Powered surgical impactor

Abstract

A powered surgical impactor is provided. The powered surgical impactor includes a housing, a stator disposed within the housing, a plurality of coils arranged about the stator and being configured to be energized to generate a magnetic field, an armature disposed within the stator and configured for movement within the stator in response to the plurality of coils being energized. The powered surgical impactor includes a hammer coupled to the armature. The powered surgical impactor includes a controller configured to measure a voltage of a first coil and a second coil of a pair of coils of the plurality of coils, determine a back EMF signal based on the voltage of the first coil and the voltage of the second coil, and determine a motion parameter of the armature based on the back EMF signal.

Description

POWERED SURGICAL IMPACTOR RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 525,393, filed Jul. 7, 2023, U.S. Provisional Patent Application No. 63 / 525,396, filed Jul. 7, 2023, U.S. Provisional Patent Application No. 63 / 525,405, filed Jul. 7, 2023, and U.S. Provisional Patent Application No. 63 / 525,410, filed Jul. 7, 2023, each of which is hereby incorporated by reference in its entirety. FIELD OF THE INVENTION

[0002] The invention is related generally to a surgical instrument. More particularly, the invention is related to a powered surgical impactor having a stator and an armature disposed within the stator. BACKGROUND

[0003] The installation of prosthetics such as hip implants is crucial for patients. Manually impacted tools play a vital role in the surgical insertion of such prostheses. For example, manually impacted tools may be used for broaching voids where a prosthesis is to be inserted. Furthermore, manually impacted tools may be used for impacting the prosthesis into the anatomy such that the prosthesis is press-fit in the anatomy. However, manually impacted tools may pose challenges that can hinder optimal outcomes. There are a number of challenges associated with manually impacting prostheses into a patient. Manually impacted tools rely on surgeon skill, leading to inconsistent force application. Additionally, manually impacted tools contribute to surgeon fatigue, such as during physically demanding hip implant surgeries. Furthermore, manually impacted tools lack real-time feedback and monitoring capabilities, hindering evaluation of implant fixation quality and necessitating adjustments.

[0004] Therefore, there is a need in the art for a powered surgical impactor for impacting a tool into a patient that addresses one or more of the challenges above. SUMMARY

[0005] A first aspect of the disclosure is directed to a powered surgical impactor. The powered surgical impactor comprising: a housing defining a longitudinal axis; a stator disposed 1 Attorney Docket No. INST2471PCT / 060210.04135within the housing and extending along the longitudinal axis between a proximal stator end and a distal stator end; a plurality of coils arranged about the stator and being configured to be energized to generate a magnetic field; an armature disposed within the stator and extending along the longitudinal axis between a proximal armature end and a distal armature end, the armature configured for movement within the stator between the proximal stator end and the distal stator end in response to the plurality of coils being energized; a hammer coupled to the armature; and a controller configured to: measure a voltage of a first coil and a second coil of a pair of coils of the plurality of coils; determine a back EMF signal based on the voltage of the first coil and the voltage of the second coil; and determine a motion parameter of the armature based on the back EMF signal.

[0006] A second aspect of the disclosure is directed to a method of operating the powered surgical impactor of the first aspect.

[0007] A third aspect of the disclosure is directed to a method of controlling a surgical impactor including a stator and an armature disposed within the stator, the stator including a first coil and a second coil, the second coil being spaced apart from the first coil, and the armature including a plurality of magnets, the armature being movable between a first position and a second position, the first position being spaced from the second position, and wherein a hammer is coupled to the armature, the method comprising determining a first electrical parameter of a first coil while the armature is in the first position; determining a second electrical parameter of a second coil while the armature is in the first position; determining an electromagnetic factor based on the first and second electrical parameters; and determining a motion parameter of the armature in the stator based on the electromagnetic factor.

[0008] A fourth aspect of the disclosure is directed to a powered surgical impactor comprising: a housing defining a longitudinal axis; a stator disposed within the housing and extending along the longitudinal axis between a proximal stator end and a distal stator end, the stator including a plurality of coils arranged about the longitudinal axis and being configured to be energized to generate a magnetic field, the plurality of coils including a first coil and a second coil; an armature disposed within the stator and extending along the longitudinal axis between a proximal armature end and a distal armature end, the armature including a plurality of magnets and the armature is configured for movement within the stator between the proximal stator end and the distal stator end in response to the plurality of coils being energized; and a controller 2 Attorney Docket No. INST2471PCT / 060210.04135configured to: measure electrical parameters of the first coil and the second coil while the armature is in a first position; and determine a position of the armature based on the measured electrical parameters of the first coil and the second coil at the first position.

[0009] A fifth aspect of the disclosure is directed to a linear motor system comprising a stator extending along a longitudinal axis between a proximal stator end and a distal stator end; a plurality of coils arranged about the stator and being configured to be energized to generate a magnetic field; an armature disposed within the stator and extending along the longitudinal axis, the armature configured for movement within the stator between the proximal stator end and the distal stator end in response to the plurality of coils being energized; a controller configured to: measure a voltage of a first coil and a second coil of a pair of coils of the plurality of coils; determine a back EMF signal based on the voltage of the first coil and the voltage of the second coil; and determine a motion parameter of the armature based on the back EMF signal.

[0010] A sixth aspect of the disclosure is directed to a method of operating the linear motor system of the fifth aspect.

[0011] A seventh aspect of the disclosure is directed to a powered surgical impactor. The powered surgical impactor includes a housing defining a longitudinal axis. The powered surgical impactor also includes a stator disposed within the housing and extending along the longitudinal axis between a proximal stator end and a distal stator end, a plurality of coils arranged about the stator and configured to be energized to generate a magnetic field, and an armature disposed within the stator and extending along the longitudinal axis between a proximal armature end and a distal armature end. The armature is configured for movement relative to the stator along the longitudinal axis in a distal direction and a proximal direction between a plurality of armature positions in response to the plurality of coils being energized. The plurality of armature positions includes a proximal armature position where movement of the armature relative to the stator is delimited in the proximal direction, and a distal armature position where movement of the armature relative to the stator is delimited in the distal direction. The powered surgical impactor further includes a hammer coupled to the distal armature end of the armature for movement with the armature in response to the plurality of coils being energized. The hammer defines a hollow region delimited by a proximal impact face and a distal impact face. A portion of the hammer that defines the hollow region is at least partially arranged within the stator when the armature is in the proximal armature position. The powered surgical impactor additionally 3 Attorney Docket No. INST2471PCT / 060210.04135includes an anvil assembly. The anvil assembly includes a shaft supported by the housing for translation along the longitudinal axis in the distal direction and the proximal direction. The shaft extends between a distal shaft end arranged to support a tool and a proximal shaft end. The anvil assembly also includes an anvil supported by the proximal shaft end of the shaft and disposed within the hollow region of the hammer. The anvil includes a distal strike face and a proximal strike face. The proximal strike face of the anvil is arranged to be impacted by the proximal impact face of the hammer as the armature moves in the distal direction to urge the shaft and the tool in the distal direction. The distal strike face of the anvil is arranged to be impacted by the distal impact face of the hammer as the armature moves in the proximal direction to urge the shaft and the tool in the proximal direction.

[0012] Any implementation described below may be incorporated in part on in whole with any of the above-described aspects.

[0013] In some implementations, the armature may include a magnet configured to generate a magnetic field. In some implementations, a battery may be electrically connected to the plurality of coils, the battery being configured to provide an electrical current to the plurality of coils to energize the plurality of coils such that the plurality of coils generate a magnetic field.

[0014] In some implementations, the magnet of the armature may be adjacent to one of the first coil and the second coil, and wherein, to determine the back EMF signal, the controller may be configured to subtract the measured voltage of the other one of the first coil and the second coil from the measured voltage of the one of the first coil and the second coil. In some implementations, a voltage of the first coil includes the back EMF signal, and the back EMF signal is generated in response to the magnet of the armature being adjacent to the first coil. In some implementations, the plurality of coils includes two pairs of coils, the first pair of coils being electrically connected in series, the second pair of coils being electrically connected in series, and the first pair of coils being electrically connected in parallel with the second pair of coils. In some implementations, the battery may be configured to: provide an electrical current to the first pair of coils such that the first coil of the first pair of coils generates a first magnetic field and the second coil of the first pair of coils generates a second magnetic field; and provide an electrical current to second pair of coils such that a first coil of the second pair of coils generates a third magnetic field and the second coil of the second pair of coils generates a fourth magnetic field. In some implementations, the battery may be electrically connected to the 4 Attorney Docket No. INST2471PCT / 060210.04135controller, and the controller may be configured to control the battery to provide an electrical current to the one of the first pair of coils and the second pair of coils based on the determined motion parameter of the armature.

[0015] In some implementations, the plurality of coils may include a first, second, third, and fourth pair of coils, the first pair of coils being electrically connected in series, the second pair of coils being electrically connected in series, the third pair of coils being electrically connected in series, the fourth pair of coils being electrically connected in series, and the first, second, third, and fourth pair of coils being electrically connected in parallel with one another. In some implementations, the battery may be configured to: provide an electrical current to the first pair of coils such that the first coil of the first pair of coils generates a first magnetic field and the second coil of the first pair of coils generates a second magnetic field; provide an electrical current to second pair of coils such that a first coil of the second pair of coils generates a third magnetic field and the second coil of the second pair of coils generates a fourth magnetic field; provide an electrical current to the third pair of coils such that the first coil of the third pair of coils generates a fifth magnetic field and the second coil of the third pair of coils generates a sixth magnetic field; and provide an electrical current to the fourth pair of coils such that the first coil of the fourth pair of coils generates a seventh magnetic field and the second coil of the fourth pair of coils generates an eighth magnetic field. In some implementations, the controller may be configured to control the battery to provide an electrical current to the one of the first, second, third, and fourth pair of coils based on the determined motion parameter of the armature.

[0016] In some implementations, the controller may be configured to: measure a voltage of a first coil and a second coil of the second pair of coils; determine a second back EMF signal based on the voltage of the first coil of the second pair of coils and the voltage of the second coil of the second pair of coils; and determine the motion parameter of the armature based on the back EMF signal and the second back EMF signal.

[0017] These and other configurations, features, and advantages of the present disclosure will be apparent to those skilled in the art. The present disclosure is not intended to be limited to or by these configurations, embodiments, features, and / or advantages. 5 Attorney Docket No. INST2471PCT / 060210.04135BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Referring now to the drawings, exemplary illustrations are shown in detail. Although the drawings represent schematic embodiments, the drawings are not necessarily to scale and certain features may be exaggerated to better illustrate and explain an innovative aspect of an illustrative embodiment. Further, the exemplary illustrations described herein are not intended to be exhaustive or otherwise limiting or restricting to the precise form and configuration shown in the drawings and disclosed in the following detailed description.

[0019] Advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

[0020] Figure 1 is a perspective view of one configuration of a powered surgical impactor according to the present disclosure with a tool coupled to the powered surgical impactor.

[0021] Figure 2 is a top view of the powered surgical impactor of Figure 1.

[0022] Figure 3 is a side view of the powered surgical impactor of Figure 1.

[0023] Figure 4 is a cross-sectional representation of the powered surgical impactor of Figures 1-3, taken along line A-A of Figure 2.

[0024] Figure 5 is an exploded view of the powered surgical impactor 20 of Figures 1- 3.

[0025] Figure 6A through 6C illustrate a sequence of operation of the powered surgical impactor of Figures 1-5 to produce a forward impact.

[0026] Figure 7A through 7C illustrate a sequence of operation of the powered surgical impactor of Figures 1-5 to produce a reverse impact.

[0027] Figures 8A and 8B a configuration of a powered surgical impactor according to the present disclosure

[0028] Figure 9 is a diagram of a motor of the powered surgical impactor of Figure 1.

[0029] Figure 10 is diagram of the motor of the powered surgical impactor of Figure 1, wherein an armature of the motor is moving relative to a stator of the motor.

[0030] Figure 11 is a diagram of a series-parallel coil configuration of coils of the motor of the powered surgical impactor of Figure 1.

[0031] Figure 12 is a flowchart of a method of controlling the motor of the powered surgical impactor of Figure 1. 6 Attorney Docket No. INST2471PCT / 060210.04135

[0032] Figure 13 is a graph of a back EMF waveform measured between coils of the motor of the powered surgical impactor of Figure 1.

[0033] Figure 14 is a circuit diagram of coils of the motor of the powered surgical impactor of Figure 1.

[0034] Figure 15 is a perspective view of a surgical impactor attachment according to the present disclosure coupled to a powered handpiece and supporting a tool that is to be impacted into a patient.

[0035] Figure 16 is a perspective view of the surgical impactor attachment of Figure 15 with a housing in phantom to reveal the internal componentry of the surgical impactor attachment.

[0036] Figure 17 is an exploded perspective view of the surgical impactor attachment of Figure 15.

[0037] Figure 18 is a cross-sectional representation of the surgical impactor attachment of Figure 15.

[0038] Figure 19 is a perspective view of a rotational member of surgical impactor attachment of Figure 15.

[0039] Figure 20 is a cross-sectional representation of the surgical impactor attachment of Figure 15, which is sectioned to reveal the cooperation of the rotational member and an intermediate member.

[0040] Figure 21 is another cross-sectional representation of the surgical impactor attachment of Figure 15, which is sectioned to reveal the cooperation of the intermediate member, a lever, and an impact hammer.

[0041] Figure 22 is yet another cross-sectional representation of the surgical impactor attachment of Figure 15, which is sectioned to reveal the cooperation of the rotational member, the intermediate member, the lever, and the impact hammer.

[0042] Figure 23 is an exploded view of the surgical impactor attachment of Figure 15 depicting the connection of the rotational member to an input shaft including a cam profile.

[0043] Figure 24A is an exploded perspective view of the surgical impactor attachment of Figure 15 depicting a stud of the rotational member aligned with a landing of the cam profile.

[0044] Figure 24B is an exploded perspective view of the surgical impactor attachment of Figure 15 depicting the stud of the rotational member displaced relative to the landing of the cam 7 Attorney Docket No. INST2471PCT / 060210.04135profile due to an overload condition. Figure 25A is another exploded perspective view of the surgical impactor attachment of Figure 15 depicting a stud of the rotational member aligned with a landing of the cam profile.

[0045] Figure 25B is exploded perspective view of the surgical impactor attachment of Figure 15 depicting the stud of the rotational member displaced relative to the landing of the cam profile due to a lack of reactionary force exerted by the patient against the tool or prosthesis.

[0046] Figure 26 is a perspective view of a surgical impactor attachment according to the present disclosure coupled to a powered handpiece and supporting a tool that is to be impacted into a patient.

[0047] Figure 27 is a cross-sectional representation of the surgical impactor attachment of Figure 26.

[0048] Figure 28 is a perspective cross-sectional representation of the surgical impactor attachment of Figure 26.

[0049] Figure 29A is a partial perspective view of the surgical impactor attachment of Figure 26 with some components hidden to reveal the componentry of the surgical impactor attachment in a home state.

[0050] Figure 29B is a partial perspective view of the surgical impactor attachment of Figure 26 with some components hidden to reveal the componentry of the surgical impactor attachment in a coupled state.

[0051] Figure 29C is a partial perspective view of the surgical impactor attachment of Figure 26 with some components hidden to reveal the componentry of the surgical impactor attachment in a compression state.

[0052] Figure 29D is a partial perspective view of the surgical impactor attachment of Figure 26 with some components hidden to reveal the componentry of the surgical impactor attachment in a release state.

[0053] Figure 29E is a partial perspective view of the surgical impactor attachment of Figure 26 with some components hidden to reveal the componentry of the surgical impactor attachment as a biasing member urges an impact hammer to an impact position to strike an anvil to impact the tool into the patient.

[0054] Figure 30 is an exploded perspective view of the surgical impactor attachment of Figure 26. 8 Attorney Docket No. INST2471PCT / 060210.04135DETAILED DESCRIPTION

[0055] The present disclosure generally relates to a number of configurations of powered surgical impactors 20 for impacting a tool 22 or prosthesis. The tool 22 or prosthesis may be configured to be operatively attached to the powered surgical impactor 20 and to be impacted into a patient by the powered surgical impactor 20. The tool 22 may be a surgical broach for preparing an intramedullary canal of a femur for receiving a prosthesis, but the attachment of other tools 22 or prosthesis requiring impaction into a patient is contemplated.

[0056] Figure 1 shows a perspective view of one exemplary configuration of a powered surgical impactor 20 according to the present disclosure, with Figure 2 showing a top view and Figure 3 showing a side view of the same. With reference to Figures 1 through 3, the powered surgical impactor 20 includes a housing 24. In the illustrated configuration, the housing 24 is implemented as a pistol form-factor with a barrel portion 26 and a grip 28 extending substantially transverse from the barrel portion 26. In the illustrated configuration, the grip 28 supports one or more user input controls 30 (implemented here as a trigger 30) which is / are arranged for user engagement to operate the powered surgical impactor 20. Additional details regarding operation of the powered surgical impactor 20 in response to user engagement with the one or more user input controls 30 are described in further detail below. It should be appreciated that other configurations of the one or more user input controls 30 are contemplated. It should also be appreciated that other form-factors of the housing 24 are contemplated. In any event, the housing 24 of the powered surgical impactor 20 defines a longitudinal axis 32 along which the motion of impacting the tool 22 is effectuated, as described in further detail below.

[0057] Figure 4 is a section view of the powered surgical impactor 20 of Figures 1 through 3 taken along line A-A of Figure 2, and Figure 5 is an exploded view of the powered surgical impactor 20 of Figures 1 through 3 which has been exploded along the longitudinal axis 32. As best shown in Figures 4 and 5, the powered surgical impactor 20 also includes a motor 34, which may be referred to herein as a “linear motor”. The motor 34 includes a stator 36 disposed within the housing 24 (e.g., the barrel portion 26 of the housing 24) and extending along the longitudinal axis 32 between a proximal stator end 36P and a distal stator end 36D. The motor 34 of the powered surgical impactor 20 additionally includes a plurality of coils 38 arranged about the stator 36 and configured to be energized to generate a magnetic field. Exemplary 9 Attorney Docket No. INST2471PCT / 060210.04135configurations of the plurality of coils 38 and the arrangement of plurality of coils 38 relative to the stator 36 are described in further detail below.

[0058] With continued reference to Figure 4 and 5, the powered surgical impactor 20 further includes an armature 40 disposed within the stator 36. The armature 40 extends along the longitudinal axis 32 between a proximal armature end 40P and a distal armature end 40D. The armature 40 is configured for movement relative to the stator 36 along the longitudinal axis 32 in response to the plurality of coils 38 be energized. More specifically, the armature 40 is configured for movement relative to the stator 36 along the longitudinal axis 32 in a distal direction D1 and a proximal direction D2 (opposite the distal direction D1) between a plurality of armature positions. As best shown in Figures 6A-7C, the plurality of armature positions includes a proximal armature position PAP and a distal armature position DAP. In the proximal armature position PAP, movement of the armature 40 relative to the stator 36 is delimited in the proximal direction D2. In the distal armature position DAP, movement of the armature 40 relative to the stator 36 is delimited in the distal direction D1. It should be appreciated that the proximal armature position PAP and the distal armature position DAP illustrated in Figures 6A- 7C are merely one example of the proximal armature position PAP and the distal armature position DAP and other configurations are contemplated.

[0059] The armature 40 may include a core 42 and a plurality of magnets 44 supported on the core 42. In some examples, the core 42 of the armature 40 may be comprised of a magnetic material such as iron, etc. In other examples, the core 42 of the armature 40 may be comprised of a non-magnetic or weakly magnetic material. For example, in configurations where it is desirable for the armature 40 to have a higher mass (e.g., for the motor 34 to produce more force in a smaller package), the core 42 may be constructed of a denser non-magnetic or weakly magnetic metal such as austenitic stainless steel, U-238 depleted uranium, etc. In other examples, the core 42 may be constructed of less dense non-magnetic or weakly magnetic metal such as carbon fiber or aluminum. In further examples, the core 42 may be constructed of a polymeric material, which may be fiber reinforced. It is also contemplated that the core 42 may be constructed in a manner such that the core 42 has a degree of compliance to isolate the plurality of magnets 44 from harsh forces during operation of the motor 34. Furthermore, it is also contemplated that the core 42 may include compliant members arranged between each of the plurality of magnets 44 to reduce harsh forces therebetween during operation of the motor 34. Attorney Docket No. INST2471PCT / 060210.04135

[0060] In some examples, the motor 34 is implemented as an internal permanent magnet configuration. In these examples, the plurality of magnets 44 are implemented as permanent magnets, and some or all of the plurality of magnets 44 are enclosed in / surrounded by a sleeve 46. The sleeve 46 may be comprised of a magnetic material such as iron, etc. The sleeve 46 may have a solid construction or may be patterned / include voids to reduce mass where desirable. Here, inclusion of the magnetic sleeve 46 allows the motor 34 to generate higher force than configurations where the plurality of magnets 44 are not enclosed in / surrounded by the sleeve 46 because a reluctance force may be supplied in addition to the magnetic force in response to the plurality of coils 38 being energized. Accordingly, an internal permanent magnet configuration may reduce cost and / or the size of the motor 34, as well as protect the plurality of magnets 44 from breaking during operation of the motor 34. Other configurations of the motor 34 are contemplated. Additional details regarding specific configurations of the motor 34 according to the present disclosure are described in further detail below.

[0061] The powered surgical impactor 20 further includes a hammer 48 coupled to the distal armature end 40D of the armature 40 for movement with the armature 40 in response to the plurality of coils 38 being energized. In some examples, such as illustrated throughout the Figures, the hammer 48 may be formed integrally with the armature 40 (e.g., formed integrally with the core 42) such that the hammer 48 extends in the distal direction D1 from the distal armature end 40D of the armature 40. However, it is contemplated that the hammer 48 may be a separate component that is fastened or otherwise coupled to the distal armature end 40D of the armature 40. As best shown in Figure 4, the hammer 48 defines a hollow region 50 delimited by a proximal impact face 52P and a distal impact face 52D. In the illustrated configuration, the hollow region 50 defines a hollow cylindrical void, but other configurations are contemplated. As described in further detail below, a portion of the hammer 48 that defines the hollow region 50 is at least partially arranged within the stator 36 when the armature 40 is in the proximal armature position PAP (best shown in Figures 6A, 7B, and 7C).

[0062] The powered surgical impactor 20 additionally includes an anvil assembly 54. One exemplary anvil assembly 54 includes a shaft 56 supported by the housing 24 for translation along the longitudinal axis 32 in the distal direction D1 and the proximal direction D2. For example, in the configuration of Figure 4, the housing 24 includes a distal housing portion 58 extending from the barrel portion 26 which supports a first linear bearing 60 or the like for Attorney Docket No. INST2471PCT / 060210.04135facilitating translation of the shaft 56 relative to the housing 24 along the longitudinal axis 32 in the distal direction D1 and the proximal direction D2. The hammer 48 may also support a second linear bearing 62 or the like for facilitating translation of the shaft 56 relative to the hammer 48 (described in further detail below). In some examples, such as illustrated in Figure 4, the second linear bearing 62 may delimit the distal end of the hollow region 50 of the hammer 48 to define the distal impact face 52D, but other configurations are contemplated. With continued reference to Figure 4, the shaft 56 extends between a distal shaft end 56D and a proximal shaft end 56P. The distal shaft end 56D is arranged to support the tool 22. The specific configuration of the distal shaft end 56D for supporting the tool 22 is not limited for the purposes of this disclosure. In one example, the distal shaft end 56D may include or be configured to support an adaptor (not shown) configured to selectively engage a coupler of the tool 22 to couple the tool 22 to the shaft 56. Other configurations are contemplated.

[0063] The anvil assembly 54 also includes an anvil 64 supported by the proximal shaft end 56P of the shaft 56 for movement with the shaft 56. For example, as shown in Figure 4, the anvil 64 may be at least partially disposed within the proximal shaft end 56P of the shaft 56 and fastened to or otherwise coupled to the proximal shaft end 56P. The anvil 64 includes a distal strike face 66D and a proximal strike face 66P. As best shown in Figure 4, the anvil 64 is disposed within the hollow region 50 of the hammer 48. By virtue of the anvil 64 being disposed within the hollow region 50 of the hammer 48, the proximal strike face 66P of the anvil 64 is arranged to be impacted by the proximal impact face 52P of the hammer 48 as the armature 40 moves in the distal direction D1 to urge the shaft 56 and the tool 22 in the distal direction D1 (referred to herein as a “forward impact”). The distal strike face 66D of the anvil 64 is arranged to be impacted by the distal impact face 52D of the hammer 48 as the armature 40 moves in the proximal direction D2 to urge the shaft 56 and the tool 22 in the proximal direction D2 (referred to herein as a “reverse impact”). It should be appreciated that in the illustrated configurations, the anvil assembly 54 is configured for movement independent of the hammer 48. Stated differently, the anvil assembly 54 is not always in a direct translational relationship with the hammer 48. Additional details regarding operation of the powered surgical impactor 20 to effectuate forward impact and / or reverse impact are described in further detail below.

[0064] In some examples, the distal housing portion 58 may define a constraining void 68. The constraining void 68 may be delimited by a distal constraining face 70D and a proximal Attorney Docket No. INST2471PCT / 060210.04135constraining face 70P. In these examples, a constraining member 72 may be disposed within the constraining void 68 and coupled to the shaft 56 such that the constraining member 72 is configured to abut the distal constraining face 70D to delimit motion of the shaft 56 in the distal direction D1 and to abut the proximal constraining face 70P to delimit motion of the shaft 56 in the proximal direction D2. In the illustrated examples, the constraining member 72 is implemented as a washer coupled to the shaft 56 and extending radially (i.e., transverse to the longitudinal axis 32) away from the shaft 56. Other configurations of the constraining member 72 are contemplated, such as a projection formed integrally with the shaft 56. Additionally, in some examples, such as shown in Figure 4, a shaft biasing member 74 may be interposed between the proximal constraining face 70P and the constraining member 72 to bias / urge the shaft 56 in the distal direction D1. Other configurations for biasing / urging the shaft 56 in the distal direction D1 are contemplated.

[0065] A variety of configurations for at least partially arranging the portion of the hammer 48 that defines the hollow region 50 within the stator 36 when the armature 40 is in the proximal armature position PAP are contemplated. In one example, referring to Figure 4, the stator 36 may define a stator length L1 between the proximal stator end 36P and the distal stator end 36D. In some examples, the armature 40 may define a armature length L2 (less than the stator length L1) between the proximal armature end 40P and the distal armature end 40D. For example, the armature length L2 may be less than 80% of the stator length L1, less than 70% of the stator length L1, less than 60% of the stator length L1, less than 50% of the stator length L1, less than 40% of the stator length L1, etc. Advantageously, by at least partially arranging the portion of the hammer 48 that defines the hollow region 50 within the stator 36 when the armature 40 is in the proximal armature position PAP, the overall size / length of the motor 34 (and, thus the powered surgical impactor 20) can be reduced while maintaining a desired level of force output from the motor 34.

[0066] In the illustrated examples, to facilitate at least partially arranging the portion of the hammer 48 that defines the hollow region 50 within the stator 36 when the armature 40 is in the proximal armature position PAP, the proximal armature end 40P may be aligned (or substantially aligned) with the proximal stator end 36P when the armature 40 is in the proximal armature position PAP. Accordingly, because the hammer 48 is coupled to the distal armature end 40D of the armature 40, by virtue of the armature length L2 being less than the stator length L1, the Attorney Docket No. INST2471PCT / 060210.04135portion of the hammer 48 that defines the hollow region 50 is at least partially arranged within the stator 36 when the armature 40 is in the proximal armature position PAP (best shown in Figures 6A, 7B, and 7C). As best shown in Figures 6C and 7A, in these examples the distal armature end 40D may be aligned (or substantially aligned) with the distal stator end 36D when the armature 40 is in the distal armature position DAP. To effectuate movement of the armature 40 between the plurality of armature positions for these configurations, the plurality of coils 38 may be arranged about the stator length L1 of the stator 36 (i.e., distributed between the proximal stator end 36P and the distal stator end 36D) such that the plurality of magnets 44 of the armature 40 are within the magnetic field generated by at least some of the plurality of coils 38 throughout movement of the armature 40 between the plurality of armature positions. Specific details regarding control / operation of the plurality of coils 38 for such a configuration are described in further detail below.

[0067] Figure 6A through 6C illustrate a sequence of operation of the powered surgical impactor 20 to produce a forward impact to urge the shaft 56 and the tool 22 in the distal direction D (e.g., to advance / impact the tool 22 further into the anatomy of a patient). Referring first to Figure 6A, here, the armature 40 is in the proximal armature position PAP, and the shaft 56 is “pre-loaded” against the anatomy to be impacted (i.e. subject to a force in the proximal direction D2) such that the anvil assembly 54 (particularly the shaft 56) is in a proximal most position, as defined by the constraining member 72 abutting the proximal constraining face 70P. Here, the portion of the hammer 48 that defines the hollow region 50 is at least partially arranged within the stator 36, as described above. Next, as shown in Figure 6B, during operation of the powered surgical impactor 20 to produce a forward impact, the armature 40 is configured to move in the distal direction D1 in response to the plurality of coils 38 being energized. Accordingly, Figure 6B illustrates the proximal impact face 52P of the hammer 48 making initial contact with the proximal strike face 66P of the anvil 64 to impact the anvil 64 in the distal direction D1. Finally, referring to Figure 6C, as the armature 40 reaches the distal armature position DAP, the hammer 48 (by virtue of the movement / inertia of the armature 40) urges the anvil assembly 54 (particularly, the shaft 56) and the tool 22 in the distal direction D1 to produce a forward impact to advance / impact the tool 22 further into the anatomy of a patient (not shown). It should be appreciated that the sequence illustrated in Figure 6A through 6C may be executed repeatedly in series to produce a series of forward impacts to advance / impact the tool 22 further Attorney Docket No. INST2471PCT / 060210.04135into the anatomy of a patient. Additional details regarding control / operation of the plurality of coils 38 to effectuate movement of the armature 40 from the proximal armature position PAP to the distal armature position PAP are described below.

[0068] Figure 7A through 7C illustrate a sequence of operation of the powered surgical impactor 20 to produce a reverse impact to urge the shaft 56 and the tool 22 in the proximal direction D2 (e.g., to remove the tool 22 from the anatomy of a patient). Referring first to Figure 7A, here, the armature 40 is in the distal armature position DAP, and the shaft 56 is “pre-loaded” for reverse operation (i.e., i.e. subject to a force in the distal direction D1) such that the anvil assembly 54 (particularly the shaft 56) is in a distal most position, as defined by the constraining member 72 abutting the distal constraining face 70D. Next, as shown in Figure 7B, during operation of the powered surgical impactor 20 to produce a reverse impact, the armature 40 is configured to move in the proximal direction D2 in response to the plurality of coils 38 being energized. Accordingly, Figure 7B illustrates the distal impact face 52D of the hammer 48 making initial contact with the distal strike face 66D of the anvil 64 to impact the anvil 64 in the proximal direction D2. Finally, referring to Figure 6C, as the armature 40 reaches the proximal armature position PAP, the hammer 48 (by virtue of the movement / inertia of the armature 40) urges the anvil assembly 54 (particularly, the shaft 56) and the tool 22 in the proximal direction D2 to produce a reverse impact to remove the tool 22 from the anatomy of a patient (not shown). It should be appreciated that the sequence illustrated in Figure 7A through 7C may be executed repeatedly in series to produce a series of reverse impacts to remove the tool 22 from the anatomy of a patient. Additional details regarding control / operation of the plurality of coils 38 to effectuate movement of the armature 40 from the distal armature position DAP to the proximal armature position DAP are described below.

[0069] In some versions, the powered surgical impactor 20 may additionally include a supplemental biasing member 76 arranged to supplement the force generated by the motor 34 as the armature 40 moves in the distal direction D1. By supplementing the force generated by the motor 34 as the armature 40 moves in the distal direction D1, inclusion of the supplemental biasing member 76 may increase the acceleration of the armature 40 relative to the stator 36, which may decrease the overall length of the motor 34 necessary to supply a desired force. In one example, referring to Figures 8A and 8B, the supplemental biasing member 76 may be interposed between the proximal armature end 40P and a rear face 78 of the housing 24. Here, Attorney Docket No. INST2471PCT / 060210.04135the supplemental biasing member 76 is schematically illustrated as a spring, but other configurations such as a pneumatic piston, opposing magnets, etc. are contemplated. Referring to Figure 8A, as the motor 34 moves the armature 40 in the proximal direction D2 toward the proximal armature position PAP, the motor 34 will compress the supplemental biasing member 76 to mechanically store the force generated by the motor 34. Accordingly, referring to Figure 8B, as the motor 34 moves the armature 40 in the distal direction D1 toward the distal armature position DAP, the supplemental biasing member 76 will release the previously stored mechanical energy to urge the armature 40 in the distal direction D1 to supplement the force generate by the motor 34 in the distal direction D1. Stated differently, as the motor 34 moves the armature 40 in the distal direction D1 toward the distal armature position DAP, the armature 40 will move the distal direction D1 by virtue of both the energization of the plurality of coils 38 and the release of stored mechanical energy by the supplemental biasing member 76. In some examples, the powered surgical impactor 20 may further include a biasing member release latch (e.g., an electromechanical latch) to selectively inhibit the supplemental biasing member 76 from urging the armature 40 in the distal direction D1. Other configurations of implementing a supplemental biasing member 76 to supplement the force generated by the motor 34 as the armature 40 moves in the distal direction D1 are contemplated.

[0070] In some versions, one or more dampers (not shown) may be interposed between the motor 34 and the housing 24 and / or arranged within the motor 34. The one or more dampers may be arranged to dampen / absorb impact energy between at least two of the housing 24, the stator 36, and the armature 40 in the distal direction D1 and / or the proximal direction D2. For example, one or more dampers may be arranged to suspend the stator 36 of the motor 34 relative to the housing to act as a passive and / or active suspension system for the motor 34 to reduce forces transmitted to a user of the powered surgical impactor 20. The one or more dampers may be realized as springs, rubber spacers / bushings, electrically adjustable mechanical dampers, electromagnetic dampers, the like, or a combination thereof to dampen the transfer of energy and / or impact shock to the user. In some examples, the one or more dampers may be adjusted in real time to actively adjust the spring constant and / or the damping constant of the one or more dampers to dampen the transfer of energy and / or impact shock to the user. In some examples, the adjustment may be based on readings from accelerometer(s) arranged within the motor 34 and or the housing 24. Additionally or alternatively, in some versions, the mass of the housing Attorney Docket No. INST2471PCT / 060210.0413524, the stator 36, and / or the armature 40 may be tuned to achieve optimal damping behaviors. For example, in one configuration, the mass of the housing 24 may be equal to or greater than the sum of the mass of the stator 36 and the armature 40, with the stator 36 having a mass equal to or greater than the armature 40. As another example, the mass of the housing 24, the stator 36, and / or the armature 40, in combination with the arrangement and parameters of the one or more dampers may be tuned to offset the inertia of the housing 24, the stator 36, and the armature 40 during operation of the motor. Other configurations for dampening the transfer of energy and / or impact shock to the user are contemplated.

[0071] As shown in FIG. 4, the powered surgical impactor 20 may include a controller CON and a power supply BAT. In some instances, the controller CON and the power supply BAT may be integrated with and / or disposed within the housing 24. In some instances, the controller CON and the power supply BAT may be externally attached to the housing 24. In the instance of FIG. 4, the controller CON is disposed within the grip 28 of the housing 24 and the power supply BAT is externally attached to the grip 28 of the housing 24. The controller CON may include any hardware and software architecture sufficient to engage in the control / operation of the plurality of coils 38. For example, the controller CON may include a circuit board. The controller CON may include a processor and memory such as non-volatile random access memory (NOVRAM). The power supply BAT may be a battery and / or include rechargeable cells. The controller CON may be electrically connected to and powered by the battery BAT. For example, the controller CON may regulate the application of energization signals and / or electrical current from the battery BAT to components of the motor 34. In the instance of FIG. 4, the controller CON is electrically connected to the battery BAT and the plurality of coils 38 such that the battery BAT is electrically connected to the plurality of coils 38 via the controller CON. In such an instance, the controller CON may regulate the application of electrical current from the battery BAT to the plurality of coils 38, energizing the plurality of coils 38 to generate a magnetic field.

[0072] An example construction of the motor 34 is shown in FIGS. 9-11. As shown, the motor 34 includes the stator 36 and the armature 40. For simplicity the stator 36 is partially shown in FIGS. 9-11. The stator 36 includes the plurality of coils 38 and the armature includes the plurality of magnets 44. Generally, the magnetic field generated by the plurality of coils 38 interacts with the magnetic field generated by the magnet 44 of the armature 40 to move the Attorney Docket No. INST2471PCT / 060210.04135armature 40 within the stator 38 between the proximal stator end 36P and the distal stator end 36D.

[0073] In the example of FIG. 9, the plurality of coils 38 includes eight coil packs, with the first coil pack being indicated as “Coil Pack #1”. In the instance of FIG. 9, the motor 34 is a three-phase motor and each coil pack includes a coil corresponding to one of the three phases. As shown, each coil pack includes an A-phase coil, a B-phase coil, and a C-phase coil. Additionally, each coil of the plurality of coils 38 may be grouped with a spaced-apart coil into a coil pair. For example, referring to FIG. 10, four such coil pairs are indicated: A2-6, B2-6, A3-7, B3-7, where coil A2 is spaced apart from A6, coil B2 is spaced apart from B6, coil A3 is spaced apart from A7, and coil B3 is spaced apart from B7. Referring to FIG. 11, the coils of each coil pair are electrically connected in series and each coil pair is electrically connected in parallel with the other coil pairs of corresponding phase. For example, in an instance where the plurality of coils 38 includes two pairs of coils for each phase, the coils of the first pair of coils are electrically connected in series, the coils of the second pair of coils are electrically connected in series, and the first pair of coils are electrically connected in parallel with the second pair of coils. As another example, in an instance where the plurality of coils 38 includes four pairs of coils for each phase, the coils of the first pair of coils are electrically connected in series, the coils of the second pair of coils are electrically connected in series, the coils of the third pair of coils are electrically connected in series, the coils of the fourth pair of coils are electrically connected in series, and the first, second, third, and fourth pair of coils are electrically connected in parallel.

[0074] For each armature position, the magnets 44 of the armature are adjacent to different coils of the plurality of coils 38. For example, in the instance of FIG. 9, the armature 40 is located at the proximal armature position PAP and the magnets 44 of the armature 40 are adjacent to coils A1-C4. In the instance of FIG. 10, the armature 40 has moved toward the distal stator end 36D such that the magnets 44 of the armature 40 are adjacent to coils A3-C6.

[0075] Referring to FIG. 12, a method 100 of controlling operation of the plurality of coils 38 to effectuate movement of the armature 40 from the proximal armature position PAP to the distal armature position DAP is shown. During the method 100, the controller CON controls movement of the armature 40 within the stator 36 based on a motion parameter. For instance, the controller CON may regulate an electrical current provided to the plurality of coils 38 based Attorney Docket No. INST2471PCT / 060210.04135on the motion parameter. In one such instance, the controller CON may determine which coil of the plurality of coils 38 is to be provided an electrical current by the battery BAT and as follows, which coil of the plurality of coils 38 generates a magnetic field to move the armature 40 based on the motion parameter. The motion parameter may be one or more of a position, velocity, acceleration, or jerk of the armature 40 within the stator 36. As such, in one such instance, the controller CON may regulate which coil of the plurality of coils 38 is provided an electrical current based on a position of the armature 40 within the stator 36. In another instance, the controller CON may regulate which coil of the plurality of coils 38 is provided an electrical current based on a velocity of the armature 40 within the stator 36.

[0076] The method 100 may perform open loop and closed loop control of the motor 34 based on the motion parameter. Specifically, the method includes a step 102 of open loop control of the motor 34 and a step 120 of closed loop control of the motor 34. Generally, during the method 100, the controller CON performs open loop control of the motor 34 during initial startup of the powered surgical impactor 20. For instance, the controller CON controls the motor 34 using open loop control while the armature 40 begins reaching an operating velocity during the initial startup. Once the powered surgical impactor 20 has sufficiently started up, e.g. once the armature 40 has reached the operating velocity, the controller CON begins closed loop control of the motor 34. Advantageously, by performing open loop control of the motor 34 before closed loop control of the motor 34, the controller CON is able to reduce the startup time of the powered surgical impactor 20.

[0077] In the instance of FIG. 12, the method 100 determines whether the motor 34 has sufficiently started up based on an electromagnetic factor of the motor 34. For example, the electromagnetic factor may be a counter-electromotive force (referred to herein as “back-EMF”) generated by the interaction of the magnetic field generated by the plurality of coils 38 and the magnetic field generated by the magnets 44 of the armature. Specifically, the method 100 of FIG. 12 includes a step 104 of determining whether an amplitude of the back-EMF is sufficient for closed-loop control. The amplitude of the back-EMF generated by the magnetic fields of the plurality of coils 38 and the magnets 44 may be indicative of a variety of motion parameters of the motor 34. As such, by evaluating the generated back-EMF, the controller CON may determine whether the motor 34 has sufficiently started-up. For example, the amplitude of the generated back-EMF may be indicative of a velocity of the armature 40 within the stator 36, Attorney Docket No. INST2471PCT / 060210.04135where the greater the amplitude of the generated back-EMF, the greater the velocity of the armature 40 within the stator 36. FIG. 13 illustrates example graphs of the back-EMF generated by the magnetic fields of the plurality of coils 38 and the magnets 44 during operation of the powered surgical impactor 20. As time increases, the amplitude of the back-EMF increases. Once the amplitude of the back-EMF is greater than a threshold value, the controller CON may proceed to step 120 and begin closed loop control of the motor 34.

[0078] The controller CON measures the back-EMF generated by the motor 34 to determine whether the motor 34 has sufficiently started-up. A back-EMF signal is generated in response to a magnet 44 of the armature 40 being adjacent to a coil of the plurality of coils 38. In instances where a magnet 44 of the armature 40 is adjacent to a coil, the coil may be defined as “active”. Similarly, in instances where a magnet 44 of the armature 40 is not adjacent to a coil of the plurality of coils 38, the coil may be defined as “inactive”. As previously stated, each coil of the plurality of coils 38 may be grouped into a coil pair. The coils may be grouped in a manner that allows the controller CON to determine the back-EMF signal generated by a coil of a coil pair. Specifically, the coils may be grouped into coil pairs such that a magnet 44 of the armature 40 is adjacent to one coil of the coil pair (i.e. one coil of the coil pair is active). For example, referring to FIG. 10, for the coil pair A2-6, the magnets 44 of the armature 40 are adjacent to either the first coil of the coil pair, A2, or the second coil of the coil pair, A6. As shown in FIG. 14, the magnet 44 of the armature is adjacent to coil A6 and, therefore, a voltage of the coil A6 includes the back-EMF signal (“VEMF”). As such, in an instance where the magnet 44 of the armature 40 is adjacent to one of a first coil and a second coil of a coil pair, the controller CON may measure a electrical parameter (e.g. voltage and / or inductance) of a first coil and a second coil of a pair of coils of the plurality of coils and determine an electromagnetic factor (e.g. a back-EMF signal) based on the voltage of the first coil and the voltage of the second coil. For example, the controller CON may determine the back-EMF signal by subtracting the measured voltage of coil to which the magnet 44 is not adjacent from the measured voltage of coil to which the magnet 44 is adjacent. In the instance of FIG 14 where the magnet 44 is adjacent to the coil A6, the controller CON may determine the back-EMF signal (“VEMF”) by placing a measurement point (e.g. measurement point A shown in FIG. 14) between coils A2 and A6, measuring a voltage across coils A2 and A6, and subtracting the voltage across coil A2 from the voltage across coil A6. Attorney Docket No. INST2471PCT / 060210.04135

[0079] As previously stated, the method 100 may perform open loop control of the motor 34 based on the motion parameter. During open loop control of the motor 34, the method 100 proceeds to a step 118 of performing open loop control of the motion parameter of the armature 40. For example, during step 118, the controller CON may perform open loop control of the position of the armature 40 within the stator 36. In such an instance, the controller CON may provide an electrical current and / or a drive voltage to the plurality of coils 38 to move the armature 40 to a desired position.

[0080] Also previously stated, the method 100 may perform closed loop control of the motor 34 based on the motion parameter. Specifically, the controller CON may determine a motion parameter of the armature 40 based on the back EMF signal and control the battery BAT to provide an electrical current and / or a drive voltage to the plurality of coils based on the determined motion parameter. In this way, while the controller CON determines whether to transition to closed loop control during step 120 based on the amplitude of the generated back- EMF, the controller CON may also control operation of the motor 34 during closed loop control based on the generated back-EMF.

[0081] The controller determines the motion parameter of the armature 40 based on back EMF signals. In order to determine the motion parameter of the armature 40 based on the phase of the back EMF signals, the controller determines a back EMF signal generated by a coil pair of a first phase and a back EMF signal generated by a coil pair of a second phase. For instance, referring to FIG. 11, the controller provides a measurement for the coil pair A2-6, as well as the coil pair B2-6, where coil pair A2-6 and coil pair B2-6 provide a different phase measurement of the back-EMF. Referring to FIG. 13, the back-EMF signal generated by the coil pair A2-6 is offset in phase from the back-EMF signal generated by the coil pair B2-6. As follows, the controller may determine the motion parameter of the armature 40 (e.g. a position of the armature 40 within the stator 36 in FIG. 13) based on the back-EMF signals generated by the coil pairs A2-6 and B2-6.

[0082] Referring to FIG. 12, the above-described process of determining a motion parameter of the armature 40 is shown in step 106. During step 106, the magnet of the armature 40 is located at a first position within the stator 36. As shown, step 106 includes a step 108 of determining a voltage of a first coil and second coil of a first coil pair (e.g. coil pair A2-6) and a step 110 of calculating the back-EMF generated by one of the first coil and the second coil. Attorney Docket No. INST2471PCT / 060210.04135Additionally, step 106 includes a step 112 of determining a voltage of a first coil and second coil of a second coil pair (e.g. coil pair B2-6) and a step 114 of calculating the back-EMF generated by one of the first coil or the second coil. Once the controller CON calculates the back-EMF generated by the coil pairs, the controller CON may calculate the motion parameter of the armature 40 based on the calculated back EMFs during step 116.

[0083] Referring to FIG. 12, once the controller CON determines the motion parameter of the armature 40 during step 106, the method 100 proceeds to a step 120 of performing closed loop control of the motion parameter of the armature 40 based on the determined motion parameter. In this way, the determined motion parameter of the armature during step 106 serves as feedback during the closed loop control of step 122. In one example, during step 122, the controller CON may provide closed loop control of the position of the armature 40 based on determining the position of the armature 40 in step 106. In such an instance, the controller CON may provide an electrical current and / or a drive voltage to the plurality of coils 38 to move the armature 40 to a desired position based on the determined position of the armature 40.

[0084] The motor 34 may include any suitable number of coil pairs.

[0085] For example, in some instances, the plurality of coils 38 may include two coil pairs. In such instances, the first pair of coils are electrically connected in series, the second pair of coils are electrically connected in series, with the first pair of coils being electrically connected in parallel with the second pair of coils. Additionally, in such an instance, the battery BAT is configured to provide an electrical current to the first pair of coils such that the first coil of the first pair of coils generates a first magnetic field and the second coil of the first pair of coils generates a second magnetic field and provide an electrical current to second pair of coils such that a first coil of the second pair of coils generates a third magnetic field and the second coil of the second pair of coils generates a fourth magnetic field. In instances where the plurality of coils includes two coil pairs, the controller CON is configured to determine the motion parameter of the armature 40 based on the back-EMF signal generated by each coil pair. Specifically, the controller CON is configured to measure a voltage of a first coil and a second coil of the second pair of coils, determine a first back EMF signal based on the voltage of the first coil of the second pair of coils and the voltage of the second coil of the second pair of coils, measure a voltage of a first coil and a second coil of the second pair of coils, determine a second back EMF signal based on the voltage of the first coil of the second pair of coils and the voltage of the Attorney Docket No. INST2471PCT / 060210.04135second coil of the second pair of coils, and determine the motion parameter of the armature based on the first back EMF signal and the second back EMF signal. The controller CON may then control the battery BAT to provide an electrical current to the one of the first pair of coils and the second pair of coils based on the determined motion parameter of the armature.

[0086] As another example, in some instances, the plurality of coils 38 may include four coil pairs. In such instances, the first pair of coils are electrically connected in series, the second pair of coils are electrically connected in series, the third pair of coils are electrically connected in series, the fourth pair of coils are electrically connected in series, and the first, second, third, and fourth pair of coils being electrically connected in parallel with one another. Additionally, in such an instance, the battery BAT is configured to provide an electrical current to the first pair of coils such that the first coil of the first pair of coils generates a first magnetic field and the second coil of the first pair of coils generates a second magnetic field, provide an electrical current to second pair of coils such that a first coil of the second pair of coils generates a third magnetic field and the second coil of the second pair of coils generates a fourth magnetic field, provide an electrical current to the third pair of coils such that the first coil of the third pair of coils generates a fifth magnetic field and the second coil of the third pair of coils generates a sixth magnetic field, and provide an electrical current to the fourth pair of coils such that the first coil of the fourth pair of coils generates a seventh magnetic field and the second coil of the fourth pair of coils generates an eighth magnetic field. In instances where the plurality of coils includes two coil pairs, the controller CON is configured to determine the motion parameter of the armature 40 based on the back-EMF signal generated by two coil pairs of the four coil pairs. Specifically, the controller CON is configured to measure a voltage of a first coil and a second coil of the second pair of coils, determine a first back EMF signal based on the voltage of the first coil of the second pair of coils and the voltage of the second coil of the second pair of coils, measure a voltage of a first coil and a second coil of the second pair of coils, determine a second back EMF signal based on the voltage of the first coil of the second pair of coils and the voltage of the second coil of the second pair of coils, and determine the motion parameter of the armature based on the first back EMF signal and the second back EMF signal. The controller CON may then control the battery BAT to provide an electrical current to the one of the first, second, third, and fourth pair of coils based on the determined motion parameter of the armature. Attorney Docket No. INST2471PCT / 060210.04135

[0087] The controller CON may determine the motion parameter based on any suitable number of back-EMF signals. For example, while the controller CON has been described herein as determining the motion parameter based on two back-EMF signals, the controller CON may determine the motion parameter based on additional back-EMF signals for increased accuracy. For example, referring to FIG. 11, the controller CON may include a measurement point between coils of coil pairs of C-phase to determine a back-EMF signal for a coil pair of C-phase. Additionally, the controller CON may include additional measurement points between coils of coil pairs of A-phase and B-phase, as shown in FIG. 11, to determine a back-EMF signal for more than one coil pair of A-phase and B-phase.

[0088] Referring to Figures 15 through 27, one configuration of a surgical impactor attachment 320 for impacting a tool 322 or prosthesis into a patient is shown. As shown in Figure 15, the surgical impactor attachment 320 is configured to be coupled to and driven by a rotary surgical handpiece 324. In other configurations, the surgical impactor attachment 320 may not be configured for attachment and may be integrally formed with the rotary surgical handpiece 324. One example of a suitable rotary surgical handpiece 324 is disclosed in U.S. Pat. No. 5,888,200, entitled “MULTI-PURPOSE SURGICAL TOOL SYSTEM”, issued March 30, 1999, and incorporated herein by reference in its entirety. Of course, other configurations of a rotary surgical handpiece 324 configured to drive the surgical impactor attachment 320 are contemplated. As is also shown in Figure 15, the tool 322 or prosthesis is configured to be operatively attached to the surgical impactor attachment 320 and to be impacted into the patient by the surgical impactor attachment 320. The illustrated tool 322 is a surgical broach for preparing an intramedullary canal of a femur for receiving a prosthesis, but the attachment of other tools 322 or prosthesis requiring impaction into a patient is contemplated.

[0089] With continued reference to Figures 15 through 23, the surgical impactor attachment 320 includes a housing 326. The housing 326 defines a striking axis 328 (best shown in Figure 16). In this example, the housing 326 defines a void where the rest of the componentry of the surgical impactor attachment 320 is disposed. The surgical impactor attachment 320 also includes an impact hammer 330. The impact hammer 330 is at least partially within the housing 326 for reciprocating movement relative to the housing 326 along the striking axis 328. The mechanism for effectuating such reciprocating movement of the impact hammer 330 is described in further detail below. The impact hammer 330 extends between a coupling end 330A and an Attorney Docket No. INST2471PCT / 060210.04135impact end 330B. The impact end 330B is configured to be coupled to the tool 322 such that the reciprocating movement of the impact hammer 330 to impact the tool 322 into the patient. Furthermore, the impactor attachment 320 may be coupled to prosthesis for impaction into a patient. Furthermore, a surgical handpiece is contemplated that includes the components of the surgical impactor attachment 320 in a dedicated device.

[0090] The surgical impactor attachment 320 also includes a rotational member 332 (best shown in Figure 19). Referring to Figures 16 through 20, the rotational member 332 is supported within the housing 326 for rotation about a rotational axis 334 that is transverse to the striking axis 328. The rotational member 332 is configured to be operatively attached to a motor of a handpiece 324 that is configured to rotate the rotational member 332 about the rotational axis 334 in at least a first rotational direction RD1. For example, the surgical impactor attachment 320 may include an input shaft 336 coupled to the rotational member 332 and configured to be coupled to the motor of the handpiece 324 to transmit the torque generated by the motor of the handpiece 324 to rotate the rotational member 332 about the rotational axis 334. The rotational member 332 also includes a radial projection 338 that revolves around the rotational axis 334 that generates impact as the rotational member 332 rotates about the rotational axis 334, as described in further detail below.

[0091] The surgical impactor attachment 320 further includes an intermediate member 340 disposed within the housing 326 for reciprocating movement along an intermediate axis 342 that is parallel to and spaced laterally from the striking axis 328. The intermediate member 340 is configured to reciprocate within the housing 326 in a first translational direction TD1 and a second translational direction TD2, opposite the first translational direction TD1. As best shown in Figures 16 and 20, the intermediate member 340 defines an impact void 344 that faces the rotational member 332 and includes a first face 346. Accordingly, the radial projection 338 of the rotational member 332 is configured to impact the first face 346 of the impact void 344 with each revolution of the rotational member 332 about the rotational axis 334 in the first rotational direction RD1 to urge the intermediate member 340 in the first translation direction TD1. The intermediate member 340 is implemented as a shaft in the illustrated implementation but other configurations are contemplated.

[0092] The surgical impactor attachment 320 also further includes a lever 348 disposed within the housing 326 and extending between a first end 348A and a second end 348B. The Attorney Docket No. INST2471PCT / 060210.04135first end 348A is disposed for pivotal movement about a pivot axis 350 that is parallel to and spaced laterally from the rotational axis 334. The second end 348B is operatively attached to the intermediate member 340. Accordingly, the lever 348 is configured to pivot in a reciprocal manner about the pivot axis 350 in response to the reciprocating movement of the intermediate member 340. As best shown in Figure 21, the lever 348 is coupled to the impact hammer 330 to move the impact hammer 330 relative to the housing 326 along the striking axis 328 to impact the tool 322 or prosthesis into the patient. Referring to Figures 21 and 22, the lever 348 may define a slot 352 and the coupling end 330A of the impact hammer 330 may define lobes 354 and a central shaft 356. The central shaft 356 may be disposed in the slot 352 of the lever 348 to couple the lever 348 to the impact hammer 330, and the lobes 354 may abut the lever 348 to permit slight movement of the impact hammer 330 relative to the lever 348 to allow the lever 348 to pivot relative to the impact hammer 330.

[0093] Thus, cumulatively, the surgical impactor attachment 320 converts the rotation of the motor of the handpiece 324 into repetitive impacts of the impact hammer 330 to impact the tool 322 or prosthesis into the patient by nature of the motor of the handpiece 324 rotating the rotational member 332 such that the radial projection 338 impacts the first face 346 of the intermediate member 340 in the first translational direction TD1, which thereby causes the lever 348 to pivot about the pivot axis 350 and move the impact hammer 330 relative to the housing 326 along the striking axis 328 to impact the tool 322 or prosthesis into the patient. The intermediate member 340 may be configured to move in the second translational direction TD2 to “reset” for the next impact cycle by virtue of the reactionary force exerted by the patient against the tool 322 or prosthesis. However, in other configurations it is contemplated to include a return biasing member may be operatively attached to the intermediate member 340 to “reset” the intermediate member 340 for the next cycle.

[0094] It should also be appreciated that the surgical impactor attachment 320 may be configured to operate in reverse of the operation described above to remove the tool 322 or prosthesis from the patient. For example, the motor of the handpiece 324 may be configured to rotate the rotational member 332 about the rotational axis 334 in the second rotational direction RD2 (i.e., opposite the first rotational direction RD1). Accordingly, the impact void 344 of the intermediate member 340 may also include a second face 358, opposite the first face 346. Thus, the motor of the handpiece 324 may rotate the rotational member 332 in the second rotational Attorney Docket No. INST2471PCT / 060210.04135direction RD2, and the radial projection 338 of the rotational member 332 may be configured to impact the second face 358 of the impact void 344 with each revolution about the rotational axis 334 in the second rotational direction RD2 to urge the intermediate member 340 in the second translation direction TD2 (and, thus, the lever 348 and impact hammer 330 away from the patient) to remove the tool 322 or prosthesis from the patient.

[0095] In some examples, the rotational member 332 may be configured to disconnect from the intermediate member 340 to temporarily halt operation of the surgical impactor attachment 320. For example, the rotational member 332 may be configured to disconnect from the intermediate member 340 if the force of the radial projection 338 impacting the intermediate member 340 exceeds a threshold force and / or if there is not sufficient reactionary force to reset the intermediate member 340 for the next cycle. As best shown in Figures 17-18 and 23-25B, in some examples, the input shaft 336 may define a cam profile 360 having a landing 362 and at least one ramp 364. Accordingly, the rotational member 332 may be engaged with the landing 362 (e.g., via a stud 366) during normal operation of the surgical impactor attachment 320 (shown in Figures 24A and 25A). Additionally, in these examples, the surgical impactor attachment 320 may further include biasing member 368 operatively attached to the input shaft 336 and the rotational member 332 and configured to urge the rotational member 332 into engagement with the landing 362 of the cam profile 360 to resume normal operation of the surgical impactor attachment 320.

[0096] Referring to the exploded view of Figure 24A, the rotational member 332 (particularly, the stud 366 of the rotational member 332) may be configured to slide relative to the at least one ramp 364 (i.e., disconnect from the landing 362) in response to the force of the radial projection 338 impacting the intermediate member 340 exceeding the threshold force to disconnect the rotational member 332 from the intermediate member 340. Additionally, referring to Figure 25A, the rotational member 332 (particularly, the stud 366 of the rotational member 332) may also be configured to slide relative to the at least one ramp 364 (i.e., disconnect from the landing 362) in response to the radial projection 338 colliding with the intermediate member 340 in the event there is not sufficient reactionary force to reset the intermediate member 340 for the next cycle.

[0097] Additionally, in these examples, the surgical impactor attachment 320 may further include biasing member 368 operatively attached to the input shaft 336 and the rotational Attorney Docket No. INST2471PCT / 060210.04135member 332 and configured to urge the rotational member 332 into engagement with the landing 362 of the cam profile 360 to resume normal operation of the surgical impactor attachment 320.

[0098] Referring to Figures 26 through 30, another configuration of a surgical impactor attachment 420 for impacting a tool 422 into a patient is shown. As shown in Figure 26, the surgical impactor attachment 420 is configured to be coupled to and driven by a rotary surgical handpiece 424. In other configurations, the surgical impactor attachment 420 may not be configured for attachment and may be integrally formed with the rotary surgical handpiece 424. One example of a suitable rotary surgical handpiece 424 is disclosed in U.S. Pat. No. 5,747,953, entitled “CORDLESS, BATTERY OPERATED SURGICAL TOOL”, issued May 5, 1998, and incorporated herein by reference in its entirety. Of course, other configurations of a rotary surgical handpiece 424 configured to drive the surgical impactor attachment 420 are contemplated. As is also shown in Figure 26, a tool 422 is configured to be operatively attached to the surgical impactor attachment 420 and to be impacted into the patient by the surgical impactor attachment 420. The illustrated tool 422 is a surgical broach for preparing an intramedullary canal of a femur for receiving a prosthesis, but the attachment of other tools 422 requiring impaction into a patient is contemplated. Furthermore, the impactor attachment 420 may be coupled to prosthesis for impaction into a patient. Furthermore, a surgical handpiece is contemplated that includes the components of the surgical impactor attachment 420 in a dedicated device.

[0099] With continued reference to Figures 26 through 30, the surgical impactor attachment 420 includes a housing 426. The housing 426 may define a striking axis 428 and extends between a proximal end 430 configured for attachment to a handpiece 424 and a distal end 432 including an anvil 434 configured to be operatively attached to the tool 422. In this example, the housing 426 is generally cylindrical in shape and defines a central void 436 where the rest of the componentry of the surgical impactor attachment 420 is disposed.

[0100] As best shown in Figures 27 and 28, the surgical impactor attachment 420 also includes a threaded screw shaft 438 supported within the housing 426 for rotation about the striking axis 428. The threaded screw shaft 438 is configured to be operatively attached to a motor of the handpiece 424 configured to rotate the threaded screw shaft 438 about the striking axis 428. As shown in Figures 27 and 28, the threaded screw shaft 438 may extend between a proximal end 440 that extends beyond the housing 426 for attachment to the handpiece 424 and a Attorney Docket No. INST2471PCT / 060210.04135distal end 442 arranged at distal end 432 of the housing 426. The distal end 442 of the threaded screw shaft 438 may be supported within the housing 426 for rotation about the striking axis 428 by a bearing or the like.

[0101] The surgical impactor attachment 420 further includes an impact hammer 444. The impact hammer 444 is supported within the housing 426 for movement relative to the housing 426 along the striking axis 428 between a loaded position LP and an impact position IP. In the loaded position LP (best shown in Figures 29C and 29D), the impact hammer 444 is spaced from the anvil 434. In the impact position IP (best shown in Figure 29E), the impact hammer 444 strikes the anvil 434 to impact the tool 422 into the patient. As best shown in Figures 26 and 27, the housing 426 may define one or more guide slots 462. In these examples, the impact hammer 444 may include one or more lateral projections 464 (in this case fasteners) corresponding to the guide slot(s) 462 that are disposed in a respective guide slot 462. As a result, the lateral projection(s) 464 are constrained within the guide slot(s) 462 such that guide slot(s) 462 to constrain the impact hammer 444 from rotating relative to the housing 426 about the striking axis 428 as the impact hammer 444 translates between the loaded position LP and the impact position IP.

[0102] As shown in the illustrated example, the impact hammer 444 may define a central aperture 446 that is configured to receive the threaded screw shaft 438 and / or the threaded member 454 such that the impact hammer 444 translates relative to the threaded screw shaft 438 and / or the threaded member 454 along the striking axis 428 between the loaded position LP and the impact position IP. As best shown in Figures 29A through 29D, the impact hammer 444 also defines one or more release slots 448 that extend from the central aperture 446. The function of the one or more release slots 448 is described in further detail below. The surgical impactor attachment 420 also includes a biasing member 450. The biasing member 450 is disposed within the housing 426 and coupled to the impact hammer 444 to urge the impact hammer 444 along the striking axis 428 from the loaded position LP towards the impact position IP to impact the tool 422 into the patient. For example, the biasing member 450 may extend between a first end 450A that abuts the impact hammer 444 and a second end 450B that abuts a proximal flange 452 of the housing 426. The biasing member 450 may take the form of a coil spring.

[0103] The surgical impactor attachment 420 also further includes a threaded member 454. The threaded member 454 is disposed within the housing 426 and engaged with the threaded Attorney Docket No. INST2471PCT / 060210.04135screw shaft 438 such that rotation of the threaded screw shaft 438 translates the threaded member 454 along the striking axis 428. More specifically, the motor of the handpiece 424 may be configured to rotate the threaded screw shaft 438 in a first direction (e.g., clockwise) such that the threaded member 454 translates along the striking axis 428 toward the proximal end of the housing 426. The motor of the handpiece 424 may also be configured to rotate the threaded screw shaft 438 in a second direction, opposite the first direction, (e.g., counter-clockwise) such that the threaded member 454 translates along the striking axis 428 toward the distal end 432 of the housing 426. As best shown in Figures 29A through 29E, the threaded member 454 also includes one or more radial projections 456 that revolve around the striking axis 428 and are configured to cooperate with the release slots 448 of the impact hammer 444, as described in further detail below.

[0104] Additionally, as best shown in Figure 29D, in some configurations, the one or more radial projections 456 may be defined as a first radial projection 456A and a second radial projection 456B arranged opposite the first radial projection 456A. Likewise, the one or more release slot(s) 448 may be further defined as a first release slot 448A and a second release slot 448B opposite the first release slot 448A. Accordingly, the first radial projection 456A may be configured to cooperate with the first release slot 448A during operation of the surgical impactor attachment 420, and the second radial projection 456B may be configured to cooperate with the second release slot 448B during operation of the surgical impactor attachment 420, as described in further detail below.

[0105] Referring to Figures 29A through 29E, the threaded member 454 may define one or more radial guides 458. The one or more radial guides 458 are each configured to engage a stud 460 or other projection that extends radially inward from the housing 426 (best shown in Figures 27 and 28). As shown in the sequence of Figures 29A through 29E, the one or more radial guides 458 are configured to constrain the threaded member 454 for coordinated movement with the impact hammer 444 and the biasing member 450 within the housing 426 between a plurality of states to impact the tool 422 into a patient. In other words, during operation of the surgical impactor attachment 420, the stud(s) 460 travel within their respective radial guide(s) 458 to guide translation and rotation of the threaded member 454 relative to the housing 426. For example, referring to the sequence between Figures 29B and 29C, the stud(s) 460 travel within their respective radial guide(s) 458 to guide translation of the threaded member 454 proximally Attorney Docket No. INST2471PCT / 060210.04135relative to the threaded screw shaft 438 between the plurality of states. Additionally, referring to the sequence between Figures 29C and 29D, for example, the stud(s) 460 travel within their respective radial guide(s) 458 to guide rotation of the threaded member 454 relative to the threaded screw shaft 438 between the plurality of states.

[0106] Referring to Figure 29A, the plurality of states includes a home state where the impact hammer 444 is in the impact position IP after striking the anvil 434 and the radial projection(s) 456 of the threaded member 454 are arranged distal to the impact hammer 444 and aligned with the release slot(s) 448. Referring to Figure 29B, the plurality of states also includes a coupled state where the impact hammer 444 is in the impact position IP after striking the anvil 434 and the radial projection(s) 456 of the threaded member 454 are arranged distal to the impact hammer 444 and rotated relative to the impact hammer 444 such that the radial projection(s) 456 are configured to abut the impact hammer 444. Referring to Figure 29C, the plurality of states further includes a compression state where the radial projection(s) 456 remain rotated relative to the impact hammer 444 such that the radial projection(s) 456 abut the impact hammer 444 as the threaded member 454 is moved proximally (via rotation of the threaded screw shaft 438) to move the impact hammer 444 to the loaded position LP and compress the biasing member 450. Referring to Figure 29D, the plurality of states also further includes a release state where the radial projection(s) 456 of the threaded member 454 are rotated relative to the impact hammer 444 such that the radial projection(s) 456 are each aligned with the release slot(s) 448. In the release state, once the radial projection(s) 456 are aligned with the release slot(s) 448, the biasing member 450 is configured to release the potential energy stored in the biasing member 450 during the compressed state to urge the impact hammer 444 along the striking axis 428 from the loaded position LP towards the impact position IP to strike the anvil 434 to impact the tool 422 into the patient.

[0107] The surgical impactor attachment 420 may be configured to operate to provide impacts forces in rapid succession. As such, the threaded member 454 may be configured to be cycled sequentially between the home state, the coupled state, the compressed state, and the release state by the handpiece 424 (via the threaded screw shaft 438) to repeatedly impact the tool 422 into the patient. More specifically, the motor of the handpiece 424 may be configured to be rotated in the first direction to sequentially move the threaded member 454 from the home state to the coupled state to the compressed state and to the released state, and the motor of the Attorney Docket No. INST2471PCT / 060210.04135handpiece 424 may be configured to be rotated in the second direction to the threaded member 454 from the released state to the home state. For example, the motor of the handpiece 424 may be configured to complete a specified number of revolutions in the first direction, then complete a specified number of revolutions in the second direction to operate the surgical impactor attachment 420 to provide impacts forces in rapid succession. As shown in Figures 29A through 4E, the stud(s) 460 remain disposed in the radial guides 458 to guide the rotation and translation of the threaded member 454 throughout this cycle.

[0108] A linear motor system may include the motor 34 as described herein, where the motor 34 may include any feature of the stator 36, armature 40, or any other component of the powered surgical impactor 20 described herein. It should be understood that the linear motor system may be used in other applications, such as non-surgical and / or industrial applications. Additionally, the linear motor system can be controlled in a manner similar to that described above in non-surgical and / or industrial applications.

[0109] Embodiments of the disclosure may be described with reference to the following exemplary clauses:

[0110] Clause 1. A surgical impactor attachment for impacting a tool or prosthesis, the surgical impactor attachment comprising: a housing defining a striking axis and extending between a proximal end configured for attachment to a handpiece and a distal end including an anvil configured to be operatively attached to the tool; a threaded screw shaft supported within the housing for rotation about the striking axis and configured to be operatively attached to a motor of the handpiece configured to rotate the threaded screw shaft about the striking axis; an impact hammer defining a release slot and supported within the housing for movement relative to the housing along the striking axis between a loaded position where the impact hammer is spaced from the anvil, and an impact position where the impact hammer strikes the anvil to impact the tool or prosthesis; a biasing member disposed within the housing and coupled to the impact hammer to urge the impact hammer along the striking axis from the loaded position towards the impact position to impact the tool or prosthesis; a threaded member disposed within the housing and engaged with the threaded screw shaft such that rotation of the threaded screw shaft translates the threaded member along the striking axis, the threaded member including a radial projection that revolves around the striking axis and a radial guide, the radial guide engaged with a stud extending radially inward from the housing to constrain the threaded member for Attorney Docket No. INST2471PCT / 060210.04135coordinated movement with the impact hammer and the biasing member within the housing between a plurality of states including: a home state where the impact hammer is in the impact position after striking the anvil and the radial projection of the threaded member is arranged distal to the impact hammer and aligned with the release slot; a coupled state where the impact hammer is in the impact position after striking the anvil and the radial projection of the threaded member is arranged distal to the impact hammer and rotated relative to the impact hammer such that the radial projection abuts the impact hammer; a compression state where the radial projection remains rotated relative to the impact hammer such that the radial projection abuts the impact hammer, and the threaded member is moved proximally such that the impact hammer moves to the loaded position and the biasing member is compressed; and a release state where the radial projection is rotated relative to the impact hammer such that the radial projection of the threaded member is aligned with the release slot and the biasing member urges the impact hammer along the striking axis from the loaded position towards the impact position to strike the anvil to impact the tool or prosthesis.

[0111] Clause 2. The surgical impactor attachment according to clause 1, wherein the threaded member is configured to be cycled sequentially between the home state, the coupled state, the compressed state, and the release state by the handpiece to impact the tool or prosthesis.

[0112] Clause 3. The surgical impactor attachment according to any one of clauses 1 or 2, wherein the threaded screw shaft is configured to be rotated in a first direction by the motor to sequentially move the threaded member from the home state to the coupled state to the compressed state and to the released state; and wherein the threaded screw shaft is configured to be rotated in a second direction, opposite the first direction, by the motor to move the threaded member from the released state to the home state.

[0113] Clause 4. The surgical impactor attachment according to any one of clauses 1-3, wherein the housing defined a guide slot and the impact hammer includes a lateral projection disposed in the guide slot to constrain the impact hammer from rotating relative to the housing about the striking axis as the impact hammer translates between the loaded position and the impact position.

[0114] Clause 5. The surgical impactor attachment according to any one of clauses 1-4, wherein the radial projection is further defined as a first radial projection and the release slot is Attorney Docket No. INST2471PCT / 060210.04135further defined as a first release slot; and wherein the threaded member includes a second radial projection arranged opposite the first radial projection and the impact hammer defines a second release slot opposite the first release slot.

[0115] Clause 6. A surgical impactor for impacting a prosthesis or tool, the surgical impactor comprising: a housing defining a striking axis and including an anvil configured to be operatively attached to the tool or prosthesis; a motor; a threaded screw shaft supported within the housing for rotation about the striking axis and coupled to the motor to rotate the threaded screw shaft about the striking axis; an impact hammer defining a release slot and supported within the housing for movement relative to the housing along the striking axis between a loaded position where the impact hammer is spaced from the anvil, and an impact position where the impact hammer strikes the anvil to impact the tool or prosthesis; a biasing member disposed within the housing and coupled to the impact hammer to urge the impact hammer along the striking axis from the loaded position towards the impact position to impact the tool or prosthesis; a threaded member disposed within the housing and engaged with the threaded screw shaft such that rotation of the threaded screw shaft translates the threaded member along the striking axis, the threaded member including a radial projection that revolves around the striking axis, the threaded member being constrained and configured for coordinated movement with the impact hammer and the biasing member within the housing between a plurality of states including: a home state where the impact hammer is in the impact position after striking the anvil and the radial projection of the threaded member is arranged distal to the impact hammer and aligned with the release slot; a coupled state where the impact hammer is in the impact position after striking the anvil and the radial projection of the threaded member is arranged distal to the impact hammer and rotated relative to the impact hammer such that the radial projection abuts the impact hammer; a compression state where the radial projection remains rotated relative to the impact hammer such that the radial projection abuts the impact hammer, and the threaded member is moved proximally such that the impact hammer moves to the loaded position and the biasing member is compressed; and a release state where the radial projection is rotated relative to the impact hammer such that the radial projection of the threaded member is aligned with the release slot and the biasing member urges the impact hammer along the striking axis from the loaded position towards the impact position to strike the anvil to impact the tool or prosthesis. Attorney Docket No. INST2471PCT / 060210.04135

[0116] Clause 7. A surgical impactor attachment for impacting a tool or prosthesis, the surgical impactor attachment comprising: a housing defining a striking axis; an impact hammer supported at least partially within the housing for reciprocating movement relative to the housing along the striking axis, the impact hammer including an impact end configured to be coupled to the tool or prosthesis to impact the tool or prosthesis; a rotational member supported within the housing for rotation about a rotational axis that is transverse to the striking axis and including a radial projection that is configured to revolve around the rotational axis, the rotational member configured to be operatively attached to a motor of a handpiece configured to rotate the rotational member about the rotational axis in at least a first rotational direction; an intermediate member disposed within the housing for reciprocating movement along an intermediate axis that is parallel to and spaced laterally from the striking axis in a first translational direction and a second translational direction, opposite the first translational direction, the intermediate member defining an impact void that faces the rotational member and includes a first face, wherein the radial projection of the rotational member is configured to impact the first face of the impact void with each revolution about the rotational axis in the first rotational direction to urge the intermediate member in the first translation direction; a lever disposed within the housing and extending between a first end disposed for pivotal movement about a pivot axis that is parallel to and spaced laterally from the rotational axis, and a second end operatively attached to the intermediate member such that the lever pivots in a reciprocal manner about the pivot axis in response to reciprocating movement of the intermediate member, wherein the lever is coupled to the impact hammer to move the impact hammer relative to the housing along the striking axis to impact the tool or prosthesis.

[0117] Clause 8. The surgical impactor attachment according to clause 7, wherein the motor of the handpiece configured to rotate the rotational member about the rotational axis in a second rotational direction, opposite the first rotational direction; and wherein the impact void also includes a second face, opposite the first face, wherein the radial projection of the rotational member is configured to impact the second face of the impact void with each revolution about the rotational axis in the second rotational direction to urge the intermediate member in the second translation direction to remove the tool or prosthesis.

[0118] Clause 9. The surgical impactor attachment according to any one of clauses 7 or 8, further comprising an input shaft coupled to the rotational member and configured to be coupled Attorney Docket No. INST2471PCT / 060210.04135to the motor of the handpiece to transmit the torque generated by the motor to the rotational member.

[0119] Clause 10. The surgical impactor attachment according to clause 9, wherein the input shaft defines a cam profile having a landing and at least one ramp, wherein the rotational member is engaged with the landing and is configured to slide along the at least one ramp in response to the force of the radial projection impacting the intermediate member exceeding a threshold force to disconnect the rotational member from the intermediate member.

[0120] Clause 11. The surgical impactor attachment according to clause 10, further comprising a biasing member operatively attached to the input shaft and the rotational member and configured to urge the rotational member into engagement with the landing of the cam profile.

[0121] Clause 12. A surgical impactor for impacting a prosthesis or tool, the surgical impactor comprising: a housing defining a striking axis; a motor; an impact hammer supported at least partially within the housing for reciprocating movement relative to the housing along the striking axis, the impact hammer including an impact end configured to be coupled to the tool to impact the tool or prosthesis; a rotational member supported within the housing for rotation about a rotational axis that is transverse to the striking axis and including a radial projection that revolves around the rotational axis, the rotational member coupled to the motor and configured to rotate the rotational member about the rotational axis in at least a first rotational direction; an intermediate member disposed within the housing for reciprocating movement along an intermediate axis that is parallel to and spaced laterally from the striking axis in a first translational direction and a second translational direction, opposite the first translational direction, the intermediate member defining an impact void that faces the rotational member and includes a first face, wherein the radial projection of the rotational member is configured to impact the first face of the impact void with each revolution about the rotational axis in the first rotational direction to urge the intermediate member in the first translation direction; a lever disposed within the housing and extending between a first end disposed for pivotal movement about a pivot axis that is parallel to and spaced laterally from the rotational axis, and a second end operatively attached to the intermediate member such that the lever pivots in a reciprocal manner about the pivot axis in response to reciprocating movement of the intermediate member, Attorney Docket No. INST2471PCT / 060210.04135wherein the lever is coupled to the impact hammer to move the impact hammer relative to the housing along the striking axis to impact the tool or prosthesis.

[0122] Several implementations have been discussed in the foregoing description. However, the implementations discussed herein are not intended to be exhaustive or limit the invention to any particular form. The terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations are possible in light of the above teachings and the invention may be practiced otherwise than as specifically described. Attorney Docket No. INST2471PCT / 060210.04135

Claims

CLAIMS What is claimed is:

1. A powered surgical impactor comprising: a housing defining a longitudinal axis; a stator disposed within the housing and extending along the longitudinal axis between a proximal stator end and a distal stator end; a plurality of coils arranged about the stator and configured to be energized to generate a magnetic field; an armature disposed within the stator and extending along the longitudinal axis between a proximal armature end and a distal armature end, wherein the armature is configured for movement relative to the stator along the longitudinal axis in a distal direction and a proximal direction between a plurality of armature positions in response to the plurality of coils being energized, the plurality of armature positions including: a proximal armature position where movement of the armature relative to the stator is delimited in the proximal direction, and a distal armature position where movement of the armature relative to the stator is delimited in the distal direction; and a hammer coupled to the distal armature end of the armature for movement with the armature in response to the plurality of coils being energized, wherein the hammer defines a hollow region delimited by a proximal impact face and a distal impact face, wherein a portion of the hammer that defines the hollow region is at least partially arranged within the stator when the armature is in the proximal armature position; and an anvil assembly including: a shaft supported by the housing for translation along the longitudinal axis in the distal direction and the proximal direction, the shaft extending between a distal shaft end arranged to support a tool and a proximal shaft end; and an anvil supported by the proximal shaft end of the shaft and disposed within the hollow region of the hammer, the anvil including a distal strike face and a proximal strike face, wherein the proximal strike face of the anvil is arranged to be impacted by the proximal impact face of the hammer as the armature moves in the distal direction to urge the shaft and the tool in the distal direction, and wherein the distal strike face of the anvil Attorney Docket No. INST2471PCT / 060210.04135is arranged to be impacted by the distal impact face of the hammer as the armature moves in the proximal direction to urge the shaft and the tool in the proximal direction.

2. The powered surgical impactor of claim 1, wherein the stator defines a stator length between the proximal stator end and the distal stator end, and wherein the armature defines an armature length, less than the stator length of the stator, between the proximal armature end and the distal armature end.

3. The powered surgical impactor of claim 2, wherein the plurality of coils is arranged about the stator length of the stator.

4. The powered surgical impactor of claim 2, wherein the proximal armature end is aligned with the proximal stator end when the armature is in the proximal armature position.

5. The powered surgical impactor of claim 2, wherein the distal armature end is aligned with the distal stator end when the armature is in the distal armature position.

6. The powered surgical impactor of claim 1, wherein a distal portion of the housing defines a constraining void delimited by a distal constraining face and a proximal constraining face; and wherein the anvil assembly further comprises a constraining member disposed within the constraining void and coupled to the shaft such that the constraining member is configured to abut the distal constraining face to delimit motion of the shaft in the distal direction and to abut the proximal constraining face to delimit motion of the shaft in the proximal direction.

7. The powered surgical impactor of claim 6, further comprising a shaft biasing member interposed between the proximal constraining face and the constraining member to bias the shaft in the distal direction.

8. The powered surgical impactor of claim 1, further comprising a controller configured to: Attorney Docket No. INST2471PCT / 060210.04135measure a voltage of a first coil and a second coil of a pair of coils of the plurality of coils; determine a back EMF signal based on the voltage of the first coil and the voltage of the second coil; and determine a motion parameter of the armature based on the back EMF signal.

9. The powered surgical impactor of claim 8, wherein the armature includes a magnet configured to generate a magnetic field.

10. The powered surgical impactor of claim 9, further comprising a battery electrically connected to the plurality of coils, the battery being configured to provide an electrical current to the plurality of coils to energize the plurality of coils such that the plurality of coils generate a magnetic field.

11. The powered surgical impactor of claim 10, wherein the magnetic field generated by the plurality of coils interacts with the magnetic field generated by the magnet of the armature to move the armature within the stator between the proximal stator end and the distal stator end.

12. The powered surgical impactor of claim 10, wherein the magnet of the armature is adjacent to one of the first coil and the second coil, and wherein, to determine the back EMF signal, the controller is configured to subtract the measured voltage of the other one of the first coil and the second coil from the measured voltage of the one of the first coil and the second coil.

13. The powered surgical impactor of claim 10, wherein voltage of the first coil includes the back EMF signal, and wherein the back EMF signal is generated in response to the magnet of the armature being adjacent to the first coil.

14. The powered surgical impactor of claim 10, wherein the pair of coils is further defined as a first pair of coils, and wherein the plurality of coils includes a second pair of coils, the first pair of coils being electrically connected in series, the second pair of coils being Attorney Docket No. INST2471PCT / 060210.04135electrically connected in series, and the first pair of coils being electrically connected in parallel with the second pair of coils.

15. The powered surgical impactor of claim 14, further comprising a battery electrically connected to the plurality of coils, the battery being configured to: provide an electrical current to the first pair of coils such that the first coil of the first pair of coils generates a first magnetic field and the second coil of the first pair of coils generates a second magnetic field; and provide an electrical current to second pair of coils such that a first coil of the second pair of coils generates a third magnetic field and the second coil of the second pair of coils generates a fourth magnetic field.

16. The powered surgical impactor of claim 14, wherein the back EMF signal is further defined as a first back EMF signal, and wherein the controller is configured to: measure a voltage of a first coil and a second coil of the second pair of coils; determine a second back EMF signal based on the voltage of the first coil of the second pair of coils and the voltage of the second coil of the second pair of coils; and determine the motion parameter of the armature based on the first back EMF signal and the second back EMF signal.

17. The powered surgical impactor of claim 16, wherein the battery is electrically connected to the controller, and wherein the controller is configured to control the battery to provide an electrical current to the one of the first pair of coils and the second pair of coils based on the determined motion parameter of the armature.

18. The powered surgical impactor of claim 10, wherein the pair of coils is further defined as a first pair of coils, and wherein the plurality of coils includes a second, third, and fourth pair of coils, the first pair of coils being electrically connected in series, the second pair of coils being electrically connected in series, the third pair of coils being electrically connected in series, the fourth pair of coils being electrically connected in series, and the first, second, third, and fourth pair of coils being electrically connected in parallel with one another. Attorney Docket No. INST2471PCT / 060210.0413519. The powered surgical impactor of claim 18, further comprising a battery electrically connected to the plurality of coils, the battery being configured to: provide an electrical current to the first pair of coils such that the first coil of the first pair of coils generates a first magnetic field and the second coil of the first pair of coils generates a second magnetic field; provide an electrical current to second pair of coils such that a first coil of the second pair of coils generates a third magnetic field and the second coil of the second pair of coils generates a fourth magnetic field; provide an electrical current to the third pair of coils such that the first coil of the third pair of coils generates a fifth magnetic field and the second coil of the third pair of coils generates a sixth magnetic field; and provide an electrical current to the fourth pair of coils such that the first coil of the fourth pair of coils generates a seventh magnetic field and the second coil of the fourth pair of coils generates an eighth magnetic field.

20. The powered surgical impactor of claim 19, wherein the back EMF signal is further defined as a first back EMF signal, and wherein the controller is configured to: measure a voltage of a first coil and a second coil of the second pair of coils; determine a second back EMF signal based on the voltage of the first coil of the second pair of coils and the voltage of the second coil of the second pair of coils; and determine the motion parameter of the armature based on the first back EMF signal and the second back EMF signal.

21. The powered surgical impactor of claim 18, wherein the battery is electrically connected to the controller, and wherein the controller is configured to control the battery to provide an electrical current to the one of the first, second, third, and fourth pair of coils based on the determined motion parameter of the armature.

22. The powered surgical impactor of claim 8, wherein the motion parameter includes one or more of a position, velocity, acceleration, or jerk of the armature. 42 Attorney Docket No. INST2471PCT / 060210.0413523. A powered surgical impactor comprising: a housing defining a longitudinal axis; a stator disposed within the housing and extending along the longitudinal axis between a proximal stator end and a distal stator end; a plurality of coils arranged about the stator and being configured to be energized to generate a magnetic field; an armature disposed within the stator and extending along the longitudinal axis between a proximal armature end and a distal armature end, the armature configured for movement within the stator between the proximal stator end and the distal stator end in response to the plurality of coils being energized; a hammer coupled to the armature; and a controller configured to: measure a voltage of a first coil and a second coil of a pair of coils of the plurality of coils; determine a back EMF signal based on the voltage of the first coil and the voltage of the second coil; and determine a motion parameter of the armature based on the back EMF signal.

24. The powered surgical impactor of claim 23, wherein the armature includes a magnet configured to generate a magnetic field.

25. The powered surgical impactor of claim 24, further comprising a battery electrically connected to the plurality of coils, the battery being configured to provide an electrical current to the plurality of coils to energize the plurality of coils such that the plurality of coils generate a magnetic field.

26. The powered surgical impactor of claim 25, wherein the magnetic field generated by the plurality of coils interacts with the magnetic field generated by the magnet of the armature to move the armature within the stator between the proximal stator end and the distal stator end. Attorney Docket No. INST2471PCT / 060210.0413527. The powered surgical impactor of claim 25, wherein the magnet of the armature is adjacent to one of the first coil and the second coil, and wherein, to determine the back EMF signal, the controller is configured to subtract the measured voltage of the other one of the first coil and the second coil from the measured voltage of the one of the first coil and the second coil.

28. The powered surgical impactor of claim 25, wherein voltage of the first coil includes the back EMF signal, and wherein the back EMF signal is generated in response to the magnet of the armature being adjacent to the first coil.

29. The powered surgical impactor of claim 25, wherein the pair of coils is further defined as a first pair of coils, and wherein the plurality of coils includes a second pair of coils, the first pair of coils being electrically connected in series, the second pair of coils being electrically connected in series, and the first pair of coils being electrically connected in parallel with the second pair of coils.

30. The powered surgical impactor of claim 29, further comprising a battery electrically connected to the plurality of coils, the battery being configured to: provide an electrical current to the first pair of coils such that the first coil of the first pair of coils generates a first magnetic field and the second coil of the first pair of coils generates a second magnetic field; and provide an electrical current to second pair of coils such that a first coil of the second pair of coils generates a third magnetic field and the second coil of the second pair of coils generates a fourth magnetic field.

31. The powered surgical impactor of claim 29, wherein the back EMF signal is further defined as a first back EMF signal, and wherein the controller is configured to: measure a voltage of a first coil and a second coil of the second pair of coils; determine a second back EMF signal based on the voltage of the first coil of the second pair of coils and the voltage of the second coil of the second pair of coils; and determine the motion parameter of the armature based on the first back EMF signal and the second back EMF signal. Attorney Docket No. INST2471PCT / 060210.0413532. The powered surgical impactor of claim 31, wherein the battery is electrically connected to the controller, and wherein the controller is configured to control the battery to provide an electrical current to the one of the first pair of coils and the second pair of coils based on the determined motion parameter of the armature.

33. The powered surgical impactor of claim 25, wherein the pair of coils is further defined as a first pair of coils, and wherein the plurality of coils includes a second, third, and fourth pair of coils, the first pair of coils being electrically connected in series, the second pair of coils being electrically connected in series, the third pair of coils being electrically connected in series, the fourth pair of coils being electrically connected in series, and the first, second, third, and fourth pair of coils being electrically connected in parallel with one another.

34. The powered surgical impactor of claim 33, further comprising a battery electrically connected to the plurality of coils, the battery being configured to: provide an electrical current to the first pair of coils such that the first coil of the first pair of coils generates a first magnetic field and the second coil of the first pair of coils generates a second magnetic field; provide an electrical current to second pair of coils such that a first coil of the second pair of coils generates a third magnetic field and the second coil of the second pair of coils generates a fourth magnetic field; provide an electrical current to the third pair of coils such that the first coil of the third pair of coils generates a fifth magnetic field and the second coil of the third pair of coils generates a sixth magnetic field; and provide an electrical current to the fourth pair of coils such that the first coil of the fourth pair of coils generates a seventh magnetic field and the second coil of the fourth pair of coils generates an eighth magnetic field.

35. The powered surgical impactor of claim 34, wherein the back EMF signal is further defined as a first back EMF signal, and wherein the controller is configured to: measure a voltage of a first coil and a second coil of the second pair of coils; Attorney Docket No. INST2471PCT / 060210.04135determine a second back EMF signal based on the voltage of the first coil of the second pair of coils and the voltage of the second coil of the second pair of coils; and determine the motion parameter of the armature based on the first back EMF signal and the second back EMF signal.

36. The powered surgical impactor of claim 33, wherein the battery is electrically connected to the controller, and wherein the controller is configured to control the battery to provide an electrical current to the one of the first, second, third, and fourth pair of coils based on the determined motion parameter of the armature.

37. The powered surgical impactor of claim 25, wherein the stator extends along the longitudinal axis between the proximal stator end and the distal stator end to define a stator length, and wherein the plurality of coils are arranged about the stator length.

38. The powered surgical impactor of claim 37, wherein the armature extends along the longitudinal axis between the proximal armature end and the distal armature end to define an armature length less than the stator length.

39. The powered surgical impactor of claim 38, wherein the stator length is at least 25% longer than the armature length.

40. The powered surgical impactor of claim 23, wherein the armature is configured for movement within the stator between the proximal stator end and the distal stator end between a plurality of armature positions in response to the plurality of coils be energized, the plurality of armature positions including: a proximal armature position where the proximal armature end is aligned with the proximal stator end, and a distal armature position where the distal armature end is aligned with the distal stator end. Attorney Docket No. INST2471PCT / 060210.0413541. The powered surgical impactor of claim 40, wherein the hammer is disposed outside of the armature such that the hammer is configured to impact a forward impact surface as the armature reaches the distal armature position and to impact a reverse impact surface as the armature reaches the proximal armature position.

42. The powered surgical impactor of claim 23, wherein the motion parameter includes one or more of a position, velocity, acceleration, or jerk of the armature.

43. The powered surgical impactor of claim 23, wherein the hammer is coupled to the distal armature end of the armature for movement with the armature in response to the plurality of coils being energized, wherein the hammer defines a hollow region delimited by a proximal impact face and a distal impact face, wherein a portion of the hammer that defines the hollow region is at least partially arranged within the stator when the armature is in the proximal armature position.

44. The powered surgical impactor of claim 43, further comprising an anvil assembly including: a shaft supported by the housing for translation along the longitudinal axis in the distal direction and the proximal direction, the shaft extending between a distal shaft end arranged to support a tool and a proximal shaft end; and an anvil supported by the proximal shaft end of the shaft and disposed within the hollow region of the hammer, the anvil including a distal strike face and a proximal strike face, wherein the proximal strike face of the anvil is arranged to be impacted by the proximal impact face of the hammer as the armature moves in the distal direction to urge the shaft and the tool in the distal direction, and wherein the distal strike face of the anvil is arranged to be impacted by the distal impact face of the hammer as the armature moves in the proximal direction to urge the shaft and the tool in the proximal direction.

45. The powered surgical impactor of claim 44, wherein a distal portion of the housing defines a constraining void delimited by a distal constraining face and a proximal constraining face; and Attorney Docket No. INST2471PCT / 060210.04135wherein the anvil assembly further comprises a constraining member disposed within the constraining void and coupled to the shaft such that the constraining member is configured to abut the distal constraining face to delimit motion of the shaft in the distal direction and to abut the proximal constraining face to delimit motion of the shaft in the proximal direction.

46. The powered surgical impactor according to claim 45, further comprising a shaft biasing member interposed between the proximal constraining face and the constraining member to bias the shaft in the distal direction.

47. A method of controlling a powered surgical impactor including a housing defining a longitudinal axis, a stator disposed within the housing and extending along the longitudinal axis between a proximal stator end and a distal stator end, a plurality of coils arranged about the stator, an armature disposed within the stator and extending along the longitudinal axis between a proximal armature end and a distal armature end; and a hammer coupled to the armature, the method comprising steps of: energizing the plurality of coils to generate a magnetic field, wherein the armature is movable within the stator between the proximal stator end and the distal stator end in response to the plurality of coils being energized; measuring a voltage of a first coil and a second coil of a pair of coils of the plurality of coils; determining a back EMF signal based on the voltage of the first coil and the voltage of the second coil; and determining a motion parameter of the armature based on the back EMF signal.

48. The method of claim 47, wherein the armature includes a magnet configured to generate a magnetic field.

49. The method of claim 48, wherein the powered surgical impactor further includes a battery electrically connected to the plurality of coils, and further comprising a step of providing, with the battery, an electrical current to the plurality of coils to energize the plurality of coils such that the plurality of coils generate a magnetic field. Attorney Docket No. INST2471PCT / 060210.0413550. The method of claim 49, wherein the magnet of the armature is adjacent to one of the first coil and the second coil, and further comprising a step of determining the back EMF signal by subtracting the measured voltage of the other one of the first coil and the second coil from the measured voltage of the one of the first coil and the second coil.

51. The method of claim 49, wherein voltage of the first coil includes the back EMF signal, and wherein the back EMF signal is generated in response to the magnet of the armature being adjacent to the first coil.

52. The method of claim 49, wherein the pair of coils is further defined as a first pair of coils, and wherein the plurality of coils includes a second pair of coils, the first pair of coils being electrically connected in series, the second pair of coils being electrically connected in series, and the first pair of coils being electrically connected in parallel with the second pair of coils.

53. The method of claim 52, wherein the powered surgical impactor further includes a battery electrically connected to the plurality of coils, and further comprising steps of: providing, with the battery, an electrical current to the first pair of coils such that the first coil of the first pair of coils generates a first magnetic field and the second coil of the first pair of coils generates a second magnetic field; and providing, with the battery, an electrical current to second pair of coils such that a first coil of the second pair of coils generates a third magnetic field and the second coil of the second pair of coils generates a fourth magnetic field.

54. The method of claim 52, wherein the back EMF signal is further defined as a first back EMF signal, and further comprising steps of: measuring a voltage of a first coil and a second coil of the second pair of coils; determining a second back EMF signal based on the voltage of the first coil of the second pair of coils and the voltage of the second coil of the second pair of coils; and Attorney Docket No. INST2471PCT / 060210.04135determining the motion parameter of the armature based on the first back EMF signal and the second back EMF signal.

55. The method of claim 54, further comprising steps of controlling the battery to provide an electrical current to the one of the first pair of coils and the second pair of coils based on the determined motion parameter of the armature.

56. The method of claim 49, wherein the pair of coils is further defined as a first pair of coils, and wherein the plurality of coils includes a second, third, and fourth pair of coils, the first pair of coils being electrically connected in series, the second pair of coils being electrically connected in series, the third pair of coils being electrically connected in series, the fourth pair of coils being electrically connected in series, and the first, second, third, and fourth pair of coils being electrically connected in parallel with one another.

57. The method of claim 56, wherein the powered surgical impactor further includes a battery electrically connected to the plurality of coils, and further comprising steps of providing, with the battery, an electrical current to the first pair of coils such that the first coil of the first pair of coils generates a first magnetic field and the second coil of the first pair of coils generates a second magnetic field; providing, with the battery, an electrical current to second pair of coils such that a first coil of the second pair of coils generates a third magnetic field and the second coil of the second pair of coils generates a fourth magnetic field; providing, with the battery, an electrical current to the third pair of coils such that the first coil of the third pair of coils generates a fifth magnetic field and the second coil of the third pair of coils generates a sixth magnetic field; and providing, with the battery, an electrical current to the fourth pair of coils such that the first coil of the fourth pair of coils generates a seventh magnetic field and the second coil of the fourth pair of coils generates an eighth magnetic field.

58. The method of claim 57, wherein the back EMF signal is further defined as a first back EMF signal, and further comprising steps of: Attorney Docket No. INST2471PCT / 060210.04135measuring a voltage of a first coil and a second coil of the second pair of coils; determining a second back EMF signal based on the voltage of the first coil of the second pair of coils and the voltage of the second coil of the second pair of coils; and determining the motion parameter of the armature based on the first back EMF signal and the second back EMF signal.

59. The method of claim 56, further comprising a step of controlling the battery to provide an electrical current to the one of the first, second, third, and fourth pair of coils based on the determined motion parameter of the armature.

60. The method of claim 47, wherein the motion parameter includes one or more of a position, velocity, acceleration, or jerk of the armature.

61. A method of controlling a surgical impactor including a stator and an armature disposed within the stator, the stator including a first coil and a second coil, the second coil being spaced apart from the first coil, and the armature including a plurality of magnets, the armature being movable between a first position and a second position, the first position being spaced from the second position, and wherein a hammer is coupled to the armature, the method comprising: determining a first electrical parameter of a first coil while the armature is in the first position; determining a second electrical parameter of a second coil while the armature is in the first position; determining an electromagnetic factor based on the first and second electrical parameters; and determining a motion parameter of the armature in the stator based on the electromagnetic factor.

62. The method of claim 61, wherein the first coil is active while the armature is in the first position and the second coil is inactive while the armature is in the first position. Attorney Docket No. INST2471PCT / 060210.0413563. The method of claim 61, wherein the second coil is active while the armature is in the second position and the first coil is inactive while the armature is in the second position.

64. The method of claim 61, wherein the stator further includes a third and fourth coil, wherein the electromagnetic factor is further defined as a first electromagnetic factor, and wherein the method further comprises: determining a third electrical parameter of a third coil while the armature is in the first position; determining a fourth electrical parameter of a fourth coil while the armature is in the first position; determining a second electromagnetic factor based on the third and fourth electrical parameters; and determining the motion parameter of the armature in the stator based on the first and second electromagnetic factors.

65. The method of claim 64, further comprising a step of providing an electrical current to the first coil and the second coil or to the third coil and the fourth coil based on the determined motion parameter of the armature.

66. The method of claim 61, wherein the first coil is active while the armature is in the first position and the second coil is inactive while the armature is in the first position, and further comprising a step of determining the electromagnetic factor by subtracting the second electrical parameter from the first electrical parameter.

67. A powered surgical impactor comprising: a housing defining a longitudinal axis; a stator disposed within the housing and extending along the longitudinal axis between a proximal stator end and a distal stator end, the stator including a plurality of coils arranged about the longitudinal axis and being configured to be energized to generate a magnetic field, the plurality of coils including a first coil and a second coil; Attorney Docket No. INST2471PCT / 060210.04135an armature disposed within the stator and extending along the longitudinal axis between a proximal armature end and a distal armature end, the armature including a plurality of magnets and the armature is configured for movement within the stator between the proximal stator end and the distal stator end in response to the plurality of coils being energized; and a controller configured to: measure electrical parameters of the first coil and the second coil while the armature is in a first position; and determine a position of the armature based on the measured electrical parameters of the first coil and the second coil at the first position.

68. The powered surgical impactor of claim 67, wherein the plurality of coils further includes a third coil and a fourth coil.

69. The powered surgical impactor of claim 68, wherein the controller is further configured to: measure electrical parameters of the third coil and the fourth coil while the armature is in a first position; and determine the position of the armature based on the measured electrical parameters of the first coil, the second coil, the third coil, and the fourth coil at the first position.

70. A linear motor system comprising: a stator extending along a longitudinal axis between a proximal stator end and a distal stator end; a plurality of coils arranged about the stator and being configured to be energized to generate a magnetic field; an armature disposed within the stator and extending along the longitudinal axis, the armature configured for movement within the stator between the proximal stator end and the distal stator end in response to the plurality of coils being energized; a controller configured to: measure a voltage of a first coil and a second coil of a pair of coils of the plurality of coils; Attorney Docket No. INST2471PCT / 060210.04135determine a back EMF signal based on the voltage of the first coil and the voltage of the second coil; and determine a motion parameter of the armature based on the back EMF signal.

71. A method of controlling a linear motor system including a stator extending along a longitudinal axis between a proximal stator end and a distal stator end, a plurality of coils arranged about the stator, and an armature disposed within the stator and extending along the longitudinal axis, the armature being movable within the stator between the proximal stator end and the distal stator end in response to the plurality of coils being energized, the method comprising: measuring a voltage of a first coil and a second coil of a pair of coils of the plurality of coils; determining a back EMF signal based on the voltage of the first coil and the voltage of the second coil; and determining a motion parameter of the armature based on the back EMF signal. Attorney Docket No. INST2471PCT / 060210.04135

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