ULTRASONIC SURGICAL SYSTEM FOR Bone TRANSSECTION

Abstract

A surgical system for transecting bone tissue includes an ultrasonic waveform generator, a control unit, an ultrasonic instrument assembly including an electromechanical transducer and an ultrasonic blade, and a robotic system. The ultrasound instrument assembly is connected to the robotic arm. The present surgical system is configured such that the robotic arm moves the ultrasonic blade through the bone at a constant forward feed rate during a cutting operation, and such that the forward movement is reduced, and preferably, the forward movement will automatically stop when the load per unit time drops or the applied power (monitored by the picker or sensor) is reduced.

Description

[0001] Divisional application

[0002] This application is a divisional application of the Chinese invention patent application with application number 2019800180486, filed on January 10, 2019, and entitled “ULTRASONIC SURGERY SYSTEM FOR BONE TRANSVERSION”. Background Art

[0003] The present invention relates to an ultrasonic surgical system which is particularly useful in transecting spinal tissue and to related surgical methods.

[0004] In the past 30 years, several ultrasonic tools have been invented for removing or cutting tissue during surgery. U.S. Patent No. 4,223,676 to Wuchinich et al. and U.S. Patent No. 5,188,1020 to Idemoto et al. disclose such devices.

[0005] Ultrasonic surgical devices are generally divided into two categories. One is a blunt hollow probe that vibrates at a frequency of 20kc to 100kc with an amplitude of up to 300 microns or more. Such devices remove tissue by means of: generating cavitation bubbles that rupture and disintegrate cells, tissue compression and relaxation stress (sometimes called the jackhammer effect), or other forces (such as bubble micro-beam forces in the tissue matrix). The effect achieved is to liquefy and separate the tissue. It is then emulsified using an irrigation fluid. The resulting emulsion is then extracted from the site. By applying energy around and below the unwanted tumor to separate it from the surrounding structures, large-scale resection of the tissue can be performed. Next, the surgeon will use common tools such as forceps to lift the tissue.

[0006] The second type of ultrasonic device is to use a sharp blade instead of a blunt hollow probe. The operation of cutting is as follows. This type of sharp ultrasonic blade is the subject of the disclosure of U.S. Patent No. 6,379,371. As disclosed therein, the blade is semicircular at its distal portion and has two straight sides parallel to the longitudinal axis, and the sides extend back to the shoulder that contacts the vibrating probe. The male thread shown matches the female thread socket of the probe (or transducer) so that the probe and the shoulder of the blade tip are in close contact. When the two are twisted together, they form a single resonant body that will vibrate with the combination of the transducer and the generator. The distal end of the blade will vibrate with an amplitude that is set by the mechanical advantage of the probe / tip geometry and the input amplitude provided by the transducer-generator combination. This action will provide a cutting effect on the tissue.

[0007] The blade disclosed in U.S. Pat. No. 6,379,371 is used in the field of surgery for cutting or removing bones or similar hard tissues. The blade is more effective in cutting hard tissues. Soft tissues will bounce off the blade. Soft tissues (i.e., spinal cord) sandwiched between the blade and the hard surface may be damaged. In delicate surgeries, such as sinus lift surgery or craniotomy, the purpose is to cut a small hole in the front of the skull to expose sinus tissue or the brain, but not to cut the membrane directly under the bone structure. This difference is very important for hard tissue and soft tissue. This is also important in spinal surgery and brain surgery, because in such surgeries, it is necessary to minimize damage to soft tissues (such as dura mater) under the bone while cutting bone tissue. In early in vitro tests, it was found that if the blade quickly penetrated the bone cortex, it might pierce or tear the membrane. Although qualified surgeons can master this technique proficiently after some practice, the learning difficulty is very large.

[0008] U.S. Patent Application No. 14 / 211,586, filed on March 14, 2014, discloses a surgical method utilizing an ultrasonic surgical instrument having a blade having a thickness along the cutting edge of between about 0.0005 inches and about 0.020 inches. The method includes manually inserting the blade into the patient's bone tissue and vibrating the blade using ultrasonic waves during the insertion process. The process is extremely urgent, as the distal-most portion of the blade is located within the patient's body, so during the insertion of the blade, the surgeon cannot see at least the distal-most portion of the blade. The surgeon manually terminates the insertion of the blade after tactilely sensing a change in the resistance to the advancement of the blade (indicating contact with soft tissue). Although the technology is easier to master, there is still a need for improved surgical methods that ensure safety and effectiveness. In particular, in spinal surgery, it is very important to avoid damage to the spinal cord within the spine.

[0009] Purpose of the Invention

[0010] It is an object of the present invention to provide a surgical system for transecting bone tissue in the vicinity of critically important structures such as the spine.

[0011] More specifically, it is an object of the present invention to provide a surgical system that is capable of selectively transecting bone tissue while minimizing (and preferably eliminating) the risk of trauma to nearby sensitive soft tissue.

[0012] These and other objects of the present invention will be apparent to those skilled in the art through the accompanying drawings and their description.Although each object will be achieved by at least one embodiment of the present invention, it is not necessary to have an embodiment that satisfies each object. Summary of the invention

[0013] The present invention relates to a surgical system for transecting bone tissue in the vicinity of a very important structure, such as the spine. The system has, as main components or subsystems, an ultrasonic waveform generator, a control unit, an ultrasonic instrument assembly including an electromechanical transducer and an ultrasonic blade, and a robotic system. The ultrasonic instrument assembly is fixed to a robotic arm. In order to ensure safe operation, the penetration rate of the instrument should not increase suddenly at the penetration point, i.e., when the blade has just penetrated the distal end of the bone to be cut. According to the present invention, the surgical system is configured so that the robotic arm can move the ultrasonic blade through the bone at a constant forward feed rate during the cutting operation, and when the load per unit time decreases or the applied power (monitored by a pickup or sensor) decreases, the forward movement will be reduced and, preferably, will stop automatically. Alternatively or additionally, the power applied to the transducer via the waveform generator can be reduced or interrupted.

[0014] The constancy of the feed rate is maintained by the servo control of the robot arm. The load variation pick-up is based on a feedback loop of the ultrasonic power application assembly (control unit, waveform generator, transducer), more precisely, on a drive voltage that varies with the load. In order to maintain a constant motion amplitude, the ultrasonic controller will maintain a constant motion current and phase angle while alternately increasing and decreasing the ultrasonic voltage according to the rise and fall of the load. At the penetration point, the voltage drop associated with the load reduction will be used as an input to the servo control to stop the servo-driven motion. In addition, the power output of the ultrasonic waveform generator can be at least significantly reduced or interrupted.

[0015] According to the present invention, the surgical system includes a bone cutting blade, an ultrasonic electromechanical transducer, a mechanical arm, a control processor and an electrical waveform generator. The bone cutting blade has a cutting edge and is configured to transmit ultrasonic vibration energy, and is operably connected to the ultrasonic electromechanical transducer and is mounted to the mechanical arm. The control processor is operably connected to the mechanical arm. The control processor is operably connected to the mechanical arm and is partially configured to control the movement of the mechanical arm so that the mechanical arm can move the bone cutting blade at a constant or uniform rate during the cutting operation to pass through the bone tissue. The electrical waveform generator is operably connected to the ultrasonic electromechanical transducer to excite it, thereby using ultrasonic mechanical waveform energy to power the bone cutting blade. The processor is operably connected to the electrical waveform generator and is configured to monitor the load on the ultrasonic electromechanical transducer. The processor is further configured to take a control action when a load is sensed or a power reduction is applied, and the control action is selected from the group consisting of: inducing the mechanical arm to stop the movement of the bone cutting blade, and at least significantly reducing the waveform energy output of the waveform generator.

[0016] A related surgical method includes: providing an ultrasonic bone cutting blade operably connected to an ultrasonic electromechanical transducer; mounting the ultrasonic bone cutting blade and the ultrasonic electromechanical transducer to a robotic arm, and driving the robotic arm through a plurality of servo mechanisms during a surgical cutting operation so that the ultrasonic bone cutting blade passes through bone tissue at a constant or uniform rate. The method also includes: operating an electrical waveform generator to excite the ultrasonic electromechanical transducer during the surgical cutting operation so that the ultrasonic bone cutting blade vibrates at an ultrasonic frequency. The operation of the electrical waveform generator includes: adjusting its power output to keep the vibration amplitude of the ultrasonic bone cutting blade constant. In addition, the method includes: automatically monitoring the load or power output of the electrical waveform generator, and when a load or applied power reduction is sensed, operating the servo mechanism to actuate the robotic arm to stop the movement of the ultrasonic bone cutting blade, and optionally at least significantly reducing the waveform energy output of the waveform generator.

[0017] A surgical system according to the present invention for transecting bone tissue in the vicinity of a very important structure comprises: an ultrasonic waveform generator, a control unit operably connected to the ultrasonic waveform generator, and an ultrasonic instrument assembly including an electromechanical transducer and an ultrasonic blade. The ultrasonic waveform generator is operably connected to the transducer to excite it. The system also includes a robotic subsystem, which includes a servo mechanism and a mechanical arm movable by the servo mechanism. A load sensor or pick-up assembly is operably connected to the electromechanical transducer and included in the ultrasonic waveform generator, and the load sensor or pick-up assembly is operably connected to the control unit. The ultrasonic instrument assembly is attached to the mechanical arm, and the control unit is operably connected to the servo mechanism and is configured to actuate the mechanical arm so as to move the ultrasonic blade through the bone tissue at a constant forward feed rate during the cutting operation. The control unit is also configured to operate the servo mechanism in response to a load drop or a reduction in applied power per unit time detected by the load sensor or pick-up assembly to at least automatically reduce the forward movement of the ultrasonic blade through the bone tissue. Optionally, the control unit is further configured to respond to a decrease in load per unit time or a decrease in applied power detected by the load sensor or the pick-off assembly to at least automatically substantially reduce the power output of the ultrasonic signal generator.

[0018] A related surgical method for transecting bone tissue near a critically important structure includes: operating an ultrasonic waveform generator to output an ultrasonic waveform signal of a preselected frequency; feeding the ultrasonic waveform signal to an electromechanical transducer in an ultrasonic instrument assembly including an ultrasonic blade; generating an ultrasonic standing wave in the ultrasonic instrument assembly including the ultrasonic blade; and controlling a robotic subsystem including a servo mechanism and a robotic arm movable by the servo mechanism to move the ultrasonic blade through the bone tissue at a constant forward feed rate during a cutting operation, wherein the ultrasonic instrument assembly is mounted on the robotic arm. In response to a drop in load or a reduction in applied power detected by a load sensor or a pickup assembly, the robotic subsystem is controlled to cause the ultrasonic blade to terminate its forward motion in the bone tissue.

[0019] According to another feature of the invention, operating the ultrasonic waveform generator includes adjusting its power output to maintain the vibration amplitude of the ultrasonic blade constant. Preferably, this is achieved by adjusting the voltage of the ultrasonic waveform generator power output while maintaining the motion current and phase angle constant.

[0020] Preferably, controlling the robotic subsystem comprises: a digital processor operating a control unit operatively connected to the servomechanism.

[0021] In response to a drop in load or a reduction in applied power detected by the load sensor or the pickup assembly, the ultrasonic waveform generator may be controlled to automatically reduce its power output, at least substantially. Controlling the robotic subsystem to reduce the power output of the ultrasonic waveform generator may include operating a digital processor operably connected to a control unit of the robotic subsystem. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A block diagram of a surgical system according to the present invention is shown. DETAILED DESCRIPTION

[0023] A surgical system for transecting bone tissue in the vicinity of a critical structure, such as the spine, includes an ultrasonic waveform generator 10 as a major component or subsystem, a control unit in the form of a digital processor 12, an ultrasonic instrument assembly 14 including an electromechanical transducer 16 and an ultrasonic blade 18, and a robotic system 20. The ultrasonic instrument assembly 14 is connected to a robotic arm 22 of the system 20. The blade 18 is an integral or integral part of a probe or tool 24, including a handle and a screw connector (neither of which are shown separately) for coupling the probe or tool to the electromechanical transducer 16.

[0024] To ensure the safety of the operation of the surgical system, the penetration rate of the blade 18 should not suddenly surge at the penetration point, that is, when the blade 18 has just penetrated the distal end of the bone being cut. The surgical system is configured so that the robotic arm 22 moves the ultrasonic blade 18 through the bone at a constant forward feed rate during the cutting operation. The digital processor or control unit 12 is connected to a plurality of translation servo mechanisms 26a, 26b, 26c and a plurality of rotation servo mechanisms 28a, 28b, 28c, which realize the necessary degrees of freedom for controlling the instrument. The digital processor or control unit 12 reduces the forward movement of the blade 18 through the bone tissue at a pre-selected surgical site, and preferably, automatically stops the forward movement of the blade when the load per unit time detected by the pickup or load sensor 30 decreases or the applied power decreases. Alternatively or additionally, the power applied to the transducer 16 by the waveform generator 10 can be reduced or interrupted. The load sensor 30 can be part of the waveform generation subsystem 32, and is actually included as part of the waveform generator 10. The waveform generation control portion of the digital processor 12 and the waveform generation subsystem 32 may take the form disclosed in US Pat. No. 8,659,208 and US Pat. No. 9,070,856, the disclosures of which are incorporated herein by reference.

[0025] In response to the selective activation of the servo mechanisms 26a, 26b, 26c and 28a, 28b, 28c by the digital processor or control unit 12, the robot 22 will maintain the feed rate of the blade 18 constant. The load change pickup detected by the load sensor 30 is implemented in the feedback loop of the ultrasonic power application assembly (control unit 12, waveform generator 10, transducer 6), more precisely, it is implemented based on the drive voltage that varies with the load change. See U.S. Patent No. 8,659,208 and U.S. Patent No. 9,070,856. In order to maintain a constant amplitude of motion, the ultrasonic controller will maintain a constant motion current and phase angle while alternately increasing and decreasing the ultrasonic voltage according to the increase and decrease of the load. At the penetration point, the voltage drop associated with the load reduction will be used as an input to the servo control (digital processor 12) to stop or interrupt the operation of the servo mechanisms 26a, 26b, 26c and 28a, 28b, 28c. Additionally, the power output of the ultrasonic wave generator 10 may be at least substantially reduced or interrupted.

[0026] The bone cutting blade 18 is formed with a cutting edge 34 at its distal end and can be in the form disclosed in U.S. Pat. No. 6,379,371 and U.S. Pat. No. 6,443,969. The blade 18 is configured to transmit ultrasonic vibration energy, and more specifically, its size is designed to carry an ultrasonic standing wave together with the probe 18 and the transducer 16, and the desired frequency of the ultrasonic standing wave is, for example, 22.5KHz. As described above, the control unit or processor 12 is operably connected to the mechanical arm 22 and is partially configured to control the movement of the mechanical arm 22 so that the mechanical arm can control the bone cutting blade 18 to pass through the bone tissue at a constant or uniform rate (speed) during the cutting operation. The electrical or ultrasonic waveform generator 10 is operably connected to the ultrasonic electromechanical transducer 16 to excite it so that the bone cutting blade 18 vibrates at a preselected (designed) ultrasonic frequency. The processor 12 is operably connected to the electrical waveform generator and is configured to monitor the load on the ultrasonic electromechanical transducer 16. The processor 12 is further configured to take control action when a reduction in load or applied power (via input from the load sensor 30) is sensed, the control action including inducing the robotic arm 22 to stop movement of the bone cutting blade 18 and / or at least significantly reducing the waveform energy output of the ultrasonic electromechanical transducer 16.

[0027] A related surgical method using the surgical system shown generally includes: mounting an ultrasonic bone cutting blade 18 and an ultrasonic electromechanical transducer 16 on a mechanical arm 22, and actuating the mechanical arm to move through servo mechanisms 26a, 26b, 26c and 28a, 28b, 28c. During the surgical cutting operation, the cutting blade passes through the bone tissue at a constant or uniform rate. During the surgical cutting operation, an electrical waveform generator 10 is operated to energize the electromechanical transducer 16 to vibrate the blade 18 at an ultrasonic frequency (e.g., 22.5kHz). Operating the waveform generator 10 includes: adjusting its power output so that the vibration amplitude of the ultrasonic bone cutting blade remains constant, as shown in U.S. Patent No. 8,659,208 and U.S. Patent No. 9,070,856. The method includes automatically monitoring the load or power output of the waveform generator 10, and when a load drop or a reduction in applied power is sensed, operating the servo mechanisms 26a, 26b, 26c and 28a, 28b to actuate the robotic arm 22 to stop the blade 18 from moving, optionally at least substantially reducing the waveform energy output of the waveform generator 10.

[0028] Operating the electric or ultrasonic waveform generator 10 includes adjusting its power output to maintain a constant vibration amplitude of the ultrasonic blade 18. Preferably, this is accomplished by adjusting the voltage of the power output of the ultrasonic waveform generator 10 while maintaining the motion current and phase angle constant. See U.S. Pat. No. 8,659,208 and U.S. Pat. No. 9,070,856.

[0029] Although the present invention has been described according to specific embodiments and applications, according to this teaching, a person skilled in the art may establish other embodiments and modifications without departing from or exceeding the spirit of the scope of the invention. Therefore, it should be understood that the drawings and descriptions herein are provided by way of example to facilitate understanding of the present invention and should not be interpreted as limiting the scope of the present invention.

Claims

1. A surgical system, comprising: a bone cutting blade having a cutting edge, the bone cutting blade being configured for transmitting ultrasonic vibration energy; an ultrasonic electromechanical transducer to which the bone cutting blade is operably connected; a robotic arm to which the bone cutting blade is mounted; a control processor operably connected to the robotic arm, the processor configured in part to control the movement of the robotic arm so that the robotic arm can move the bone cutting blade through bone tissue at a constant or uniform rate during a cutting operation; as well as an electrical waveform generator operably connected to the ultrasonic electromechanical transducer to energize it to power the bone cutting blade with ultrasonic mechanical waveform energy; The processor is operably connected to the electrical waveform generator and configured to monitor the loading of the ultrasonic electromechanical transducer; The processor is further configured to take control action upon sensing a drop in load or a reduction in applied power, the control action being selected from the group consisting of: inducing the robotic arm to stop movement of the bone cutting blade, and at least substantially reducing the waveform energy output of the electrical waveform generator.

2. A surgical system for transecting bone tissue near a critically important structure, comprising: Ultrasonic wave generator; a control unit operatively connected to the ultrasonic waveform generator; an ultrasonic instrument assembly including an electromechanical transducer and an ultrasonic blade, the ultrasonic waveform generator being operatively connected to the transducer to energize it; as well as A robotic subsystem comprising a servo mechanism and a robotic arm movable by the servo mechanism, wherein: a load sensor or pick-off assembly operatively connected to the electromechanical transducer and included in the ultrasonic waveform generator, the load sensor or pick-off assembly operatively connected to the control unit; The ultrasound instrument assembly is attached to the robotic arm; The control unit is operably connected to the servo mechanism and is configured to actuate the robotic arm so that the ultrasonic blade is moved through bone tissue at a constant forward feed rate during a cutting operation; The control unit is further configured to operate the servomechanism to at least automatically reduce forward movement of the ultrasonic blade through bone tissue in response to a decrease in load per unit time or a decrease in applied power detected by the load sensor or pickup assembly.

3. A surgical system for transecting bone tissue near a critically important structure, comprising: Ultrasonic wave generator; a control unit operatively connected to the ultrasonic waveform generator; an ultrasonic instrument assembly including an electromechanical transducer and an ultrasonic blade, the ultrasonic waveform generator being operatively connected to the transducer to energize it; as well as A robotic subsystem comprising a servo mechanism and a robotic arm movable by the servo mechanism, wherein: a load sensor or pickoff assembly operably connected to the electromechanical transducer and included in the ultrasonic wave generator, the load sensor or pickoff assembly operably connected to the control unit; The ultrasound instrument assembly is attached to the robotic arm; The control unit is operably connected to the servo mechanism and is configured to actuate the robotic arm so as to move the ultrasonic blade through bone tissue at a constant forward feed rate during a cutting operation; The control unit is further configured to operate the servomechanism to automatically reduce the power output of the ultrasonic signal generator at least substantially in response to a decrease in load or applied power per unit time detected by the load sensor or pickoff assembly.

4. A surgical method comprising: providing an ultrasonic bone cutting blade operably connected to an ultrasonic electromechanical transducer; Mounting the ultrasonic bone cutting blade and the ultrasonic electromechanical transducer to a robotic arm; During a surgical cutting operation, actuating the robotic arm via a plurality of servo mechanisms so that the ultrasonic bone cutting blade passes through bone tissue at a constant or uniform rate; During the surgical cutting operation, operating an electrical waveform generator to excite the ultrasonic electromechanical transducer so that the ultrasonic bone cutting blade vibrates at an ultrasonic frequency, wherein the operation of the electrical waveform generator includes adjusting its power output to keep the vibration amplitude of the ultrasonic bone cutting blade constant; automatically monitoring the load or power output of the electrical waveform generator; and When a load drop or a reduction in applied power is sensed, a control action is taken, the control action comprising the group consisting of: operating the servo mechanism to actuate the robotic arm so that the ultrasonic bone cutting blade stops moving, and at least significantly reducing the waveform energy output of the electrical waveform generator.

5. The method according to claim 4, wherein: Adjusting the power output of the electrical waveform generator to maintain the vibration amplitude of the ultrasonic blade constant includes adjusting the voltage of the power output while maintaining the motion current and phase angle constant.

6. A surgical method for transecting bone tissue near a critically important structure, comprising: operating the ultrasonic waveform generator to output an ultrasonic waveform signal of a preselected frequency; feeding the ultrasonic waveform signal to an electromechanical transducer in an ultrasonic instrument assembly including an ultrasonic blade; generating an ultrasonic standing wave in the ultrasonic instrument assembly including the ultrasonic blade; controlling a robotic subsystem to move the ultrasonic blade through bone tissue at a constant forward feed rate during a cutting operation, wherein the robotic subsystem includes a servo mechanism and a robotic arm movable by the servo mechanism, the ultrasonic instrument assembly being mounted to the robotic arm; and In response to a drop in load or a reduction in applied power detected via the load sensor or the pickup assembly, the robotic subsystem is controlled to terminate forward movement of the ultrasonic blade in the bone tissue.

7. The method according to claim 6, wherein: Operating the ultrasonic waveform generator includes adjusting its power output to maintain a constant vibration amplitude of the ultrasonic blade.

8. The method according to claim 7, wherein: Adjusting the power output of the electrical waveform generator to maintain a constant vibration amplitude of the ultrasonic blade includes adjusting the voltage of the power output while maintaining a constant motion current and phase angle.

9. The method according to claim 6, wherein: Controlling the robotic subsystem includes a digital processor operating a control unit operably connected to the servomechanism.

10. A surgical method for transecting bone tissue near a critically important structure, comprising: operating the ultrasonic waveform generator to output an ultrasonic waveform signal of a preselected frequency; feeding the ultrasonic waveform signal to an electromechanical transducer in an ultrasonic instrument assembly including an ultrasonic blade; generating an ultrasonic standing wave in the ultrasonic instrument assembly including the ultrasonic blade; controlling a robotic subsystem to move the ultrasonic blade through bone tissue at a constant forward feed rate during a cutting operation, wherein the robotic subsystem includes a servo mechanism and a robotic arm movable by the servo mechanism, the ultrasonic instrument assembly being mounted to the robotic arm; and In response to a drop in load or a reduction in applied power detected via the load sensor or the pick-off assembly, the ultrasonic wave generator is controlled to at least automatically and substantially reduce its power output.

11. The method according to claim 10, wherein: Operating the ultrasonic waveform generator includes adjusting its power output to maintain a constant vibration amplitude of the ultrasonic blade.

12. The method according to claim 11, wherein: Adjusting the power output of the electrical waveform generator to maintain a constant vibration amplitude of the ultrasonic blade includes adjusting the voltage of the power output while maintaining a constant motion current and phase angle.

13. The method according to claim 10, wherein: Controlling the robotic subsystem includes operating a digital processor of a control unit operably connected to the robotic subsystem; controlling the ultrasonic waveform generator includes operating the digital processor.

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