Orthopedic devices that deliver controlled, repeatable impacts

Abstract

A motor-driven orthopedic impact tool is provided for orthopedic impacts in the hip, knee, shoulder, etc. The tool can accommodate a puller, bone chisel, or other end effector. When gently tapped into a cavity with controlled impact, the tool can enlarge the size or volume of the cavity opening, or facilitate the removal of the puller, implant, or other surgical instrument from the opening. An energy storage drive mechanism stores potential energy and then releases it to launch a projectile or firing pin, thereby transmitting the impact force to an adapter in a forward or reverse direction. The tool may further include a combined anvil and adapter, as well as an energy regulation mechanism to adjust the impact force transmitted from the projectile to the adapter according to the patient's condition.

Description

[0001] Cross-reference to related applications

[0002] This application is a continuation-in-part of U.S. Patent Application No. 15 / 439,692, filed February 22, 2017, and also claims priority to U.S. Provisional Patent Application No. 62 / 393,975, filed September 13, 2016, and U.S. Provisional Patent Application No. 62 / 381,864, filed August 31, 2016, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to locally powered tools for delivering impacts in surgical applications, such as orthopedic surgery, and more specifically to handheld motor-driven tools for bidirectional surgical impacts driven by a launching mass to deliver controlled, repeatable impacts to a puller or other end effector. Background Technology

[0004] In the field of orthopedics, prosthetic organs (such as artificial joints) are frequently implanted or placed into a patient's bone cavity. The cavity is typically created during the surgical procedure before the prosthesis is inserted or implanted; for example, a surgeon may remove and / or compress existing bone to create the cavity. The prosthesis usually includes a stem or other protrusion that can be inserted into the cavity.

[0005] Surgeons can create a cavity using a retractor shaped to conform to the stem of the prosthesis. Known approaches in the art include providing a retractor handle that the surgeon manually taps during the procedure to push the retractor into the implantation area. Unfortunately, this method is crude and notoriously inaccurate, resulting in unnecessary mechanical stress on the bone. The outcome may be unpredictable and dependent on the surgeon's skill. Historically, this method has often led to inaccuracies in the location and structure of the cavity. Furthermore, the surgeon expends considerable physical and mental effort tapping the retractor and manipulating the bone and prosthesis. Most importantly, this method carries the risk of causing unnecessary further trauma to the surgical area and damaging other healthy tissues, bone structures, etc.

[0006] Another technique for creating a prosthetic cavity is to pneumatically (i.e., by compressed air) drive a broach. The disadvantages of this method are that it hinders the portability of the impact tool, for example, due to the presence of a tethered air line to allow air to escape from the tool into the sterile operating area, and the fatigue of the surgeon operating the tool. As shown in U.S. Patent No. 5057,112, this method does not allow for precise control of the impact force or frequency; instead, it functions more like a hand drill during actuation. Secondly, the lack of any measurement for precise control makes accurate briquetting of the cavity more difficult, leading to unnecessary complications and trauma for the patient.

[0007] The third technique for creating cavities relies on computer-controlled robotic arms. While this method overcomes the problems of fatigue and accuracy, it suffers from very high costs and also eliminates the tactile feedback that surgeons can obtain from manual methods.

[0008] The fourth technique relies on the inventor's previous work and uses a linear compressor to compress air on a single-stroke basis. After sufficient pressure is generated, the air is released through a valve onto a firing pin. This pin then travels down a conduit and impacts an anvil containing a scalpel and / or other surgical instruments. However, due to the air pressure, this arrangement results in enormous forces in the gear train and linear motion converter components, leading to premature wear of these components.

[0009] The fifth technique also relies on the inventor's previous work, using a linear actuator to create a vacuum to stop the brake. After a sufficient vacuum volume is generated, the stop releases the firing pin and allows it to travel down the guide tube and impact the anvil containing a scalpel or other surgical instrument. However, this arrangement places excessive stress on the drive components and is subject to environmental conditions (such as atmospheric pressure). Furthermore, this technique is limited in its ability to generate reverse or rearward impacts.

[0010] Therefore, there is a need for an impact tool with improved drive components that overcome the various shortcomings of existing systems and previous solutions by the inventors. Summary of the Invention

[0011] In view of the above-mentioned drawbacks, a motor-driven orthopedic impact tool is provided for orthopedic impacts in the hip, knee, shoulder, etc. This tool can accommodate a puller, chisel, or other end effector and uses controlled percussion impacts to gently tap the puller, chisel, or other end effector into the cavity, thereby better fitting the prosthesis or implant. Furthermore, the control provided by this electrically operated puller, chisel, or other end effector allows the impact settings to be adjusted according to the patient's specific bone type or other profile. This tool also enables proper positioning and, with bidirectional movement, the insertion or removal of the prosthesis or implant into or out of the implantation cavity, and advantageously enhances the surgeon's skill in controlling existing instruments.

[0012] In an exemplary embodiment, the motor-driven orthopedic impact tool includes: a local power source (such as a battery or fuel cell), a motor, a controller, a housing, a method for converting rotational motion into linear motion (hereinafter referred to as a linear motion converter), an energy storage drive system or mechanism (such as a gas spring or mechanical spring capable of storing and releasing potential energy), and an impact pin excited by said energy storage drive system that operates in a forward and / or backward direction, wherein the impact pin is capable of generating impact forces on surgical instruments. The tool may further deliver focused illumination to the surgical area via a semiconductor light source (such as an LED) or a conventional incandescent light source. A handle may be provided for a surgeon to hold the tool, or a suitable mounting interface may be provided for integrating the tool into a robotic assembly. A local power source (such as a battery) may also be included. Typically, at least some of the various components are preferably contained within the housing. The tool is capable of applying cyclic, repeatable impact forces to a puller, chisel, or other end effector or implant. Given the repeatability of the impact forces, it is also conceivable that the impact forces can be fine-tuned to multiple levels. For this purpose, multiple gas springs can be supplied as a kit with the device, allowing different visually coded gas springs to be detachably introduced into the tool as needed during surgery to provide a range of driving forces.

[0013] Regarding the energy storage drive system, this system is preferably actuated by a cam via a combination of a motor and gearbox. The cam rotates in a first direction, compressing a spring and storing potential energy within the energy storage drive system. The cam continues to rotate further and releases the stored energy, which in turn can accelerate the mass to generate a forward impact force on the drive assembly. As an example, after sufficient displacement of a mechanical or gas spring, where the stored potential energy increases, the cam continues to rotate until it moves past its point of release, where it stops acting on the mass, and then releases the stored energy. Upon release, the stored potential energy accelerates the mass in a forward direction until it effectively contacts the point of impact (such as an anvil or another impact surface). Conversely, for a bidirectional impact system, the cam can alternatively rotate in the opposite, second direction, compressing the spring and again storing potential energy within the spring storage system. The cam continues to rotate further to its point of release, where it stops acting on the spring storage system, and the spring storage system can release the stored energy, which in turn can accelerate the mass to generate a backward impact force. For example, after the spring has been fully displaced (where the potential energy stored in the spring increases), the cam continues to rotate until it moves past the release point where it stops acting on the mass, and then releases the energy storage drive system (or mechanism). Upon release, the potential energy in the energy storage drive system causes the mass to accelerate in the opposite, rearward direction until it operatively contacts the point of impact (such as an anvil or another impact surface).

[0014] In an exemplary embodiment, the ejector mass (which may comprise part or all of the energy storage drive system) separates from the pusher or actuating surface before its point of impact. Therefore, in this embodiment, a surprisingly high efficiency is achieved because the entire energy storage drive system is the ejector mass. In another embodiment using a mechanical spring, the spring's compression ratio is approximately less than 50% of its free length, and more preferably, less than 40% of its free length. The inventors have found that this compression ratio increases the consistency of the transmitted impact energy and reduces the likelihood of permanent spring deformation.

[0015] In another exemplary embodiment, the handle may be repositionable or foldable back into the tool to reveal an inline tool, in which the surgeon pushes or pulls the tool collinearly with the direction of the puller. This has the advantage of limiting the amount of torque the surgeon can place on the tool during manipulation. In further refinements to the handle, additional handles may be present to guide the surgical instrument during impact operations and provide increased stability. In yet another embodiment, the tool may be attached to a robot, thereby eliminating the need for a handle, and the tool may use a tethered or remote power source.

[0016] In another exemplary embodiment, the broach, bone chisel, or other end effector can be rotated to multiple positions while maintaining axial alignment, for example, as... Figure 9 As shown, the adapter is rotatable in four different positions, each capable of being rotated 90°. This facilitates various anatomical demonstrations during surgery using the adapter or retractor.

[0017] In an exemplary embodiment, the anvil of the tool includes at least one of two impact points (a forward impact surface or a first surface and a rearward impact surface or a second surface), and a guiding assembly, such as a guide roller, bearing, or polytetrafluoroethylene (PTFE) or Teflon track, to constrain the movement of the striker in a generally axial direction. The resultant force of the striker's impact point and the surgical tool can be directed in both forward and reverse directions. In bidirectional impact operation, when a forward force is generated on the surgical tool, the striker moves along the guiding assembly and continues in the forward direction. A steering mechanism can be used to change the resultant force of the striker's impact point and the surgical tool. Using such a steering mechanism generates a rearward force applied to the anvil and / or pull cutter or other surgical attachments. As used herein, "forward direction" means movement of the striker toward the pull cutter, chisel, or patient, while "reverse direction" means movement of the striker away from the pull cutter, chisel, or patient. The selectivity of bidirectional or unidirectional impact provides surgeons with flexibility when cutting or compressing material within the implant cavity, as the choice between material removal or compression is often a critical decision in surgery, as discussed, for example, in U.S. Patent No. 8,602,124. Furthermore, based on the inventors' own prior work, it has been found that if the reverse impact force can be approximated as the forward impact force, the tool can be used for a wider range of surgical procedures. In embodiments, the forward and backward forces impact at least two separate and distinct points.

[0018] In an exemplary embodiment, the anvil and the adapter comprise a single element, or one may be integrally formed with the other.

[0019] As shown in U.S. Patent No. 6,938,705, in a typical impactor used in demolition work, changing the speed alters the impact force, making it impossible to maintain a constant (defined as + / - 20%) impact energy during variable-speed operation. Therefore, in an exemplary embodiment, the tool includes a control element or controller that includes an energy regulating element or mechanism, and this energy regulating element can control the impact force of the tool by controlling the storage and release of energy output from the energy-driven mechanism. The energy can be regulated electrically or mechanically (e.g., see...). Figure 9 (Switch 34 in the middle). Furthermore, the energy adjustment element can be analog or have fixed settings. This control element allows for precise control of the impact operation. The energy adjustment element allows the surgeon to increase or decrease the impact energy of the tool according to the patient's condition.

[0020] In another exemplary embodiment, the tool can also, for example, use Figure 9The mechanical switch 36 shown controls the frequency of the striking pin's impact motion. By adjusting the striking pin's frequency, the tool can, for example, impart a greater total weighted time of striking impact while maintaining the same impact magnitude. This allows the surgeon to control the cutting speed of the retractor or chisel. For example, the surgeon can choose to cut at a faster rate (higher frequency impact) for most of the retractor or chisel's movement, and then slow the cutting rate as the retractor or chisel approaches the desired depth. Indeed, during testing of the tool, it was found that a higher frequency impact rate (such as 3 impacts per second, more preferably, up to 10 impacts per second) combined with a fixed energy per impact (such as between 2 and 6 joules per second, more preferably up to 40 joules per second) allows the surgeon to better position specific surgical instruments. For example, in acetabular placement, it was found that an impact frequency of at least 3 impacts per second with energy of 2 to 6 joules per second resulted in better control of the acetabulum's position than previous manual striking techniques.

[0021] In an exemplary embodiment, the energy storage drive mechanism or energy storage and release mechanism mechanically or electrically defines the operating point. Therefore, the energy of each impact is delivered according to the selected operating point. In fact, the energy of each impact can be controlled to be greater than 20%. In yet another embodiment, a timing element can be incorporated into the system so that impacts can be delivered at a predetermined frequency selected by the user. The use of electronic control elements or controllers and precise control of the impact rate allows the surgeon to control the total energy delivered by the tool.

[0022] In an exemplary embodiment, the direction of the impact is controlled by a biasing force applied by the user to the tool and detected by a sensor (such as a locator sensor) on the anvil. For example, biasing the tool in a forward direction causes the projectile to be launched forward and generate a forward impact, while biasing the tool in a backward direction causes the projectile to be launched backward and generate a backward impact.

[0023] In an exemplary embodiment, the tool may have an illumination element to illuminate the work area and accurately position the broach, chisel, or other end effector at the desired location on the prosthesis or implant.

[0024] In an exemplary embodiment, a buffer is pre-positioned between the head of the piston and the end of the firing pin, thereby reducing impact stress and extending the life of the entire assembly.

[0025] In an exemplary embodiment, the tool may also include a feedback system that warns the user of no progress when a bending or offline orientation exceeding a certain size is detected at the puller, chisel, or other end effector, implant interface, or orthopedic device.

[0026] In an exemplary embodiment, the tool may also allow for interchangeable cylinders to vary the impact force. These cylinders can be evaluated based on the total energy delivered by the energy storage system when actuated by the linear motion converter. For example, low-power cylinders limited to a range of 2 to 3 joules or less can be used for cartilage or osteoporotic bone. For young, hard bone, a power cylinder with an impact energy of 4 joules or more can be selected. By allowing for a variety of cylinders, which in one embodiment can be visually encoded according to power, the surgeon can flexibly determine the impact energy for each cycle by simply selecting the appropriate power cylinder from the toolbox.

[0027] These features, along with other aspects of this disclosure and various features characterizing the novelty of this disclosure, are specifically pointed out in the appended claims and form part of this disclosure. For a better understanding of this disclosure, its operational advantages, and the specific non-limiting purposes achievable through its use, reference should be made to the accompanying drawings and detailed description in which exemplary embodiments of this disclosure are shown and described. Attached Figure Description

[0028] A more comprehensive understanding of this disclosure and its many accompanying advantages will become more readily apparent when considered in conjunction with the accompanying drawings, and with reference to the following detailed description, wherein:

[0029] Figure 1 A perspective view of an orthopedic impact tool according to an exemplary embodiment of the present disclosure is shown, wherein a mechanical spring assembly system is used to generate a forward impact force;

[0030] Figure 2 Examples Figure 1 An exemplary embodiment of the tool in the embodiment, wherein the cam positions the piston in an operable position to release a forward impact;

[0031] Figure 3 Examples Figure 1 An exemplary embodiment of the tool in which the emitted mass is accelerated toward the point of impact in a forward direction after the stored energy is released;

[0032] Figure 4 A perspective view of an orthopedic impact tool according to an exemplary embodiment of the present disclosure is shown, wherein a mechanical spring is used to generate a rearward impact force;

[0033] Figure 5 Examples Figure 4 Another perspective view of the impact tool from another angle;

[0034] Figure 6 Examples Figure 4 An exemplary embodiment of the tool in the embodiment, wherein a cam of a mechanical spring positions a piston in an operable position to release for a rearward impact;

[0035] Figure 7 Examples Figure 4 An exemplary embodiment of the tool in which the launching mass is accelerated toward the point of impact in a rearward direction after the spring is released;

[0036] Figure 8 This is an exemplary flowchart illustrating the cyclic operation of an orthopedic impact tool according to an exemplary embodiment of the present disclosure;

[0037] Figure 9 An exemplary embodiment of a tool having a mechanical switch for controlling energy and frequency-related parameters is illustrated;

[0038] Figure 10 An exemplary embodiment of a tool having a positioning sensor for determining the direction of an impact is illustrated. Specific Implementation

[0039] A motor-driven orthotic impact tool with controlled percussion impact is provided. The motor can be electric (e.g., brushless), autoclaved, or similar, such as those commonly available from Maxon. and / or The obtained motor. The tool has the capability to perform single or multiple impacts, as well as variable, variable-direction, variable-force, and variable-frequency impacts. In one embodiment, the impact energy is adjustable. In another embodiment, the impact is transmitted to a broach, bone chisel, or other end effector connected to the tool.

[0040] The tool may further include a housing. This housing securely covers and accommodates at least one component of the tool, and the housing is formed of a material suitable for surgical applications, such as aluminum or polyphenylene sulfone (PPSF or PPSU), also known as… In an embodiment, the housing includes: a motor, at least one reduction gear, a linear motion converter, a spring element (preferably a mechanical spring or a gas spring), a firing pin or launching mass, a control circuit or module, an anvil, a first surface or forward impact surface for forward impact, and different second surfaces or rearward impact surfaces for backward impact.

[0041] The tool may further include: a handle portion having an optional handle for comfortable and secure gripping of the tool, or a suitable mounting interface for integrating the tool into a robotic assembly during use, as well as an adapter, battery, position sensor, orientation sensor, and torque sensor. The tool may further provide focused illumination in the surgical work area where the surgeon uses the tool, via a semiconductor light source (such as an LED) or a conventional incandescent light source. The anvil may be coupled to a broach, chisel, or other end effector known in the art via an interface adapter, which may have a quick-connect mechanism to facilitate rapid changes in broaching sizes. The anvil may further include a locking rotating component to allow the tool to be positioned differently to access tissue spaces to tool components (such as the handle).

[0042] In another embodiment, the axis of the launched or ejected mass is preferably axially aligned within 20 degrees of the axis of the adapter along the direction of motion, and more preferably, within 10 degrees of the axis of the adapter. This axial alignment is important in maximizing the energy transmitted to the surgical instrument and minimizing the off-axis forces generated that could lead to adverse surgical outcomes (e.g., fractures).

[0043] Now, for general reference Figures 1 to 7 In an exemplary embodiment, a dual mechanical spring assembly system can be used to generate a bidirectional impact force, for example... Figure 1 As shown. Alternatively, a single mechanical spring assembly can be used. Figure 1A perspective view of an orthopedic impact tool according to an embodiment of the present disclosure is shown, wherein a motor and gearbox 8 of a mechanical spring assembly system is coupled with a linear motion transducer (which includes a cam 12 and a cam follower 13) to actuate a first spring piston 19a (hereinafter referred to as "first piston 19a") and / or a launching mass or firing pin 15 to ultimately generate a forward impact force. It should be noted that a piston generally refers to a pushing or pushing element and can have any of a variety of shapes. The cam 12 is shown as having a symmetrical profile and a double-wedge shape, but this design is contemplated to use any shape that provides rapid release of the spring. Alternatives for actuating and rapidly releasing the spring include, but are not limited to, the use of interrupted racks and pinions or climbing mechanisms. Among other components, the spring assembly system also includes a reduction gear 7 and an anvil 5. The first piston 19a engages a first spring 2a, which can be a mechanical spring or a gas spring. In a mechanical spring assembly system, the deflection with respect to the free length of the spring is preferably less than 50%. Piano wire or, more preferably, stainless steel or titanium, is a suitable material for the spring. Preferably, the spring is a compression spring, but other types of springs are also considered. For example, in a gas spring assembly system, the gas spring operates at pressures ranging from approximately 100 psi to 3000 psi (pounds per square inch). The gas spring is preferably pre-filled with a non-oxidizing gas (such as nitrogen) or an inert gas (such as argon). One advantage of using nitrogen is the ability to include a lower permeation rate through the seals of the gas spring, resulting in a potentially longer shelf life for both the seals and the spring itself.

[0044] Figure 2 yes Figure 1 An exemplary embodiment of the tool in the embodiment, wherein a cam 12 for actuating the first piston 19a "cocked" the first piston 19a into a ready-to-release operating position, or in other words, the motor 8 rotates the cam 12 in a first direction (considered a synonym for counterclockwise), as indicated by arrow 42a, and presses the first piston 19a against the first push plate 26a, thereby storing potential energy in the first spring 2a. During the "cocked phase," the first piston 19a, coupled with the launching mass or firing pin 15, contacts and is pushed by the cam follower 13, which is driven by the cam 12 in the first direction. As the cam 12 continues to rotate in the first direction, the energy stored in the first spring 2a increases until the cam 12 moves past its stop and acts on the firing pin 15 (e.g., see...). Figure 3The release point of the first piston 19a. The firing pin (or launching mass) 15 now travels freely under the potential energy stored in the first spring 2a. Specifically, after the first piston 19a has been fully displaced, and after the cam 12 releases the combination of the first piston 19a and / or the launching mass 15, the first piston 19a moves in a forward direction, i.e., toward the impact point, and simultaneously accelerates the launching mass or firing pin 15 that is in contact with the surface of the first piston 19a. For example, as Figure 3 As shown, the first piston 19a is released from the firing pin 15, which fires it toward the anvil 5. Unexpectedly, it was found in this invention that the release of the firing pin 15 from the push plate 26a essentially produces a portion of free flight during its stroke, significantly reducing the recoil force generated and borne by the surgeon's hand, resulting in a more controllable tool. The firing pin 15, now fired toward the end of the tool near the end effector or patient, then strikes the first surface or forward impact surface of the anvil 5, wherein the maximum displacement of the anvil upon contact with the firing pin is less than 15 mm. It was unexpectedly found that when the maximum forward displacement of the anvil is limited to less than 15 mm, and more preferably less than 10 mm, the surgeon achieved better results during tool testing, in terms of precision and accuracy. By limiting the stroke, the resulting surgical procedure was performed more accurately and better aligned with surgical objectives compared to a larger stroke. In stark contrast, the use of a mallet, for example, during surgery typically results in displacements of 20 mm or more, leading to lower accuracy during the procedure.

[0045] The impact of the firing pin 15 on the anvil 5 transmits a forward impact force to the adapter (not shown) and from there to the broach, chisel, or other orthopedic instrument. The firing mass or firing pin 15 can be constructed of a suitable material, such as steel or any other material with similar properties, allowing for repeated impacts. In embodiments, the weight or mass of the firing mass or firing pin 15 is preferably less than 25% of the weight or mass of the tool, and the firing mass 15 has a certain amount of free flight before contact; both factors contribute to further reducing the resulting recoil force.

[0046] In another embodiment, it was unexpectedly found that by increasing the weight or mass of the emitter mass relative to the weight or mass of the anvil, the impact energy was transferred to the surgical instrument more efficiently. For example, when the ratio of the mass of the emitter mass to the mass of the anvil was less than 25%, the resulting transfer efficiency was extremely low, i.e., less than 50% relative to a typical coefficient of restitution of 0.8. Similarly, it was found that a mass ratio below 50% produced the lowest impact transfer efficiency.

[0047] In another embodiment, for example, such as Figure 2As shown, as the firing pin 15 moves rearward toward the push plate 26a, the buffer 14a acts as a stop to prevent the end face of the piston 19a from impacting the firing pin 15. The buffer 14a absorbs the impact of the piston 19a immediately before the ejector mass or firing pin 15 is launched in the forward direction. During the invention process, it was discovered that excessive wear and tear, leading to piston 19a failure, would occur if the piston 19a were not stopped moving on the buffer 14a. Therefore, in repeated operation, such a buffer 14a prevents damage to the spring assembly system, particularly the piston 19a. The buffer 14a can be made of plastic or, more preferably, rubber or polyurethane.

[0048] As stated above, the inventors have determined that previous designs occasionally resulted in surgical instruments becoming stuck in the biocavity and that the impact of the firing pin 15 in the rearward direction might not be sufficient to pull the instrument out. Furthermore, it was found that in order to pull out the surgical instrument, the rearward force needed to be transmitted as a sharp contractile impact. Therefore, in this bidirectional impact system, there are at least two distinct impact surfaces, and when the instrument is pulled out of the cavity, the firing pin 15 will impact another surface on the anvil 5, thereby transmitting the rearward force to the anvil 5.

[0049] For example, Figures 4-7 A perspective view of an orthopedic impact tool according to an embodiment of the present disclosure is shown, wherein the motor and gearbox 8 of the mechanical spring assembly system rotate the cam 12 in a second direction (considered a synonym for clockwise), as indicated by arrow 42b, and launches the mass or striker 15 to ultimately generate a rearward impact force. Figure 4 This shows that cam 12 is rotating; similarly, Figure 5 yes Figure 4 Another perspective view of the impact tool shown from another angle. As the motor 8 continues to rotate the cam 12 in the second direction, the second spring piston 19b (hereinafter referred to as "second piston 19b") engages the second spring 2b and presses against the second push plate 26b, thereby storing potential energy within the second spring 2b. The second piston 19b is then "flipped up" to the ready-to-release operating position (see...). Figure 6 During the "flip-up phase," the second piston 19b, which engages with the launching mass or firing pin 15, contacts and is actuated by the cam follower 13. For example, in Figure 6 and Figure 7 As shown, the end face of the firing pin or launching mass 15 includes a pair of extensions or protrusions 32, which are integral with the launching mass 15 or provided as separate elements bolted to the launching mass 15. As the cam 12 continues to rotate in the second direction, the energy stored inside the second spring 2b increases until the cam 12 moves past its release point where it stops acting on the firing pin 15 (see, for example, [reference needed]). Figure 7The firing pin or launching mass 15 now travels freely under the potential energy stored in the second spring 2b. Specifically, after the second piston 19b has been fully displaced, and after the cam 12 releases the combination of the second piston 19b and / or the launching mass 15, the second piston 19b moves in a rearward direction, i.e., toward the point of impact, and simultaneously accelerates the launching mass or firing pin 15 in contact with the surface of the second piston 19b. For example, as... Figure 7 As shown, the second spring 2b is released from the firing pin 15, which launches it from the end of the tool near the end effector or the patient. The extension or protrusion 32 of the launching mass 15 impacts another, second, or rearward impact surface of the anvil 5, thereby applying a rearward impact force to the anvil 5 in a striking manner.

[0050] Similar to Figure 2 The spring buffer 14a shown, and as described above, as the piston 19b moves in the rearward direction, Figure 4 The spring buffer 14b shown also acts as a stopper to prevent the end face of the piston 19a from impacting the firing pin 15. The buffer 14b absorbs the impact of the piston 19b immediately before the ejector mass or firing pin 15 is launched in a rearward direction. As mentioned above, it was found during the invention process that excessive wear would occur if the piston 19b was not stopped moving on the buffer 14b, leading to piston 19b failure. Therefore, in repeated operation, such a buffer 14b prevents damage to the spring assembly system, particularly to the piston 19b. Similar to the buffer 14a, the buffer 14b can be made of plastic or, more preferably, rubber or polyurethane material.

[0051] In an exemplary embodiment, such as Figure 10 As shown, the direction of the force on the anvil 5 is controlled by the manual force exerted by the user (such as a surgeon) on the tool, which is detected by sensor 28, which may be a positioning sensor located on the anvil 5. For example, biasing the tool in the forward direction causes the firing mass or firing pin 15 to be fired forward and deliver a forward impact, while biasing the tool in the backward direction causes the firing pin 15 to be fired backward and deliver a backward impact.

[0052] In an embodiment, for example, in Figure 5As shown, when the cam 12 assembly completes its stroke, it preferably actuates a sensor 22 operatively coupled to the controller 21. The sensor 22 assists in regulating the preferred cyclic operation of the cam 12. For example, the sensor 22 can signal the motor 8 to stop, causing the cam 12 to be at or near the point of minimum potential energy storage. Thus, in a complete cycle, a forward or backward impact force can be applied to a broach, chisel, or other end effector, or to an implant or prosthesis. In another embodiment, it is advantageous to insert a delay or calculate the number of impacts for any given procedure before starting the next cycle, enabling precise control of the impact rate and, in turn, allowing the surgeon to precisely control the efficiency of energy transfer under any given operation. In another embodiment, it is advantageous to stop the cam 12 near the point of maximum potential energy storage to reduce delay in the surgeon's hands. As defined, delay is the time between the surgeon's (or user's) activation of the orthopedic impact tool and the tool actually producing an impact. The inventors have determined that a delay of approximately 100 milliseconds or less is essentially considered an instantaneous response. By stopping the cam 12 at a point where at least some potential energy has been stored, the tool has the function of releasing the potential energy almost instantaneously when the tool trigger 30 is actuated.

[0053] In another embodiment, an additional sensor (not shown) can be used to detect that the surgical instrument has not advanced between the impacts. If the surgical instrument has stopped advancing for less than 10 seconds, or more preferably less than 3 seconds, the tool can provide feedback to the surgeon. This feedback can be provided by light, reducing or stopping the impact, or other means. The surgeon will then have the opportunity to evaluate the surgery and determine whether to restart the impact operation.

[0054] Figure 8This is an exemplary flowchart illustrating the cyclic operation of an orthopedic impact tool according to an exemplary embodiment of the present disclosure. At the start of the cycle, a trigger is pressed in step 800, and in step 802, it is first determined whether the orthopedic impact tool is charged and ready for use. If the voltage of the local power source (e.g., a battery) is less than a minimum threshold, the battery is set to charge in step 804. If the battery voltage is greater than the minimum threshold, then in step 806, it is determined whether the anvil and / or puller or other surgical attachment is correctly positioned relative to the cavity of the patient's bone. If the anvil and / or puller or other surgical attachment is correctly positioned, the operation proceeds to step 810; otherwise, the system waits until the position is corrected in step 808. Next, in step 810, it is determined whether a decision has been made regarding which direction the motor and gearbox should be rotated, based on whether the tool is used to generate a forward or backward impact force. If the rotation direction has been determined, then in step 814, the motor and gearbox assembly begins to rotate to complete the impact cycle; otherwise, the system waits until the rotation direction is determined in step 812. Once the motor gearbox completes the impact cycle, step 816 determines whether the cam sensor has been activated. If the sensor is activated, the process proceeds to step 818 to determine whether the trigger should still be maintained; otherwise, the process returns to step 814 to allow the motor to continue rotating until the cam sensor has been activated. If the trigger is maintained in step 818, the operation cycle returns to step 814, where the motor continues to rotate, causing the tool to continue generating impacts; otherwise, the operation of the straightening impact tool is stopped in step 820.

[0055] Controller 21 preferably utilizes the implementation Figure 8 The firmware described herein operates in a cyclic manner, enabling the orthopedic impact tool to generate repeatable, controlled impact forces. The controller 21 may include, for example, intelligent hardware devices, such as any data processor, microcontroller, or FPGA device, such as those manufactured by Intel Corporation (Santa Clara, CA) or AMD (Sunnyvale, CA). Other types of controllers may also be used, as those skilled in the art will recognize.

[0056] Advantageously, the piston and spring assembly system requires no or no brakes or magnets to generate high-energy impacts. Taking into account factors such as spring constant, spring preload, and total spring compression during the operating cycle, the magnitude of the system's energy output is consistent for any given set of operating conditions. For any given operating cycle, the impact energy output from the energy storage drive system is between 1 joule and 10 joules, varying by no more than 20%, and more preferably no more than 10%. For example, an impact tool may include a spring with a spring constant of 100 pounds per inch, operating at a preload force of 100 pounds, and a spring with a cam stroke of 0.5 inches, minus friction and other losses, such that the energy storage drive system outputs a total impact energy of approximately 7.1 joules.

[0057] In this bidirectional impact system, the efficiency of the piston and spring assembly mechanism in the rearward direction is approximately 80%, compared to approximately 20% in existing designs. For example, in the inventors' previous design, a forward impact of 3.5 joules (J) of energy resulted in a rearward impact of approximately 0.4 J of energy, leading to a loss of nearly 80% of the energy, which is undesirable.

[0058] The inventors have determined that the mass ratio and materials of the projectile or impactor, anvil, and adapter are crucial for effectively transferring the kinetic energy of the thrown mass to the surgical instrument. For the purposes of this invention, the ratio of energy transferred to the surgical instrument as a function of the kinetic energy in the projectile or impactor is called the transfer function. The transfer function is used to measure performance in terms of how effectively the tool performs shoveling, impact, or extraction procedures. For example, in a design where the projectile, anvil, and adapter are all made of rigid stainless steel, the ratio of energy transferred to the surgical instrument to the kinetic energy of the projectile is found to be less than 50%. By increasing the mass ratio of the projectile to the impacted mass (the sum of the masses of the anvil, adapter, and surgical instrument), the efficiency of the system, particularly the transfer function, increases to greater than 60%, and in many cases, approaches 75%.

[0059] Furthermore, it was unexpectedly found that spring life and impact consistency were maximized by keeping the spring compression ratio less than 50% of its free length, and more preferably less than 30%. An unintended effect was the generation of more consistent impact between the firing pin 15 and the anvil 5, a result of the spring not undergoing permanent deformation. In fact, because the impact energy is only slightly affected by environmental conditions, the consistency of impacts generated by gas springs or mechanical springs was found to be within + / -10% of the nominal design value.

[0060] For example, the tool can further facilitate controlled, continuous impacts, which depend, for instance, on the position of a trigger switch 30 operably coupled to a power source or motor. For such continuous impacts, the tool can complete the entire cycle proportionally to the position of the trigger switch 30, for example, after the trigger switch is activated. Therefore, whether in a single-impact or continuous-impact operating mode, the surgeon can easily control the creation or shaping of the surgical area.

[0061] As discussed above, this tool can vary the amount of impact energy per cycle by selecting appropriate internal pressure, for example, for a replaceable gas spring cylinder (not shown) or a different mechanical spring in the energy storage drive system. It is understood that since the drive mechanism for applying potential energy to the gas spring is a fixed stroke, different impact energies can be obtained in any given surgery by simply using spring cylinders with different preloads or spring constants. In another embodiment, the amount of compression in the energy storage drive system can be varied, for example, by changing the position of the push plate, using elements such as linear cams. By controlling the impact energy, surgeons have greater flexibility during surgery.

[0062] In yet another embodiment, the tool may be further designed to facilitate the extraction of a well-fixed implant or a "potted" puller. In this embodiment, the cam 12 rotates in the second direction, clockwise 42b, and launches the mass or firing pin 15, causing the firing pin 15 to move away from the patient, thereby inducing a retracting or rearward force on the anvil 5.

[0063] The tool may further include a flexible element (not shown) inserted between the impact pin 15 and the anvil 5. Preferably, the flexible element is an elastic material that recovers well from impact and exerts minimal damping on the total energy. As an example, a polyurethane assembly can be inserted at the interface between the impact pin 15 and the anvil 5. In another embodiment, the flexible element can be inserted in such a way that it reduces the impact force only in the forward direction without affecting the desired sharp impact force in the rearward direction. This type of flexible element can limit the peak force during the impact process, thereby eliminating such peaks that could cause fractures in the patient's bones, while maintaining the high peak forces required to retract and lock a pull-back scalpel or other surgical instrument.

[0064] In yet another embodiment, it is understood that the impactor may, for example, be coupled to a robot, thereby potentially eliminating the need for a portable power source (battery) and / or a handle on the tool.

[0065] In another embodiment, the coupling of the adapter (not shown) to the tool may include linkages or other adjustment mechanisms known in the art, enabling modification of the position of the broach, chisel, or other end effector without requiring the surgeon to rotate the tool. The orthotic tool disclosed herein offers various advantages over the prior art. It helps control the impact on the surgical site, thereby minimizing unnecessary damage to the patient's body, and allows for precise shaping of the implant or prosthesis seat. The tool also allows the surgeon to adjust the direction, force, and frequency of the impact, which enhances the surgeon's ability to manipulate and control the tool. For example, depending on the ongoing surgical procedure, the orthotic tool may be used solely for retraction purposes. Similarly, the tool can be customized to have different forward and reverse impact forces. For example, in a mechanical spring assembly system, different metering springs can be used for forward and reverse impacts. Force and flexibility control adjustments to the impact settings allow the surgeon to set the impact force according to the patient's specific bone type or other contour parameters. Furthermore, improved efficiency and reduced linear motion converter load allow for the use of smaller batteries and lower-cost components. Thus, the tool enables the proper placement or removal of a prosthesis or implant from the implantation cavity. Additionally, the piston and spring assembly provides a simple means of adjusting the impact energy for a specific surgical procedure. Furthermore, since the spring assembly is largely governed by the mechanical properties of the spring (such as deflection, preload, and spring constant), the resulting tool possesses predictable impact energy independent of the operating speed. Additionally, in one embodiment where the gas spring cylinder is replaceable, highly worn components (such as seals and pistons) can be replaced during each procedure, resulting in a more robust, longer-lasting tool and fewer points of failure.

[0066] The foregoing description of specific embodiments of this disclosure has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit this disclosure to the exact forms disclosed, and it will be apparent that many modifications and variations can be made in accordance with the foregoing teachings. Exemplary embodiments were chosen and described in order to best explain the principles of this disclosure and its practical application, thereby enabling others skilled in the art to best utilize this disclosure and the various embodiments with various modifications to suit their intended particular use.

Claims

1. A surgical impact tool, comprising: Mechanical springs, configured to release energy stored therein to drive operable, linked surgical instruments; A cam, configured to rotate and thereby store energy in the mechanical spring; An electric motor configured to drive the rotation of the cam; An electronic controller configured to control the motor and monitor and manage the storage and release of energy in the mechanical spring; An adapter configured to be fastened to the surgical instrument; A mass, configured to transmit an impact force in response to the released energy to a surgical instrument fastened to the adapter, causing the surgical instrument to advance relative to the surgical target; as well as A sensor, operatively connected to the controller and configured to sense whether the surgical instrument has not yet moved forward in response to the transmitted impact force, wherein the controller is configured to provide feedback to the user of the tool in response to the sensor sensing that the surgical instrument has not yet moved forward in response to the transmitted impact force.

2. The surgical impact tool according to claim 1, further comprising: Anvil, The mass can be manipulated to impact the anvil.

3. The surgical impact tool according to claim 1, further comprising an energy adjustment mechanism configured to adjust the released energy according to the patient's condition.

4. The surgical impact tool according to claim 1, wherein, The amount of impact energy transmitted during each impact is constant.

5. The surgical impact tool according to claim 1, wherein, The mass has an axial orientation that is offset from the axis of the adapter by no more than 10 degrees.

6. The surgical impact tool according to claim 1, wherein, The adapter is configured to transfer at least 60% of the impact energy to the surgical instrument.

7. The surgical impact tool of claim 1, further comprising at least one timing element configured to time the length of each of a plurality of impact cycles during sustained impact, wherein, The controller is configured to receive feedback from the at least one timing element and to manage the storage and release of energy in part based on the at least one timing element.

8. The surgical impact tool according to claim 1, wherein, The change in energy released across multiple shock cycles is at most 20%.

9. The surgical impact tool according to claim 1, wherein, The mechanical spring is configured to release stored energy at a rate between 1 and 10 times per second to drive the operably linked surgical instrument.

10. The surgical impact tool according to claim 1, wherein, The energy is released at a rate between 3 joules per second and 30 joules per second.

11. The surgical impact tool according to claim 1, further comprising: A cam follower, which is operatively coupled to the cam; as well as A piston, operatively coupled to the cam follower, such that rotation of the cam is configured to cause the cam follower to push the piston and thereby compress the mechanical spring to store energy in the mechanical spring.

12. The surgical impact tool according to claim 11, wherein, The stored energy is configured to be released from the mechanical spring in response to the cam follower ceasing to push the piston.

13. The surgical impact tool according to claim 1, wherein, The mechanical spring comprises a single mechanical spring.

14. A surgical impact tool, comprising: Cam; A cam follower configured to move in response to being driven by the cam; A mechanical spring operatively connected to the cam follower, the mechanical spring being configured to store energy therein in response to movement of the cam follower and to release energy therefrom in response to movement of the cam follower; An electric motor configured to drive the movement of the cam; An electronic controller configured to control the motor and thereby control the movement of the cam and thereby control the storage of energy in and release from the mechanical spring; An adapter configured to secure to surgical instruments; A mass, configured to transmit the impact force in response to the released energy to a surgical instrument fastened to the adapter; as well as A sensor, operatively connected to the controller and configured to sense whether the surgical instrument has not yet advanced in response to the transmitted impact force, wherein: The controller is configured to provide feedback to the user of the tool in response to the sensor detecting that the surgical instrument has not yet moved forward in response to the transmitted impact force, and The feedback includes at least one of light, a decrease in the release of energy from the spring, and a cessation of the release of energy from the spring.

15. The surgical impact tool according to claim 14, wherein, The motion of the cam includes rotational motion, the energy storage includes compression of the mechanical spring, and the energy release includes decompression of the mechanical spring.

16. The surgical impact tool according to claim 14, wherein, The controller is configured to control the cyclical motion of the mass, causing the mass to move repeatedly and repeatedly transmit the impact force.

17. The surgical impact tool according to claim 14, wherein, The mechanical spring includes a helical spring.

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