Rotary impactor for cosmetic surgery

Abstract

The rotary impactor for orthopedic surgery includes an output anvil and a hammer capable of applying linear and rotational forces to the output anvil. The anvil may be movable on a lead screw element, thereby alternately generating energy in the energy storage means and moving along the lead screw element to impact the anvil. A viscoelastic or damping mechanism is used to reduce the reflected force and / or reflected torque of the rotary impactor during surgery. The high frequency linear impacts by the impactor avoid the need for the surgeon to supply an external pushing force to the impactor in order to successfully perform the surgical procedure.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application is a non - provisional application and claims the benefit of priority under 35 U.S.C. § 119 to U.S. Patent Application No. 63 / 141,786, filed January 26, 2021, U.S. Patent Application No. 63 / 188,542, filed May 14, 2021, and U.S. Patent Application No. 63 / 277,754, filed November 21, 2021, the disclosures of which are incorporated herein by reference.

[0002] The present disclosure relates to a rotary impact reamer for use by a surgeon and / or a surgical robot, and more particularly, to a rotary impact reamer with reduced reaction force transmitted to the surgeon and / or the robot.

Background Art

[0003] Current trends in surgery are towards the use of robotic assistance in the surgical process. In this regard, the end - effector of a robot can be used, for example, by a robot to perform a surgical procedure. The end - effector is, in one embodiment, a device, tool, or manipulator at the tip of the robot that can engage and interact with the surgical site. The end - effector is guided by the robot to perform a surgical procedure. In the field of robotic surgery, the end - effector may comprise a surgical tool.

[0004] To date, robotic automation in surgery has been sufficiently effective in laparoscopic procedures with low energy requirements, but in orthopedic environments where large forces and energy are routine, the adoption of robots has been slow. In such environments and in the field of orthopedic surgery, surgical robots cannot handle the large reaction forces generated by common large - bone surgical tools (such as saws, drills, or reamers), so that due to the higher energy requirements, another approach (such as machining) is required.

[0005] An example of a robot used in large bone surgery is Stryker's MAKO product. MAKO serves three purposes: enhanced planning, dynamic fusion balancing, and robotic arm-assisted bone preparation.

[0006] As part of its operation, a robot needs to identify the bone geometry of the surgical site in order to accurately move, guide, and manipulate its end effector through the surgical site. Such identification of bone geometry is referred to as registration. Existing surgical power instruments, when used in orthopedic surgery, generate a considerable amount of recoil torque (such as in the case of surgical reamers) or impact (such as in the case of surgical impact tools). This torque and / or impact can not only impair the robot's registration but also damage the robot's highly complex mechanisms and components.

[0007] Rotary reamers are used in hip surgery and hip replacement surgery, such as when preparing the cavity for the acetabular cup in a prosthetic hip. These rotary tools have considerable recoil torque associated with the surgical procedure. This can cause the tool to be pulled from the surgeon's grip while performing the surgery, and in severe cases, can cause injury to the surgeon's wrist or forearm. Obviously, such recoil torque can cause navigation or guidance errors, and in the case of robotic use, registration is often lost and the robot stops. This has been shown to be a fact by testing and is one of the most common complaints regarding the use of robots in orthopedic surgery of large bones.

[0008] Navigation capabilities are almost certainly the most important feature of orthopedic robotics. For surgical success, the robot must hold the tool (or instrument) in precise orientation and position relative to the bone. If the surgical instrument deviates from the stereotactic boundary, the surgery can suffer several drawbacks, including injury to soft tissue if the instrument remains powered. Rotary tools currently available can generate significant destabilizing forces (reaction torque resulting from a reamer encountering and / or catching on hard parts of the bone). These forces can interfere with the robot's programmed navigation and potentially cause the robot to stop.

[0009] Furthermore, simply placing surgical power instruments designed for surgeons onto a robot presents at least two problems. Firstly, the reaction force / torque transmitted from the tool can cause the robot to deviate from its guide path. Secondly, in large bone surgery, the robot is often unable to supply sufficient linear force to allow the reamer to advance into the acetabulum. Surgeons typically need to apply linear force to the tool to achieve the desired result.

[0010] Therefore, in addition to making surgeries easier for surgeons, there is a need for impact tools (also referred to herein as impactors) that create pathways to robots and ultimately enable fully autonomous surgery. Thus, this disclosure provides a rotary surgical tool and / or rotary / linear surgical tool that, by using impact, achieves similar results to existing rotary surgical reamers while significantly reducing reflected torque. Furthermore, when linear impact is used to supplement rotary impact, both the linear and rotational force requirements are significantly reduced compared to conventional surgical reamers and drills. For example, with current technology, the surgeon must apply all the linear force necessary to advance the surgical reamer into the surgical site. This linear force can exceed 25 pounds, which is far greater than the force that a surgical robot can provide. Linear impact with the disclosed tool has been shown to reduce the required linear support force from the surgeon by approximately 50%. [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] In light of the aforementioned shortcomings inherent in the prior art, the object of this disclosure is to provide solutions to the large recoil forces resulting from the use of orthopedic surgical tools. These solutions function to reduce the recoil forces acting on surgical robots and / or surgeons so that surgical instruments (e.g., their positioning) can be better controlled during surgery. In addition to reducing recoil forces, this disclosure also aims to mechanically supply all or a substantial portion of the force necessary to complete the surgery so that the surgeon and / or robot can guide the tool with minimal force. [Means for solving the problem]

[0012] In one embodiment, the disclosure provides a rotary impact tool for orthopedic surgery configured to minimize reaction force during orthopedic surgery on large bones. The tool preferably includes a mechanism (such as an absorption means) that reduces the peak reaction force acting from the tip of the tool to the gripping surface of the tool. Such a gripping surface may include, but is not limited to, a handgrip in the case of a tool designed for manual operation by a surgeon, or a cylindrical body or other mounting means in the case of a tool operated in conjunction with a surgical robot. It should be understood that “surgical tool” and “impactor” refer to the present invention disclosed herein, and “surgical instrument” refer to an accessory to the output of a surgical tool. For example, a surgical tool may refer to a rotary impact handpiece, and a surgical instrument may refer to a quasi-hemispherical reamer that attaches to the output of a surgical tool.

[0013] In one embodiment, the reaction force is further reduced by using a damping mechanism that can disperse the reaction force over a longer period of time, thereby reducing the reaction force at the gripping surface or the reaction force felt at the gripping surface. In the embodiment, the damping mechanism includes a viscoelastic or non-Newtonian fluid between the motor mount and the tool housing so that the reaction torque is isolated from the tool housing and therefore isolated from the surgeon / robot. This damping mechanism may also be used to isolate the motor drive from the hammering mechanism, so it is clear that the position of this damping mechanism is preferably between the gripping surface and the tool housing and / or between the motor mount and the tool housing, but can vary. In another embodiment, the tool may also include a counter-movement element to absorb the reaction force and disperse it over a longer period of time.

[0014] In one embodiment, a torque sensing means provided by the tool may activate a rotational impact mechanism that transmits rotational impact force to a surgical instrument when it reaches or exceeds a threshold torque value. The threshold torque value is preferably lower than the torque that could injure the operating robot or the surgeon's wrist. This transition has been shown to occur around 30–50 inch-pounds. The tool may then activate a rotational impact force on an impact hammer, which is transmitted to and / or translated to the surgical instrument.

[0015] In yet another embodiment, the disclosure provides rotary and linear impact tools for orthopedic surgery configured to minimize reaction force during orthopedic surgery on large bones. The tool may include a mechanism (such as an absorption means) that reduces the peak reaction force acting from the tool tip to the gripping surface of the tool. Such a gripping surface may include, but is not limited to, a handgrip in the case of a tool designed for manual operation by a surgeon, or a cylindrical body or other mounting means in the case of a tool operated in conjunction with a surgical robot. It should be understood that “surgical tool” refers to the present invention as disclosed herein, and “surgical instrument” refers to an accessory to the output of a surgical tool. For example, a surgical tool may refer to a rotary / linear impact handpiece, and a surgical instrument may refer to a quasi-hemispherical reamer that attaches to the output of a surgical tool.

[0016] In one embodiment, the impactor or impact tool comprises a hammer, an output anvil, and an energy storage means (in one embodiment, this means may include a spring). The hammer and anvil are operably coupled and can be rotated by a lead screw element (one example being Torqspline®). The term "Torqspline®" is used in this disclosure as an exemplary embodiment of the lead screw element, and it is understood that the term "Torqspline®" should not be considered limiting. When the output anvil is rotated and sufficiently loaded, the output anvil and hammer can temporarily halt rotation by the Torqspline element, and the hammer can move along the Torqspline in translation, away from the target object to be impacted, and energize the energy storage means, and finally, when the hammer and output anvil are aligned so that the energized energy storage means can act on the hammer, the hammer can move back along the Torqspline (rotating) in translation, impacting the output anvil with minimal reaction torque.

[0017] The minimum reaction torque is a result of two things: firstly, the hammer is substantially separated from the output anvil. This limits the reaction torque to a certain threshold that relies solely on the energy storage means (e.g., springs) and the pitch of the torque splines. Secondly, by applying a sharp impact from the hammer to the output anvil, the impact reamer can overcome high-load areas (such as scleral bone / osteophytes in the acetabulum) with minimal reaction torque to the surgeon. The large impact force generated as a result of the hammer's impact on the anvil allows the high-load areas to be overcome with minimal reaction torque.

[0018] Those skilled in the art will understand that the parallel and rotational motions of the hammer in the aforementioned mechanism can be distributed in such a way that they simultaneously deliver impacts in both the rotational and linear directions. Adding a linear impact element to the reaming process has been shown to increase the overall speed of the reaming stage and reduce surgeon fatigue (the surgeon does not need to apply the linear pressing force using a conventional reamer, which can exceed 25 pounds). In one embodiment, the linear impact of the hammer is achieved by an impact element disposed on the hammer and / or output anvil, which delivers or receives a linear impact when the hammer comes into contact with the output anvil, as will be described more specifically elsewhere in this specification.

[0019] In one embodiment, a torque sensing means provided by the tool may stop the rotational motion of the output anvil and / or hammer.

[0020] In another embodiment, the surgical impact tool comprises a hammer, an output anvil, and an energy storage means (in one embodiment, this means may comprise a corrugated spring). The hammer and the anvil are operably coupled and can be rotated by a lead screw (such as a torque spline screw) element. The tool further comprises a cam (such as a cylindrical cam) and a cam follower, and an impact rod. As the hammer rotates, the anvil rotates, and the anvil can output torque to the impact rod. The impact rod can rotate the cylindrical cam, compressing the corrugated spring. After the cam follower clears the cylindrical cam, the corrugated spring can extend, pushing the cam and impact rod forward and generating a linear impact on the anvil.

[0021] In another embodiment, a rotary and linear impactor or impact tool comprises a hammer, an output anvil, and an energy storage means (in one embodiment, this means comprises at least one corrugated spring, and in a further embodiment, a linear actuator spring and a rotary spring). The hammer and anvil are operably coupled and can be rotated by a lead screw element (such as a torque spline). When the user presses the output anvil into a bone surface, the anvil also compresses the linear actuator spring, depending on the amount of force the user applies to press the output anvil into the bone surface, thereby supplying either rotary impact only or both rotary and linear impact.

[0022] The benefits and features of this disclosure will be better understood by referring to the modes and claims for carrying out the invention described below, together with the accompanying drawings, where similar elements are identified by similar symbols. [Brief explanation of the drawing]

[0023] [Figure 1] This figure shows a rotary hammer used to impart rotational motion to a surgical instrument, according to an exemplary embodiment of the present disclosure. [Figure 2] This figure shows an exemplary embodiment of the present disclosure of a damping mechanism for reducing impact reflected by a surgeon and / or surgical robot. [Figure 3]A diagram showing a calculation example of reducing this force by expanding the period during which a reaction force is applied, according to an exemplary embodiment of the present disclosure. [Figure 4] A diagram showing a damping mechanism for reducing the impact reflected from both rotational impact and linear impact to a surgeon and / or a surgical robot, according to an exemplary embodiment of the present disclosure. [Figure 5] A cross-sectional view of an orthopedic impact tool according to an exemplary embodiment of the present disclosure. [Figure 6] A diagram showing an exemplary hammer and an exemplary output anvil of an orthopedic impact tool according to an exemplary embodiment of the present disclosure. [Figure 7] A diagram showing a linear and rotary impacter with a cam, according to an exemplary embodiment of the present disclosure. [Figure 8] Another diagram showing a linear and rotary impacter with a cam and an impact bar, according to an exemplary embodiment of the present disclosure. [Figure 9] A diagram showing a linear and rotary impacter with at least one buffer, according to an exemplary embodiment of the present disclosure. [Figure 10] A diagram showing a linear and rotary impacter with at least one buffer that transmits an impact to an output according to a position, according to an exemplary embodiment of the present disclosure. [Figure 11] A diagram showing a linear and rotary impacter with at least one buffer, according to another exemplary embodiment of the present disclosure. [Figure 12] A diagram showing a linear and rotary impacter with at least one buffer, according to another exemplary embodiment of the present disclosure. [Figure 13] A diagram showing a comparison between the force applied to the rear part of a general surgical reamer and the linear force provided by an exemplary embodiment of a linear and rotary impacter.

Modes for Carrying Out the Invention

[0024] The exemplary embodiments described herein, detailed for illustrative purposes, are subject to numerous structural and design modifications. However, it should be emphasized that this disclosure is not limited to any specific surgical tool, robot, robot end-effector, or any intermediary shown and described. That is, while various omissions and substitutions of equivalents are intended where circumstances may be suggested or expressed as convenient, these are intended to cover applications or implementations without departing from the spirit or scope of the claims of this disclosure. In this specification, terms such as “first,” “second,” etc., are used to distinguish one element from another and not to indicate any order, quantity, or importance, and the terms “one (a)” and “one (an)” are used in this specification to indicate that there is at least one cited item and not to indicate a limit on quantity.

[0025] This disclosure provides a rotational linear impact tool for orthopedic surgery, more specifically, a tool designed to minimize reaction forces during orthopedic surgery on large bones. The tool as used herein may also be referred to as a rotational impactor or a rotational and linear combined impactor. A rotational impact tool in this context may be understood as a tool that brings a constant rotational motion to a surgical instrument and can further supply rotational impact under certain conditions (i.e., when the reaction torque reaches and / or exceeds a threshold). The tool may further include a mechanism for generating a rotational and linear combined impact.

[0026] The tools disclosed herein include a mechanism (such as an absorption means) that reduces the peak reaction force acting from the tool tip to the gripping surface of the tool. Such a gripping surface may include, but is not limited to, a handgrip in the case of a tool designed for manual operation by a surgeon, or a cylindrical body or other mounting means in the case of a tool that is operated in conjunction with a surgical robot. As used herein, “reaction force” may include linear or rotational impact and / or force or torque reflected off the mounting or gripping surface of the robot and / or surgeon.

[0027] In one embodiment, as shown in Figure 1, rotational force on the surgical instrument 50 is transmitted via an impact mechanism 20, such as a rotary hammer. In one embodiment, the tool 100 includes a motor drive 10 operably coupled to an impact bar (such as a rotary hammer 20). The motor 10 provides rotational motion to the rotary hammer. The rotary hammer 20 is operably coupled to a cumming surface 30 via steel roller balls. The rotary hammer selectively engages with an output anvil, which may be coupled to an interface of the tool. The interface can receive and rotate the surgical instrument. The tool may also include at least one bearing 42 for holding the output anvil 40 in the working position while it is being actuated by the rotary hammer. The rotary hammer 20 rotates the output anvil until a threshold torque is reached on the output anvil. After the threshold torque is reached, the roller balls pull the rotary hammer back against a spring 22 until there is no contact between the rotary hammer and the output anvil. At this point, the rotating hammer is accelerated to a faster speed, the spring 22 pushes the rotating hammer forward, and the hammer is able to re-engage with the output anvil and deliver a rotational impact.

[0028] It has been shown that incorporating a mitigation mechanism between the rotational impact mechanism and the output improves the safety profile of existing rotational impact mechanisms without sacrificing output impact energy. This finding allows for increased torque while keeping the maximum output RPM at a reasonable speed and avoiding the possibility of excessive rotational speed of the output (otherwise, bodily fluids may splatter in the operating room, leading to uncontrolled reaming and damage to soft tissues).

[0029] In one embodiment, the output anvil 30 can move linearly along the impact axis. The spring 22 can impart a linear impact by moving the rotating hammer 20 such that the surface of the rotating hammer 20 contacts the surface of the output anvil 24, thereby transferring energy linearly from the spring 22 while also imparting a rotational impact from the hammer. In this embodiment, the spring may also be able to move parallel through the output anvil so that a linear impact is also imparted to the surgical instrument. The advantages of linear impact during the reaming process are shown in Figure 13. Curve 501 shows a typical constant force (typically above 25 pounds) that a surgeon applies to the rear of a reamer handpiece during the reaming process. Curve 502 shows a sudden linear impact applied to the surgical site by the linear impact mechanism disclosed herein. The advantage of high-frequency linear impact is that the surgeon and / or robot does not need to supply similar external pressure to the rear of the tool to successfully perform the surgical operation.

[0030] In one embodiment shown in Figure 2, a viscoelastic or damping mechanism 70 is used to reduce the reflected force and / or torque of a surgical impact tool during surgery. The mechanism 70 may be positioned on, around, or near the motor 10 of the tool 100, allowing for some degree of rotational freedom of movement, but will also have a rotational spring constant to allow for predictable compensation, damping, and recovery during impacts by the impact hammer 20. It will become apparent that this mechanism 70 may also be incorporated into rotary impact tools, which will be further described below in this specification. Referring to Figure 4, damping mechanisms 80 and 90 may be provided to reduce the reflected rotational and / or linear forces of the impact tool.

[0031] In a further embodiment, the tool comprises one or more sensors 39 that establish a spatial position relative to the patient. In a further embodiment, the measurement determining the spatial position is integrated with the impact so that the tool recovers to at least 90% of its pre-impact position before communicating the tool's position to a robot or other device. This integrated sensor measurement system is clearly advantageous because it efficiently utilizes computing power by measuring only when necessary and collects and communicates only the most accurate and valid position data.

[0032] In one embodiment, the tool is designed in such a way that it isolates the tool function from rebound or reaction forces by using a “free-flying impact member.” The free-flying (or ejected) member as used herein is a movable member of the tool or a movable member within the tool, the part of which is free-flying relative to the tool. The impact of the ejected member on the receiving member imparts a uniform force (e.g., output 40) to the surgical instrument of the tool, but equally important is the fact that the launch of the ejected member is a predictable impact that can be compensated for by a sleeve, slide cage, etc. In one embodiment, the reaction force at the gripping surface is reduced by extending the period over which the ejected member impacts the surface (as shown in Figure 3). This is achieved by conservation of momentum (m1v1=m2v2), which can also be written with respect to the impact as F1Δt1=F2Δt2 (where F is the force and Δt is the period over which this force occurs). Although this equation concerns linear momentum, the concept is equally applicable to rotational momentum.

[0033] Next, with reference to Figure 3, an example of calculation of the reduction of this force by extending the period over which the reaction force is applied is shown according to an exemplary embodiment of the present disclosure. In one embodiment, the reaction force generated by the impact hammer can be reduced by extending the period over which the force is applied to the motor mount or gripping surface, for example (as shown in Figure 4). This occurs by the law of conservation of momentum, as discussed above. The period (Δt) can be extended, for example, by using a viscoelastic mechanism or damping mechanism 70 between the motor mount and the tool housing, or between the gripping surface and the tool housing.

[0034] In another embodiment shown in Figure 4, the rotational action of the tool 100 may be combined with a linear action. The linear impact intended by this disclosure includes a throw of less than 1 mm per impact, and this impact is performed in the initial stage of acetabular reaming. Surprisingly, it has been found that adding small linear impacts in combination with rotational impacts reduces the linear force required by the surgeon in the initial acetabular reaming by more than 50%. In one embodiment, the motor 10 provides both linear and rotational motion of the hammer 20. In such an embodiment, the cumming surface 30 may include a linear ramp to enable the conversion of the linear (i.e., axial) motion force of the impact bar 20 into an output 40 (and surgical instrument 50) and a rotational ramp to enable the conversion of the rotational motion force of the hammer 20 into an output 40 (and surgical instrument 50). In one embodiment, a spring further provided by the tool may be compressed when the cumming surface for linear impacts translates the hammer away from the output. The spring may be compressed by the translation of the hammer. After the hammer disengages from the linear ramp of the cumbling surface, a spring acts on the hammer, causing it to move linearly and impact the output. The tool 100 may further include bearings 42 to facilitate the rotational and linear motion of the output 40. In one embodiment, the tool 100 may allow the conversion of both linear and rotational force to the output 40 by the hammer 20, and the conversion of rotational force only to the output 40, to be selected (e.g., by a switch 36). In one embodiment, the linear impact is limited to less than 0.5 mm per revolution of the tool's spindle.

[0035] In one embodiment, the tool has the ability to determine the stiffness of the impact site (i.e., the surgical site) by measuring the force of the impact as it relates to changes in either linear and / or rotational displacement. For example, the tool may count 10 impacts from a rotating hammer and determine (by a sensor, etc.) that over the duration of the impacts, the reamer rotated 0.1 degrees and moved linearly 0.001 inches. The tool may then indicate to the surgeon / robot (by status lights, sound, or cessation or deceleration of the tool's movement) that the reamer is no longer advancing, allowing either the surgeon or the robot to decide whether to continue or stop impacting.

[0036] In a further embodiment, as shown in Figure 2, the gripping or mounting surface may be aligned with a force-absorbing sleeve, i.e., sleeve 80, which may be made from a material (such as sorbothane). This may be used to reduce the reaction force of a tool against a surgeon and / or robot by absorbing the reaction force and diffusing it over a long period of time.

[0037] In one embodiment, the internal absorbing means of the tool includes, for example, an impact-absorbing material such as urethane (including, but not limited to, sorbothane and viscose). In a further embodiment, the internal absorbing means comprises a damping material and / or a damping mechanism and a spring restoring mechanism. In a further embodiment, such a mechanism may be combined with a single material for impact absorption, such as urethane, rubber, foam, or plastic. Such a single material is not limited to non-metallic materials.

[0038] In another embodiment, the internal absorption means includes a fluid damping system.

[0039] In one embodiment, the rotary impact tool is equipped with an overload clutch to limit the reaction torque as seen from the tool body.

[0040] In yet another embodiment, as shown in Figures 5 and 6, a rotary-linear impact tool 200 is shown, characterized by rotational and linear motion, which allows a hammer 220 to strike an output anvil 230, which can then transmit impact to a surgical area, for example. In one embodiment, the tool 200 comprises a motor and gearbox 210 operably coupled to a lead screw, such as a torque spline 215. The motor provides rotational motion to the torque spline. The lead nut 216, which is included in the torque spline 215, rotates as the torque spline 215 rotates, and the torque transmitted to the anvil is less than a threshold torque for impact. The hammer 220 is operably coupled to the lead nut 216 so as to rotate together with the lead nut 216. When rotating, the hammer 220 can selectively engage and rotate with the output anvil 230.

[0041] In one embodiment, the hammer 220 includes at least one tooth or other projection 221 extending longitudinally away from the surface 222 of the hammer 220. In one embodiment, the output anvil 230 includes at least one tooth or other projection 231 extending laterally away from the body 232 of the anvil. In one embodiment, at least one tooth (or projection) 221 of the hammer may engage with at least one tooth (or projection) 231 of the output anvil 230 such that when the hammer 220 rotates, such engagement causes the output anvil 230 to rotate. This rotation may continue until a sufficiently large load is applied to the output anvil 230 so that the output anvil 230 stops rotating. As a result, the engagement between the projection 231 and the output anvil 230 and the engagement between the projection 221 and the hammer 220 continue, and the rotation of the hammer 220 also stops.

[0042] In one embodiment, the impact tool 200 further comprises an energy storage means 240 (e.g., a die spring) and a lead screw element (a typical example being a torque spline 215). In one embodiment, the die spring 240 is positioned between the lead nut 216 of the tool 200 and the motor 210. It will be apparent that the coil of the spring facilitates positioning the spring 240 around the torque spline 215. In one embodiment, the torque spline is constantly rotating. In such an embodiment, when the rotation of the hammer 220 stops, the lead nut 216 and the hammer 220 to which the lead nut 216 is attached will be translated backward (away from the output anvil 230). Such backward translation of the lead nut 216 and the hammer 220 compresses the die spring 240. The movement and compression continue until the hammer 220 moves a sufficient distance backward so that at least one projection 221 of the hammer 220 disengages from at least one projection 231 of the output anvil 230.

[0043] As the hammer 220 moves a sufficient distance backward so that at least one of its projections 221 disengages from at least one projection 231 of the output anvil 230, the hammer teeth slide along the anvil teeth until they clear the anvil teeth, and the spring 240 extends, causing the high-speed rotational motion of the hammer 220 to push the torque spline 215 toward the return output anvil 230. This high-speed rotational motion of the hammer 220 results in a sudden rotational impact on the anvil, and this sudden force is sufficient to overcome any bone structure or deformity that was hindering the reaming action of the impact tool 200. In one embodiment, the motor 210 may be programmed to increase its speed when the hammer 220 is retracting (indicating that it has reached a threshold torque and is set to produce a rotational impact). This has the advantage of maintaining a constant output RPM whether it is a rotational impact stage or a constant rotation stage.

[0044] Such an impact mechanism makes it possible to achieve a much greater rotational torque during reaming compared to conventional orthopedic reaming tools. This improvement is at least 200%, and the reduction in reaction torque is more than twice that which can be achieved with conventional orthopedic reaming tools. In an unexpected discovery, it was found that the tool switches from an impact mode (where an acoustic signal is generated from the impact) to a non-impact mode (where the acoustic signal is minimized) when surgical reaming is complete or nearly complete.

[0045] As the spring 240 extends, the hammer 220 returns along the torque spline 215, making linear and rotational energy available from the hammer 220. In one embodiment, a compression element 250 is provided to facilitate the transmission of linear impact and linear force from the hammer 220 to the output anvil 230. The compression element 250 is preferably positioned between the surface 222 of the hammer and the output anvil 230. In one embodiment, as the hammer 220 returns along the torque spline 215 as a result of the extension of the spring 240, the surface 222 of the hammer 220 impacts the body 232 of the output anvil 230. In one embodiment, the compression element 250 comprises a friction disc made of elastomer material. In such an embodiment, the element 250 absorbs a portion of the rotational energy of the hammer 220 and converts this energy into a linear force acting on the output anvil 230.

[0046] In a further embodiment, the tool 200 includes one or more sensors (not shown) that establish its spatial position relative to the patient. In a further embodiment, the measurement determining the spatial position is integrated with the impact so that the tool 200 recovers to at least 90% of its pre-impact position before communicating the tool's position to a robot or other device. This integrated sensor measurement system is clearly advantageous because it efficiently utilizes computing power by measuring only when necessary and communicates only the most accurate position data.

[0047] In one embodiment, the tool 200 has the ability to determine the stiffness of the impact site (i.e., the surgical site) by measuring the impact force as it relates to changes in either linear and / or rotational displacement. For example, the tool 200 may count 10 impacts from the output anvil 230 and determine that over the duration of the impact, the reamer rotated 0.1 degrees and moved linearly 0.001 inches. The tool 200 can then instruct the surgeon / robot that the reamer is no longer advancing, which can be determined by either the surgeon or the robot. In one embodiment, internal absorbing means (not shown) provided by the tool 200 may be located inside the tool housing or on the grip or mounting surface of the tool and may include impact-absorbing elastomer materials such as urethane sorbothane or viscose.

[0048] In another embodiment, as shown in Figures 7 and 8, the rotary linear impact tool 300 comprises a motor 310, a hammer 320, an output anvil 330, a linear energy storage means 340 (in one embodiment, this means may comprise a corrugated spring), and a rotational energy storage means 342. The hammer and anvil are operably coupled and can be rotated by a lead screw such as a torque spline 315. The tool further comprises a cam 350 (such as a cylindrical cam) and at least one cam follower 352, and an impact rod 360. The impact rod 360 is at least partially contained within the cam 350 and can provide rotational force to the cam, causing it to rotate or circulate. The tool 300 further comprises at least one shock absorber 380. The anvil 330 is provided with grooves 332 to receive and allow linear movement of the cam 350 and the impact rod 360 relative to the anvil 330.

[0049] In this embodiment, the rotational impact by tool 300 is achieved in the same way as the rotational impact performed by tool 200 disclosed elsewhere in this specification. In one embodiment, motor 310 brings about the rotational motion of torque spline 315. Lead nut 316 included in torque spline 315 rotates as torque spline 315 rotates. Hammer 320 is operably coupled to lead nut 316 so as to rotate together with lead nut 316. As hammer 320 rotates, it selectively engages with output anvil 330 to rotate output anvil 330 and may or may not impart impact depending on a threshold torque.

[0050] For linear impact by tool 300, the impact rod 360 is partially positioned inside the anvil 330 and is operably coupled to the cam 350. The rotation of the anvil 330 (due to the rotation of the hammer 320) outputs torque to the impact bar 360, which rotates the cylindrical cam 350. The cam follower 352 is operably coupled to the corrugated spring 340 and the cylindrical cam. As the cylindrical cam 350 rotates, the cam follower 352 follows the path of the cylindrical cam, compressing the corrugated spring 340 in a process of storing potential energy in the spring. The grooves in the anvil 330 allow the impact rod 360 and the cylindrical cam 350 to move linearly relative to the anvil 330 during this phase of operation. After the cam follower 352 clears the path of the cylindrical cam 350, the wave spring releases the stored energy, pushing the cam 350 and impact rod 360 toward the surgical site. The cam and rod impact the anvil 330, such as at the tip of the anvil groove 332 proximal to the surgical site, thereby imparting a linear impact force to the tool's output. To reduce tool rebound and improve control, a buffer 380 may be provided to limit the linear movement of the anvil 330, as shown in Figure 7.

[0051] In another embodiment, as shown in Figures 9, 10, 11, and 12, the rotary linear impact tool 400 comprises a motor 410, a hammer 420, an output anvil 430, and an energy storage means 440 which in one embodiment may include at least one corrugated spring. The hammer 420 and the anvil 430 are operably coupled and can be rotated by a lead screw element (such as a torque spline 415). The tool 400 may include at least one shock absorber, such as a stop shock absorber 481 and a shock shock absorber 482. The stop shock absorber is preferably disposed between the anvil 430 and the housing. The shock shock absorber 482 may be disposed, for example, at the tip of the anvil 430 that contacts the hammer 420. When a surgeon or robot pushes a surgical instrument 485, which is attached to the anvil, toward the bone surface, the anvil compresses at least one spring 440 (and, in one embodiment, a linear actuator spring 441 and a rotary spring 442) to enable linear and rotational impacts.

[0052] In this embodiment, the rotational impact by tool 400 is achieved in the same way as the rotational impact performed by tools 200 and 300 disclosed elsewhere in this specification. In one embodiment, motor 410 brings about the rotational motion of torque spline 415. The lead nut 416 included in the torque spline 415 rotates as the torque spline 415 rotates. Hammer 420 is operably coupled to the lead nut 416 so as to rotate together with the lead nut 416. When rotating, hammer 420 can selectively engage with the output anvil 430 to rotate the output anvil 430.

[0053] In one embodiment, the hammer 420 includes at least one tooth or other projection 421 extending longitudinally away from the surface 422 of the hammer 420. In one embodiment, the output anvil 430 includes at least one tooth or other projection 431 extending laterally away from the body 432 of the anvil. In one embodiment, at least one tooth (or projection) 421 of the hammer may engage with at least one tooth (or projection) 431 of the output anvil 430, and such engagement causes the output anvil 430 to rotate as the hammer 420 rotates. The rotation may continue until the output anvil 430 is subjected to a sufficiently large load (such as the tool encountering a bone spur during surgical reaming) so that the output anvil 430 stops rotating. As a result, the rotation of the hammer 420 also stops because the engagement between the projection 431 and the output anvil 430 and the engagement between the projection 421 and the hammer 420 remain.

[0054] In one embodiment, the spring 440 is positioned between the lead nut 416 of the tool 400 and the motor 410. In one embodiment, the spring 440 is a corrugated spring. It will be apparent that the coil of the spring 440 facilitates positioning the spring 440 around the torque spline 415. In one embodiment, the torque spline is constantly rotating. In such an embodiment, when the rotation of the hammer 420 stops, the lead nut 416 and the hammer 420 to which the lead nut 416 is attached will move backward (away from the output anvil 430). Such backward translation of the lead nut 416 and the hammer 420 compresses the spring 440. The translation and compression continue until the hammer 420 has moved a sufficient distance backward so that at least one projection 421 of the hammer 420 is separated from at least one projection 431 of the output anvil 430 as shown in Figure 16.

[0055] As the hammer 420 moves a sufficient distance backward so that at least one of its projections 421 disengages from at least one projection 431 of the output anvil 430, the hammer continues to rotate until its teeth slide over the teeth of the anvil, and then the rotor spring 442 extends, pushing the high-speed rotational motion of the hammer 420 toward the output anvil 430 and the shock absorber 482 toward away from the torque spline 415. This high-speed rotational motion of the hammer 420 results in a sudden rotational shock to at least one projection 431 of the output anvil 430, and this sudden force on the output anvil 430 is sufficient to overcome any bone structure or deformity that was hindering the reaming action of the shock tool 400. In one embodiment, the motor 410 may be programmed to increase its speed when the hammer 420 is retracting (indicating that it has reached a threshold torque and is set to produce a rotational shock). This would be convenient for maintaining a constant output RPM, whether it's a rotating impact stage or a constant rotation stage.

[0056] As the rotary spring 442 extends, pushing the hammer 420 away from the torque spline 415, linear and rotational energy may become available in the anvil 430 to deliver an impact to the surgical site. That is, the tool may deliver both linear and rotational impacts to the anvil 430, depending on the degree of compression of the linear actuator spring 441 prior to the hammer moving away from the torque spline. In one embodiment, an impact buffer 482 facilitates the transmission of linear impact and linear force from the hammer 420 to the output anvil 430. In one embodiment, the surface 422 of the hammer 420 impacts the impact buffer 482, and the impact buffer 482 transmits a linear impact to the anvil 430 as a result of the extension of the rotary spring 442.

[0057] It will be apparent that the linear actuator spring 441 can be compressed by the user and / or by the mass of the tool 400 when the tool 400 is placed against the surgical site. When the tool 400 is positioned against the surgical site, the user may increase the compression of the spring 441 by applying additional pressure to the tool 400. If the spring 441 is sufficiently compressed and does not have enough time (depending on the spring constant of this spring) to extend before the linear impact and linear force from the hammer 420 is transmitted to the output anvil 430, the anvil 430 will receive and transmit the linear force to the surgical site. If the linear actuator spring 441 is not sufficiently compressed before the hammer 420 transmits its rotational energy to the output anvil 430, the energy will be absorbed by rotation or through the stop buffer 481.

[0058] This disclosure offers the benefit of reducing reaction forces from surgical tools to the gripping and / or mounting surfaces. Another benefit is that the tool can supply the considerable force necessary to complete the surgery without requiring external forces (e.g., external forces from a surgeon leaning forward towards a reamer handpiece to advance the reamer into the surgical site). This results in less wear and abrasion on the robotic platform in the case of robotic surgery, and less fatigue when a surgeon is performing the surgery. This also improves the precision and capability of the robot in the case of robotic surgical tools and can drastically reduce instances of registration loss by surgical robots.

[0059] The foregoing descriptions of specific embodiments of the Disclosure are provided for illustrative and explanatory purposes only. These descriptions are not intended to be exhaustive or to limit the Disclosure to the exact form disclosed, and obviously, many modifications and variations are possible from the perspective of the teachings described above. The exemplary embodiments are selected and described in such a way as to best illustrate the principles of the Disclosure and its practical applications, so that those skilled in the art may best utilize the Disclosure and the various embodiments with various modifications suitable for their specific intended use. [Explanation of symbols]

[0060] 10 Motor drive unit 20 Impact mechanism, rotary hammer, impact hammer 22 springs 30 Coming surface, output anvil 39 Sensors 40 Output Anvil 42 Bearings 50 Surgical instruments 70 Damping mechanism 80 Damping mechanism, sleeve 90 Damping mechanism 100 Tools 200 Rotation Linear Impact Tool 210 Motors and Gearboxes 215 Torque Spline 216 Lead Nut 220 Hammer 221 At least one tooth or other projection 222 Hammer surface 230 Output Anvil 231 At least one tooth or other projection 232 Anvil body 240 Energy storage means, die spring 250 compression elements 300 Rotation Linear Impact Tool 310 Motor 315 Torque Spline 316 Lead Nut 320 Hammer 330 Output Anvil 332 grooves, anvil grooves 340 Linear energy storage means, wave spring 342 Rotational energy storage means 350 cam, cylindrical cam 352 Cam follower 360 Impact Rod 380 buffer 400 Rotation Linear Impact Tool 410 Motor 415 Torque Spline 416 Lead Nut 420 Hammer 421 At least one tooth or other projection 422 Hammer surface 430 Output Anvil 431 At least one tooth or other projection 440 Energy storage means, spring 441 Linear actuator spring 442 Rotary spring 481 Stop buffer 482 Shock absorber 485 Surgical instruments

Claims

1. Rotational and linear impact tools for orthopedic surgery, Housing and Motor and, Impact hammer and, Output anvil and, Energy storage means, A lead screw consisting of a lead nut and a shaft, Equipped with, The energy storage means is located near the impact hammer for part of the tool's operating cycle. The impact hammer is disposed on the lead screw, rotated by the motor, and contacts the output anvil to selectively rotate the output anvil. When the output anvil stops rotating, the impact hammer moves in parallel along the lead screw, transferring energy to the energy storage means. A tool wherein, after the impact hammer has moved a sufficient distance in parallel away from the output anvil, the energy storage means imparts its energy to the impact hammer, causing it to accelerate along the lead screw and impart at least one of a rotational force and a linear force to the output anvil.

2. The tool according to claim 1, wherein the energy storage means comprises a spring.

3. The surgical instrument further comprises a damping mechanism, the damping mechanism reducing the reaction force applied to the surgical instrument to less than 50% of the linear force, The damping mechanism is arranged around the motor and is composed of shock-absorbing material. The tool according to claim 1.

4. The tool according to claim 1, wherein the linear impact is limited to a stroke of less than 1 millimeter of the output anvil relative to the housing per impact.

5. The tool according to claim 1, wherein the transition between impact and non-impact is indicated by a change in sound produced by the impact.

6. The tool according to claim 1, further comprising a sensor that determines the position of the tool during impact and after it has recovered to at least 90% of the position of the reamer before impact.

7. The tool according to claim 1, wherein a linear impact force is applied to the surgical site by a force applied to the tool by a surgeon or surgical robot.

8. The tool according to claim 1, further comprising control means such that the speed of the motor is adapted to maintain a constant output RPM while it is rotating or rotating and impacting.

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