Rotary impactor for orthopedic surgery

Abstract

A rotary impactor for orthopedic surgery includes an output anvil and a hammer body capable of imparting linear and rotational forces on the anvil. The anvil can be moved on a screw element to alternately generate energy in an energy storage device and move along the screw element to impact the anvil. A viscoelastic or damping mechanism is used to reduce the reaction force and / or torque during operation of the rotary impactor. High frequency linear impacts by the impactor make it unnecessary for the surgeon to provide an external thrust force to the impactor for successful surgical procedures.

Description

[0001] Cross-reference to related applications

[0002] This application is a non-provisional application and claims priority under 35 USC §119 to the following applications: U.S. Provisional Patent No. 63 / 141,786, filed January 26, 2021, which is pending; U.S. Provisional Patent Application No. 63 / 188,542, filed May 14, 2021, which is pending; and U.S. Provisional Patent Application No. 63 / 277,754, filed November 21, 2021, the disclosures of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a rotary impact reamer for use by surgeons and / or surgical robots, and more specifically, to a rotary impact reamer that exerts negligible reaction force on the surgeon and / or robot. Background Technology

[0004] Current surgical trends are moving towards the use of robots to assist in surgical procedures. In this regard, robotic end effectors can be used by the robot, for example, to perform surgical procedures. In one embodiment, an end effector is a device, tool, or manipulator at the end of a robot that can engage and interact with the surgical site. The end effector is guided by the robot to perform surgical actions. In the field of robotic surgery, end effectors can include surgical instruments.

[0005] To date, robotic automation in surgery has performed well in laparoscopic and low-energy-demand procedures. However, its use has been hampered in orthopedic settings where strong and high-energy operations are routinely employed. In such settings, and within the field of orthopedic surgery in general, the enormous reaction forces generated by conventional large orthopedic tools (such as saws, drills, or reamers) necessitate different approaches (e.g., mechanical manipulation) to meet the greater energy demands.

[0006] An exemplary robot used in major orthopedic surgeries is Stryker's MAKO product. MAKO has three objectives: augmentation planning, dynamic joint balancing, and robotic arm-assisted bone preparation.

[0007] As part of its operation, the robot must identify the bone geometry of the surgical site in order to accurately navigate, guide, and manipulate its end effector through the site. This identification of bone geometry is called registration. Existing surgical power tools, when used in orthopedic surgery, generate significant amounts of reaction torque (e.g., in the case of surgical reamers) or shock (e.g., in the case of surgical impact tools). This torque and / or shock can not only cause the robot to lose registration but also damage its highly complex mechanics and components.

[0008] Rotary reamers are used in hip and hip replacement surgeries, such as when preparing the cavity for the acetabular cup in a prosthetic hip joint. These rotating tools have enormous reaction torque associated with the surgery. This can cause the tool to slip from the surgeon's hand, and in severe cases, injure the surgeon's wrist or forearm. Clearly, in the case of robotic use, this reaction torque can lead to navigation or guidance errors, which often result in lost robot registration and shutdown. Tests have shown this to be true, and it is one of the most common problems encountered when using robots in major orthopedic surgeries.

[0009] Navigation capability is arguably the most important feature of orthopedic robots. For a successful surgery, the robot must maintain tools (or instruments) in the correct orientation and alignment relative to the bone. Allowing surgical instruments to move out of stereotactic boundaries can lead to any of a number of drawbacks, including soft tissue injury if the instruments are still driven. Currently available rotating tools generate significant instability forces (reaction torques caused by the reamer encountering and / or becoming stuck on hard parts of the bone). These forces can interfere with the robot's programmed navigation and may cause the robot to stop.

[0010] Furthermore, simply mounting surgical power tools designed specifically for surgeons onto a robot presents at least two problems. First, the reaction force / torque applied by the tool may cause the robot to deviate from its guide path. Second, in large bone surgeries, the robot often cannot provide sufficient linear force to allow the reamer to enter the acetabulum. Surgeons frequently have to apply linear force to the tool to achieve the desired outcome.

[0011] Therefore, there is a need for an impact tool (also referred to herein as an impactor) that allows surgeons to more easily manipulate and create pathways to robotic surgery and ultimately fully autonomous surgery. Thus, this disclosure provides a rotary and / or rotary / linear surgical tool that significantly reduces feedback torque through the use of impact, while achieving results similar to current rotary surgical reamers. Furthermore, by using linear impact to enhance rotary impact, both linear and rotary force requirements are significantly reduced compared to conventional surgical reamers and drills. For example, current technology requires surgeons to apply all necessary linear force to advance the surgical reamer to the surgical site. This linear force can exceed 25 pounds, far exceeding the linear force that a surgical robot can provide. It has been found that the linear impact provided by the tool of this disclosure reduces the required linear support force provided by the surgeon by ~50%. Summary of the Invention

[0012] In view of the aforementioned drawbacks inherent in the prior art, the object of this disclosure is to provide a solution to the high reaction forces generated when using orthopedic surgical instruments. These solutions aim to reduce the reaction forces experienced by the surgical robot and / or surgeon during surgery in order to better control the surgical instruments (e.g., their positioning). In addition to reducing reaction forces, the object of this disclosure is also to mechanically provide all or most of the force required to complete the surgery so that the surgeon and / or robot can guide the instruments with minimal force.

[0013] In one embodiment, this disclosure provides a rotary impact tool for orthopedic surgery configured to minimize reaction forces during major orthopedic procedures. The tool preferably includes a mechanism (e.g., an absorption device) that reduces peak reaction forces from the tool tip acting on the gripping surface of the tool. Such a gripping surface may include, but is not necessarily limited to, hand grips designed for manual operation by a surgeon, or cylindrical or other assembly devices coupled to and operated by a surgical robot. It should be understood that “surgical tool” and “impacter” refer to the invention disclosed herein, while “surgical instrument” refers to an attachment to the output end of a surgical tool. For example, a surgical tool refers to a rotary impact hand grip, while a surgical instrument may refer to a hemispherical reamer attached to the output end of a surgical tool.

[0014] In one embodiment, the reaction force is further reduced by using a damping mechanism that allows the reaction force to be distributed over a longer time period, thereby reducing the reaction force seen or felt on the gripping surface. In this embodiment, the damping mechanism comprises a viscoelastic or non-Newtonian fluid disposed between the motor support and the tool housing, such that the reaction torque is isolated from the tool housing, and therefore also from the surgeon / robot. Clearly, such a damping mechanism can also be used to isolate the motor drive from the hammering mechanism, so the position of the damping mechanism can be varied, although its preferred position is between the gripping surface and the tool housing and / or between the motor support and the tool housing. In yet another embodiment, the tool may further include a counter-motion element to absorb and disperse the reaction force over an even longer time period.

[0015] In one embodiment, the tool includes a torque sensing device that, when a threshold torque value is reached or exceeded, can activate a rotary impact mechanism that transmits a rotary impact force to a surgical instrument. The threshold torque value is preferably a torque below that which could damage the surgical robot or the surgeon's wrist. It has been found that this conversion should occur at approximately 30 to 50 inch-pounds. The tool can then generate a rotary impact force on the impact hammer, which will be transmitted and / or converted to the surgical instrument.

[0016] In yet another embodiment, this disclosure provides a rotary and linear impact tool for orthopedic surgery, configured to minimize reaction forces during major orthopedic procedures. The tool may include a mechanism (e.g., an absorption device) that reduces peak reaction forces acting on the tool end of the tool's gripping surface. Such a gripping surface may include, but is not necessarily limited to, hand grips designed for manual operation by a surgeon, or cylindrical or other assembly devices coupled to and operated by a surgical robot. It should be understood that "surgical tool" refers to the invention disclosed herein, while "surgical instrument" refers to an attachment to the output end of a surgical tool. For example, a surgical tool may refer to a rotary / linear impact hand grip, while a surgical instrument may refer to a hemispherical reamer attached to the output end of a surgical tool.

[0017] In one embodiment, the impactor or impact tool includes a hammer, an output anvil, and an energy storage device (in one embodiment, the device may include a spring). The hammer and anvil are operatively coupled to a lead screw element (an example of which is Torqspline®) and are rotatable by the lead screw element. It should be understood that the term "torqspline" is used in this disclosure as an exemplary embodiment of the lead screw element, and therefore the term "torqspline" should not be considered limiting. During rotation, when a sufficient load is reached on the output anvil, the output anvil and hammer can temporarily stop being rotated by the Torqspline element, and the hammer can translate the Torqspline upward away from the object being impacted to power the energy storage device until the hammer and output anvil are aligned to allow the currently powered energy storage device to act on the hammer, such that the hammer translates the Torqspline downward (while rotating) to impact the output anvil with minimal reaction torque.

[0018] Minimal reaction torque is a result of two factors: First, the hammer is essentially decoupled from the output anvil. This limits the reaction torque to a certain threshold that depends only on the energy storage device (e.g., a spring) and the torqspline pitch. Second, the sharp impact of the hammer on the output anvil allows the impact reamer to overcome high-load areas (e.g., sclerotic bone / osteophytes in the acetabulum) with minimal reaction torque for the surgeon. The high impact force generated by the hammer's impact on the anvil breaks through high-load areas with minimal reaction torque.

[0019] It will be apparent to those skilled in the art that the translation and rotation of the hammer in the above-described mechanism can be divided as applying impact simultaneously in both the rotational and linear directions. It has been found that adding a linear impact element during the reaming process increases the overall speed of the reaming phase while also reducing surgeon fatigue (the surgeon does not need to apply the linear thrust as with a conventional reamer, which could exceed 25 pounds). In one embodiment, the linear impact of the hammer is accomplished by an impact element disposed on the hammer and / or the output anvil, which applies or receives a linear impact when the hammer contacts the output anvil, as described in more detail elsewhere herein.

[0020] In one embodiment, the tool includes a torque sensing device that can cause the rotational movement of the output anvil and / or hammer to stop.

[0021] In another embodiment, the surgical impact tool includes a hammer, an anvil, and an energy storage device (in one embodiment, this device may include a wave spring). The hammer and anvil are operatively coupled to and rotatable via a lead screw element (e.g., a Torqspline lead screw). The tool also includes a cam (e.g., a barrel cam) and a cam follower, as well as an impact rod. Rotation of the hammer causes the anvil to rotate, outputting torque to the impact rod. The impact rod can rotate the barrel cam, compressing the wave spring. After the cam follower disengages from the barrel cam, the wave spring can expand to force the cam and impact rod forward, thereby producing a linear impact on the anvil.

[0022] In another embodiment, the rotary linear impactor or impact tool includes a hammer, an output anvil, and an energy storage device (in one embodiment, this device may include at least one wave spring, and in a further embodiment, a linear actuator spring and a rotary spring). The hammer and anvil are operatively coupled to a lead screw element (e.g., a torqspline) and are rotatable via the lead screw element. When the user pushes the output anvil into the bone surface, the anvil also compresses the linear actuator spring to provide either a rotary impact alone or both a rotary and linear impact, depending on the force with which the user pushes the output anvil into the bone surface. Attached Figure Description

[0023] The advantages and features of this disclosure will be better understood by referring to the following detailed description and claims in conjunction with the accompanying drawings, wherein similar elements are identified by similar symbols, wherein: Figure 1 A rotating hammer according to an exemplary embodiment of the present disclosure is shown, which is used to achieve the rotational movement of a surgical instrument.

[0024] Figure 2 A damping mechanism according to an exemplary embodiment of the present disclosure is shown, which reduces the feedback impulse to the surgeon and / or surgical robot.

[0025] Figure 3 Sample calculations of reducing reaction force by extending the time period of applied force according to an exemplary embodiment of this disclosure are shown.

[0026] Figure 4 A damping mechanism according to an exemplary embodiment of the present disclosure is shown, which reduces the feedback impulse to the surgeon and / or surgical robot from both rotational and linear impacts.

[0027] Figure 5 A cross-sectional view of an orthopedic impact tool according to an exemplary embodiment of the present disclosure is shown.

[0028] Figure 6An exemplary hammer and an exemplary output anvil of an orthopedic impact tool according to an exemplary embodiment of the present disclosure are shown.

[0029] Figure 7 Linear and rotary impactors including cams are shown according to exemplary embodiments of the present disclosure.

[0030] Figure 8 Another view of linear and rotary impactors including a cam and an impact rod according to an exemplary embodiment of the present disclosure is shown.

[0031] Figure 9 A linear and rotary shocker including at least one buffer is shown according to an exemplary embodiment of the present disclosure.

[0032] Figure 10 A linear and rotary shocker according to an exemplary embodiment of the present disclosure is shown, which includes at least one buffer depending on the position to apply an impact to the output.

[0033] Figure 11 A linear and rotary shocker including at least one buffer is shown according to another exemplary embodiment of the present disclosure.

[0034] Figure 12 A linear and rotary shocker including at least one buffer is shown according to another exemplary embodiment of the present disclosure.

[0035] Figure 13 A comparison is shown of the force applied to the back of a conventional surgical reamer and the linear force applied by linear and rotary impactors of an exemplary embodiment. Detailed Implementation

[0036] The exemplary embodiments described in detail herein are for illustrative purposes and may vary in structure and design. However, it should be emphasized that this disclosure is not limited to the specific surgical instruments, robots, robotic end effectors, or any intermediate mechanisms shown and described. That is, it is understood that various omissions and substitutions of equivalents may be considered when circumstances may suggest or make it advantageous, but these are also intended to cover the described application or implementation without departing from the spirit or scope of the claims of this disclosure. The terms “first,” “second,” etc., used herein do not indicate any order, quantity, or importance, but are used to distinguish one element from another, and the term “an” (“a”, “an”) used herein does not indicate a limitation of quantity, but indicates the presence of at least one referenced item.

[0037] This disclosure provides rotational linear impact tools for orthopedic surgery, and more specifically, tools designed to minimize reaction forces during major orthopedic surgeries. As used herein, the tool may also be referred to as a rotational impactor or a combination of rotational and linear impactors. In this context, a rotational impact tool can be understood as a tool that generates a constant rotational motion on surgical instruments and can further provide rotational impact under certain conditions (i.e., when the reaction torque reaches and / or exceeds a threshold). The tool may also include mechanisms for generating the combined rotational and linear impacts.

[0038] The tools disclosed herein include a mechanism (such as an absorption device) that reduces the peak reaction force from the tool tip acting on the tool's gripping surface. Such a gripping surface may include, but is not limited to, hand grips in the case of tools designed for manual operation by a surgeon, or cylindrical or other assembly devices in the case of tools coupled to and operated by a surgical robot. As used herein, "reaction force" may include linear or rotational impacts and / or forces or torques fed back to the assembly or gripping surface of the robot and / or surgeon.

[0039] In one implementation scheme, such as Figure 1 As shown, the rotational motion is transmitted to the surgical instrument 50 via an impact mechanism 20, such as a rotating hammer. In one embodiment, the tool 100 includes a drive motor 10 operably coupled to an impact rod (such as the rotating hammer 20). The motor 10 provides rotational motion to the rotating hammer. The rotating hammer 20 is operably coupled to a cam surface 30 via steel balls. The rotating hammer selectively engages an output anvil, which can be coupled to an interface of the tool. The interface is capable of receiving and rotating the surgical instrument. The tool may also include at least one bearing 42 to hold the output anvil 40 in an operating position when it is subjected to the action of the rotating hammer. The rotating hammer 20 rotates the output anvil until a threshold torque is reached on the output anvil. After the threshold torque is reached, the balls resist a spring 22 to pull the rotating hammer back until the rotating hammer is no longer in contact with the output anvil. At this point, the rotating hammer is accelerated to a higher speed, and the spring 22 pushes the rotating hammer forward to cause the hammer body to re-engage and rotate to impact the output anvil.

[0040] It has been found that the safety of existing rotary impact mechanisms can be improved without sacrificing output impact energy by placing a mitigation device between the rotary impact mechanism and the output end. This discovery allows for torque multiplication while keeping the maximum speed at the output end at a reasonable level and avoiding the possibility of excessive output speed (which could otherwise lead to fluid splashing into the operating room, resulting in uncontrolled orifice rupture and soft tissue damage).

[0041] In one embodiment, the output anvil 30 is capable of linear movement along the impact axis. The spring 22 can apply a linear impact by moving the rotating hammer 20, causing the surface of the rotating hammer 23 to contact the surface of the output anvil 24, and transferring energy from the spring 22 in a linear direction, while the hammer also causes a rotational impact. In this embodiment, the spring allows the linear impact to also be applied to the surgical instrument via translation of the output anvil. The advantages of linear impact during the reaming process include... Figure 13 As shown. Curve 501 illustrates the conventional constant force (typically exceeding 25 pounds) applied by the surgeon to the back of the reamer handpiece during the reaming process. Curve 502 illustrates the intense 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 do not need to provide the same external thrust on the back of the tool for successful surgical execution.

[0042] In such Figure 2 In the illustrated embodiment, a viscoelastic or damping mechanism 70 is used to mitigate reaction forces and / or torques during operation of the surgical impact tool. The mechanism 70 may be positioned on, around, or near the motor 10 of the tool 100, allowing for a certain degree of rotational freedom; however, the mechanism 70 will also have a rotational spring constant to allow predictable compensation and damping, as well as recovery, between impacts from the impact hammer 20. It is evident that this mechanism 70 can also be incorporated into rotary impact tools further described herein. Reference Figure 4 Damping mechanisms 80 and 90 can be provided to reduce the reaction rotational force and / or linear force of impact tools.

[0043] In a further embodiment, the tool includes one or more sensors 39 that establish spatial position relative to the patient. In a further embodiment, the measurement determining the spatial position is coordinated with the impact, such that the tool has recovered to at least 90% of its pre-impact position before transmitting the tool position to a robot or other device. Clearly, this integrated sensor measurement system is advantageous because it measures only when needed, thus efficiently utilizing computing power, and because it only collects and transmits the most accurate and useful position data.

[0044] In one embodiment, the tool is designed to isolate its function from recoil or reaction forces by using a "freeflight impacting member." The freeflight (or ejection) member used herein is a moving part of the tool and is located within the tool, where a portion of its motion is in freeflight relative to the tool. The impact force of the ejection member on the receiving part continuously applies force to the surgical instrument (e.g., output 40) of the tool, but equally important, the ejection of the ejection member is a predictable impulse that can be compensated for by a sleeve, sliding retainer, etc. In one embodiment, by extending the time period of the ejection member's impact on the surface (e.g., ... Figure 3 (As shown) This reduces the reaction force seen at the gripping surface. This is achieved through the conservation of momentum (m1v1 = m2v2), which can also be written in terms of impulse as F1Δt1 = F2Δt2 (where F is the force and Δt is the time interval during which the force occurs). Although this equation applies to linear momentum, the concept also applies to rotational momentum.

[0045] Now for reference Figure 3 As illustrated in the exemplary embodiments of this disclosure, sample calculations show how to reduce reaction forces by extending the time period for which the force is applied. In one embodiment, for example, this is achieved by extending the time period for which the force is applied to the motor mount or gripping surface (e.g., Figure 4 (As shown) can reduce the reaction force generated by the impact hammer. This is due to the law of conservation of momentum discussed above. For example, this time period (Δt) can be extended by using a viscoelastic mechanism or damping mechanism 70 between the motor support and the tool housing or between the gripping surface and the tool housing.

[0046] In such Figure 4In another embodiment shown, the rotational motion of tool 100 can be combined with linear motion. The linear impact envisioned in this disclosure includes a stroke of less than 1 mm per impact, which occurs in the early stages of the acetabular reaming. Surprisingly, it has been found that adding a small linear impact force in combination with the rotational impact in the initial acetabular reaming reduces the linear force required by the surgeon by more than 50%. In one embodiment, motor 10 causes both linear and rotational motion of hammer 20. In such an embodiment, cam surface 30 may include a linear ramp for allowing the linear (or axial) kinetic force of impact rod 20 to be transmitted to output end 40 (and surgical instrument 50), and a rotational ramp for allowing the rotational kinetic force of hammer 20 to be transmitted to output end 40 (and surgical instrument 50). In one embodiment, the tool also includes a spring that can be compressed when the cam surface for linear impact causes the hammer to translate away from the output end. The spring can be compressed by the translation of the hammer. After the hammer disengages from the linear ramp of the cam surface, the spring acts on the hammer, moving the hammer in a linear direction to impact the output end. The tool 100 may further include a bearing 42 for facilitating rotational and linear motion of the output end 40. In one embodiment, the tool 100 may allow (e.g., via switch 36) selection of both linear and rotational forces transmitted from the hammer 20 to the output end 40, and only rotational forces transmitted to the output end 40. In one embodiment, the linear impact is limited to less than 0.5 mm per revolution of the tool's spindle.

[0047] In one implementation, the tool has the ability to determine the stiffness of the impact site (i.e., the surgical site) by measuring the impact force related to changes in linear and / or rotational displacement. For example, the tool might calculate 10 impacts from a rotating hammer and determine (e.g., via a sensor) that the reamer rotates only 0.1 degrees and moves linearly 0.001 inches during the impact. Therefore, the tool can instruct the surgeon / robot (via status lights, sounds, or pauses or slows down tool operation) that the reamer should no longer advance, and the surgeon or robot can decide to continue or stop the impact.

[0048] In further implementation schemes and as follows Figure 2 As shown, the gripping or fitting surface may be lined with one or more suction sleeves 80, which may be made of a material such as Sorbothane. This can be used to absorb and disperse reaction forces over a long period of time, thereby reducing the reaction force of the tool on the surgeon and / or robot.

[0049] In one embodiment, for example, the tool includes an internal absorption device comprising a damping material such as polyurethane (including, but not limited to, sobotan and viscose fiber). In a further embodiment, the internal absorption device includes a damping material and / or mechanism, as well as a spring-return mechanism. In still a further embodiment, such a mechanism may be incorporated into a single material, such as damping polyurethane, rubber, foam, plastic, etc. This single material is not limited to non-metallic materials.

[0050] In another embodiment, the internal absorption device includes a fluid damping system.

[0051] In one embodiment, the rotary impact tool includes an overload clutch to limit the reaction torque visible on the tool body.

[0052] In yet another implementation scheme, and as Figure 5 and Figure 6 As shown, a rotary linear impact tool 200 with rotational and linear motion characteristics is illustrated. This motion allows a hammer 220 to strike an output anvil 230, which can then deliver the impact to, for example, a surgical area. In one embodiment, the tool 200 includes a motor and a gearbox 210 operatively coupled to a leadscrew such as a torqspline 215. The motor provides rotational motion to the torqspline. The torqspline 215 includes a guide nut 216 that rotates when the torqspline 215 rotates and the torque transmitted to the anvil is below a threshold torque for impact. The hammer 220 is operatively coupled to the guide nut 216 such that the hammer rotates with the guide nut 216. As the hammer 220 rotates, it can selectively engage and rotate the output anvil 230.

[0053] In one embodiment, the hammer 220 includes at least one tooth or other protrusion 221 extending longitudinally away from the face 222 of the hammer 220. In one embodiment, the output anvil 230 includes at least one tooth or other protrusion 231 extending laterally away from the body 232 of the anvil. In one embodiment, at least one tooth (or protrusion) 221 of the hammer can engage at least one tooth (or protrusion) 231 of the output anvil 230, such that when the hammer 220 rotates, this engagement causes the output anvil 230 to rotate. The rotation can continue until a sufficiently high load is applied to the output anvil 230, causing the output anvil 230 to stop rotating. This causes the hammer 220 to also stop rotating due to the still engaging protrusions 231 and 221 of the output anvil 230 and the hammer 220.

[0054] In one embodiment, the impact tool 200 further includes an energy storage device 240 (e.g., a die spring) and a lead screw element (an exemplary example of which is a torqspline 215). In one embodiment, the die spring 240 is disposed between the guide nut 216 of the tool 200 and the motor 210. Clearly, the coil of the spring facilitates the placement of the spring 240 around the torqspline 215. In one embodiment, the torqspline is continuously rotating. In such an embodiment, when the hammer 220 stops rotating, the guide nut 216 and the hammer 220 to which it is attached will translate backward (away from the output anvil 230). This backward translation of the guide nut 216 and the hammer 220 causes the die spring 240 to be compressed. Translation and compression continue until the hammer 220 has moved backward a sufficient distance such that at least one protrusion 221 of the hammer 220 has disengaged from at least one protrusion 231 of the output anvil 230.

[0055] Once the hammer 220 has moved backward a sufficient distance, such that at least one of its protrusions 221 has disengaged from at least one protrusion 231 of the output anvil 231, the teeth of the hammer slide along the teeth of the anvil until they disengage from the teeth of the anvil and the spring 240 decompresses, causing the hammer 220 to rotate at high speed along the torqspline 215 toward the output anvil 230. This high-speed rotational movement of the hammer 220 will create a violent rotational impact on the anvil, strong enough to allow the impact tool 200 to overcome bone structures or deformities that hinder the reaming action. In one embodiment, the motor 210 can be programmed to increase its speed as the hammer 220 is pulled backward (this indicates that a threshold torque has been reached and a rotational impact is set). This has the advantage of maintaining a constant output speed, both during the rotational impact phase and the constant rotation phase.

[0056] Compared to traditional orthopedic reaming tools, this impact mechanism allows for significantly higher rotational torque in the ream. This improvement is at least 200%, with a reduction in reaction torque more than twice that of traditional orthopedic reaming tools. In an unexpected finding, the tool switches from an impact mode (with an audible signal generated by the impact) to a non-impact mode (minimal audible signal) when the surgical ream is completed or near completion.

[0057] When the hammer 220 moves downward along torqspline 215 due to the decompression of spring 240, there is both linear and rotational energy from the hammer 220. In one embodiment, a compression element 250 is provided to facilitate the transmission of linear impact and force from the hammer 220 to the output anvil 230. The compression element 250 is preferably disposed between the face 222 of the hammer and the output anvil 230. In one embodiment, as the hammer 220 translates downward along torqspline 215 due to the decompression of spring 240, the face 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 of elastomeric 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.

[0058] 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 coordinated with the impact, such that the tool 200 has recovered to at least 90% of its pre-impact position before transmitting the tool position to a robot or other device. Clearly, this integrated sensor measurement system is advantageous because it takes measurements only when needed, thus effectively utilizing computing power, and because it transmits only the most accurate position data.

[0059] 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 related to changes in linear and / or rotational displacement. For example, the tool 200 can calculate 10 impacts from the output anvil 230 and determine that the reamer rotated only 0.1 degrees and moved linearly by 0.001 inches during the impact. The tool 200 can instruct the surgeon / robot to stop the reamer from advancing, and this decision can be made by the surgeon or the robot. In one embodiment, the tool 200 includes an internal absorption device (not shown), which may be located inside the tool housing or on the gripping or mounting surface of the tool, and may include a shock-absorbing elastomeric material, such as polyurethane sobotan or viscose fiber.

[0060] In another implementation, such as Figure 7 and Figure 8As shown, the rotary linear impact tool 300 includes a motor 310, a hammer 320, an output anvil 330, a linear energy storage device 340 (in one embodiment, this device may include a wave spring), and a rotary energy storage device 342. The hammer and anvil are operatively coupled to and capable of rotation via a lead screw such as a torqspline 315. The tool also includes a cam 350 (e.g., a barrel 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 is capable of applying a rotational force to the cam to rotate or cycle it. The tool 300 also includes at least one damper 380. The anvil 330 includes a groove 332 to receive and allow linear movement of the cam 350 and the impact rod 360 relative to the anvil 330.

[0061] In this embodiment, a rotary impact performed by the tool 300 is performed similarly to the rotary impact performed by the tool 200 as disclosed elsewhere in this document. In one embodiment, the motor 310 provides the rotational motion of the torqspline 315. The torqspline 315 includes a guide nut 316, which rotates as the torqspline 315 rotates. The hammer 320 is operatively coupled to the guide nut 316 such that the hammer rotates with the guide nut 316. As the hammer 320 rotates, it selectively engages and rotates the output anvil 330, and can apply or not apply an impact force depending on a threshold torque.

[0062] For a linear impact via the tool 300, an impact rod 360 is partially disposed within an anvil 330 and further operably coupled to a cam 350. Rotation of the anvil 330 (caused by rotation of the hammer 320) outputs a torque to the impact rod 360, which causes the barrel cam 350 to rotate. A cam follower 352 is operably coupled to the barrel cam and a wave spring 340. As the barrel cam 350 rotates, the cam follower 352 follows the trajectory of the barrel cam and compresses the wave spring 340 in the process to store potential energy in the spring. A slot in the anvil 330 allows the impact rod 360 and the barrel cam 350 to move linearly relative to the anvil 330 during this operational phase. After the cam follower 352 disengages from the trajectory of the barrel cam 350, the wave spring releases the stored energy to drive the cam 350 and the impact rod 360 in the direction of the surgical site. The cam and rod impact the anvil 330, for example, at the end of the anvil groove 332 near the surgical site, thereby applying a linear impact force to the output end of the tool. This can be as follows: Figure 7 A buffer 380 is provided to limit the linear travel of the anvil 330, thereby reducing recoil and increasing control over the tool.

[0063] In another implementation, such as Figure 9 , 10 As shown in Figures 11 and 12, a rotary linear impact tool 400 includes a motor 410, a hammer 420, an output anvil 430, and an energy storage device 440, which in one embodiment may include at least one wave spring. The hammer 420 and anvil 430 are operatively coupled to and rotatable via a lead screw element (e.g., a torqspline 415). The tool 400 may include at least one damper, such as a stop damper 481 and an impact damper 482. The stop damper is preferably disposed between the anvil 430 and the housing. The impact damper 482 may be disposed, for example, at the end of the anvil 430 contacted by the hammer 420. When a surgeon or robot pushes a surgical instrument 485 coupled to the anvil onto a bone surface, the anvil compresses at least one spring 440 (and in one embodiment, a linear actuator spring 441 and a rotary spring 442), which allows for both linear and rotary impacts.

[0064] In this embodiment, a rotary impact similar to that performed by tools 200 and 300 as disclosed elsewhere in this document is performed by tool 400. In one embodiment, motor 410 provides the rotational motion of torqspline 415. Torqspline 415 includes a guide nut 416 that rotates as torqspline 415 rotates. Hammer body 420 is operatively coupled to guide nut 416 such that hammer body rotates together with guide nut 416. As hammer body 420 rotates, it selectively engages and rotates output anvil 430.

[0065] In one embodiment, the hammer body 420 includes at least one tooth or other protrusion 421 extending longitudinally away from the face 422 of the hammer body 420. In one embodiment, the output anvil 430 includes at least one tooth or other protrusion 431 extending laterally away from the body 432 of the anvil. In one embodiment, at least one tooth (or protrusion) 421 of the hammer body can engage at least one tooth (or protrusion) 431 of the output anvil 430 such that when the hammer body 420 rotates, this engagement causes the output anvil 430 to rotate. The rotation can continue until a sufficiently high load is applied to the output anvil 430 (e.g., during surgical reaming, the tool encounters a bone spur) causing the output anvil 430 to stop rotating. This causes the hammer body 420 to also stop rotating due to the still-engaging protrusions 431 and 421 of the output anvil 430 and the hammer body 420.

[0066] In one embodiment, spring 440 is disposed between guide nut 416 of tool 400 and motor 410. In one embodiment, spring 440 comprises a wave spring. Clearly, the coil of spring 440 facilitates the placement of spring 440 around torqspline 415. In one embodiment, torqspline is continuously rotating. In such an embodiment, when hammer 420 stops rotating, guide nut 416 and the hammer 420 to which it is attached will translate backward (away from output anvil 430). This backward translation of guide nut 416 and hammer 420 causes spring 440 to be compressed. Translation and compression continue until hammer 420 has moved a sufficient distance backward such that at least one protrusion 421 of hammer 420 has disengaged from at least one protrusion 431 of output anvil 430.

[0067] Once the hammer 420 has moved backward a sufficient distance, such that at least one protrusion 421 has disengaged from at least one protrusion 431 of the output anvil 430, the hammer continues to rotate until its teeth slide past the teeth of the anvil. Then, the rotational spring 442 decompresses to drive the hammer 420 to rotate at high speed along the torqspline 415 toward the output anvil 430 and the impact buffer 482. This high-speed rotational motion of the hammer 420 will cause a severe rotational impact on at least one protrusion 431 of the output anvil 430. This force on the output anvil 430 should be sufficient to allow the impact tool 400 to overcome any bone structure or deformity that hinders the reaming action. In one embodiment, the motor 410 can be programmed to increase its speed as the hammer 420 is pulled backward (meaning a threshold torque has been reached and a rotational impact is set). This helps maintain a constant output speed, both during the rotational impact phase and the constant rotation phase.

[0068] As the hammer 420 moves downward along the torqspline 415 due to the decompression of the rotary spring 442, both linear and rotational energy can be available for the anvil 430 to impact the surgical site. That is, depending on the degree of compression of the linear actuator spring 441 before the hammer moves downward along the torqspline, the tool can apply both linear and rotational impacts to the anvil 430. In one embodiment, an impact buffer 482 facilitates the transfer of linear impact force and force from the hammer 420 to the output anvil 430. In one embodiment, as a result of the decompression of the rotary spring 442, the surface 422 of the hammer 420 impacts the impact buffer 482, which transmits the linear impact to the anvil 430.

[0069] It is evident that when the tool 400 is placed on the surgical site, 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 positioned on the surgical site, the user can increase the compression of the spring 441 by applying additional pressure to the tool 400. If the spring 441 is sufficiently compressed such that it has no time (depending on the spring constant) to expand before the linear impact and force from the hammer 420 is transmitted to the output anvil 430, the anvil 430 will receive the linear force and transmit it 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 is absorbed by rotation or by the stop damper 481.

[0070] This disclosure provides the following advantages: reduced reaction forces from the surgical instrument to the gripping and / or mounting surfaces. Another advantage is that the tool will provide the sufficient amount of force required to complete the surgery without external forces (e.g., forces applied by the surgeon to the reamer handpiece to advance the reamer at the surgical site). In the case of robotic surgery, this reduces wear on the robotic platform and reduces surgeon fatigue. It also improves the accuracy and capability of the robot in the case of robotic surgical instruments and can significantly reduce the occurrence of registration loss in surgical robots.

[0071] For purposes of illustration and description, the above description of specific embodiments of this disclosure has been given. They are not intended to be exhaustive or to limit this disclosure to the exact form disclosed, and many modifications and variations will obviously be made in accordance with the foregoing teachings. The exemplary embodiments described were chosen and described in order to best explain the principles of this disclosure and its practical application, thereby enabling those skilled in the art to best utilize the contents of this disclosure and various embodiments, and to make various modifications according to the particular purpose contemplated.

Claims

1. A rotary impact tool for orthopedic surgery, the rotary impact tool comprising: case, motor, Impact hammer body, Output anvil, Lead screw components, and Energy storage devices The energy storage device is located near the impact hammer during a portion of the operating cycle of the rotary impact tool. The impact hammer is mounted on the lead screw element and rotated by the motor, wherein the impact hammer contacts the output anvil, causing the output anvil to rotate selectively. When the output anvil stops rotating, the impact hammer translates along the lead screw element to energize the energy storage device. Wherein, after the impact hammer body moves a sufficient distance away from the output anvil, the energy storage device transfers its energy to the impact hammer body, causing the impact hammer body to accelerate and rotate along the lead screw element to impact the output anvil.

2. The rotary impact tool according to claim 1, characterized in that, When the threshold torque exceeds 10 inch-pounds, the impact hammer is powered by the energy storage device.

3. The rotary impact tool according to claim 1, characterized in that, The rotary impact tool also includes a surgical instrument and a damping mechanism that reduces the reaction torque to less than 50% of the peak torque applied to the surgical instrument.

4. The rotary impact tool according to claim 1, characterized in that, Linear impact is limited to a stroke of less than 1 mm per impact.

5. The rotary impact tool according to claim 1, characterized in that, The transition between impact and non-impact includes auditory signals.

6. The rotary impact tool according to claim 1, further comprising a sensor that, if the tool advances less than 0.01 mm in 10 impacts, causes the rotary impact tool to shut down, decelerate, and emit light.

7. The rotary impact tool of claim 1, further comprising a sensor, wherein the position of the rotary impact tool is determined between impacts and after the rotary impact tool has recovered at least 90% of its original position.

8. The rotary impact tool according to claim 1, characterized in that, The linear impact force is applied to the surgical site depending on the amount of force applied to the rotating impact tool by the operator or surgical robot.

9. The rotary impact tool according to claim 1, further comprising a control device, wherein during rotary operation or rotary impact, the motor speed is adjusted to maintain a constant output rotational speed.

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