Orthopedic Surgery Impactor

Abstract

The surgical electromagnetic impactor includes: a housing defining an internal cavity extending along a longitudinal axis; a striker disposed within the internal cavity and configured to move along the longitudinal axis; an anvil system including a first anvil configured to move in a first direction along the longitudinal axis from a first rest position toward a first end point; an electromagnetic drive system configured to drive the striker to move in the first direction to impact the first anvil such that a first force directed in the first direction is imparted to an external object via the first anvil; and a centering system configured to bias the first anvil toward the first rest position. The centering system includes one or more first resilient members configured to bias the first anvil toward a first rest position in response to displacement of the first anvil toward the first end point beyond a first engagement position, and one or more second resilient members configured to bias the first anvil toward the first rest position in response to displacement of the first anvil toward the first end point beyond a second engagement position, the second engagement position being located between the first engagement position and the first end point. Each of the first resilient members has a lower stiffness than each of the second resilient members.

Description

[Technical Field]

[0001] The present disclosure relates to electromagnetic surgical impactors. In particular, but not exclusively, the present disclosure relates to electromagnetically driven orthopedic surgical impactors. [Background technology]

[0002] When performing surgery, particularly orthopedic surgery, it may be necessary to apply an impact force. This can be done using a surgical mallet or a slap hammer. For example, in a total hip replacement, a surgeon may use a broach tool to prepare the femur and insert the hip implant (femoral broaching). A surgical mallet may be used to drive the broach tool into the femur. Using a surgical mallet or a slap hammer can be imprecise and stressful for the surgeon. Summary of the Invention

[0003] The present disclosure relates to a surgical electromagnetic impactor, and more particularly to a surgical electromagnetic impactor having an improved centering system for increasing impact force.

[0004] According to a first aspect, a surgical electromagnetic impactor is provided. The surgical electromagnetic impactor includes: a housing defining an internal cavity extending along a longitudinal axis; a striker disposed within the internal cavity and configured to move along the longitudinal axis; an anvil system including a first anvil configured to move in a first direction along the longitudinal axis from a first rest position toward a first end point; an electromagnetic drive system configured to drive the striker to move in the first direction and impact the first anvil so that a first force directed in the first direction is imparted to an external object via the first anvil; and a centering system configured to bias the first anvil toward the first rest position. The centering system includes one or more first resilient members configured to bias the first anvil toward a first rest position in response to displacement of the first anvil toward the first end point beyond a first engagement position, and one or more second resilient members configured to bias the first anvil toward the first rest position in response to displacement of the first anvil toward the first end point beyond a second engagement position, the second engagement position being located between the first engagement position and the first end point. Each of the first resilient members has a lower stiffness than each of the second resilient members.

[0005] In certain embodiments, two resilient members are provided: a first resilient member having a lower stiffness than a second resilient member and engaging the anvil system at a low displacement, thereby helping to center the anvil system while reducing the adverse effect of the centering system on the impact force applied by the impactor.

[0006] In one embodiment, the one or more first resilient members are configured to bias the first anvil toward the first rest position through a first range of motion of the first anvil that includes at least a portion of the range between the second engagement position and the first rest position. The first range of motion may completely encompass the range between the second engagement position and the first rest position. The first range of motion may range from a first endpoint to the first rest position. The first engagement position may be the first rest position.

[0007] In one embodiment, the one or more second resilient members are configured to bias the first anvil toward the first rest position through a second range of motion of the first anvil, the second range of motion extending over at least a portion of a range between the second engagement position and the first endpoint. The second range of motion may completely encompass the range between the second engagement position and the first endpoint. The second range of motion may range from the first endpoint to the second engagement position.

[0008] The one or more second elastic members may provide a stronger biasing force per unit distance of travel of the anvil system than the one or more first elastic members, and the first and second elastic members may be considered biasing members.

[0009] In one embodiment, the surgical impactor is configured to prevent the first anvil from moving beyond a first endpoint, which may be a position or point that defines an end of the first anvil's range of motion.

[0010] According to one embodiment, the first and second elastic members are springs, and each second elastic member has a higher spring constant than each first elastic member, or conversely, each first elastic member may have a lower spring constant than each second elastic member.

[0011] According to one embodiment, the one or more first elastic members include one or more coil springs and / or the one or more second elastic members include one or more leaf springs.

[0012] According to one embodiment, the centering system further includes one or more third resilient members configured to bias the first anvil toward the first rest position in response to displacement of the first anvil toward the first end point beyond the third engagement position, the third engagement position being located between the second engagement position and the first end point.

[0013] The one or more third elastic members may be configured to bias the first anvil toward the first rest position through a third range of motion of the first anvil, the third range including at least a portion of the range from the first end point to the third engagement position. Both the first end point and the third engagement position may be located farther in the first direction from the first rest position than the second engagement position. The third range of motion may be within the first range of motion and / or the second range of motion. The third range of motion may be outside one or both of the first range of motion and the second range of motion. In one embodiment, the third range of motion is between the first end point and the third engagement position. The one or more third elastic members may be configured to prevent the first anvil from moving beyond the first end point.

[0014] The one or more third elastic members may have a stiffness greater than the one or more first elastic members and / or the one or more second elastic members, although this is not required. Thus, the one or more third elastic members may have a stiffness less than or equal to the one or more first elastic members and / or the one or more second elastic members.

[0015] According to one embodiment, the one or more third resilient members include one or more dampers, each damper including a shock-absorbing material. The shock-absorbing material may be silicone. The one or more dampers may be silicone dampers. The one or more third resilient members may be configured to damp movement of the anvil (in the first direction) beyond the third engagement position.

[0016] In one embodiment, the centering system is configured to prevent the striker from moving beyond the first endpoint.

[0017] According to one embodiment, the anvil system includes a second anvil connected to the first anvil, the second anvil configured to move in a second direction opposite the first direction from a second rest position to a second end point, the first and second anvils being positioned on opposite sides of the striker, and the electromagnetic drive system further configured to drive the striker to move in the second direction to impact the second anvil, thereby applying a second force directed in the second direction to the external object via the second anvil. According to this embodiment, the centering system further includes one or more fourth elastic members configured to bias the second anvil toward the second rest position in response to displacement of the second anvil toward the second end point beyond the fourth engagement position, and one or more fifth elastic members configured to bias the second anvil toward the second rest position in response to displacement of the second anvil toward the second end point beyond the fifth engagement position, the fifth engagement position being located between the fourth engagement position and the second end point, and each of the fourth elastic members having a lower stiffness than each of the fifth elastic members.

[0018] In one embodiment, the one or more fourth resilient members are configured to bias the second anvil toward the second rest position through a fourth range of motion of the second anvil that encompasses at least a portion of the range between the fourth engagement position and the second rest position. The fourth range of motion may completely encompass the range between the fourth engagement position and the second rest position. The fourth range of motion may range from the second endpoint to the second rest position. The fourth engagement position may be the second rest position.

[0019] In one embodiment, the one or more fifth resilient members are configured to bias the second anvil toward the second rest position through a fifth range of motion of the second anvil, the fifth range of motion extending over at least a portion of the range between the fifth engagement position and the second endpoint. The fifth range of motion may completely encompass the range between the fifth engagement position and the second endpoint. The fifth range of motion may range from the second endpoint to the fifth engagement position.

[0020] The one or more fifth elastic members may provide a stronger biasing force per unit distance of travel of the anvil system than the one or more fourth elastic members, and the fourth and fifth elastic members may be considered biasing members.

[0021] In one embodiment, the surgical impactor is configured to prevent the second anvil from moving beyond the second endpoint. The second endpoint may be a position or point that defines an end of a full range of motion for the second anvil. The anvil system may have a full range of motion between the first endpoint and the second endpoint.

[0022] According to one embodiment, the fourth and fifth elastic members are springs, each fifth elastic member having a higher spring constant than each fourth elastic member.

[0023] According to one embodiment, the one or more fourth elastic members include one or more coil springs and / or the one or more fifth elastic members include one or more leaf springs.

[0024] According to one embodiment, the centering system further includes one or more sixth resilient members configured to bias the second anvil toward the second rest position in response to displacement of the second anvil toward the second end point beyond the sixth engagement position, the sixth engagement position being located between the fifth engagement position and the second end point.

[0025] The one or more sixth elastic members may be configured to bias the second anvil toward the second rest position through a sixth range of motion of the second anvil, which range extends over at least a portion of the range between the second end point and the fifth engagement position. Both the second end point and the sixth engagement position may be located farther from the second rest position in the second direction than the fifth engagement position. The sixth range of motion may be within the fourth range of motion and / or the fifth range of motion. The sixth range of motion may be outside one or both of the fourth range of motion and the fifth range of motion. In one embodiment, the sixth range of motion is the range between the second end point and the sixth engagement position.

[0026] The one or more sixth elastic members may have a stiffness greater than the one or more fourth elastic members and / or the one or more fifth elastic members, although this is not required. Thus, the one or more sixth elastic members may have a stiffness that is equal to or less than the stiffness of the one or more fourth elastic members and / or the one or more fifth elastic members.

[0027] The one or more sixth resilient members may be configured to prevent the second anvil from moving beyond the second endpoint.

[0028] According to one embodiment, the one or more sixth resilient members include one or more dampers, each damper including a shock-absorbing material. The shock-absorbing material may be silicone. The one or more dampers may be silicone dampers. The one or more sixth resilient members may be configured to damp movement of the anvil (in the second direction) beyond the sixth engagement position.

[0029] According to one embodiment, the centering system is configured to prevent the striker from moving beyond the second endpoint.

[0030] According to one embodiment, the spacing between the first anvil and the second anvil in the first direction is less than the maximum range of motion over which the electromagnetic drive system is configured to drive the striker.

[0031] According to one embodiment, the surgical electromagnetic impactor further includes circuitry configured to control the electromagnetic drive system to drive the striker according to an operating mode selectable between a first operating mode in which the electromagnetic drive system controls the striker to drive in a first direction to impact a first anvil and apply a primary force in the first direction, a second operating mode in which the electromagnetic drive system controls the striker to drive in a second direction to impact a second anvil and apply a primary force in the second direction, and a reciprocating operating mode in which the electromagnetic drive system controls the striker to alternately drive in the first and second directions to impact the first anvil and apply a primary force in the first direction and the second anvil and apply a primary force in the second direction.

[0032] The first and second operating modes actuate the striker to impart a primary force in a first and second direction, respectively, but the striker can also be actuated to move in the opposite direction (e.g., ready to drive). When ready to drive, the striker can impart a secondary force to the anvil system in the opposite direction to the primary force in that operating mode. This secondary force can be smaller (e.g., smaller in magnitude) than the primary force.

[0033] According to one embodiment, the first anvil is connected to the second anvil via a rod that passes through a channel in the striker. The rod may be a central rod that passes through a central channel (e.g., along the longitudinal axis) in the striker. The striker may be configured to move (e.g., slide) along the rod.

[0034] According to one embodiment, at least one of the one or more first elastic members and the one or more second elastic members are configured to apply a first biasing force to the second anvil in a second direction to tension the anvil system when biasing the first anvil toward the first rest position. Additionally or alternatively, at least one of the one or more fourth elastic members and the one or more fifth elastic members may be configured to apply a second biasing force to the first anvil in the first direction to tension the anvil system when biasing the second anvil toward the second rest position.

[0035] By applying tension, the biasing force can stretch (rather than compress) the connection (e.g., rod) between the first and second anvils. This can be achieved by applying a biasing force to the anvil opposite the impacted anvil. This can reduce the risk of the anvil system buckling during use. In specific embodiments, the one or more second elastic members are configured to apply a first biasing force to the second anvil in a second direction, and the one or more fifth elastic members apply a second biasing force to the first anvil in the first direction.

[0036] According to one embodiment, the centering system is configured to apply a biasing force to the striker via the anvil system after each impact between the striker and the anvil system, biasing the striker toward a center position. In a specific embodiment, the centering system does not act directly on the striker, but instead acts via the anvil system. The striker may not be directly biased toward the center position. The center position may be a position where the striker is separated from the anvil system when the striker and the anvil system are stationary. The center position may be a stationary position of the striker.

[0037] According to one embodiment, the surgical electromagnetic impactor further includes a tool or tool holder connected to the second anvil to apply a force from the second anvil to the external object. The tool may be a hammer, a broach, an extractor / extractor (e.g., an implant extraction tool), etc.

[0038] According to one embodiment, the centering system is configured to allow the anvil system to float within the housing, thereby allowing a user to adjust the position of the anvil system relative to the striker by pushing or pulling the electromagnetic surgical impactor to vary the impact force between the striker and the anvil system, thereby adjusting the rest positions (e.g., first rest position and second rest position) of the anvil system. [Brief explanation of the drawings]

[0039] The inventive arrangements will be more fully understood and appreciated from the following detailed description, which is provided by way of example only and is taken in conjunction with the drawings in which: [Figure 1] FIG. 1 is a side view of an electromagnetic impactor according to one embodiment. [Figure 2] FIG. 2 is a cross-sectional view of a drive mechanism of the electromagnetic impactor. [Figure 3] FIG. 2 is an enlarged cross-sectional view of the front end of the drive mechanism. [Figure 4] FIG. 4 is an enlarged cross-sectional view of the rear end of the drive mechanism. [Figure 5] FIG. 2 is an enlarged cross-sectional view of the center of the drive mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0040] This application relates to surgical impactors used to apply impact forces (e.g., as an alternative to traditional hammers and mallets). In particular, this application relates to electromagnetically driven surgical impactors.

[0041] Surgical impactors are driven by accelerating a striker (or striking assembly) against an anvil (connected to a tool for transmitting force to an external object). Impactor devices can be pneumatically driven, but such pneumatic devices can be large and cumbersome. Utilizing an electromagnetic drive system can make impactor systems smaller and easier to use.

[0042] Because the striker is driven linearly, a linear motor can be used to drive the striker. Using a linear motor eliminates the need to convert rotary motion to linear motion (e.g., via gears). A problem with linear motors is that if the motor matures (in this case, the striker) overextends (overtravel cogging), the motor can jam. Therefore, it is advantageous to include a centering system (e.g., in the form of one or more resilient members, such as one or more springs) to return the striker to a centered position so that it can be driven again. This allows the striker to overtravel, applying additional force without jamming the linear motor due to overtravel cogging.

[0043] With the above in mind, biasing the striker toward a central position counteracts the drive force provided by the motor, thereby reducing the impact force of the striker. The embodiments described herein provide a centering system that acts on the anvil to prevent the initial impact force of the striker from being reduced. After impact, the centering system can press the anvil against the striker, thereby forcing the striker back toward the central position.

[0044] Additionally, in the embodiments described herein, the centering system includes two sets of resilient members with different stiffnesses. The stiffer resilient members engage the anvil at a greater distance of travel than the less stiffer resilient members. The less stiffer resilient members provide a centering force to position the anvil and striker at their resting positions without unduly restricting impact force. The stiffer resilient members help stop the anvil (and striker) toward the end of their travel before pushing them back toward a more central position. Through their interaction with the anvil, the stiffer resilient members return the anvil to a more central position, allowing the striker to be driven by the motor. This allows the striker to be moved outside the motor's normal operating range by the centering system, but still be returned to this range by the centering system. Thus, the striker can be driven to impact the anvil at higher speeds without risking over-travel cogging. A stiffer elastic member will engage with a greater displacement than a less stiff elastic member (e.g., there is a range of motion of the anvil where the stiffer elastic member does not act), and therefore the impact force imparted to the external object will be greater.

[0045] 1 shows a side view of an electromagnetic impactor 100 according to one embodiment. The impactor 100 includes a tool holder 110, a housing 120, and a handle .

[0046] The tool holder 110 is configured to removably secure and drive a tool (not shown). A coupling mechanism 112 is provided on the tool holder 110 for securing the tool within the tool holder 110. For example, a broach tool, a hammer tool, or an extraction tool (e.g., an implant extractor) can be secured to the tool holder 110 and driven by movement of the tool holder 110. Instead of including the tool holder 110, the impactor 100 may include an integral tool. For ease of explanation, the remainder of this application will be described based on an impactor 100 having a tool holder 110.

[0047] A drive mechanism (not shown) for driving and moving the tool holder 110 is housed within the housing 120. The drive mechanism may include a linear motor configured to drive a striker that strikes an anvil system connected to the tool holder 110. The drive mechanism may be configured to drive the striker along a longitudinal axis. The drive mechanism is discussed in more detail below. The drive mechanism may be controlled via a processing circuit. The processing circuit may be housed within the housing 120 (e.g., in the handle 130).

[0048] The handle 130 may be configured to be held in one hand and includes a trigger 140, a power control dial 142, and a mode switch 144. The trigger 140, the power control dial 142, and the mode switch 144 may each provide inputs to the processing circuitry.

[0049] The trigger 140 provides an input to control the operation of the impactor 100. When the trigger 140 is depressed, the tool holder 110 is actuated.

[0050] The power control dial 142 provides an input to control the impact force of the impactor 100. The impact force can be increased or decreased depending on the input from the power control dial 142. Based on this input, the processing circuitry can adjust the speed at which the striker is driven by the linear motor.

[0051] A mode switch 144 provides an input for switching between different modes of operation. The impactor 100 can be configured to operate in three different modes: forward mode, reverse mode, and reciprocating mode (alternatively referred to as oscillating mode).

[0052] In the forward mode, the impactor 100 applies a primary force in a forward direction (a first direction along the longitudinal axis). In this mode, the striker is driven to impact the front anvil in the anvil system. The forward mode can apply an impact force, i.e., a push-out force.

[0053] In the rearward mode, the impactor 100 applies a primary force in a rearward direction (a second direction along the longitudinal axis) opposite to the forward direction. In this mode, the striker is driven to impact the rear anvil in the anvil system. The rearward mode can apply a removal force, i.e., a pulling force.

[0054] In the reciprocating model, the impactor 100 reciprocates between forward and reverse force. The striker is alternately driven to strike the front anvil to provide a forward force and the rear anvil to provide a reverse force. The specific processes involved in each mode are described in detail below.

[0055] In this embodiment, the input components are described as including a "trigger," a "power control dial," and a "mode switch," but it will be understood that the functions of each of these input components can be realized by various means. For example, these inputs can be in the form of any one or combination of triggers, dials, switches, sliders, touch screens, or other input devices.

[0056] The impactor 100 is provided with a power source. This can be in the form of either a wired connection (e.g., connection to a mains power source) or a connection to a battery. For example, a battery dock may be provided at the bottom end of the handle 130. A battery may be secured to the battery dock and provide power to the impactor 100.

[0057] In certain embodiments, the electromagnetic impactor 100 is a surgical impactor. In this case, the electromagnetic impactor 100 is suitable for use in a surgical environment. This may require the use of sterilizable materials. Additionally or alternatively, the electromagnetic impactor 100 may be required to be waterproof. For example, a waterproof housing may be provided. Furthermore, the electromagnetic impactor 100 may be made of materials suitable for reprocessing (sterilization and disinfection processes). While the electromagnetic impactor 100 itself may be suitable for reprocessing, the tools that fit within the device (e.g., broaching tools, hammering tools, extraction tools, etc.) may be replaceable.

[0058] Figure 2 shows a cross section of the drive mechanism of the electromagnetic impactor.

[0059] The drive mechanism includes anvil system 200, centering system 300, motor 400, and striker 500. The system shown in Figure 2 shows anvil system 200 in a rest position, where no external forces are acting on anvil system 200 and motor 400 is not engaged (e.g., centering system 300 and anvil system 200 are in equilibrium). Striker 500 is similarly shown in a corresponding rest position, which may be centered within motor 400.

[0060] The anvil system 200 includes a front anvil 210, a rear anvil 220, and a connector 230. The front anvil 210 is connected to (e.g., integral with) the tool holder 110, such that movement of the anvil system 200 also moves the tool holder 110. The front anvil 210 and the rear anvil 220 are positioned on opposite sides of the striker 500. The connector 230 connects the front anvil 210 to the rear anvil 220, thereby forming an integral unit of the anvil system 200. In this embodiment, the connector 230 is in the form of a shaft that extends along the longitudinal axis of the impactor 100.

[0061] The striker 500 is attached to the connector 230 so as to be slidable along a longitudinal axis within a cavity in the housing. The striker 500 includes a bearing 505 (e.g., a linear bearing) configured to assist longitudinal movement of the striker 500. The bearing 505 may act on an inner wall 150 within the impactor 100. The inner wall 150 may define a longitudinal cavity in which the striker 500 is housed. The longitudinal cavity may be cylindrical.

[0062] The striker 500 is driven by the motor 400 and is configured to impact the anvil system 200 and apply a force to the tool holder 110. When the striker 500 is driven in a first direction, the striker 500 impacts the front anvil 210 and applies a force in the first direction. When the striker 500 is driven in a second direction, the striker 500 impacts the rear anvil 220 and applies a force in the second direction. The first and second directions are opposite to each other and are both parallel to the longitudinal axis.

[0063] The first direction may be considered a forward direction, and the second direction may be considered a rearward direction. The terms "forward" and "rearward" are relative terms (i.e., relative to the structure of the impactor 100) and do not relate to any orientation of the impactor 100 during use. In the following description, the terms "forward" and "forward" will be used to refer to the first direction, and the terms "rearward" and "rearward" will be used to refer to the second direction.

[0064] Centering system 300 includes a plurality of resilient members (e.g., springs, dampers, etc.). Centering system 300 is configured to bias anvil system 200 toward a rest position. For example, after driving anvil system 200 forward within housing 120, centering system 300 is configured to bias anvil system 200 rearward, i.e., toward the rest position of anvil system 200. Similarly, after driving anvil system 200 rearward within housing 120, centering system 300 is configured to bias anvil system 200 forward, i.e., toward the rest position of anvil system.

[0065] The biasing force provided by the centering system 300 helps return the striker 500 to a centered position. When the anvil system 200 returns to its rest position, the anvil system 200 applies a return force to the striker, returning the striker 500 to its rest position. This allows the striker 500 to return to a centered position suitable for re-activation by the motor 400 without applying a return force to the motor 400 (although the motor 400 may apply such a return force).

[0066] By configuring the centering system 300 to act on the anvil system 200, the striker 500 can be returned to a centered position without directly biasing the striker 500 itself. This allows the striker 500 to be accelerated by the motor 400 without being subjected to a biasing force that resists the acceleration. On the other hand, if the striker 500 is directly biased (e.g., via a spring acting directly on the striker 500), then the return force acting on the striker 500 will act against the acceleration of the striker 500, limiting the initial force imparted by the striker 500 to the anvil system 200.

[0067] Furthermore, by providing the centering system 300, the striker 500 can be driven beyond the maximum operating range of the motor 400. For example, the motor 400 may have a maximum displacement of the striker 500 beyond which the motor 400 can no longer effectively drive the striker 500. For example, the brushless linear motor 400 may not be able to return the motor mature (in this case, the striker 500) if the brushless linear motor 400 moves further beyond its full cogging distance. Beyond this point, the motor 400 may become stuck due to cogging. Therefore, by providing the centering system 300 configured to bias the anvil system 200 toward a rest position, the motor 400 can drive the striker 500 beyond its maximum operating range while still returning the striker 500 to a centered position within the motor 400 for continued operation. This allows the motor 400 to drive the striker 500 at higher speeds without risking the motor 400 becoming stuck.

[0068] Figure 3 shows an enlarged cross-sectional view of the front end of the drive mechanism. Figure 4 shows an enlarged cross-sectional view of the rear end of the drive mechanism. Centering system 300 will be described with reference to both Figures 3 and 4.

[0069] The front anvil 210 is located in front of the striker 500. The rear anvil 220 is located in the rear of the striker 500. The anvil system 200 is configured to move back and forth along a longitudinal axis. The front anvil 210 is provided with a bearing 215 (e.g., a linear bearing). A similar bearing 225 (e.g., a linear bearing) is provided on the rear anvil 220. The bearings 215, 225 of the anvil system 200 are configured to assist in the longitudinal movement of the striker-anvil system 200. The bearings 215, 225 can act on the inner wall 150 (e.g., one or more outer surfaces of the inner wall 150). The one or more outer surfaces of the inner wall 150 can be cylindrical.

[0070] The centering system 300 includes a pair of weak springs 310, 340 and a pair of stiff springs 320, 350. The stiff springs 320, 350 have a higher stiffness than the weak springs 310, 340. The terms "weak" and "stiff" herein are relative terms and refer to the fact that the stiff springs 320, 350 have a higher stiffness than the weak springs 310, 340. The relative terms "weak" and "stiff" do not imply any specific amount of stiffness other than this relative stiffness. In this embodiment, the weak springs 310, 340 are coil springs and the stiff springs 320, 350 are leaf springs, although other types of springs (or other types of elastic members other than springs) may be used.

[0071] The higher the "stiffness" of an elastic member (e.g., a spring), the stronger the biasing force per distance traveled (e.g., per compression or extension distance). For a linear spring, this may be indicated by a high spring constant k throughout the linear region of the spring's stress-strain curve. However, the springs discussed here need not be linear; nonlinear springs are equally contemplated. When comparing the stiffness of two springs, the same range of motion (e.g., compression or extension) can be utilized. Spring stiffness can be compared using similar environmental parameters (e.g., the same temperature, e.g., 20°C).

[0072] In this embodiment, the weak springs 310, 340 are located at the front of the impactor 100 and bias the anvil system 200 toward its rest position through interaction with the front anvil 210. The first weak spring 310 provides a rearward biasing force in response to the first anvil 210 moving forward beyond its rest position. The second weak spring 340 provides a forward biasing force in response to the first anvil 210 moving rearward beyond its rest position. The first and second weak springs 310, 340 are located at the front of the impactor 100 and act on the front anvil 210, although this is not required. The locations of the weak springs 310, 340 can be varied and can act on different portions of the anvil system 200 (e.g., positioned toward the rear of the impactor 100 and acting on the rear anvil 220).

[0073] The first weak spring 310 (e.g., a set of one or more first elastic members) biases the first anvil 210 in response to the first anvil 210 being displaced forward beyond a first weak spring engagement position (e.g., a first engagement position). In this embodiment, the first weak spring engagement position is the same as the rest position of the first anvil 210. However, the first weak spring engagement position may be located between the rest position of the first anvil 210 and the first end point. In this embodiment, the first weak spring 310 biases the first anvil 210 over a range of motion from the rest position of the first anvil 210 to the first end point. The first end point defines a forward limit that the anvil system 200 cannot pass through.

[0074] The second weak spring 340 (e.g., one or more sets of fourth elastic members) biases the second anvil 220 in response to the second anvil 220 being displaced rearward beyond the second weak spring engagement position (e.g., the fourth engagement position).

[0075] In this embodiment, the second weak spring engagement position is the same as the rest position of the second anvil 220. However, the second weak spring engagement position may be located between the rest position of the second anvil 220 and the second end point. In this embodiment, the second weak spring 340 biases the second anvil 220 through a range of motion from the rest position of the second anvil 220 to the second end point. The second end point defines a rearward limit that the anvil system 200 cannot pass through.

[0076] In this embodiment, a first set of rigid springs 320 (e.g., a set of one or more second elastic members) is provided at the rear of the impactor 100, and a second set of rigid springs 350 (e.g., a set of one or more fifth elastic members) is provided at the front of the impactor 100.

[0077] The first set of rigid springs 320, through interaction with the rear anvil 220, bias the anvil system 200 toward a rest position (e.g., bias the front anvil 210 toward its rest position). In this embodiment, the first set of rigid springs 320 is provided on the rear anvil 220. The first set of rigid springs 320 bias the rear anvil 220 against a rearward-facing abutment 152 connected to the housing 120. The first set of rigid springs 320 provide a rearward biasing force. The rearward-facing abutment 152 may be the rear surface of the inner wall 150.

[0078] The second set of rigid springs 350, through interaction with the front anvil 210, bias the anvil system 200 toward a rest position (e.g., bias the rear anvil 220 toward its rest position). In this embodiment, the second set of rigid springs 350 is provided on the front anvil 210. The second set of rigid springs 320 bias the front anvil 210 against a forward abutment 154 connected to the housing 120. The second set of rigid springs 350 provide a forward biasing force. The forward abutment 154 may be a front surface of the inner wall 150.

[0079] By providing a rearward biasing force acting on the rear anvil 220 and a forward biasing force acting on the front anvil 210, the stiff springs 320, 350 act to apply tension to stretch the anvil system 200 when stopping the movement of the anvil system 200, thereby preventing the connector 230 from buckling.

[0080] When the anvil system 200 is in a rest position (when the first anvil 210 and the second anvil 220 are each in their rest positions), a gap is provided between the stiff springs 320, 350 and the respective abutments 152, 154. Thus, the anvil system 200 has a central range of motion where the stiff springs 320, 350 do not engage the anvil system 200.

[0081] When the anvil system 200 moves forward beyond a first stiff spring engagement position (e.g., the second engagement position), the first set of stiff springs 320 engage with the anvil system 200. The distance between the first stiff spring engagement position and the rest position is equal to the gap between the first set of stiff springs 320 and the rearward abutment 152 when the anvil system 200 is in the rest position.

[0082] When the anvil system 200 moves rearward beyond a second stiff spring engagement position (e.g., the fifth engagement position), the second set of stiff springs 350 engages with the anvil system 200. The distance between the second stiff spring engagement position and the rest position is equal to the gap between the second set of stiff springs 350 and the forward abutment 154 when the anvil system 200 is in the rest position.

[0083] There is a central range of motion where the stiff springs 320, 350 are not engaged, and so in this range of motion the stiff springs 320, 350 do not reduce the force applied by the anvil system 200. Thus, the stiff springs 320, 350 do not limit the initial impact force provided by the impactor 100. However, once the anvil system 200 moves beyond this initial range of motion, the stiff springs 320, 350 engage and help stop the anvil system 200, helping to return the anvil system 200 to its rest position.

[0084] The weak springs 310, 340 bias the anvil system 200 through a range of motion that extends over at least a portion of the range between a first stiff spring engagement position and a second stiff spring engagement position. For example, the first weak spring 310 biases the anvil system 200 through a range of motion that includes at least a portion of the range between the first stiff spring engagement position and a rest position. Similarly, the second weak spring 340 biases the anvil system 200 through a range of motion that includes at least a portion of the range between the second stiff spring engagement position and a rest position.

[0085] In this embodiment, provided that each of the weak springs 310, 340 engages the anvil system 200 before the stiff springs 320, 350 (e.g., at a lower displacement than the stiff springs 320, 350), each of the weak springs 310, 340 biases the anvil system 200 through a range of motion that ends at the rest position of the anvil system 200, although this is not required. This means that the weak springs 310, 340 can help to center the anvil system 200 (and, upon expansion, the striker 500) after the stiff springs 320, 350 are disengaged. Similarly, while the weak springs 310, 340 bias the anvil system 200 through a range of motion that ends at first and second endpoints, this is also not required, as long as the weak springs 310, 340 provide a biasing force over at least a portion of the central range (between the first and second stiff spring engagement positions).

[0086] In addition to the weak and stiff springs, dampers 330, 360 are also provided to provide end stops. The dampers 330, 360 are configured to prevent the anvil system 200 from moving beyond the first or second end points. The dampers 330, 360 may be made of a shock-absorbing material such as rubber or silicone. The dampers 330, 360 may be configured to cushion shocks and damp vibrations between the anvil system 200 and the housing 120.

[0087] The dampers 330, 360 may be replaced by another set of springs (or other type of elastic member) that has a higher stiffness (or at least provides a stronger biasing force) than the stiff springs 320, 350.

[0088] The first damper 330 (e.g., one or more sets of third resilient members) is positioned to provide a rearward biasing force in response to forward displacement of the anvil system 200 beyond a first damper engagement position (e.g., a third engagement position). The first damper engagement position is located between the first stiff spring engagement position and the first end point. That is, the first damper 330 engages with the anvil system 200 at a greater displacement than the first set of stiff springs 320. The first damper 330 provides a biasing force throughout a range of motion between the first damper engagement position and the first end point.

[0089] The second damper 360 (e.g., a sixth set of one or more resilient members) is positioned to provide a forward biasing force in response to rearward displacement of the anvil system 200 beyond a second damper engagement position (e.g., a sixth engagement position). The second damper engagement position is located between the second stiff spring engagement position and the second end point. That is, the second damper 360 engages with the anvil system 200 at a greater displacement than the second set of stiff springs 350. The second damper 360 provides a biasing force throughout a range of motion between the second damper engagement position and the second end point.

[0090] The first damper 330 and the second damper 360 may each be considered an elastic member. Each damper 330, 360 is configured not to move beyond its respective engaged position. In one embodiment, one or both dampers 330, 360 are made of a compressible material such as rubber or silicone. One or both dampers 330, 360 may have a stiffness greater than that of the stiff springs 320, 350, although this is not required. In an alternative embodiment, one or both dampers 330, 360 are configured to resist movement with a biasing force proportional to the velocity of the respective anvils 210, 220 (e.g., one or both dampers 330, 360 may include a dashpot). One or both dampers 330, 360 may utilize viscous friction to resist movement.

[0091] In this embodiment, both dampers 330, 360 act on the rear anvil 220. However, this is not required, and one or both dampers 330, 360 may act on the front anvil 210 or on other parts of the anvil system 200.

[0092] In this embodiment, the dampers 330, 360 are ring-shaped, however this is not required and alternative shapes, numbers and arrangements of dampers may be used.

[0093] 5 shows an enlarged cross-sectional view of the center portion of the drive mechanism. The motor 400 surrounds a cavity in which the striker 500 is positioned. The striker 500 includes a cylindrical body 510 having a central cavity through which the connector 230 extends. The striker 500 is configured to slide back and forth along a longitudinal axis defined by the connector 230.

[0094] The striker 500 includes a magnet 520 configured to be driven by the motor 400. In this embodiment, the magnet 520 is annular (ring-shaped) and radially magnetized. In this embodiment, two ring-shaped magnets 520 are provided. However, a different number of magnets 520 (e.g., four magnets) may be used. Furthermore, magnets 520 of different shapes may be used.

[0095] The motor 400 includes a plurality of electromagnets 410. In this case, the motor 400 is a linear motor configured to drive the striker 500 back and forth along the longitudinal axis. The motor 400 can provide a driving force by adjusting the current flowing through each electromagnet 410 to generate a moving magnetic field. The force provided by the motor 400 can be controlled by adjusting the magnitude and rate of change of the current. In this embodiment, two electromagnets 410 are provided, but a different number of electromagnets 410 (e.g., four electromagnets) may also be used. The motor 400 may include the same number of electromagnets 410 as the number of magnets 520 in the striker 500.

[0096] A processing circuit (not shown) is configured to control the motor 400. The processing circuit is configured to control the motor 400 to drive the striker 500 in response to input from a user via the trigger 140.

[0097] The motor 400 can be controlled to drive the striker 500 to deliver a single impact or a series of impacts. When the user engages the trigger 140, the striker 500 is driven to deliver a single impact to the anvil system 200. If the user continues to engage (press) the trigger 140, the processing circuitry then controls the motor 400 to reciprocate the striker 500 to deliver a series of impacts. When the user releases the trigger 140, the motor 400 then disengages and the striker 500 is returned to a rest position by the centering system 300.

[0098] The processing circuitry is configured to control the motor 400 according to one of three selectable operating modes: forward mode, reverse mode, and reciprocating mode. The processing circuitry is configured to switch between these operating modes based on input from a user via the mode switch 144.

[0099] In forward mode, the impactor 100 is configured to apply a primary force in a forward direction. In reverse mode, the impactor 100 is configured to apply a primary force in a rearward direction. In reciprocating mode, the impactor 100 is configured to apply alternating primary forces in a forward and rearward direction. The strength of the primary force applied by the impactor 100 can be set by user input via the power control dial 142.

[0100] When the motor 400 is actuated (e.g., in response to input via the trigger 140), it can activate the striker 500 by moving the striker 500 to a start position. In the forward mode, the start position can be rearward of the rest position of the striker 500. In the reverse mode, the start position can be forward of the rest position of the striker 500. In the reciprocating mode, the start position can vary depending on whether the initial primary impact is a forward impact or a rearward impact. In certain embodiments, the initial primary impact in the reciprocating mode is a forward impact. Positioning the striker 500 in the start position increases the distance the striker 500 can accelerate toward the anvil system 200.

[0101] The actuation may cause the striker 500 to contact the anvil system 200. Furthermore, the actuation may cause the striker 500 to move the anvil system 200. For example, when actuating prior to forward drive (e.g., forward mode), the striker 500 may contact the rear anvil 220. When actuating prior to reverse drive (e.g., reverse mode), the striker 500 may contact the front anvil 210. The actuation may impart a force (e.g., a secondary force) to the anvil system (opposite the primary force), but the secondary force is less than the primary force imparted when actuating the striker 500. Thus, in forward mode, the secondary force is imparted rearward and the primary force is imparted forward before driving the striker 500 forward. Similarly, in reverse mode, the secondary force is imparted forward and the primary force is imparted rearward before driving the striker 500 rearward.

[0102] When initiated prior to forward drive, the starting position can move the front anvil 210 and cause the second set of stiff springs 350 to begin contacting the forward-facing abutments 154 (e.g., moving the front anvil 210 to the second stiff spring engagement position). When initiated prior to reverse drive, the starting position can move the rear anvil 230 and cause the first set of stiff springs 320 to begin contacting the rear-facing abutments 152 (e.g., moving the rear anvil 220 to the first stiff spring engagement position).

[0103] After activation, the striker 500 is driven and impacts the anvil system 200 to apply a primary force (e.g., via a tool secured to the tool holder 110). In forward mode, the striker 500 is driven forward and impacts the front anvil 210 to apply a primary force in the forward direction. In reverse mode, the striker 500 is driven forward and impacts the rear anvil 220 to apply a primary force in the rearward direction. After activation, the centering system 300 urges the striker 500 (via the anvil system 200) toward a center position (e.g., the rest position of the striker 500) and assists the striker 500 in returning to the center position. This allows the striker 500 to be driven outside the normal operating range of the motor 400 and still be able to return to its original position.

[0104] The normal operating range of the motor 400 may be the range of positions of the striker 500 over which the motor 400 can maintain control of the striker 500. Outside this normal operating range, the motor 400 may not be able to control the striker 500 (e.g., back off the striker 500) without external assistance (e.g., from the centering system 300). Similarly, outside the normal operating range, the motor 400 and striker 500 may jam (e.g., due to cogging) without external assistance (e.g., from the centering system 300).

[0105] Once the striker 500 returns to its normal operating range, the motor 400 can engage the striker 500 to return it to its rest position, although in an alternative embodiment this can be achieved using only the centering system 300.

[0106] If the striker 500 is driven again during the forward or reverse mode (e.g., if the user continues to engage the trigger 140), then the motor 400 may return the striker 500 to the starting position before driving the striker 400 to impact the anvil system 200 again.

[0107] In reciprocating mode, the striker 500 may be moved to a starting position before the initial impact, similar to forward or reverse mode (depending on the direction of the initial impact), but the drive process from this point onward may be different. Instead of using the motor 400 to move the striker 500 to the starting position, the striker 500 may be driven in the opposite direction to generate an impact with a primary force in the opposite direction. As the drive direction switches, the centering system 300 can position the striker 500 and anvil system 200 in a starting position for the next drive. For example, after a forward impact, the striker 500 can be driven to impact the rear anvil 220, delivering a rearward impact. Similarly, after a rearward impact, the striker 500 can be driven to impact the front anvil 210, delivering a forward impact. In this manner, the anvil system 300 can reciprocate to deliver alternating forward and rearward impact forces. Because the range of motion of the striker 500 is greater than the distance between the front anvil 210 and the rear anvil 220, the striker 500 can reciprocate, alternately striking the front anvil 210 and the rear anvil 220. This process can continue until the user releases the trigger 140. In a particular embodiment, the motor 400 is configured to drive the striker with a displacement range of ±9 mm, and the first and second anvils are spaced 16 mm apart from each other, although other arrangements are possible.

[0108] The reciprocating mode is useful for broaching. During the broaching process, a broaching tool (broach) is driven into a channel and then withdrawn from the channel. As the tool is withdrawn from the channel, debris that had accumulated within the channel is also withdrawn from the channel. This frees up space within the channel and allows the broach to be inserted further into the channel. Removing debris from the channel reduces the radial force on the channel walls, thereby reducing the chance of fracture of the material being broached. Broaching can be used to enlarge the size of a channel or cavity within bone. For example, in femoral broaching (e.g., for total hip replacements), a channel is formed within the medullary canal to receive the femoral stem portion of a hip implant. Reciprocating the broaching tool removes debris from the channel, thereby reducing the risk of radial fracture of the femur during the broaching process.

[0109] The forward mode can be used to hammer an object. For example, the hammer attachment can be used to drive an implant into a channel or fitting. The reverse mode can be used to extract an object. For example, the extraction attachment can connect, secure, engage, or grasp an object, and the reverse mode can be used to extract an object (e.g., extract one object from another). For example, the reverse mode can be used to extract (or remove) an implant from a channel or fitting in which the implant is seated.

[0110] The above description refers to a "rest position" of the anvil system 200. It will be understood that the first anvil 210 and the second anvil 220 are spaced apart from one another and therefore may have different rest positions.

[0111] The use of the term "rest position" generally refers to the position of a particular component (e.g., the anvil system 200) when it is not subjected to an external force. It should be noted that the position of the anvil system 200 may move in response to an external force applied to the anvil system 200. For example, when the impactor 100 is pressed against an object, a rearward force may be applied to the anvil system 200, which may cause the anvil system 200 to move rearward within the housing 120. Similarly, when the impactor 100 is pulled away from the object (e.g., by use of an extraction tool), a forward force may be applied to the anvil system 200, which may cause the anvil system 200 to move forward within the housing 120. By shifting the position of the anvil system 200 through the application of an external force (e.g., pushing / pulling the impactor 100), the force applied by the impactor 100 can be varied by adjusting the relative positions of the anvil system 200, the striker 500, and the centering system 300.

[0112] The embodiments described herein provide an impactor 100 that includes a centering system 300. The centering system 300 allows the striker 500, which is electromagnetically driven by the motor 400, to be driven over a wider range of motion without jamming. The centering system 300 is provided to act on the anvil system 200, which in turn drives the striker 500. Because the centering system 300 acts on the anvil system 200 rather than directly on the striker 500, the centering system 300 can return the striker 500 to a center position without adversely affecting the initial impact force transmitted between the striker 500 and the anvil system 200. The centering system 300 includes an elastic member (e.g., a spring and a damper) that increases stiffness and engages as displacement increases, effectively centering the striker 500 and arresting its movement, reducing the impact of the impactor 100 on the initial impact force.

[0113] Certain embodiments include a front anvil 210 and a rear anvil 220, allowing forward and rearward forces to be applied by the impactor 100. The range of motion of the striker 500 can be greater than the distance between the front anvil 210 and the rear anvil 220, thereby providing a reciprocating motion by alternately striking the front anvil 210 and the rear anvil 220.

[0114] While the "forward direction" and "rear direction" are discussed herein, it will be understood that these directions are relative to each other and relative to the placement of the impactor 100, and do not imply a particular orientation of the impactor 100 during use. More generally, the forward direction can be considered a first direction along the longitudinal axis of the impactor 100. The second direction can be considered a second direction along the longitudinal axis of the impactor 100, the second direction being opposite the first direction. Similarly, the front anvil 210 can be considered a first anvil that applies a force in a first direction, and the rear anvil 220 can be considered a second anvil that applies a force in a second direction.

[0115] The embodiments described herein may include processing circuitry for controlling the operation of the impactor 100, which may be implemented in digital electronic circuitry, computer software, firmware, and / or hardware. Examples of hardware elements may include processors, microprocessors, circuits, circuit elements (e.g., transistors, resistors, capacitors, inductors, etc.), integrated circuits, application specific integrated circuits (ASICs), programmable logic devices (PLDs), digital signal processors (DSPs), field programmable gate arrays (FPGAs), logic gates, registers, semiconductor devices, chips, microchips, chipsets, etc.

[0116] Although specific configurations have been described, these configurations are presented for illustrative purposes only and are not intended to limit the scope of protection. The inventive concepts described herein can be realized in various other forms. Furthermore, various omissions, substitutions and modifications can be made to the specific embodiments described herein without departing from the scope of protection defined in the following claims.

Claims

1. A surgical electromagnetic impactor, comprising: a housing defining an interior cavity extending along a longitudinal axis; a striker disposed within the internal cavity and configured to move along the longitudinal axis; an anvil system including a first anvil configured to move in a first direction along the longitudinal axis from a first rest position toward a first end point; an electromagnetic drive system configured to drive the striker to move in the first direction and impact the first anvil, such that a first force directed in the first direction is applied to an external object via the first anvil; a centering system configured to bias the first anvil toward the first rest position; The centering system comprises: one or more first resilient members configured to bias the first anvil toward the first rest position in response to displacement of the first anvil toward the first end point beyond a first engagement position; one or more second resilient members configured to bias the first anvil toward the first rest position in response to displacement of the first anvil toward the first end point beyond the second engagement position; the second engagement position is located between the first engagement position and the first end point, and each of the first elastic members has a lower stiffness than each of the second elastic members. Electromagnetic surgical impactor.

2. 2. The surgical electromagnetic impactor of claim 1, wherein the first and second elastic members are springs, and each second elastic member has a higher spring constant than each first elastic member.

3. 3. The surgical electromagnetic impactor of claim 2, wherein the one or more first elastic members include one or more coil springs, and / or the one or more second elastic members include one or more leaf springs.

4. 4. The surgical electromagnetic impactor of claim 1, wherein the centering system further includes one or more third resilient members configured to bias the first anvil toward the first rest position in response to displacement of the first anvil toward the first end point beyond a third engagement position, the third engagement position being located between the second engagement position and the first end point.

5. The surgical electromagnetic impactor of claim 4 , wherein the one or more third resilient members include one or more dampers, each damper including a shock absorbing material.

6. The surgical electromagnetic impactor of claim 4 or claim 5, wherein the centering system is configured to prevent the striker from moving beyond the first endpoint.

7. the anvil system includes a second anvil connected to the first anvil, the second anvil configured to move in a second direction opposite the first direction from a second rest position to a second end point, the first and second anvils positioned on opposite sides of the striker; the electromagnetic drive system is further configured to drive the striker to move in the second direction and impact the second anvil, thereby applying a second force directed in the second direction to the external object via the second anvil; The centering system comprises: one or more fourth resilient members configured to bias the second anvil toward the second rest position in response to displacement of the second anvil toward the second end point beyond a fourth engagement position; and one or more fifth resilient members configured to bias the second anvil toward the second rest position in response to displacement of the second anvil toward the second end point beyond a fifth engagement position; 7. The surgical electromagnetic impactor according to claim 1, wherein the fifth engagement position is located between the fourth engagement position and the second end point, and wherein each of the fourth elastic members has a lower rigidity than each of the fifth elastic members.

8. 8. The surgical electromagnetic impactor of claim 7, wherein the fourth and fifth elastic members are springs, each fifth elastic member having a higher spring constant than each fourth elastic member.

9. 9. The surgical electromagnetic impactor of claim 8, wherein the one or more fourth elastic members include one or more coil springs, and / or the one or more fifth elastic members include one or more leaf springs.

10. 10. The surgical electromagnetic impactor of claim 7, wherein the centering system further includes one or more sixth resilient members configured to bias the second anvil toward the second rest position in response to displacement of the second anvil toward the second end point beyond a sixth engagement position, the sixth engagement position being located between the fifth engagement position and the second end point.

11. The surgical electromagnetic impactor of claim 10 , wherein the one or more sixth resilient members include one or more dampers, each damper including a shock absorbing material.

12. 12. The surgical electromagnetic impactor of claim 7, wherein the centering system is configured to prevent the striker from moving beyond the second endpoint.

13. 13. The surgical electromagnetic impactor of claim 7, wherein a spacing between the first anvil and the second anvil in the first direction is less than a maximum range of motion over which the electromagnetic drive system is configured to drive the striker.

14. further comprising a circuit configured to control the electromagnetic drive system to drive the striker according to an operating mode; The operating mode is a first operating mode that controls the electromagnetic drive system to drive the striker in the first direction to impact the first anvil and apply a primary force in the first direction; a second operating mode for controlling the electromagnetic drive system to drive the striker in the second direction to impact the second anvil and apply a primary force in the second direction; 14. The surgical electromagnetic impactor of claim 7, wherein the electromagnetic drive system is controllable to select between a reciprocating mode of operation in which the striker is alternately driven in the first direction and the second direction to impact the first anvil to apply a primary force in the first direction and the second anvil to apply a primary force in the second direction.

15. 15. The surgical electromagnetic impactor of claim 7, wherein the first anvil is connected to the second anvil via a rod that passes through a channel in the striker.

16. at least one of the one or more first resilient members and the one or more second resilient members are configured to apply a first biasing force to the second anvil in the second direction to tension the anvil system when biasing the first anvil toward the first rest position; and / or 16. The surgical electromagnetic impactor of claim 7, wherein at least one of the one or more fourth elastic members and the one or more fifth elastic members are configured to apply a second biasing force to the first anvil in the first direction to apply tension to the anvil system when biasing the second anvil toward the second resting position.

17. 17. The surgical electromagnetic impactor of claim 1, wherein the centering system is configured to impart a biasing force to the striker via the anvil system to bias the striker toward a center position after each impact between the striker and the anvil system.

18. 18. The surgical electromagnetic impactor of claim 1, further comprising a tool or tool holder connected to a second anvil for applying a force from the second anvil to the external object.

19. 19. The surgical electromagnetic impactor of claim 1, wherein the centering system is configured to allow the anvil system to float within the housing, thereby allowing a user to adjust the position of the anvil system relative to the striker by pushing or pulling the surgical electromagnetic impactor to vary the impact force between the striker and the anvil system.

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