, there may be insufficient hoop strain, which may hinder bone ingrowth. This is particularly problematic during revision cases where bone quality may be poor. Conversely, if too strong an impact force is used, the implant may generate excessive strain in the bone, which may lead to fracture.

[0004] To address this issue, powered impactor devices have been developed that are capable of delivering a more consistent impact force and can also reduce the physical effort required by the surgeon.

[0005] US Patent No. 10,342,591 B2 discloses an orthopedic impacting tool including a motor, an energy storage chamber, a striker, and an anvil. The motor stores energy in the energy storage chamber and then releases the energy to cause the striker to apply a controlled force to an adapter to generate a precise impact for use in a surgical environment. As explained by this document, the energy storage chamber can contain a vacuum or compressed gas.

[0006] US Patent No. 10,342,591 B2 requires that a pressurized energy storage chamber be provided and maintained. This can lead to bulky impaction tools and can be problematic if the integrity of the pressurized chamber is compromised. In particular, damage to the chamber during surgery can cause significant injury to the patient or compromise the success of the surgical procedure (e.g., if escaping pressurized gas applies undesirable lateral forces to the implant). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] U.S. Patent No. 10,342,591B2 Summary of the Invention [Means for solving the problem]

[0008] According to an aspect of the present disclosure, an orthopaedic impactor is described that includes: a strike assembly arranged to impart a force to an object; and a winding arranged to receive an electric current and thereby induce a magnetic field, the winding arranged to interact with the strike assembly such that, in use, the magnetic field generated by the winding causes the strike assembly to move so as to impart a force to the object.

[0009] The use of windings allows for rapid delivery of force to an object and also allows the frequency of the impact to be varied independently of the force of each impact.

[0010] According to aspects of the present disclosure, an orthopedic impactor is described, the impactor including: a strike assembly; a connector arranged to impart a force to an object; and a winding arranged to receive an electric current and thereby generate a magnetic field, the winding, strike assembly, and connector arranged such that, in use, a magnetic field generated by the winding moves the strike assembly to impact the connector; the connector arranged to move between a first position and a second position, where in the first position, when the strike assembly impacts the connector, the connector imparts a force to the object in a first direction, and where in the second position, when the strike assembly impacts the connector, the connector imparts a force to the object in a second direction; the first direction and the second direction are different.

[0011] Preferably, the body of the strike assembly comprises a ferromagnetic material arranged to be moved by a magnetic field.

[0012] Preferably, the winding is arranged to interact with the strike assembly such that application of an electric current causes the strike assembly to move.

[0013] Preferably, the winding is arranged to interact with a strike assembly such that removal of the current causes the strike assembly to move.

[0014] Preferably, the impactor includes a connector arranged to receive a force from the strike assembly and to apply the force to the object.

[0015] Preferably, the connector includes a fastening mechanism for fastening the object.Preferably, the fastening mechanism includes a grip for gripping the object.

[0016] Preferably the strike assembly is arranged to move to impact the connector and preferably the connector is arranged such that in the rest position it is spaced from the strike assembly.

[0017] Preferably, the connector is arranged to receive a first force from a first, proximal striker of the strike assembly and the connector is arranged to receive a second force from a second, distal striker of the strike assembly; a direction of the first force is different from a direction of the second force.

[0018] Preferably, the connector is arranged to at least partially surround a striker of the strike assembly and is adapted to receive a first force when the strike assembly moves in a first direction and a second force when the strike assembly moves in a second direction, preferably the second direction being opposite to the first direction.

[0019] Preferably, the first force is an implantation force.

[0020] Preferably, the second force is a removal force.

[0021] Preferably, the connector is arranged to remain substantially stationary during use of the impactor.

[0022] Preferably, the connector is arranged such that in the rest position it is spaced from the strike assembly. Preferably, the impactor is arranged such that it is spaced at least 3mm, at least 5mm, at least 10mm, and / or at least 20mm.

[0023] Preferably, the strike assembly weighs at least 0.6 kg, at least 1.2 kg, at least 1.8 kg, at least 2.5 kg, and / or at least 4 kg.

[0024] Preferably, the connector weighs 1 kg or less, 0.5 kg or less, 0.2 kg or less, and / or 0.1 kg or less.

[0025] Preferably, the strike assembly has a mass that is at least two times the mass of the connector, at least three times the mass of the connector, at least five times the mass of the connector, and / or at least ten times the mass of the connector.

[0026] Preferably, the strike assembly is arranged to be capable of moving at least 1 m / s, at least 1.5 m / s, at least 2 m / s, at least 3 m / s, and / or at least 5 m / s.

[0027] Preferably, the strike assembly and / or connector is arranged to move between a first position and a second position, the strike assembly and / or connector applying a first force when the strike assembly and / or connector is in the first position and applying a second force when the strike assembly and / or connector is in the second position.

[0028] Preferably, the impactor includes a retention mechanism, the retention mechanism arranged to retain the strike assembly in the first position and / or the second position.

[0029] Preferably, in the first position a forward surface of the strike assembly abuts a surface of the impactor and in the second position a rearward surface of the connector abuts a surface of the impactor.

[0030] Preferably, the impactor further includes a power source for supplying current to the winding. Optionally, the power source includes a battery. Optionally, the power source includes a capacitor. Optionally, the power source includes both a battery and a capacitor.

[0031] Preferably, the impactor further includes an input for modifying a parameter of the force.

[0032] Preferably, the input is arranged to vary at least one of: the direction of the force; the magnitude of the force; the rate of application of the force; the frequency of application of the force; the duration of the force; and the energy of an impact associated with the force.

[0033] Preferably, the input is arranged to vary the current supplied to the windings to vary the force parameter. Preferably, the input is arranged to vary at least one of: the direction of the current; the magnitude of the current; the duration of the current; the frequency of the current; the frequency of delivery of pulses of the current.

[0034] Preferably the impactor includes two inputs, each input arranged to vary a different parameter of the force. Preferably a first input is arranged to vary the magnitude of the force and a second input is arranged to vary the velocity of the force.

[0035] Preferably, the input includes at least one of: a rotatable input; a slidable input; a variable input; and a touch-sensitive screen.

[0036] Preferably, the impactor is arranged to determine usage data. Preferably, the usage data includes one or more of: bone quality; implant stability; impact force; difference between impact force and desired force; impact frequency; user of the device; and hoop stress.

[0037] Preferably, the impactor is arranged to transmit the usage data to an external server.

[0038] Preferably, the impactor further includes control electronics arranged to vary the supply of current to the winding. Preferably, the control electronics is arranged to interact with one or more of the input and the power source.

[0039] Preferably, the control electronics are arranged to vary the supply of current and / or the force provided based on a previous force applied to the object and / or based on a property of the object. Preferably, the control electronics are arranged to vary the current and / or force based on one or more of: determined bone quality; implant stability; impact force; a difference between a previously measured force and a desired force.

[0040] Preferably, the control electronics is arranged to vary the supply of current and / or the force provided based on one or more of: previous use of the impactor; a user of the impactor; and / or characteristics of the object being impacted.

[0041] Preferably, the control electronics includes a feedback loop and / or a closed feedback loop.

[0042] Preferably, the control electronics includes a proportional-integral-derivative (PID) controller.

[0043] Preferably, the strike assembly is arranged to move between a first (rest) position and a second (active) position, Preferably, in the first position the strike assembly is spaced from the connector and in the second position the strike assembly is in contact with the connector.

[0044] Preferably, the strike assembly is arranged to be further moved to a third (active) position. Preferably, movement to the second position involves applying a force in a first direction and movement to the third position involves applying a force in a second direction.

[0045] Preferably, the strike assembly is arranged to move to either the second position or the third position depending on an external force applied to the impactor.

[0046] Preferably the impactor comprises a plurality of spools, preferably arranged to provide forces of different magnitudes and / or in different directions.

[0047] Preferably, the plurality of spools comprises axially separated spools.Preferably, the plurality of spools comprises axially separated spools having coincident central axes.

[0048] Preferably, the impactor includes at least one spool positioned on a first side of the strike assembly and at least one spool positioned on a second side of the strike assembly.

[0049] Preferably, the first spool is arranged to move the strike assembly in a first direction and the second spool is arranged to move the strike assembly in a second direction, preferably the second direction being opposite to the first direction.

[0050] Preferably, the plurality of spools includes radially separated spools.Preferably, the plurality of spools includes radially separated spools having coincident central axes.

[0051] Preferably, the impactor further includes a bearing arranged to support the strike assembly and / or the connector.

[0052] Preferably, the impactor further includes a bearing holder arranged to limit movement of the connector.

[0053] Preferably, the impactor further includes a spacer arranged to limit movement of the strike assembly and / or the connector.

[0054] Preferably, the impactor further includes an end cap arranged to limit movement of the strike assembly.

[0055] Preferably, the impactor further includes a biasing mechanism. Preferably, the biasing mechanism includes a spring.

[0056] Preferably, the biasing mechanism is arranged to bias the strike assembly towards the first (rest) position.

[0057] Preferably, the biasing mechanism is arranged to compress when the strike assembly is moved from the first position to the second (active) position, and / or the biasing mechanism is arranged to expand when the strike assembly is moved from the first position to the third (active) position.

[0058] Preferably, the second position is associated with providing an implantation force and / or the third position is associated with providing a removal force.

[0059] Preferably, the strike assembly is arranged to move to provide one or more of: an implantation force when the strike assembly is in a distal position and current is provided to the spool; a removal force when the strike assembly is in a proximal position and current is removed from the spool; an implantation force when the strike assembly is in a distal position and current is removed from the spool; and a removal force when the strike assembly is in a proximal position and current is provided to the spool.

[0060] Preferably, the biasing mechanism is arranged to exert a force to move the strike assembly to provide the implantation and / or removal force when the electrical current is removed.

[0061] Preferably, the windings are arranged to provide a force that acts (and / or counteracts) against the biasing mechanism.

[0062] Preferably, the windings are arranged to act against a biasing mechanism such that when current is removed from the windings, the biasing mechanism interacts with the strike assembly to apply a force to the object.

[0063] Preferably, the winding comprises a solenoid and / or the winding comprises one or more loops of wire.

[0064] Preferably, the windings are arranged to radially surround the ferromagnetic body of the strike assembly throughout the range of movement of the body.

[0065] Preferably, the windings are arranged to axially surround the ferromagnetic body of the strike assembly throughout the range of movement of the body.

[0066] Preferably, the ferromagnetic body portion of the strike assembly body is axially spaced from the windings throughout part (or all) of the body portion's range of movement.

[0067] Preferably, the striker of the strike assembly comprises a ferromagnetic material.

[0068] Preferably, the windings are disposed about the support member.

[0069] Preferably, the body portion of the strike assembly is positioned within the support member.

[0070] Preferably, the body of the strike assembly is constrained to move along a single axis. Preferably, the body is constrained by a support member.

[0071] Preferably the connector is constrained to move along a single axis.Preferably the body of the strike assembly is constrained by a linear bearing.

[0072] Preferably, the impactor further includes a casing that surrounds one or more of the components of the impactor.

[0073] Preferably, the casing includes a fixation mechanism arranged to hold the connector in place at one or more locations, preferably including an implantation location and / or a removal location.

[0074] Preferably, the impactor is arranged to provide one or more of: an implantation force; and a removal force.

[0075] Preferably, the central axis of the winding is coincident with the central axis of the body of the strike assembly.

[0076] Preferably, the central axis of the winding coincides with the central axis of the connector.

[0077] Preferably, the impactor further comprises a sensor. Preferably, the sensor is arranged to measure at least one of: impact force; object stability; implant stability; and impact energy.

[0078] Preferably, the impactor further includes a user interface for displaying at least one of the force parameters; and the characteristics of the impactor's motion.

[0079] Preferably, the body of the strike assembly comprises a ferromagnetic material. Preferably, the body comprises iron. Preferably, the body comprises at least 70% iron.

[0080] Optionally, the body portion of the strike assembly includes a permanent magnet.

[0081] Preferably, the windings comprise copper wire and / or the windings comprise at least 70% copper.

[0082] Preferably, the windings are arranged to provide current for less than 1 s, for less than 0.5 s, and / or for less than 0.1 s.

[0083] Preferably, the winding comprises at least 300 turns; at least 500 turns, and / or at least 800 turns.

[0084] Preferably, the windings are arranged to accept a current of at least 5A, at least 8A, at least 10A, and / or at least 15A.

[0085] Preferably, the impactor is arranged to provide an impact energy of 5J or less, 3J or less, 1J or less, and / or 0.5J or less.

[0086] Preferably, the impactor is arranged to provide an impact energy of 10J or more, 15J or more, 20J or more, and / or 30J or more.

[0087] Preferably, the impactor is arranged to provide an impact force of 5kN or less, 3kN or less, 1 kN or less, and / or 0.5kN or less.

[0088] Preferably, the impactor is arranged to provide an impact energy of 20 kN or more, 25 kN or more, 30 kN or more, and / or 50 kN or more.

[0089] Preferably, the impactor is arranged to provide an impact impulse of 2Ns or less, 1Ns or less, and / or 0.5Ns or less.

[0090] Preferably the impactor is arranged to provide an impact impulse of 3Ns or more, 5Ns or more and / or 7Ns or more.

[0091] Preferably, the impactor is arranged to provide an impact frequency of 3 Hz or less, 1 Hz or less, and / or 0.5 Hz or less.

[0092] Preferably, the impactor is arranged to provide an impact frequency of 7 Hz or greater, 10 Hz or greater, and / or 15 Hz or greater.

[0093] Preferably, the striker of the strike assembly includes a hardened coating.

[0094] Preferably, the striker of the strike assembly includes a coating. Preferably, the striker includes a soft and / or flexible coating. Preferably, the coating is arranged to deform when the strike assembly applies a force to the object.

[0095] Preferably, the impactor comprises an orthopaedic impactor.Preferably, the impactor comprises an orthopaedic impactor for performing a total hip arthroplasty (THA).

[0096] Preferably, the impactor includes a plurality of windings.

[0097] Preferably, the impactor includes one or more proximal impact windings arranged to provide a force in a first direction; and one or more distal impact windings arranged to provide a force in a second direction.

[0098] Preferably, the proximal impact winding is arranged to provide a greater impact energy and / or force to the object than the distal impact winding.

[0099] Preferably, the proximal impact winding has a larger volume, length, and / or surface area than the distal impact winding.

[0100] Preferably, the impactor includes a greater number of proximal impact windings than distal impact windings.

[0101] According to another aspect of the invention, an orthopaedic impactor is described, the impactor including: a strike assembly arranged to apply a force to an object; a plurality of windings arranged to receive an electric current and thereby generate a magnetic field, the windings arranged to interact with the strike assembly, such that, in use, the magnetic field generated by the windings moves the strike assembly to apply a force to the object; the impactor includes a plurality of proximal impact windings arranged to provide a force in a first direction; and one or more distal impact windings arranged to provide a force in a second direction, the impactor including a greater number of proximal impact windings than the distal impact windings.

[0102] Preferably, the proximal and distal impact windings are provided in an alternating arrangement.

[0103] Preferably, the impactor includes two proximal windings and one distal winding, the distal winding being positioned between the proximal windings.

[0104] Preferably the impactor is arranged to use the winding as a sensor.

[0105] Preferably, the impactor is arranged to measure the operating parameter in dependence on the current and / or voltage in the winding.

[0106] According to aspects of the present disclosure, an orthopaedic impactor is described, the impactor including: a strike assembly arranged to impart a force to an object; and a winding arranged to receive an electric current and thereby induce a magnetic field, the winding arranged to interact with the strike assembly such that, in use, a magnetic field generated by the winding moves the strike assembly to impart a force to the object; and the impactor arranged to measure an operating parameter dependent on the current and / or voltage in the winding.

[0107] Preferably, the impactor is arranged to determine at least one of: the position of the strike assembly; and the force of the impact in dependence on the current and / or voltage in the winding.

[0108] According to another aspect of the present disclosure, an impactor is described that includes a strike assembly; and a connector arranged to receive a force from the strike assembly and to impart a force to an object, the connector arranged to be spaced apart from the strike assembly in a rest position.

[0109] Preferably, the connector is arranged such that in the rest position it is spaced from the strike assembly. Preferably, the impactor is arranged such that it is spaced at least 3mm, at least 5mm, at least 10mm, and / or at least 20mm.

[0110] Preferably, the strike assembly weighs at least 0.6 kg, at least 1.2 kg, at least 1.8 kg, at least 2.5 kg, and / or at least 4 kg.

[0111] Preferably, the connector weighs 1 kg or less, 0.5 kg or less, 0.2 kg or less, and / or 0.1 kg or less.

[0112] Preferably, the strike assembly has a mass that is at least two times the mass of the connector, at least three times the mass of the connector, at least five times the mass of the connector, and / or at least ten times the mass of the connector.

[0113] Preferably, the strike assembly includes a striker.

[0114] Preferably, the connector is positioned to at least partially surround a striker of the strike assembly and is positioned to receive force from the striker and to impart force to the object.

[0115] Preferably, the connector is arranged to move between a first position and a second position, in which in the first position the striker impacts a first surface of the connector causing the connector to impart a first force to the object in a first direction; and in the second position the striker impacts a second surface of the connector causing the connector to impart a second force to the object in a second direction.

[0116] Preferably, the first direction and the second direction are different.

[0117] According to another aspect of the present disclosure, a method of operating an impactor and / or an impactor as described above is described.

[0118] According to another aspect of the disclosure, a method of operating an impactor is described, the impactor including: a strike assembly arranged to impart a force to an object; and a winding arranged to receive an electric current and thereby induce a magnetic field, the winding arranged to interact with the strike assembly such that, in use, a magnetic field generated by the winding moves the strike assembly to impart a force to the object, the method including providing an electric current to the winding to generate the magnetic field; and / or removing the current from the winding to cease generating the magnetic field.

[0119] Preferably, the method includes providing a current to the winding that is greater than a maximum operating current and / or a desired operating current for the winding.

[0120] Preferably, the method includes the step of providing current to the spool when the current in the spool is below a lower limit.

[0121] Preferably, the method includes ceasing to provide current to the spool when the current in the spool exceeds an upper limit.

[0122] Preferably, the method includes the steps of determining that the current in the winding is approaching and / or exceeding a maximum operating current; and ceasing to supply current to the winding.

[0123] Preferably, the method includes the step of repeatedly providing and terminating a current provided to the winding to maintain a current in the winding that is similar to and / or below a maximum operating current for the winding.

[0124] Preferably, the method includes the step of applying an initial force to the impactor.

[0125] Preferably, the impactor is arranged such that the direction of the force exerted by the impactor is dependent on an initial force applied to the impactor.

[0126] According to another aspect of the present disclosure, a method of calibrating an impactor is described, the impactor including: a strike assembly arranged to impart a force to an object; and a winding arranged to receive an electric current and thereby induce a magnetic field, where a body portion of the strike assembly includes a ferromagnetic material; the winding surrounds the body portion such that, in use, a magnetic field generated by the winding moves the strike assembly into contact with a connector; the method includes determining a characteristic of a force imparted to an object during use of the impactor; determining a difference between the characteristic and a desired characteristic; and determining calibration information for modifying future currents to be provided to the winding based on the difference.

[0127] According to another aspect of the disclosure, a method of operating an impactor is described, the impactor including: a strike assembly arranged to impart a force to an object; and a winding arranged to receive an electric current and thereby induce a magnetic field, the winding arranged to interact with the strike assembly such that, in use, a magnetic field generated by the winding moves the strike assembly to impart a force to the object, the method including providing an electric current to the winding to generate the magnetic field; and / or removing the current from the winding to remove the magnetic field and / or to cease generating the magnetic field.

[0128] Preferably, the method further comprises the step of applying an initial force to the impactor.

[0129] According to another aspect of the present disclosure, an orthopedic impactor is described, the impactor including a strike assembly including a striker; a winding arranged to receive an electric current and thereby generate a magnetic field; and a connector arranged to at least partially surround the striker of the strike assembly and arranged to receive a force from the striker and to impart a force to an object, the winding arranged to interact with the strike assembly such that, in use, a magnetic field generated by the winding moves the strike assembly such that the striker impacts the connector; the connector arranged to move between a first position and a second position, where in the first position the striker impacts a first surface of the connector and the connector imparts a first force to the object in a first direction; and where in the second position the striker impacts a second surface of the connector and the connector imparts a second force to the object in a second direction; the first direction and the second direction are different.

[0130] According to another aspect of the disclosure, there is provided a method of operating an impactor, the impactor including: a strike assembly including a striker; a winding arranged to receive an electric current and thereby induce a magnetic field; and a connector arranged to at least partially surround the striker of the strike assembly and arranged to receive a force from the striker and to impart a force to an object, the winding arranged to interact with the strike assembly such that, in use, a magnetic field generated by the winding moves the strike assembly such that the striker impacts the connector. A method is described that includes positioning the connector in either a first position or a second position; providing current to the windings to generate a magnetic field; and / or removing current from the windings to stop generating the magnetic field, where in the first position, the striker impacts a first surface of the connector such that the connector imparts a first force to the object in a first direction; and in the second position, the striker impacts a second surface of the connector such that the connector imparts a second force to the object in a second direction; the first direction and the second direction are different.

[0131] According to another aspect of the disclosure, there is provided a method of calibrating an impactor, the impactor comprising: a strike assembly including a striker; a winding arranged to receive an electric current and thereby induce a magnetic field; and a connector arranged to at least partially surround the striker of the strike assembly and arranged to receive a force from the striker and to apply a force to an object, the body of the strike assembly comprising a ferromagnetic material; the winding surrounding the body such that, in use, a magnetic field generated by the winding moves the strike assembly such that the striker impacts the connector; the connector moving between a first position and a second position; a first position, the striker impacts a first surface of the connector causing the connector to impart a first force to the object in a first direction; and a second position, the striker impacts a second surface of the connector causing the connector to impart a second force to the object in a second direction; the first direction and the second direction are different, and the method includes determining a characteristic of a force imparted to the object during use of the impactor; determining a difference between the characteristic and a desired characteristic; and determining calibration information for modifying future current to be provided to the winding based on the difference.

[0132] Any features described as being performed by an apparatus, an application, and a device may be performed by either the apparatus, the application, or the device. Where multiple apparatuses are described, each apparatus may be located on a single device.

[0133] Any feature of one aspect of the present disclosure may be applied to other aspects of the invention in any suitable combination, in particular method aspects may be applied to apparatus aspects and vice versa.

[0134] Moreover, features implemented in hardware may be implemented in software and vice versa, and any references to software and hardware features in this specification should be interpreted accordingly.

[0135] Any apparatus features as described herein may also be provided as method features, and vice versa. As used herein, means-plus-function features may alternatively be expressed in terms of their corresponding structure (e.g., a suitably programmed processor and associated memory, etc.).

[0136] It should also be recognized that specific combinations of the various features described and defined in any aspect of the present disclosure can be implemented and / or provided and / or used independently.

[0137] The present disclosure extends to methods and / or apparatus substantially as herein described with reference to the accompanying drawings.

[0138] An "impact" as used herein can refer to an impact that acts to implant an object (e.g., driving an object into another object) and / or an impact that acts to remove an object (e.g., pulling an object from another object).

[0139] The present disclosure will now be described, by way of example only, with reference to the accompanying drawings. [Brief description of the drawings]

[0140] [Figure 1] FIG. [Figure 2a] FIG. 1 is a diagram of the actuator mechanism of the impactor. [Figure 2b] FIG. 1 is a diagram of the actuator mechanism of the impactor. [Figure 2c] FIG. 1 is a diagram of the actuator mechanism of the impactor. [Figure 3a] FIG. 1 illustrates an embodiment of an actuator mechanism. [Figure 3b] FIG. 1 illustrates an embodiment of an actuator mechanism. [Figure 3c] FIG. 1 illustrates an embodiment of an actuator mechanism. [Figure 3d] FIG. 1 illustrates an embodiment of an actuator mechanism. [Figure 4a] FIG. 13 illustrates the position of the actuator mechanism when the impactor is being used to implant an implant. [Figure 4b] FIG. 13 illustrates the position of the actuator mechanism when the impactor is being used to remove the implant. [Diagram 5] FIG. 13 illustrates a method for providing an impact depending on input parameters. [Figure 6a] FIG. 1 illustrates an open loop control system for determining the current to supply to the spool. [Figure 6b] FIG. 1 illustrates a closed loop control system for determining the current to supply to the spool. [Figure 7a] FIG. 13 illustrates another embodiment of an actuator mechanism. [Figure 7b] FIG. 13 illustrates another embodiment of an actuator mechanism. [Figure 8a] FIG. 13 shows the arrangement of spools in the impactor. [Figure 8b] FIG. 13 shows the arrangement of spools in the impactor. [Figure 9a] 13A-13C illustrate a method of powering a spool. [Figure 9b] 13A-13C illustrate a method of powering a spool. [Figure 9c] 13A-13C illustrate a method of powering a spool. [Figure 9d] 13A-13C illustrate a method of powering a spool. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0141] 1, an impactor 1 is shown that includes a power supply 2, control electronics 4, a primary input 6, a secondary input 8, a display 10, and an actuator mechanism 100. The actuator mechanism includes a connector 112.

[0142] The power source 2 is arranged to provide power to the other components. The power source typically includes a lithium ion battery. However, in various embodiments, the power source also or alternatively includes a capacitor, a supercapacitor, an interface for receiving mains power, an external power source, and / or a chemical power source. Combining a battery and a capacitor / supercapacitor allows for the provision of a large power source that can provide large instantaneous or short-term currents via charging the capacitor. Typically, the power source includes an internal battery, such that the impactor is portable. This internal battery can then be charged between uses (e.g., using a connection to a mains power source).

[0143] The control electronics 4 includes a CPU, which is arranged to execute instructions. The control electronics may also include memory (e.g., ROM or RAM) for storing information such as instructions for the CPU; mass storage (e.g., HDD) for storing larger amounts of information; and / or a communications interface (e.g., a USB port or a wireless area network connector) for communicating with other components or external devices. More generally, the impactor 1 and / or the control electronics typically include a computing device (which may include one or more microcontrollers) arranged to control and coordinate the electrical components of the impactor.

[0144] The primary input 6 and secondary input 8 allow the user to vary the parameters of the impact delivered by the impactor 1. The primary input typically includes a force input that allows the user of the impactor to vary the force of the impact. The secondary input typically includes a velocity input that allows the user of the impactor to vary the speed of the impact. In some embodiments, only a single input is provided (which may control only a single impact parameter or may control multiple parameters simultaneously). In some inputs, three or more inputs are provided. In some embodiments, a user interface (e.g., a touch-sensitive display) is provided that allows precise control and observation of a range of impact parameters. Parameters that may be controlled by the inputs include the speed of the impact; the force of the impact; the frequency of the impact; the direction of the impact (e.g., whether to drive the implant or extract the implant); the depth of the implant (e.g., how far the implant should be driven into the bone); and the stability of the implant (e.g., as may be measured by hoop stress). These parameters may relate to a single impact or multiple impacts, and typically achieving the desired stability requires multiple impacts. Each input sends information to the control electronics 4, which modifies the operation of the actuator mechanism 100, thus realizing the input parameters. The screen 10 provides a user interface through which a user of the impactor 1 can view information about the impactor. This information can be related to the impact parameters (e.g., input force / velocity of the impact), to the operation of the impactor (e.g., remaining battery level), or to the impact performance of the impactor (e.g., number of impacts generated, determined impact stability, or total impact energy transferred to the implant).

[0145] The actuator mechanism 100 receives instructions from the control electronics 4 and applies a force to the connector 112 according to input impact parameters. The connector is arranged to impact an object to either attach the object to a further object or remove the object from the further object.

[0146] Typically, the actuator mechanism 100 includes a winding, coil, or spool of wire. Typically, the winding forms a solenoid. The actuator mechanism 100 further includes a ferromagnetic body portion positioned inside the spool. The spool is arranged to induce a magnetic field when a current is passed through the wire. The magnetic field exerts a force on the body portion, which causes the body portion to interact with the connector 112 such that the connector can exert a force on an object.

[0147] The impactor 1 typically includes an orthopedic impactor used to fixate or remove an implant from a bone. In particular, the impactor may be suitable for total hip arthroplasty (THA). More generally, the impactor may be arranged to provide a driving force or a pulling / removal force to a wide range of objects. By way of example, the impactor may be used to drive or remove nails. It will be appreciated that the components of the impactor may be configured for the intended purpose of the impactor. For example, if the impactor is used to drive nails, a connector may be used to which the nail can be secured.

[0148] The remainder of this specification refers to the "distal" and "proximal" ends of the impactor 1. The distal and proximal directions are shown in FIG. 1. The proximal end of the impactor is the end from which the connector 112 protrudes (the end closest to the object to be impacted), and the distal end is the end closer by the user. In use, the proximal end of the impactor is placed next to an object; the connector is placed in contact with the object; and the actuator mechanism 100 is operated to apply a force to the object (e.g., to drive an implant into bone).

[0149] Typically, the connector 112 and / or the object include an attachment structure and / or mechanism arranged to secure the connector to the object. For example, the object may include a click-fit or snap-fit ​​attachment structure into which the connector is pressed. If the connector includes an attachment structure and / or mechanism, the attachment structure / mechanism may include one or more of a gripping structure (e.g., a clamp); a snap-fit ​​structure; an interference-fit structure; a magnetic attachment mechanism; a releasable attachment mechanism; and / or an interchangeable attachment structure / mechanism. In some embodiments, the connector is arranged to be used with multiple attachment structures, for example, a snap-fit ​​structure may be used when implanting the object and a gripping structure may be used to remove the object. It may also be beneficial for the connector to be arranged to be used with multiple attachment structures, as different implant manufacturers may require different attachment structures.

[0150] 2a-2c, there is shown an embodiment of an actuator mechanism 100. Specifically, an end view of the actuator mechanism is shown, along with a side view and a cross-sectional view.

[0151] The actuator mechanism 100 includes a casing 102 , a body portion 104 , a distal striker 106 , a proximal striker 108 , a strike chamber 110 , a connector 112 , a spool 114 , a bearing holder 116 , an end cap 118 , a spacer 120 , a return spring 122 , and a cap 124 .

[0152] The casing 102 is arranged to house, protect and hold in place the other components of the actuator mechanism 100 .

[0153] The body portion 104 is arranged to move the distal striker 106 when the body portion 104 is moved, which in turn moves the proximal striker 108, which then impacts the connector 112. In this manner, the body portion can transmit a force to the connector. Together, the body portion 104, the distal striker 106, and the proximal striker 108 comprise a strike assembly. In the following description, references to movement of the body portion include references to movement of the strike assembly, and vice versa.

[0154] The body portion 104 is arranged to be moved by a magnetic field and typically comprises a ferromagnetic material. It is desirable for the body portion to comprise a material with a significant density (e.g., greater than 5 grams per cubic centimeter) so as to efficiently transfer forces via the distal striker 106 and the proximal striker 108 to the connector 112. For these reasons, the body portion typically comprises a high percentage of iron (e.g., greater than 70% iron by weight, greater than 80% iron by weight, or greater than 90% iron by weight). Typically, the ferromagnetic material has a high magnetic permeability (e.g., greater than 1×10 -5 H / m or greater than 1×10 -4 H / m or greater than 1×10 -3In some embodiments, the body comprises a material having a magnetization coefficient (H / m) greater than 0.015. In some embodiments, the body comprises a permanent magnet. In some embodiments, the body comprises a ferromagnetic material that is arranged to be magnetized by the spool 114.

[0155] The distal striker 106 is arranged to move with the body portion 104. Typically, this involves the distal striker being connected to the body portion (e.g., via a rigid connector or by the distal striker being an integral part of the body portion). In this embodiment, the distal striker 106 is embedded within the body portion 104.

[0156] The proximal striker 108 is positioned to move as the distal striker 106 moves. This may include the proximal striker being an integral part of the distal striker and / or body. This may include the proximal striker being rigidly connected to the distal striker.

[0157] Typically, the distal striker 106 and the proximal striker 108 are integral parts of a single striker component; therefore, the distal and proximal strikers can be thought of as two parts of a single striker.

[0158] Each of the body portion 104, the distal striker 106, and the proximal striker 108 can include the same material and / or can include different materials. Because the distal striker and the proximal striker impact other components, the strikers can include a hard material and / or a hard coating to prevent damage to the striker. Additionally, the striker can include a non-ferromagnetic material (e.g., a plastic material) to prevent any force from being applied to the striker by the spool 114.

[0159] In some embodiments, one or more of the body portion 104, the distal striker 106, and the proximal striker 108 include a deformable, flexible, and / or soft material (e.g., a plastic, polymer, or rubber coating). Such a material can reduce the peak force applied by the impactor to reduce the likelihood of crushing. The peak force can also be controlled by controlling the current provided to the spool 114, where a damping force can be applied to the body portion 104 using the spool to reduce the peak force of the impact and / or to increase the duration of the impact.

[0160] The strike chamber 110 includes a chamber in which the proximal striker 108 impacts the connector 112. In the rest position (before impact), there is typically a gap between the proximal striker and the connector. As the body portion 104 moves, the proximal striker also moves (via the distal striker 106). Specifically, the proximal striker moves through the strike chamber toward the connector 112 and then strikes the connector.

[0161] The strike chamber 110 may be arranged to be stationary within the casing 102 (e.g., the strike chamber may be fixed to the casing) or the strike chamber may be arranged to move with the connector 112 (e.g., the strike chamber may be connected to the connector). Indeed, typically the strike chamber 110 is fixed to the connector (e.g., the strike chamber and the connector may be an integral part or may be fixed together).

[0162] The connector 112 is positioned to be impacted by the proximal striker 108 and then transmit the impact to the object. The connector typically includes a dense, tough, and / or rigid material (e.g., iron and / or steel) and / or a hardened coating to enable the connector to experience repeated impacts without structural damage or excessive vibration.

[0163] In some embodiments, the connector 112 is arranged to secure an object (e.g., an implant). This allows for a removal force to be applied to the object as well as an implantation force, and may allow the object to be secured laterally such that it is directly pushed into or pushed out of the bone (e.g., such that the impact is entirely in the proximal-distal direction and / or entirely aligned with one or more of the central axis of the connector, the central axis of the body portion 104, and the central axis of the spool 114). The securing mechanism may include a grip, a magnet, and / or an adhesive. The securing mechanism may include a quick release mechanism arranged to rapidly grip or release the object.

[0164] Each object with which the impactor 1 is used may require a different fixation mechanism. Thus, in some embodiments, the connector 112 is removable and / or interchangeable. This allows the same impactor to be used with a variety of implants. Similarly, the connector can be arranged to be used with multiple attachment structures or mechanisms (where these structures / mechanisms can be attached to the ends of the connector) to allow for use with different objects.

[0165] The spool 114 comprises a spool of wire that is disposed about the body 104 and is arranged to receive electrical current from the power source 2. Typically, the spool 114 forms a solenoid. Typically, the spool comprises a material having high electrical conductivity, such as copper.

[0166] In some embodiments, the spool 114 is positioned to surround the body 104 (or the ferromagnetic portion of the body) throughout the range of movement of the body. This can include having the axial length of the spool be greater than 50%, greater than 75%, or greater than 100% of the axial length of the body. This ensures that a consistent force can be applied to the body throughout the body's range of movement.

[0167] The body 104 may be axially offset (and spaced) from the spool in the rest position and / or may be axially offset from the center of the spool (while still being radially and / or axially surrounded by the spool). Typically, the body is positioned such that in the rest position it is axially closer to one end of the spool 114 than the other end. For example, the body may be closer to the distal end of the spool. Thus, when the spool is energized, a magnetic force is applied to the body that acts to draw the body into the spool (along the centerline of the spool). Ensuring that the axes of the body and spool are aligned may ensure that undesirable radial forces are not applied to the body.

[0168] In some embodiments, a portion of the body 104 is disposed to extend beyond the spool 114 and / or is disposed to be axially offset from the center of the spool. Particularly when a non-permanent magnet is used for the body, the body typically extends beyond the spool or is axially offset from the center of the spool. Providing a current to the spool will generate a magnetic field. The current will also induce a current in the body, which leads to the generation of an additional magnetic field that opposes the magnetic field generated by the spool. This can be used to impart a force to the body (and the strike assembly). In some embodiments, the ferromagnetic portion of the body or strike assembly is positioned outside the spool (in the distal-proximal axis). As an example, the strikers 106, 108 can include ferromagnetic material, while the "body" 104 of Figures 2a-2c does not. In this example, the strikers can be considered to constitute the body of the strike assembly by virtue of their inclusion of ferromagnetic material. Providing an electrical current in the spool 114 can then be used to push the striker towards / away from the spool and provide a force to the connector 112. As explained further below, the magnetic field generated by the spool can be used to provide an implantation and / or removal force by adjusting the alignment of the strike assembly and connector.

[0169] The flow of current through the spool 114 results in a magnetic field being induced. Due to the placement of the spool 114 around the body portion 104, this magnetic field induces a force on the body portion 104. This force acts to move the body portion (and thus the proximal striker 108) such that the proximal striker impacts the connector 112. The force applied to the magnetic field depends on the characteristics of the spool and the current flowing through the spool. To vary the magnetic force applied to the body portion (and thus the impact parameters), the control electronics 4 is arranged to control the transmission of current from the power source 2 to the spool 114 (e.g. the magnitude of the current flow, the duration of the current flow, and / or the direction of the current flow) in response to the primary input 6 and the secondary input 8.

[0170] The characteristics of the spool 114 (e.g., number of loops, loop spacing, wire thickness, and wire material) can be selected based on the desired impact force. In some embodiments, a user can modify the characteristics of the spool (e.g., number of loops on the spool or spool spacing, etc.) to change the force applied to the body portion 104.

[0171] Among other things, the arrangement of spool 114 (and the inputs to spool 114) allows for the following variations: - Impact force. By varying the period that current is applied to the spool, the time that the magnetic force is applied to the body 104 can be varied. This allows the force to be applied for a long period of time (to cause a high force impact) or for a short period of time (to cause a lower force impact). Similarly, the magnitude of the applied current can be varied. Applying a large current will result in a large force acting on the body and therefore a high force impact. Applying a smaller current will result in a smaller force acting on the body and a lower force impact. Similarly, the frequency of the current can be changed, where a higher frequency will result in a larger impact force. - Frequency of impact. Typically, current is applied to the spool 114 in pulses such that the connector 112 repeatedly impacts the implant. The frequency of impact can be changed by changing the frequency of the pulses. Similarly, a continuous current can be applied to the spool 114, causing a continuous driving or removal force to be applied to the implant. - Impact direction: By changing the direction of the current entering the spool 114, the direction of the force applied to the body portion 104 can be changed. This allows a driving or removal force to be applied depending on the direction of the current.

[0172] Typically, the spool 114 has one or more of the following characteristics: - Made of copper (e.g., copper wire). The spool may comprise 75% copper, 90% copper, and / or substantially 100% copper. - containing at least 300 turns, at least 500 turns, and / or at least 800 turns (where a turn is a single coil surrounding the body portion 104). - A rated current of at least 5 amps, at least 8 amps, at least 10 amps, and / or at least 15 amps. Typically, the power source 2 is capable of providing at least 5 amps, at least 8 amps, at least 10 amps, and / or at least 15 amps to the spool. - At least 50mm, at least 80mm, and / or at least 100mm in length. - A diameter of at least 40mm, at least 55mm and / or at least 70mm.

[0173] Typically, the spool 114 is arranged as follows: - Provide an impact and / or removal force of 5kN or less, 3kN or less, 1 kN or less, and / or 0.5 kN or less. - Providing impact and / or removal forces of 20kN or more, 25kN or more, 30kN or more, and / or 50kN or more. - providing an impact force and / or removal force in the range of 0.5kN to 50kN and / or 1kN to 30kN; - Provide impact and / or removal energy of 5J or less, 3J or less, 1J or less, and / or 0.5J or less. - Providing impact and / or removal energies of 10J or more, 15J or more, 20J or more, and / or 30J or more. - Providing an impact energy and / or removal energy in the range of 0.5J to 30J and / or 1J to 20J. - Providing an impact impulse and / or a removal impulse of 2Ns or less, 1Ns or less, and / or 0.5Ns or less. - Providing impact impulses and / or removal impulses of 3Ns or more, 5Ns or more, and / or 7Ns or more. - Providing an impact impulse and / or removal impulse in the range of 0.5Ns to 7Ns and / or 1Ns to 5Ns. - Provide shock and / or removal frequencies (number of shocks per second) of 3 Hz or less, 1 Hz or less, and / or 0.5 Hz or less. - Providing shock and / or removal frequencies of 7Hz or greater, 10Hz or greater, and / or 15Hz or greater. - Providing shock and / or removal frequencies in the range of 0.5Hz to 15Hz and / or 1Hz to 10Hz.

[0174] Typically, the spool 114 is arranged to provide "semi-automatic" shocks, e.g., a user can activate the spool, provide a single shock, and then reactivate the spool to provide another shock. Similarly, the spool can provide "automatic" shocks, e.g., a user can hold down the trigger to provide repeated shocks. The frequency and number of shocks can also be controlled by the control electronics 4, where the user can input one or more of the shock frequency; number of shocks; desired stability; and desired total shock energy, and the control electronics provides the appropriate current to the spool. This allows the user to input usage parameters before commencing shock or removal, after which the energization of the spool proceeds automatically.

[0175] Using the spool 114, the impact force and impact frequency can be varied independently. Notably, there is no need to recharge the impact mechanism. If desired, multiple impacts (e.g., of different forces) can be provided with essentially no break between impacts.

[0176] Typically, the axis of the spool 114 (e.g., the central axis of the solenoid) is aligned with the axis of the body 104 (e.g., the central axis of the body). Typically, these axes are coincident. Typically, the same axis of the spool (e.g., the central axis of the solenoid) is aligned with the axis of the connector 112 (e.g., the central axis of the body). Typically, these axes are coincident.

[0177] Typically, the body is a cylindrically shaped component that is positioned within the spool, and the coincidence of the respective axes of these components then allows the spool to exert a force on the body that is aligned with the axes of the spool, the body, and the connector 112. This prevents undesirable lateral forces from being applied to the implant.

[0178] The coincident axis of the body 104, the spool 114, and the connector 112 is shown in Figure 2c as axis ZZ, and the distal striker 106 and the proximal striker 108 may have central axes that coincide with this axis ZZ.

[0179] Typically, the actuator mechanism 100 is rotationally and / or circularly symmetric about a central axis (e.g., axis ZZ). This ensures that the force provided is independent of the angle at which the impactor 1 is held.

[0180] The spool 114 is typically wound on a support component, within which the body 104 is positioned and within which the body can move. The support component may be smooth and / or lubricated to aid in the movement of the body within the support component. The body typically fits snugly within the support component. This allows the support component to be used to ensure that the body remains aligned with the connector 112 such that no lateral forces (forces perpendicular to the proximal-distal axis) are applied to the connector. Similarly, the support component can be used to ensure that the central axis of the spool 114 remains aligned with the axis of the body and / or the axis of the connector.

[0181] The bearing holder 116 supports a linear bearing that guides the connector 112. The linear bearing ensures that the connector does not move substantially perpendicular to the anterior-posterior direction and also helps support the connector as it moves (either proximally to drive the implant into the bone or distally to remove the implant from the bone). The linear bearing allows the strike assembly to move freely as the implant is driven or removed, while also ensuring that the force provided by the connector is entirely along the proximal-distal axis. In some embodiments, the distal end of the bearing holder is used to limit the movement of the connector. This can also be thought of as the casing 102 abutting the connector (and limiting the movement of the connector) since the bearing holder is typically part of the casing. Specifically, as the connector moves proximally, a surface of the connector is positioned to impact the bearing holder and define the maximum proximal displacement of the connector (and the striker assembly) (i.e., the maximum extension of the connector from the impactor 1).

[0182] An end cap 118 captures the spool 114 near the distal end of the impactor 1 .

[0183] A spacer 120 restrains the spool 114 near the proximal end of the impactor 1. Together, the end cap 118 and the spacer form a boundary for the spool. The spacer also prevents excessive movement of the distal striker 106 as the body moves distally. Specifically, it is positioned such that as the body (and distal striker) moves distally, the rear surface of the distal striker impacts the spacer, defining the maximum distal displacement of the striker assembly (and connector 112).

[0184] The return spring 122 is arranged to provide a force to return the body portion 104 (and striker assembly) from the proximal position to the rest position. The return spring is arranged to be compressed when the striker assembly is moved from the rest position to the proximal position (to contact the connector). In use, an electric current is provided to the spool 114 to apply a force to the body portion 104 such that the proximal striker 108 contacts the connector 112. When (or before) the proximal striker impacts the connector, the flow of electric current to the spool is stopped and the compressive force in the return spring acts to return the body portion to the distal position. In some embodiments, the return spring 122 is not used and the return force is provided by reversing the direction of the electric current in the spool and / or by providing a resilient surface.

[0185] Similarly, return spring 122 can be arranged to expand when body portion 104 is moved from a rest position to a distal position (eg, to remove an implant).

[0186] A cap 124 is attached to the distal end of the body 104 and is used to hold the return spring 122 in place. Specifically, the return spring is held between the casing 102 and the cap such that the return spring is compressed when the body moves from the rearward position (or rest position) to the forward position. This allows the return spring to provide a return force that returns the body to the rest position when the magnetic force applied to the body by the spool 114 is removed.

[0187] Typically, the body portion 104 (and the striker assembly) is arranged to move between a rest position and an active position, which can be different depending on the mode of the impactor 1 (e.g., whether the impactor is in a driving / impact mode or a removal mode).

[0188] In the impact mode, in the rest position, the proximal striker 108 is spaced from the connector 112, and in the active position, the proximal striker is in contact with the connector. Thus, when the striker assembly moves from the rest position to the active position, the connector is impacted by the proximal striker, driving the implant into the bone. The proximal striker can then be returned to the rest position (e.g., by a compressive force exerted by the return spring 122) to prepare the impactor 1 for another impact.

[0189] In the removal mode, in the rest position, the distal striker 106 is distanced from the strike chamber 110, and in the active position, the distal striker is in contact with the strike chamber. Thus, when the striker assembly moves from the rest position to the active position, the strike chamber is impacted by the proximal striker and the connector (which is connected to the strike chamber) removes the implant from the bone. The distal striker can then be returned to the rest position (e.g., by a tension force exerted by the return spring 122) to prepare the impactor 1 for another impact.

[0190] The rest position can depend on the mode, such that in the impaction mode the body portion 104 can be positioned towards the distal end of the impactor 1 in the rest position, and in the removal mode the body portion can be positioned towards the proximal end of the impactor in the rest position.

[0191] In some embodiments, the impactor 1 has a rest position that is between a "forward" active position (where the proximal striker 108 contacts the connector 112) and a "rearward" active position (where the distal striker 106 contacts the strike chamber 110). From the rest position, the body portion 104 can be moved toward the forward position to provide an implantation force. Similarly, the body portion can be moved toward the rearward position to provide a removal force.

[0192] In such an embodiment, the return spring 122 may be arranged to compress when the body portion is moved from the rest position to the forward position, and to expand when the body portion is moved from the rest position to the rearward position, such that in either position the return spring acts to return the body portion 104 to the rest position.

[0193] A damping component can be included in the impactor 1 to damp movement of the body portion 104 to prevent it from passing the rest position. This damping component can be part of a linear bearing supported by a bearing holder 116. In some embodiments, the spool 114 is used to provide a damping force to prevent the body portion from passing the rest position (e.g., by providing a current to the spool to induce a damping magnetic field). The damping force is typically arranged to be applied such that the body portion is critically damped or overdamped.

[0194] In some embodiments, the damping force is only applied when the body portion is returned from an active position (either a forward or rearward position) to a rest position. This can be achieved using a spool 114. A current is supplied to the spool to move the body portion 104 from the rest position to either the forward or rearward position. Once the body portion reaches this position (and the connector provides the implantation or removal force), the current is removed and the return spring 122 acts to return the body portion to the rest position. At this point, a current can be supplied to the spool to provide the damping force.

[0195] To return the connector 112 to the rest position following an impact from the proximal striker 108, the distal striker 106 can be arranged to impact the strike chamber 110 as the body portion 104 moves from the forward position to the rest position. This may involve the body portion moving past the rest position. The strike chamber being connected to the connector results in the connector being moved rearward (towards the distal end of the impactor 1) with the strike chamber after the connector is impacted by the distal striker 106.

[0196] In some embodiments, the bearing holder 116 is used to limit the forward movement of the impact assembly. Specifically, the contact of the connector 112 on the bearing holder and the contact of the proximal striker 108 on the connector can form the limit of travel for the proximal striker. In some embodiments, the return spring 122 can be used to limit the forward movement of the impact assembly. Specifically, the return spring can be selected such that compression of the spring limits the movement of the body portion (where the return spring acts on the body portion via the cap 124).

[0197] In some embodiments, the connector 112 moves during use (e.g., the connector moves from a rest position to an active position after the connector is impacted). In some embodiments, the connector is arranged to be substantially stationary during use. For example, to apply an impact force, the connector can be held in the active position and then struck by the proximal striker 108 (as the proximal striker moves from the rest position to the active position). The force applied to the connector is then transmitted by the proximal striker to the implant that is contacted by the connector.

[0198] Positioning the connector 112 in an active position for implanting an object typically involves applying a force to the connector to place the body portion in a rearward (e.g., distal-most) position where the distal striker 106 is in contact with the rear of the strike chamber 110, which in turn is in contact with the spacer 120. Such a force occurs when the connector is pressed against the implant to force the implant into the bone.

[0199] Similarly, when the impactor 1 is being used to remove an implant, a force is typically applied to the body portion 104 to move it to a forward-most position (e.g., a proximal-most position), where the connector 112 is in contact with the rear of the bearing holder 116 and the proximal striker 108 is in contact with the connector. The distal striker 106 is then spaced from the rear of the strike chamber 110. A force applied to the distal striker then moves the distal striker to strike the strike chamber and impart a removal force to the connector.

[0200] The above description with reference to Figures 2a-2c has described a detailed embodiment of the actuator mechanism 100. Referring to Figure 3a, in a simpler embodiment, the actuator mechanism 100 comprises: - A strike assembly 126. The strike assembly typically comprises a ferromagnetic material. Typically, the strike assembly comprises a body portion 104 and one or more strikers. The strikers may be positioned to impact the connector and / or may be positioned to impact an object directly. The strikers may be positioned to provide both an implantation force and a removal force. - A spool 114 (and / or windings, coils, and / or solenoids) arranged to apply a (magnetic) force to a strike assembly 126 when a current is provided to the spool, which is arranged to move (e.g., impact an object) as a result of the magnetic force.

[0201] Referring to FIG. 3b, the actuator mechanism 100 typically further includes a connector 112. The connector is arranged to be impacted by a striker of the strike assembly 126 and transmit the impact force to the object. The connector can be arranged to provide force only in a single direction (and can be positioned entirely on one side of the strike assembly). Alternatively, the connector can be arranged to provide force in either direction. In this case, the connector is arranged to at least partially surround a component of the strike assembly, as shown in FIG. 3b, which allows different forces to be provided by moving the strike assembly in different directions. More specifically, the connector typically includes and / or is attached to a strike chamber 110, and a striker of the strike assembly is positioned within the strike chamber. This allows the striker to move proximally to impact the connector to provide an implantation force, and distally to impact the strike chamber to provide a removal force.

[0202] The use of a connector 112 that is separate from the strike assembly 126 and is decoupled from the strike assembly in the rest position allows the strike assembly to increase speed before applying a force to the impactor. This increase in speed (and kinetic energy) can be used to deliver a large impact force (e.g., by causing the strike assembly to decelerate quickly when impacting the connector). This allows objects to be implanted using a small number of impacts, which is beneficial for orthopedic procedures, since the use of a large number of impacts can reduce fixation of the implant into the bone.

[0203] Moreover, the spacing of the strike assembly 126 from the connector 112 allows significant impact energy to be provided using a low mass connector and / or strike assembly. The energy imparted to the connector by the strike assembly is

[0204]

number

[0205] where m is the mass of the strike assembly and V is the velocity of the strike assembly just prior to impact. Thus, to provide a high energy impact, either a large mass or a large velocity must be provided. It may be desirable to use a high mass and a low velocity for the strike impactor, since this may improve implant fixation. Thus, the strike assembly 126 may be positioned as follows: - Weighs at least 0.6 kg, at least 1.2 kg, at least 1.8 kg, at least 2.5 kg, at least 4 kg, and / or at least 5 kg. - Capable of moving at least 1 m / s, at least 1.5 m / s, at least 2 m / s, at least 3 m / s, and / or at least 5 m / s upon impact.

[0206] With a weight of 4 kg and an impact velocity of 1 m / s, the strike assembly 126 is capable of imparting an impact energy of 2 J.

[0207] Using a large mass for the connector 112 can reduce implant fixation. Thus, in some embodiments, the connector weighs 1 kg or less, 0.5 kg or less, 0.2 kg or less, and / or 0.1 kg or less.

[0208] Typically, the strike assembly 126 is larger in terms of mass than the connector 112. In some embodiments, the strike assembly has a mass that is at least two times the mass of the connector, at least three times the mass of the connector, at least five times the mass of the connector, and / or at least ten times the mass of the connector.

[0209] To achieve the different weights, the strike assembly and the connector can include materials of different densities. In particular, the strike assembly can include a material that is denser (e.g., twice as dense, three times as dense, five times as dense, and / or ten times as dense) than the connector.

[0210] To provide adequate space for the strike assembly 126 to gain speed, the connector 112 and strike assembly are typically positioned such that the strike assembly (e.g., the proximal striker 108 of the strike assembly) is spaced from the connector in the rest position by at least 3 mm, at least 5 mm, at least 10 mm, and / or at least 20 mm.

[0211] Similarly, the strike assembly (e.g., the distal striker 106 of the strike assembly) can be at least 3 mm, at least 5 mm, at least 10 mm, and / or at least 20 mm from the connector (e.g., rear of the strike chamber 110) in the rest position.

[0212] It is recognized that a similar increase in velocity can be achieved without the connector 112, e.g., the strike assembly 126 can be accelerated a similar distance before directly impacting the object. However, directly impacting the object with the strike assembly can result in a less efficient force transmission (as the strike assembly would bounce off the object). Using a connector (which can be substantially stationary (e.g., moving less than 2 mm, less than 1 mm, and / or less than 0.5 mm) at the time of impact) improves the efficiency of force transmission.

[0213] It will be appreciated that the use of spaced strike assemblies and connectors can be provided without a spool arrangement, particularly where the strike assembly is of substantially greater mass than the connector. For example, the spaced arrangement can be used with gas-powered or manually-powered actuator mechanisms.

[0214] Referring to FIG. 3c, an embodiment of the actuator mechanism 100 including multiple spools 114-1, 114-2 is shown. The multiple spools can be provided either in series or in parallel. Notably, spools provided in series at different locations along the strike assembly 126 can be used to provide different forces. A first spool positioned distally to the strike assembly can be used to provide a removal force, while a second spool positioned proximally to the strike assembly can be used to provide an implantation force. Moreover, multiple spools can be used to provide a consistent force on the strike assembly by energizing the spools with a ripple effect. Spools with different diameters (e.g., spools positioned in parallel) can be used to provide different magnitudes of force, where a spool with a small cross-sectional area can be used to provide a low impact force and a spool with a large cross-sectional area can be used to provide a higher impact force.

[0215] Embodiments using multiple spools are described in more detail with reference to Figures 7, 8a and 8b, in particular Figure 8a shows an embodiment with multiple parallel spools and Figure 8b shows an embodiment with multiple spools positioned in series.

[0216] 3d, an embodiment of the actuator mechanism 100 is shown that includes an electromagnet 128. The electromagnet is typically formed from a non-moving core of iron that is positioned within the spool 114. With this arrangement, the strike assembly 126 includes an iron mass that can be moved by the force generated by the electromagnet. The strike assembly can include a permanent magnet and / or a ferromagnetic material.

[0217] The electromagnet 128 can be used to provide either an implantation force or a removal force by changing the direction of the current provided to the electromagnet.

[0218] As shown in FIG. 3d, in some embodiments, the actuator mechanism 100 includes an energy storage mechanism, such as a spring 130. In such embodiments, energy can be stored in the spring by providing a current to the electromagnet. The current provided to the electromagnet can then be removed, and the force stored in the spring moves the strike assembly 126 to provide the impact force. In such embodiments, the spring is typically positioned between the electromagnet and the strike assembly.

[0219] This arrangement allows a single direction of current to be used to provide a force in either direction, for example: To provide an implantation force, a current is provided that acts to rapidly move the strike assembly 126 away from the electromagnet 128. - To provide the removal force, a current is provided which acts to slowly move the strike assembly away from the electromagnet, which current is then quickly removed causing the spring to compress and move the strike assembly rapidly towards the electromagnet. or To provide the removal force, an electrical current is provided that acts to rapidly push the strike assembly 126 towards the electromagnet 128. - To provide the implantation force, a current is provided which acts to slowly move the strike assembly towards the electromagnet, which current is then quickly removed causing the spring to expand and rapidly move the strike assembly towards the electromagnet.

[0220] The operation of an embodiment of the actuator mechanism will now be described with reference to Figure 2, which shows the actuator mechanism in a rest position.

[0221] In this rest position, the proximal striker 108 is spaced apart from the connector 112 within the strike chamber 110, the rest spring 122 is in a relaxed state, and no current is provided to the spool 114 by the power source 2.

[0222] An electrical current is provided from power source 2 to spool 114 to provide an impact force to drive the implant into the bone. The characteristics of this current (e.g., direction, duration, and magnitude) are determined by control electronics 4 and depend on primary input 6 and secondary input 8 selected by the user.

[0223] Current supplied to the spool 114 by the power source 2 leads to the generation of a magnetic force acting on the ferromagnetic body 104, causing it to move towards an active position (here, a forward position). As the body moves towards the forward position, the proximal striker 108 also moves in a proximal direction. Eventually, the proximal striker impacts the connector 112, which pushes the connector forward, causing the connector to impact the implant. The acceleration of the body (and therefore the impact force / energy) depends on the current induced in the spool.

[0224] Moreover, as body portion 104 moves proximally, return spring 122 is compressed, causing a compressive force to build up in the spring.

[0225] As the connector 112 moves proximally, it impacts the implant. Following this, the rear surface of the connector impacts the bearing holder 116, which prevents further proximal movement of the connector. Once this position is reached (or before this position is reached), the current in the spool 114 is removed. Thus, the magnetic force acting to move the body portion 104 to the proximal position is removed. This causes the compressive force in the return spring 122 to act to move the body portion distally away from the proximal position to a rest position. Using the return spring, a consistent rest position can be achieved (e.g., where the return spring is balanced) so that a consistent force can be applied using the connector.

[0226] In some embodiments, as the body portion 104 moves towards the rest position, the distal striker 106 contacts the rear of the strike chamber 110. This causes the strike chamber (and the secured connector 112) to move in a distal direction (e.g., to return the connector to the rest position).

[0227] This process can be repeated multiple times to drive the implant into the bone.

[0228] Although the above description with reference to FIG. 2 considered the connector 112 moving to impact the implant, typically the connector remains substantially stationary as the implant is driven into the bone. In these embodiments, the connector can be fixed in place by the spacer 120, the bearing holder 116, a connection to the casing 102, and / or a force applied by the user. In some embodiments, a retaining structure or mechanism is provided on the casing (e.g., a protrusion from the casing), where the mechanism can be operated to prevent movement of the connector or removed to allow movement of the connector. As an example, a latch on the casing can be placed into a notch on the connector 112 to hold the connector 112 in place, where the latch can be removed once the impaction procedure is completed. An implementation in which the connector remains substantially stationary when providing a driving / embedding force to the implant is described below with reference to FIG. 4a.

[0229] Typically, current is provided to the spool 114 for only a short period of time (e.g., less than 1 second, less than 0.5 seconds, or less than 0.1 seconds). This results in a force being applied to the body portion 104 for only a short amount of time. The body portion can then move quickly forward and impact the connector before returning to a rest position under the influence of the return spring 122.

[0230] A similar process is used to remove the implant: specifically, current is provided to the spool 114 in a first direction to provide an implantation force, and current is supplied in the opposite direction to provide a removal force.

[0231] This causes the body portion 104 to move from the rest position to the distal position. The distal striker 106 also moves distally, eventually striking the rear of the strike chamber 110. The strike chamber is connected to the connector 112, so that the impact of the distal striker acts to move the connector to the distal position, removing the implant from the bone. As the body portion moves towards the distal position, the return spring 122 expands.

[0232] As the strike chamber 110 and connector 112 move distally, the rear side of the strike chamber eventually contacts the spacer 120, preventing further movement of the connector. At (or before) this point, the current to the spool is removed and the tension in the return spring 122 acts to return the body portion 104 to the rest position.

[0233] This process can be repeated multiple times to remove the implant from the bone.

[0234] By having the impactor 1 have rest positions between a proximal (e.g., implantation) position and a distal (e.g., removal) position, the impactor can be used to both install and remove implants from bone. Typically, this involves providing a current in a first direction to provide an implantation force, and providing a current in an opposite, second direction to provide a removal force.

[0235] In some embodiments, the return spring 122 is changeable and / or interchangeable. By changing the characteristics of the return spring (e.g., the rest tension applied to the return spring), the rest position of the strike assembly can be changed. This allows the impactor to be used, for example, with a distal rest position to provide an impact force and a proximal rest position to provide a removal force. By changing the rest position, the distance between the striker and the connector / strike chamber in the rest position can be maximized. This gives the strike assembly more space to gain speed and provide a high energy impact.

[0236] Another implementation of the impactor 1 is described with reference to Figures 4a and 4b. In this implementation, the connector 112 is arranged to be substantially stationary when the impactor is in use.

[0237] 4a, when a user is attempting to implant an object, the user will likely provide a proximal force that acts to push the connector 112 into the implant. This causes a force to be applied to the connector when the impactor 1 is in the rest position (and the spool 114 is unpowered). This force causes the connector and strike chamber 110 to be pushed distally such that the strike chamber comes to rest on the spacer 120 (as shown in FIG. 4a) when no current is applied to the spool. The connector can then be secured in place in this position (e.g., using a retention feature on the casing 102).

[0238] With the impactor in this rest position (and the strike chamber 110 resting on the spacer 120), an application of electrical current is provided to the spool. This electrical current generates a magnetic field that acts on the strike assembly 126, causing the strike assembly (and proximal striker 108) to move in a proximal direction, impacting the connector 112 and providing an implantation force to the object.

[0239] This movement also compresses the return spring 122 such that when the spool is no longer powered, the return spring acts to move the striker assembly (and the proximal striker) away from the connector to a rest position. It is recognized that embodiments of the impactor 1 can be provided without a return spring. A separate biasing mechanism can be provided and the strike assembly can be returned to the rest position by applying an appropriate force to the spool 114 and / or a user can manually move the strike assembly back to the rest position. The use of a biasing mechanism (e.g., a return spring) is beneficial because it provides a reliable manner for consistently returning the strike assembly to the rest position.

[0240] In this implementation, the connector 112 is typically substantially stationary, where the connector acts to transmit force from the proximal striker 108 to the implant. The use of a moving strike assembly and a substantially stationary connector allows for the delivery of large impact forces because the strike assembly 126 accelerates, gaining velocity (and energy) over time before decelerating more rapidly.

[0241] The strike chamber 110, resting on the spacer 120 in the rest position, prevents the application of a distal force (e.g., when the strike assembly returns to the rest position) because the strike assembly remains spaced apart from the distal striker 106.

[0242] Typically, the return spring 122 is positioned such that, in the rest position, the body portion 104 is spaced from both the strike chamber 110 and the connector 112 .

[0243] Referring to FIG. 4b, when a user is attempting to remove an object, the user will likely provide a small distal force that acts to move the connector 112 away from the implant. This results in a force being applied to the connector when the impactor 1 is in the rest position (and the spool 114 is unpowered). This force causes the connector and strike chamber 110 to be pushed in a proximal direction such that when no spool current is applied, the connector typically comes to rest on the bearing holder 116. Application of an appropriate current to the spool then moves the distal striker 106 in a distal direction, impacting the strike chamber and exerting a removal force on the connector. The strike assembly and body portion 104 then return to the rest position under the force of the return spring 122.

[0244] The impactor 1 can also be provided with a single impaction direction that is used for both impacting and removing the implant. In impactor embodiments, the implantation process works as described above, where a force is applied to the spool 114 that acts to move the body portion 104 in a proximal direction.

[0245] As explained above, to remove the implant, the power source 2 is capable of providing an electrical current that acts to move the body portion distally.

[0246] Alternatively, to remove the implant, the power source 2 can provide a current that acts to move the body portion 104 towards a proximal position. When the user is attempting to remove the implant, the user applies a distal force to the impactor (pushes the impactor away from the implant). This causes the connector 112 to move in a proximal direction until it abuts the bearing holder 116. When a force is applied to move the body portion, the body portion moves towards a forward position. However, before the proximal striker 108 can contact the connector, the movement of the body portion (and the proximal striker) is stopped by the compression of the return spring 122. This compression moves the body portion towards a rearward position (distal direction). The distal striker 106 also moves backwards, eventually impacting the strike chamber 110, which moves the connector in a distal direction and applies a removal force to the implant. In this way, both the impaction force and the removal force can be applied using a current having the same direction. Moreover, both impaction and removal forces can be provided using a non-permanent magnet for the body portion. This design also reduces the range of movement required for the body portion. By moving the starting position of the connector, the body portion moving through a fixed range of movement can be used to either impact or remove the implant. In other words, if an initial proximal force is applied to the impactor, the movement of the body portion acts to impact the implant. If an initial distal force is applied to the impactor, the same movement of the body portion acts to remove the implant.

[0247] Similarly, and referring again to FIG. 4b, to provide a removal force, the spool 114 can be powered in a rest position and unpowered in an active position, where the strike assembly 126 exerts a force on the connector 112 after current is removed from the spool.

[0248] In particular, the spool 114 is capable of receiving an electric current in a rest position, which results in the generation of a magnetic field that acts to move the strike assembly 126 to a proximal position (e.g., in the rest position, the connector 112 rests against the rear surface of the linear bearing 116). In this position, the return spring 122 is compressed. The strike assembly is then held in place by a matching force provided by the spool and return spring (and, optionally, a user, who may be applying a distal force).

[0249] Typically, the spool is arranged to accept gradually increasing current to slowly move the strike assembly 126 towards the proximal rest position and avoid providing undesirable implantation forces.

[0250] When the user is ready to provide a removal force to the object, the current provided to the spool 114 is removed. The strike assembly (and body portion 104) then moves distally due to the compressive force in the return spring 122. This moves the distal striker 106 distally until it strikes the strike chamber 110. This provides a removal force to the connector 112 that acts to remove the implant.

[0251] In this manner, the electrical current acting to move the strike assembly proximally can be used to provide a distal force.

[0252] Another current can then be provided to the spool 114 and the process can be repeated to provide multiple shocks.

[0253] The implementations described above, in which driving and removal forces are provided using the same directional movement of the body portion 104 and the strike assembly, may be particularly relevant when non-permanent magnets are used in connection with the body portion. In such embodiments, the current (and resulting magnetic field) induced in the body portion can act to counter the magnetic field generated by the current in the spool. Thus, changing the direction of the current does not change the direction of movement of the body portion (because switching the direction of the current in the spool merely switches the direction of the current induced in the body portion).

[0254] Typically, to provide an implantation force, a large current is provided quickly to the spool 114. This applies a large momentary force to the strike assembly 126, causing it to move rapidly in the proximal direction. Typically, to provide a removal force, current is provided gradually to the spool. Thus, the strike assembly moves slowly in the proximal direction and the return spring 122 compresses slowly. The current is then removed quickly (or momentarily), causing the compressive force on the return spring to move the strike assembly rapidly in the distal direction.

[0255] In the above example, the return spring 122 is used to provide a removal force when the current provided to the spool 114 is removed. It will be appreciated that the return spring can be used to provide a driving / implanting force as well. For example, the strike assembly 126 can be positioned such that the current provided to the spool acts to move the strike assembly in a distal direction (e.g., the body portion 104 can be provided proximally relative to the spool in a rest position). Thus, when the spool is powered, the strike assembly moves to a distal position and the return spring is extended. This removal of power to the spool causes the strike assembly to move forward and provide an implanting force to the connector 112.

[0256] Similarly, the removal force can be provided using the provision of an electrical current to the spool 14. In particular, the strike assembly 126 can be positioned such that an electrical current provided to the spool acts to move the strike assembly in a distal direction (e.g., where the body portion can be provided distally relative to the body portion 104 in the rest position). Thus, the provision of an electrical current to the spool will act to move the strike assembly (and thus the distal striker 106) in a distal direction, which leads to the distal striker impacting the strike chamber 110 and the connector moving in a distal direction to provide the removal force.

[0257] In some embodiments, the impactor 1 is arranged to acquire data related to the impact. For example, the impactor can determine the impact force, impact energy, or implant stability. The data can be acquired by monitoring the current induced in the spool 114 by the body 104 after the body strikes the connector. The return of the body from a forward position to a rest position will induce a current in the spool 114. The characteristics of this current (e.g., the magnitude and duration of the current) can be used to determine the characteristics of the impact. Similarly, sensors (e.g., accelerometers) can be used to determine the impact velocity, impact frequency, or impact resistance. The data acquired by the impactor 1 is typically presented to the user of the impactor via the screen 10. The data can also or alternatively be transmitted to an external device (e.g., following use) so that the implant procedure can be analyzed.

[0258] In some embodiments, the connector 112 includes one or more sensors (e.g., load cells, accelerometers, and / or strain gauges, etc.) The sensors are positioned to acquire impact data, and typically the sensors are positioned to measure impact energy, impact force, and / or implant stability.

[0259] The impact parameters (e.g., impact force) can be altered based on the determined impact characteristics. As an example, if the first impact is determined to have an undesirably low impact force or an undesirably low penetration force, the subsequent impact can be performed using a higher impact force (e.g., higher spool current). The patient's bone characteristics (e.g., bone density, etc.) can affect the impact procedure, such that the same impact energy used for a different patient can result in substantially different impact forces being provided. Thus, typically the impactor is arranged to determine object and / or patient characteristics from the first impact, and is used to adjust the impact energy and / or force for future impacts. This adjustment typically uses a closed control loop and / or a proportional-integral-derivative (PID) controller to adjust the impact force. Specifically, the user inputs the desired parameters (e.g., impact force) via inputs 6, 8. The impact is then delivered and measured, and the measured characteristics are used to modify the characteristics of the current delivered to the spool 114 for the subsequent impact.

[0260] The impactor 1 is typically arranged to allow a user to modify (or input) one or more of the following: - Impact Energy: A selected impact energy can be provided by providing an appropriate current to the spool 114. - Impact force. The impact force typically depends on both the impact energy and the object being impacted. Thus, the desired impact force is typically provided by applying a first impact at a first impact energy, by determining the difference between the determined (e.g., measured) impact force and the desired impact force, and by providing a second impact at an appropriately modified impact energy (e.g., if the determined impact force is 20% less than the desired impact force, the second impact can be arranged to have an impact energy 20% greater than the first impact). - Desired implant stability: Stability can be determined by measuring (eg, by applying a force to the implant and detecting the resistance of the implant to movement).

[0261] In some embodiments, the control electronics 4 is arranged to receive information about the use, for example the control electronics can receive information about the object to be implanted (e.g. the material and / or density of the object) and / or the surface into which the object is to be implanted (e.g. bone density and / or age of the patient). This information can be used by the control electronics 4 to determine appropriate impact characteristics (e.g. appropriate impact energy and / or force, etc.).

[0262] How it works 5, a method of implanting an object using a control system is shown. Such a method can be implemented by the control electronics 4 of the impactor 1.

[0263] In a first step 12, the control electronics 4 identifies an input parameter (or input parameters). Typically, the parameters are entered by a user (e.g., using the first input 6 and / or the second input 8), where the parameters may include a desired stability, a desired impact energy, and / or a desired impact force.

[0264] In a second step 14, the control electronics 4 generate impact characteristics based on the input parameters. Typically, this involves determining an appropriate current that can be provided to the spool 114 to achieve an impact with the desired input parameters. This can involve determining an appropriate impact energy and then determining a current profile related to this impact energy. The relationship between current and energy typically depends on the characteristics of the strike assembly 126 and the characteristics of the spool 114.

[0265] The energy transmitted to the spool is related

[0266]

number

[0267] (where L is the inductance in henries and I is the current in amperes). The energy density of the generated magnetic field can then be determined using the relationship

[0268]

number

[0269] where A is the cross-sectional area of ​​the spool and l is the length of the spool. These equations can be used to determine the appropriate current for the spool 114.

[0270] Since the produced values ​​may differ from the calculated values ​​(e.g. due to manufacturing tolerances, resistance in components of the impactor 1, heat losses, etc.), the control electronics 4 may be arranged to perform a calibration process. This calibration process typically involves determining the relationship between the input current and the resulting impact energy, where the calibration may use data from test procedures and / or previous impact application procedures.

[0271] Typically, the impact characteristics generated based on the input parameters are arranged to provide a first impact having an impact energy lower than the calculated impact energy related to the input parameters, in this way the risk of causing a fragmentation remains small if the actual impact energy is greater than the calculated impact energy.

[0272] As has been explained above, providing a removal force can include removing current from the spool 114. In these cases, the force on the strike assembly 126 that acts to move the strike assembly towards the strike chamber 110 / connector 112 is typically provided by the return spring 122. Specifically, the compression force in the return spring acts to move the body portion 104 when the magnetic force applied to the body portion by the spool is removed. In this case, the force of the impact (and thus the impact energy) can still be controlled by controlling the flow of current to the spool, thus controlling the compression of the spring.

[0273] The energy in the return spring 122 is given by the formula

[0274]

number

[0275] where k is the spring constant and x is the displacement from the unstretched position. The spring constant is typically measured prior to the impact procedure and provided to the control electronics. The displacement can be measured, for example, using a strain gauge. Similarly, the energy in the return spring can be calculated using the equation E=Fx. Here, the force in the return spring can be determined by determining the force that must be applied to the strike assembly (by the spool 114) to hold the return spring in a particular position. Thus, the current provided to the spool (which is related to the force applied by the spool to the body 104) can be used to determine the energy stored in the return spring and the compression force of the return spring.

[0276] In a third step 16, an impulse is provided based on the impulse characteristics. Providing the impulse typically includes providing an electrical current to the spool 114. As has been described above, providing a removal force can include removing the electrical current from the spool.

[0277] In a fourth step 18, it is determined whether the desired stability has been reached. This determination can be made by the control electronics 4 or by a user of the impactor 1. For example, a small current can be provided to the spool 114 and the resulting movement (or lack of movement) of the implant can then be detected by a sensor in the impactor.

[0278] In a fifth step 20, if the desired stability has been reached the impact application process is terminated. This decision can be made by the control electronics 4 and / or by the user of the impactor 1.

[0279] In a sixth step 22, if the desired stability has not been reached, the control electronics 4 determine whether the measured parameters of the impact are equal to the input parameters. For example, the control electronics can compare the measured impact energy to the input impact energy and / or the measured impact force to the input impact force. The comparison can be made with respect to multiple parameters.

[0280] If the measured parameters are in accordance with the input parameters, the method returns to a third step 16 where another impact is provided based on the previously generated impact characteristics. This impact can occur automatically, such that the user initiates the impact application process and then does not need to take any further action (e.g., multiple impacts can occur without further action). Alternatively, each impact may require user input (e.g., pressing a trigger).

[0281] If the measured parameters are not in accordance with the input parameters, then in a seventh step 24 the control electronics 4 generates new impulse characteristics. These new impulse characteristics typically include a modification of the previous impulse characteristics. For example, if the measured impulse force was lower than the input impulse force, the previously provided current is increased. The magnitude of the change in the impulse characteristics typically depends on the difference between the measured and input parameters, for example the characteristics may be changed in proportion to the percentage difference (so a 20% deficit in impulse force results in a 20% increase in current).

[0282] The third step 16, fourth step 18, fifth step 20, and sixth step 22 are then repeated until the desired stability is achieved and / or the user stops the process.

[0283] Data collected during use can be used to modify the operation of the impactor 1 for a single situation (e.g., a single THA procedure) or for different situations (e.g., future THA procedures). Among other things, the current provided by the power source 2 to the actuator mechanism 100 can depend on characteristics determined from impacts from previous uses. This allows a desired impact energy to be provided over the life of the impactor, where the current required for a given impact energy can change over time (e.g., as the power source 2 degrades). By taking previous use into account, the changes required can be continuously reviewed. The impact characteristics can also depend on the user of the impactor, where different users may apply different initial forces and / or have different preferences. Thus, typically the control electronics 4 is arranged to determine the user of the impactor, for example by allowing the user to log into the impactor.

[0284] Data collected during use, inter alia, relating impact energy and / or impact force to impact stability, can be used to determine appropriate impact energies for future procedures. The determination of beneficial impact energies (and, for example, whether it is preferable to use multiple low force impacts or fewer higher force impacts in a given situation, or whether it is preferable to use a large current delivered over a short period of time or a smaller current delivered over a longer period of time) may rely on artificial intelligence and / or machine learning.

[0285] Data collected during use can also be analyzed to determine characteristics of the procedure (e.g., to determine success rates and / or to analyze any problems that have arisen). In some embodiments, this involves data collected during surgery being transmitted to an external server (e.g., via a USB cable or via an area network connection).

[0286] 6a and 6b, two alternative control systems are described for providing energy to the spool 114 (and thus the strike assembly 126 and connector 112). The control electronics 4 may implement either or both of these control systems, where a user may be able to select the control system to use.

[0287] Referring to FIG. 6a, an open loop control system is illustrated.

[0288] In a first step 32, a user inputs impact energy.

[0289] In a second step 34, the control electronics 4 determine the current to provide to the spool 114 based on this input energy. Determining the current typically involves determining the magnitude and / or duration of the current to provide to the spool. The current determination is typically based on a table, graph, or formula. Usually, the impact energy is proportional to the magnitude / duration of the current provided to the spool.

[0290] In a third step 36, impact energy is applied to the external object as previously described. In particular, power source 2 provides a determined current to spool 114. This current results in the generation of a magnetic field that moves strike assembly 126 such that it impacts connector 112, which in turn impacts the object.

[0291] In a fourth step 38, the external object experiences a force that depends on the applied impact energy. The impact force is typically proportional to the impact energy. However, this force also depends on other factors (e.g., the material of the implant and the hardness of the bone into which the implant is inserted, etc.).

[0292] In this regard, impact force (as opposed to impact energy) is typically a significant factor in bone fracture during implant seating. The impact force (and, in particular, the peak impact force) provided to the implant is dependent on the impact energy (and thereby on the energy provided to the spool 114). However, the relationship between impact energy and impact force is not always simple, since it depends on several factors, such as: - Geometry (e.g. implant / rasp / impactor geometry). - Stiffness / damping of the impacting body (e.g. implant / rasp / impactor stiffness) - The stiffness / damping properties of the material supporting the impacting body (e.g. stiffness of the bone and soft tissue surrounding the implant / rasp)

[0293] Lower stiffness tends to lead to lower impact forces because the impact energy is provided to the implant over a longer duration. In other words, if the components of the impactor are able to deform, the impactor will provide a relatively low force over a relatively high duration (compared to impactors with stiffer components).

[0294] It is not straightforward to determine the relationship between impact energy and impact force, particularly since this relationship depends on variables external to the impactor 1 (e.g., bone stiffness), and therefore it is not straightforward to determine the relationship between the current / energy provided to the spool 114 and the impact force.

[0295] Therefore, it may be difficult to provide an optimal impact force in the open loop system described with reference to FIG. 6a.

[0296] Referring to FIG. 6b, the control electronics 4 are capable of providing a closed loop system.

[0297] In a first step 42, the user inputs the impact force (as opposed to the impact energy).

[0298] In a second step 44, the control electronics 4 determine the current to provide to the spool 114 based on this input energy. The energy determination typically relies on a Proportional-Integral-Derivative (PID) controller, as described with reference to FIG.

[0299] In a third step 46, impact energy is applied to the external object, and in a fourth step 48, the external object experiences a force that is dependent on the impact energy.

[0300] In a closed loop system, a sensing step 47 is provided in which the force being applied to the external object is measured by a force sensor. This force sensor typically includes a force sensor positioned along the impact path (e.g., proximal to the impact chamber and / or integrated into the connector 112) such that the force sensor can measure the output impact force. More specifically, the force sensor can determine the difference between the expected impact force (which can be determined based on a formula relating spool energy to impact force) and the actual impact force.

[0301] The closed loop system also provides a feedback step 43 such that a second step 44 of determining the impact energy for the second impact is dependent on the output of the force sensing step 47 and thereby on the actual impact force detected by the force sensor for the first impact.

[0302] The use of this closed loop system allows variables (such as bone hardness and implant material) to be taken into account by the control electronics 4.

[0303] To avoid inadvertently providing excessive impact force with the first impact (before the force sensor has an opportunity to determine the relationship between the impact energy and the impact scheme), the impactor is typically arranged to provide a low energy impact as the first impact, and then to increase the impact energy to meet but not significantly exceed the input force. The ramp-up from the first impact to the desired impact (where the desired input force is expected to be provided) typically includes only a small number of ramp-up impacts (e.g., 5 or less and / or 3 or less ramp-up impacts). In other words, the impactor can provide a first impact and / or multiple first impacts with an impact force lower than the desired impact force, and then determine a desired impact energy based on the first impact, which is associated with the desired impact force.

[0304] In some embodiments where the control loop is fully reactive, the control electronics 4 can affect the impact force during the impact, eliminating the need for multiple "ramp up" hits. Specifically, the control electronics can determine at the beginning of the impact whether the impact force being delivered is greater or less than the expected impact force, and can modify the current delivered to the spool while the impact is ongoing.

[0305] Sensing In order to provide a consistent and desired force, it is desirable to measure various operating parameters (eg, the location of the strike assembly 126 and the force applied to the object by the connector 112, etc.).

[0306] These parameters may be measured using various sensors; for example, a position sensor may be provided that detects the position of the strike assembly 126 and a separate force sensor that detects the force applied by the connector 112.

[0307] In some embodiments, the spool 114 is used as a sensor such that one or more operating parameters are determined in dependence upon the spool. In this regard, movement of the strike assembly 126 induces a current in the spool (e.g., via a back electromotive force or back emf) that opposes the current provided by the power source 2. The magnitude and duration of this induced current can be used to determine multiple operating parameters.

[0308] More specifically, the spool 114 can be modeled as a series inductor and resistor, and the characteristics of this inductor and resistor circuit (and, among other things, the relationship between the current and voltage in the circuit) can be used to determine operating parameters.

[0309] Exemplary operating parameters that may be determined depending on the current and / or voltage at the spool 114 include: - Solenoid resistance (e.g. spool resistance): By applying a voltage / current from power supply 2 to the spool 114 and then measuring the resulting voltage / current in the spool, the spool resistance can be determined according to Ohm's law:

[0310]

number

[0311] Typically, current and voltage readings are taken over several hundred milliseconds to mitigate the transient impedance of the spool inductor. - Temperature: The resistivity (ρ) of the spool 114 is a function of the temperature of the spool. By measuring the spool resistance (R) and using the mechanical parameters of the spool (spool length (l) and spool cross-sectional area (A)), the spool resistivity can be calculated using the formula:

[0312]

number

[0313] The resistivity can then be looked up in a lookup table to find the temperature of the spool. - Location: The inductance of the spool 114 is a function of the displacement of the strike assembly 126 relative to the spool. By monitoring the current flowing through the spool when it is powered and by taking into account the spool resistance (e.g., via the methods described above), the inductance of the spool can be calculated. This inductance can then be looked up in a lookup table to find the position of the strike assembly 126. This method can be used to ensure that the strike assembly is positioned in the same position before each impact, which helps ensure that the impactor 1 provides a consistent impact force. - Mechanical load: Energizing the spool 114 causes the striker assembly 126 to move relative to the spool (as described above). When the strike assembly encounters resistance (due to impacting the connector 112, which impacts the object), it decelerates, which results in the generation of a back emf across the solenoid. By monitoring the profile of this back emf, the mechanical load on the strike assembly (and thus the impact force delivered to the object) can be calculated. This allows the spool to be used as a force sensor.

[0314] The use of the spool reduces the number of components required in the impactor 1, thus allowing for the provision of a compact impactor. Moreover, because the spool is already connected to the control electronics 4, variables measured using the spool can be recorded, output and / or transmitted with minimal further processing.

[0315] Multiple spools 7a and 7b, and as previously described with reference to FIG. 3c, in some embodiments, the impactor 1 (and, more specifically, the actuation mechanism 100) includes multiple spools. This can be considered to be an impactor including a spool 114, which is formed from multiple component spools 114-1, 114-2, 114-3.

[0316] Specifically, the impactor 1 of Figures 7a and 7b includes two proximal impacting spools 114-1, 114-3 and one distal impacting spool 114-2.

[0317] The proximal impacting spools 114-1, 114-3 are positioned such that application of an electrical current to the proximal impacting spool results in a magnetic field that moves the strike assembly 126 in a proximal direction.

[0318] The distal impacting spool 114-2 is positioned such that application of an electrical current to the distal impacting spool results in a magnetic field that moves the strike assembly 126 in a distal direction.

[0319] In practice, this typically includes proximal impaction spools 114-1, 114-3 and distal impaction spool 114-2 which contain wires wound around body portion 104 in different directions.

[0320] Typically, the force required to remove an implant is lower than the force required to insert an implant, and therefore the impactor 1 can be arranged to provide a maximum proximal force that is greater than the maximum distal force the impactor can provide. This is reflected in the layout of the impactor. The number of proximal impacting spools can be greater than the number of distal impacting spools. More generally, the total volume, total surface area, and / or total length of the proximal impacting spools can be greater than the total surface area and / or total length of the distal impacting spools.

[0321] 7 has two proximal impacting spools 114-1, 114-3 and one distal impacting spool 114-2, but more generally, the impactor 1 can include multiple component spools, including one or more proximal impacting spools and / or one or more distal impacting spools. The impactor can include multiple proximal impacting spools and / or multiple distal impacting spools. Typically, the impactor includes more proximal impacting spools than distal impacting spools.

[0322] The use of different numbers / surface areas of component spools allows for the provision of appropriate proximal and distal forces while minimizing the weight of the impactor 100.

[0323] The strike assembly 126 can similarly include multiple component bodies and / or multiple component strikers. Such an arrangement can be used to minimize the stroke length of the strike assembly and provide a compact impactor, where each of the component bodies impacts a different part of the connector. Each component body can be positioned depending on the corresponding component spool.

[0324] Each of the component spools 114-1, 114-2, 114-3 may have different lengths (or a single proximal impacting spool may be provided that is longer than a single distal impacting spool).

[0325] Typically, the spools are arranged in an alternating configuration, for example, in Figure 7, distal impacting spool 114-2 is positioned between proximal impacting spools 114-1 and 114-3. More generally, the spools can be arranged such that the proximal and distal impacting spools are each positioned axially symmetrically about the location of the body portion 104 and / or strike assembly 126 (e.g., its center). This provides an impactor with equivalent proximal and distal strokes.

[0326] With reference to Figures 8a and 8b, two possible arrangements of the component spools 114-1, 114-2, 114-3 are shown.

[0327] 8a, a series arrangement of component spools 114-1, 114-2, 114-3 is shown, which provides multiple spools positioned axially adjacent to one another.

[0328] 8b, a side-by-side arrangement of component spools 114-1, 114-2, 114-3 is shown, which provides multiple spools positioned radially adjacent to one another.

[0329] In each of these arrangements, the distal impaction spool 114-2 is disposed between the proximal impaction spools 114-1 and 114-3. While an alternating arrangement is typical in embodiments with multiple component spools, it will be recognized that this alternating arrangement is not required.

[0330] A combination of series and parallel arrangements may be provided. Additionally, a multi-strand arrangement may be provided, where the component spools 114-1, 114-2, 114-3 are overlapping.

[0331] Current Profile Typically, the spool 114 relies on semiconductor devices (e.g., transistors) to operate, where the supply of current to the spool relies on semiconductors. In particular, the spool may be operated using metal oxide semiconductor field effect transistors (MOSFETs).

[0332] Referring to FIG. 9a, a typical motion profile for the spool 114 is shown when a semiconductor is used to control the flow of current into the spool.

[0333] There are five important points about this behavior profile: 1. Current is supplied to the spool 114 by the power supply 2. The current in the spool induces a magnetic field, which acts to move the strike assembly 126. 2. The strike assembly 126 encounters some resistance (e.g., the strike assembly may strike the connector 112). This leads to the induction of a back emf, which causes a reduction in the current in the spool 114. 3. The strike assembly 126 reaches its maximum proximal or distal position, and thus the impactor 1 stops providing energy to the object (and back emf stops being induced). 4. The current reaches a maximum steady state current (this maximum current depends on the resistance / inductance of the spool 114). 5. Power supply 2 stops providing current to spool 114.

[0334] As seen by this profile, the spool 114 is not able to reach its maximum current until after the impact occurs. When the impact occurs before the spool reaches its maximum current, only a small impact force can be achieved (compared to when the impact occurs after the spool reaches its maximum current).

[0335] 9b, when the power supply 2 is positioned to aim for a target current (e.g., maximum operating current) based on the resistance in the spool 114, such a situation (where the spool never reaches its maximum current) is common. In this situation, the useful energy output (area under the curve shown in the current / time graph of FIG. 9b) is significantly less than the energy that would be output if the spool were to instantly reach its maximum operating current. The difference between the actual energy output and the maximum possible energy output is the lost energy shown in FIG. 9b.

[0336] Thus, as shown in FIG. 9c, the spool 114 can be provided with a high EMF such that the steady state current provided by the power supply 2 to the spool exceeds the maximum operating current of the spool (and providing a high EMF in this manner can be thought of as the power supply providing a current to the spool that is higher than the maximum operating current of the spool). Providing such a high EMF results in the maximum operating current of the spool being reached quickly. However, if such a high EMF is provided to the spool for an extended period of time, the current in the spool can increase beyond the maximum operating current of the spool. This can cause damage to the spool.

[0337] One way to mitigate overcurrent (where the current in the spool 114 exceeds the maximum operating current) is to introduce current monitoring and rapid spool switching. This method of operation is shown in FIG. 9d. Specifically, when the control electronics 4 detect that the current in the spool has exceeded the maximum operating current, the semiconductor is switched off so that the current begins to drop. When the control electronics 4 subsequently detects that the current in the spool has returned below the maximum operating current, the semiconductor is switched on again to increase the current in the spool. This process can be repeated to provide a current that oscillates around (or just below) the maximum operating current. By doing this, the spool 114 is adjusted to draw a maximum safe current under maximum load conditions while preventing damage to the power supply 2 or the spool under no-load conditions.

[0338] In practice, the control electronics 4 can be arranged to activate (e.g. switch on) the semiconductor when the current in the spool 114 falls below a first value and to deactivate (e.g. switch off) the semiconductor when the current in the spool exceeds a second value.

[0339] It will be appreciated that the graph of FIG. 9d shows an exaggerated switching region, and that in reality rapid switching can be used to essentially hold the current at (or just below) the maximum operating current.

[0340] Moreover, as explained with reference to Figure 9a, the current in the spool 114 depends on the position of the strike assembly 126 and whether the strike assembly is applying a force to the connector 112. Therefore, it is not possible to hold the spool at a constant current by simply providing a constant voltage and / or EMF to the spool. Providing a high EMF intermittently by the power source 2 via the semiconductors (which causes a high EMF to be provided to the spool) allows the maximum operating current of the spool to be maintained throughout the impact, even in the presence of a back emf.

[0341] The method described with reference to Fig. 9d allows for a maximally effective spool drive without incurring the risk of overcurrent under load variations. In other words, it significantly increases the amount of energy that can be provided to the spool 114, and therefore the maximum impact force that can be provided by the impactor 1. Similarly, by setting current limits in software, the energy delivered to the spool and the stiffness during impact (between stages 2 and 3) can be carefully controlled.

[0342] Alternatives and Modifications It will be understood that the present invention has been described above purely by way of example and that modifications of detail can be made within the scope of the invention.

[0343] Although the actuation mechanism 100 has been described above as using a spool 114 to provide a force to the body portion 104, other force providing mechanisms could be used. For example, hydraulic, pneumatic, or chemical arrangements could be used to apply a force to the body portion. In such arrangements, the feedback mechanism and bidirectional operation of the impactor 1 still provide advantages over conventional products.

[0344] Moreover, the separate strike assembly and connector still allows for the provision of a high mass strike assembly and / or a low mass connector, which has beneficial properties such as reducing the risk of crushing when the impactor is used for implantation.

[0345] In some embodiments, the connector 112 is affixed to or is an integral part of the body 104. A (magnetic) force applied to the body can then directly impact an external object via the connector. In other words, the spool 114 can be used to apply / induce a force to the body, which can be used to directly impart a force to an external object. In such an embodiment, the connector can be considered to be part of the strike assembly, which also includes the body, the distal striker 106, and the proximal striker 108.

[0346] Reference numerals appearing in the claims are for illustrative purposes only and shall have no limiting effect on the scope of the claims. [Explanation of symbols]

[0347] 1 Impactor 2 power supply 4 Control electronics 6 Primary Input 8 Secondary Input 10 Display, Screen 100 Actuator mechanism 102 Casing 104 Main body 106 Distal Striker 108 Proximal Striker 110 Strike Chamber 112 Connector 114 Spool 114-1 Proximal Impact Spool 114-2 Distal Impact Spool 114-3 Proximal Impact Spool 116 Bearing holder 118 End Cap 120 Spacer 122 Return spring 124 Cap 126 Strike Assembly 128 Electromagnet 130 Spring ZZ axis

Claims

1. Strike assembly and; a connector arranged to apply a force to the object; a winding arranged to receive a current and thereby generate a magnetic field; Including, the winding, the strike assembly and the connector are arranged such that, in use, a magnetic field generated by the winding moves the strike assembly to impact the connector; the connector is arranged to move between a first position and a second position; In the first position, when the strike assembly impacts the connector, the connector applies a force to the object in a first direction; In the second position, when the strike assembly impacts the connector, the connector applies a force to the object in a second direction; The orthopedic impactor, wherein the first direction and the second direction are different.

2. 2. The impactor of claim 1, wherein the strike assembly includes a striker arranged to impact the connector, the connector being arranged to be impacted by the striker.

3. 3. The impactor of claim 2, wherein the connector at least partially surrounds the striker of the strike assembly and is positioned to receive a force from the striker and to impart a force to the object.

4. the connector is arranged to move between a first position and a second position; In the first position, the striker is positioned to impact a first surface of the connector to impart a force to the object in a first direction; In the second position, the striker is positioned to impact a second surface of the connector to impart a force to the object in a second direction; the first direction and the second direction are opposite directions; 3. The impactor of claim 2, wherein the force in the first direction is an implantation force and the force in the second direction is a removal force.

5. 2. The impactor of claim 1, wherein the connector is positioned to receive a first force from a first proximal striker of the strike assembly, and the connector is positioned to receive a second force from a second distal striker of the strike assembly.

6. 10. The impactor of claim 1, wherein the strike assembly body comprises one or more of the following ferromagnetic materials arranged to be moved by the magnetic field: iron; at least 70% iron; or a permanent magnet.

7. 10. The impactor of claim 1, wherein providing an electric current and generating the magnetic field are configured to move the strike assembly to provide an implantation or removal force.

8. 10. The impactor of claim 1, wherein removal of the electrical current and cessation of generation of the magnetic field are configured to move the strike assembly to provide an implantation or removal force.

9. 2. The impactor of claim 1, wherein the winding is disposed to radially or axially surround a ferromagnetic body portion of the strike assembly.

10. The impactor of claim 1, further comprising a biasing mechanism arranged to bias the strike assembly toward a first rest position.

11. 11. The impactor of claim 10, wherein the biasing mechanism includes a spring arranged to compress when the strike assembly is moved from the first position to the second position, and / or the spring arranged to expand when the strike assembly is moved from the first position to the third position.

12. 10. The impactor of claim 1, wherein the impactor includes a plurality of windings arranged to provide forces of different magnitudes and / or in different directions.

13. 13. The impactor of claim 12, wherein the impactor includes a first winding arranged to move the strike assembly in a first direction and a second winding arranged to move the strike assembly in a second direction, the second direction being opposite to the first direction.

14. The impactor is one or more proximal impact windings arranged to provide a force in a first direction; one or more distal impact windings arranged to provide a force in a second direction; 2. The impactor of claim 1 comprising:

15. the proximal impact winding is arranged to provide a greater impact energy and / or force to the object than the distal impact winding; and / or the proximal impact winding has a larger volume, length, and / or surface area than the distal impact winding; and / or 15. The impactor of claim 14, wherein the impactor includes a greater number of proximal impacts than distal impact windings.

16. The impactor of claim 1 , further comprising a power source for supplying the current to the winding, the power source comprising a battery and / or a capacitor.

17. 2. The impactor of claim 1, further comprising an input for varying parameters of the force, the input arranged to vary at least one of: a direction of the force; a magnitude of the force; a speed of application of the force; a frequency of application of the force; a duration of the force; and an impact energy associated with the force.

18. An impactor as described in claim 1, further comprising an input arranged to modify the current supplied to the winding to change at least one of: a direction of the current; a magnitude of the current; a duration of the current; a frequency of the current; and a frequency of transmission of pulses of the current.

19. 10. The impactor of claim 1, wherein the impactor further comprises a sensor positioned to measure at least one of: impact force; object stability; implant stability; and impact energy.

20. 2. The impactor of claim 1, wherein the impactor is arranged to determine at least one of: a position of the strike assembly; and a force of impact in dependence on the current and / or voltage in the windings.

21. 13. The impactor of claim 1, wherein the impactor is arranged to determine usage data including one or more of: bone quality; implant stability; impact force; difference between impact force and desired force; impact frequency; user of the device; and hoop stress.

22. 2. The impactor of claim 1, further comprising control electronics arranged to vary a supply of current to the winding, the control electronics arranged to interact with one or more of an input / the inputs and a power source / the power source.

23. 23. The impactor of claim 22, wherein the control electronics are arranged to vary the supply of current and / or the force provided based on one or more of previous forces applied to the object and / or based on characteristics of the object, previous uses of the impactor; a user of the impactor; and / or characteristics of the object to be impacted, determined bone quality; implant stability; impact force; a difference between a previously measured force and a desired force.

24. The impactor is a bearing arranged to support the strike assembly and / or connector / connector; a connector / bearing holder arranged to limit movement of said connector; the strike assembly and / or connector; a spacer and / or end cap arranged to limit movement of the connector; 13. The impactor of claim 1, further comprising one or more of:

25. The impactor of claim 1 , wherein the impactor comprises an orthopedic impactor.

26. 1. A method of operating an impactor, comprising: Providing the impactor of claim 1; providing a current to the winding to generate the magnetic field; and / or removing current from the winding to cease generating the magnetic field. A method comprising:

27. a strike assembly including a striker; a winding arranged to receive an electric current and thereby generate a magnetic field; a connector disposed to at least partially surround the striker of the strike assembly and configured to receive a force from the striker and to apply a force to an object; Including, the winding is arranged to interact with the strike assembly such that, in use, a magnetic field generated by the winding causes the strike assembly to move such that the striker impacts the connector; the connector is arranged to move between a first position and a second position; In the first position, the striker impacts a first surface of the connector such that the connector imparts a first force to the object in a first direction; in the second position, the striker is adapted to impact a second surface of the connector such that the connector imparts a second force to the object in a second direction; The orthopedic impactor, wherein the first direction and the second direction are different.

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