US20100022824A1 - Tissue modification devices and methods of using the same - Google Patents

Abstract

Tissue modification devices are provided. Aspects of the devices include an elongated member having a proximal end and a distal end. The distal end of the elongated member is dimensioned to pass through a minimally invasive body opening and includes a distal end integrated visualization sensor and tissue modifier. In some instances, the devices further include an integrated articulation mechanism that imparts steerability to at least one of the visualization sensor, the tissue modifier and the distal end of the elongated member. Also provided are methods of modifying internal target tissue of a subject using the tissue modification devices.

Description

CROSS-REFERENCE TO RELATED APPLICATION
• Pursuant to 35 U.S.C. §119 (e), this application claims priority to U.S. Provisional Application Ser. No. 61/082,774 filed Jul. 22, 2008; the disclosure of which priority application is herein incorporated by reference.
INTRODUCTION
• Traditional surgical procedures, both therapeutic and diagnostic, for pathologies located within the body can cause significant trauma to the intervening tissues. These procedures often require a long incision, extensive muscle stripping, prolonged retraction of tissues, denervation and devascularization of tissue. These procedures can require operating room time of several hours and several weeks of post-operative recovery time due to the destruction of tissue during the surgical procedure. In some cases, these invasive procedures lead to permanent scarring and pain that can be more severe than the pain leading to the surgical intervention.
• The development of percutaneous procedures has yielded a major improvement in reducing recovery time and post-operative pain because minimal dissection of tissue, such as muscle tissue, is required. For example, minimally invasive surgical techniques are desirable for spinal and neurosurgical applications because of the need for access to locations within the body and the danger of damage to vital intervening tissues. While developments in minimally invasive surgery are steps in the right direction, there remains a need for further development in minimally invasive surgical instruments and methods.
SUMMARY
• Tissue modification devices are provided. Aspects of the devices include an elongated member having a proximal end and a distal end. The distal end of the elongated member is dimensioned to pass through a minimally invasive body opening and includes a distal end integrated visualization sensor and tissue modifier. In some instances, the devices further include an integrated articulation mechanism that imparts steerability to at least one of the visualization sensor, the tissue modifier and the distal end of the elongated member. Also provided are methods of modifying internal target tissue of a subject using the tissue modification devices.
BRIEF DESCRIPTION OF THE FIGURES
• FIGS. 1A and B provide two different views of a disposable tissue modification device according to an embodiment of the invention.
• FIGS. 2A to 2C provide cross-sectional views of the distal ends of devices according to certain embodiments of the invention.
• FIGS. 3A to 3E provide cross-sectional views of the distal ends of devices according to certain embodiments of the invention.
• FIG. 4 provides an alternative view of the distal end of a device according to an embodiment of the invention, where the device is shown accessing the nucleus pulposus of an intervertebral disc.
• FIG. 5 provides an alternative view of the distal end of a device according to an embodiment of the invention, where the device is shown accessing the nucleus pulposus of an intervertebral disc.
• FIGS. 6A to 6E provide various views of the distal end of a device according to one embodiment of the invention.
• FIG. 7 provides a cutaway view of the device shown inFIGS. 1A and 1B.
• FIG. 8 provides a depiction of a system according to one embodiment of the invention, where the system includes both a disposable tissue modifier device and an extra-corporeal control unit.
• FIG. 9 provides a block diagram showing the architecture of a system according to one embodiment of the invention and how that system interacts with a user.
• FIG. 10 shows a CMOS visualization sub-system that may be incorporated into a tissue modification system according to an embodiment of the invention.
DETAILED DESCRIPTION
• Tissue modification devices are provided. Aspects of the devices include an elongated member having a proximal end and a distal end. The distal end of the elongated member is dimensioned to pass through a minimally invasive body opening and includes a distal end integrated visualization sensor and tissue modifier. In some instances, the devices further include an integrated articulation mechanism that imparts steerability to at least one of the visualization sensor, the tissue modifier and the distal end of the elongated member. Also provided are methods of modifying internal target tissue of a subject using the tissue modification devices.
• Before the present invention is described in greater detail, it is to be understood that this invention is not limited to particular embodiments described, as such may, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.
• Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention.
• Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are now described.
• All publications and patents cited in this specification are herein incorporated by reference as if each individual publication or patent were specifically and individually indicated to be incorporated by reference and are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.
• It is noted that, as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may be drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as “solely,” “only” and the like in connection with the recitation of claim elements, or use of a “negative” limitation.
• As will be apparent to those of skill in the art upon reading this disclosure, each of the individual embodiments described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several embodiments without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of events recited or in any other order which is logically possible.
• In further describing various aspects of the invention, aspects of embodiments of the subject tissue modification devices are described first in greater detail. Next, embodiments of methods of modifying an internal target tissue of a subject in which the subject tissue modification devices may find use are reviewed in greater detail.
Tissue Modification Devices
• Aspects of the invention include tissue modification devices useful for modifying an internal target tissue site, e.g., a spinal location that is near or inside of an intervertebral disc (IVD). As summarized above, the tissue modification devices are dimensioned such that at least the distal end of the devices can pass through a minimally invasive body opening. As such, at least the distal end of the devices may be introduced to an internal target site of a patient, e.g., a spinal location that is near or inside of an intervertebral disc, through a minimal incision, e.g., one that is less than the size of an incision employed for an access device having a outer diameter of 20 mm or smaller, e.g., less than 75% the size of such an incision, such as less than 50% of the size of such an incision, or smaller. In some instances, at least the distal end of the elongated member is dimensioned to pass through a Cambin's triangle. The Cambin's triangle (also known in the art as the Pambin's triangle) is an anatomical spinal structure bounded by an exiting nerve root and a traversing nerve root and a disc. The exiting root is the root that leaves the spinal canal just cephalad (above) the disc, and the traversing root is the root that leaves the spinal canal just caudad (below) the disc. Where the distal end of the elongated member is dimensioned to pass through a Cambin's triangle, at least the distal end of the device has a longest cross-sectional dimension that is 10 mm or less, such as 8 mm or less and including 7 mm or less. In some instances, the elongated member has an outer diameter that is 7.5 mm or less, such as 7.0 mm or less, including 6.7 mm or less, such as 6.6 mm or less, 6.5 mm or less, 6.0 mm or less, 5.5 mm or less, 5.0 mm or less.
• As summarized above, tissue modification devices of the invention include an elongated member. As this component of the devices is elongated, it has a length that is 1.5 times or longer than its width, such as 2 times or longer than its width, including 5 or even 10 times or longer than its width, e.g., 20 times longer than its width, 30 times longer than its width, or longer. The length of the elongated member may vary, an in some instances ranges from 5 cm to 20 cm, such as 7.5 cm to 15 cm and including 10 to 12 cm. The elongated member may have the same outer cross-sectional dimensions (e.g., diameter) along its entire length. Alternatively, the cross-sectional diameter may vary along the length of the elongated member.
• The elongated members of the subject tissue modification devices have a proximal end and a distal end. The term “proximal end”, as used herein, refers to the end of the elongated member that is nearer the user (such as a physician operating the device in a tissue modification procedure), and the term “distal end”, as used herein, refers to the end of the elongated member that is nearer the internal target tissue of the subject during use. The elongated member is, in some instances, a structure of sufficient rigidity to allow the distal end to be pushed through tissue when sufficient force is applied to the proximal end of the elongate member. As such, in these embodiments the elongated member is not pliant or flexible, at least not to any significant extent.
• Depending on the particular device embodiment, the elongated member may or may not include one or more lumens that extend at least partially along its length. When present, the lumens may vary in diameter and may be employed for a variety of different purposes, such as irrigation, aspiration, electrical isolation (for example of conductive members, such as wires), as a mechanical guide, etc., as reviewed in greater detail below. When present, such lumens may have a longest cross section that varies, ranging in some in stances from 0.5 to 5.0 mm, such as 1.0 to 4.5 mm, including 1.0 to 4.0 mm. The lumens may have any convenient cross-sectional shape, including but not limited to circular, square, rectangular, triangular, semi-circular, trapezoidal, irregular, etc., as desired. These lumens may be provided for a variety of different functions, including as irrigation and/or aspiration lumens, as described in greater detail below.
• As summarized above, the devices include a distal end integrated visualization sensor and a distal end integrated tissue modifier. As the visualization sensor is integrated at the distal end of the device, it cannot be removed from the remainder of the device without significantly compromising the structure and functionality of the device. Accordingly, the devices of the present invention are distinguished from devices which include a “working channel” through which a separate autonomous device, such as a tissue modifier, is passed through. In contrast to such devices, since the visualization sensor of the present device is integrated at the distal end, it is not a separate device from the elongated member that is merely present in a working channel of the elongated member and which can be removed from the working channel of such an elongated member without structurally compromising the elongated member in any way. The visualization sensor may be integrated with the distal end of the elongated member by a variety of different configurations. Integrated configurations include configurations where the visualization sensor is fixed relative to the distal end of the elongated member, as well as configurations where the visualization sensor is movable to some extent relative to the distal end of the elongated member. Movement of the visualizations sensor may also be provided relative to the distal end of the elongated member, but then fixed with respect to another component present at the distal end, such as a distal end integrated tissue modifier. Specific configurations of interest are further described below in connection with the figures.
• Visualization sensors of interest include miniature imaging sensors that have a cross-sectional area which is sufficiently small for its intended use and yet retains a sufficiently high matrix resolution. Imaging sensors of interest are those that include a photosensitive component, e.g., array of photosensitive elements that convert light into electrons, coupled to an integrated circuit. The integrated circuit may be configured to obtain and integrate the signals from the photosensitive array and output image data, which image data may in turn be conveyed to an extra-corporeal device configured to receive the data and display it to a user. The image sensors of these embodiments may be viewed as integrated circuit image sensors. The integrated circuit component of these sensors may include a variety of different types of functionalities, including but not limited to: image signal processing, memory, and data transmission circuitry to transmit data from the visualization sensor to an extra-corporeal location, etc. The miniature imaging sensors may further include a lens component made up of one or more lenses positioned relative to the photosensitive component so as to focus images on the photosensitive component. Where desired, the one or more lenses may be present in a housing. Specific types of miniature imaging sensors of interest include complementary metal-oxide-semiconductor (CMOS) sensors and charge-coupled device (CCD) sensors. The sensors may have any convenient configuration, including circular, square, rectangular, etc. Visualization sensors of interest may have a longest cross-sectional dimension that varies depending on the particular embodiment, where in some instances the longest cross sectional dimension (e.g., diameter) is 4.0 mm or less, such as 3.5 mm or less, including 3.0 mm or less, such as 2.5 mm or less, including 2.0 mm or less, including 1.5 mm or less, including 1.0 mm or less.
• Imaging sensors of interest may be either frontside or backside illumination sensors, and have sufficiently small dimensions while maintaining sufficient functionality to be integrated at the distal end of the elongated members of the devices of the invention. Aspects of these sensors are further described in one or more the following U.S. Patents, the disclosures of which are herein incorporated by reference: U.S. Pat. Nos. 7,388,242; 7,368,772; 7,355,228; 7,345,330; 7,344,910; 7,268,335; 7,209,601; 7,196,314; 7,193,198; 7,161,130; and 7,154,137.
• As the visualization sensor is a distal end integrated visualization sensor, it is located at or near the distal end of the elongated member. Accordingly, it is positioned at 3 mm or closer to the distal end, such as at 2 mm or closer to the distal end, including at 1 mm or closer to the distal end. In some instances, the visualization sensor is located at the distal end of the elongated member. The visualization sensor may provide for front viewing and/or side-viewing, as desired. Accordingly, the visualization sensor may be configured to provide image data as seen in the forward direction from the distal end of the elongated member. Alternatively, the visualization sensor may be configured to provide image data as seen from the side of the elongate member. In yet other embodiments, a visualization sensor may be configured to provide image data from both the front and the side, e.g., where the image sensor faces at an angle that is less than 90° relative to the longitudinal axis of the elongated member, e.g., as illustrated inFIGS. 6A to 6C, described in greater detail below.
• Because the visualization sensor is a distal end integrated visualization sensor, the visualization sensor also includes functionality for conveying image data to an extra-corporeal device, such as an image display device. In some instances, a signal cable (or other type of signal conveyance element) may be present to connect the image sensor at the distal end to a device at the proximal end of the elongate member, e.g., in the form of one or more wires running along the length of the elongate member from the distal to the proximal end. Alternatively, wireless communication protocols may be employed, e.g., where the imaging sensor is operatively coupled to a wireless data transmitter, which may be positioned at the distal end of the elongated member (including integrated into the visualization sensor, at some position along the elongated member or at the proximal end of the device, e.g., at a location of the proximal end of the elongated member or associated with the handle of the device).
• Where desired, the devices may include one or more illumination elements configured to illuminate a target tissue location so that the location can be visualized with a visualization sensor, e.g., as described above. A variety of different types of light sources may be employed as illumination elements, so long as their dimensions are such that they can be positioned at the distal end of the elongated member. The light sources may be integrated with a given component (e.g., elongated member) such that they are configured relative to the component such that the light source element cannot be removed from the remainder of the component without significantly compromising the structure of the component. As such, the integrated illumination element of these embodiments is not readily removable from the remainder of the component, such that the illumination element and remainder of the component form an inter-related whole. The light sources may be light emitting diodes configured to emit light of the desired wavelength range, or optical conveyance elements, e.g., optical fibers, configured to convey light of the desired wavelength range from a location other than the distal end of the elongate member, e.g., a location at the proximal end of the elongate member, to the distal end of the elongate member. As with the image sensors, the light sources may include a conductive element, e.g., wire, or an optical fiber, which runs the length of the elongate member to provide for power and control of the light sources from a location outside the body, e.g., an extracorporeal control device. Where desired, the light sources may include a diffusion element to provide for uniform illumination of the target tissue site. Any convenient diffusion element may be employed, including but not limited to a translucent cover or layer (fabricated from any convenient translucent material) through which light from the light source passes and is thus diffused. In those embodiments of the invention where the system includes two or more illumination elements, the illumination elements may emit light of the same wavelength or they may be spectrally distinct light sources, where by “spectrally distinct” is meant that the light sources emit light at wavelengths that do not substantially overlap, such as white light and infra-red light. In certain embodiments, an illumination configuration as described in copending U.S. application Ser. Nos. 12/269,770 and 12/269,772 (the disclosures of which are herein incorporated by reference) is present in the device.
• In addition to a distal end integrated visualization sensor, devices of the invention further include an integrated distal end tissue modifier. As the tissue modifier is integrated at the distal end of the device, it cannot entirely be removed from the remainder of the device without significantly compromising the structure and functionality of the device. While the tissue modifier cannot entirely be removed from the device without compromising the structure and functionality of the device, components of the tissue modifier may be removable and replaceable. For example, an RF electrode tissue modifier may be configured such that the wire component of the tissue modifier may be replaceable while the remainder of the tissue modifier is not. Accordingly, the devices of the present invention are distinguished from devices which include a “working channel” through which a separate autonomous tissue modifier device, such as autonomous RF electrode device, is passed through. In contrast to such devices, since the tissue modifier of the present device is integrated at the distal end, it is not a separate device from the elongated member that is merely present in a working channel of the elongated member and which can be removed from the working channel of such an elongated member without structurally compromising the elongated member in any way. The tissue modifier may be integrated with the distal end of the elongated member by a variety of different configurations. Integrated configurations include configurations where the tissue modifier is fixed relative to the distal end of the elongated member, as well as configurations where the tissue modifier is movable to some extent relative to the distal end of the elongated member may be employed in devices of the invention. Specific configurations of interest are further described below in connection with the figures. As the tissue modifier is a distal end integrated tissue modifier, it is located at or near the distal end of the elongated member. Accordingly, it is positioned at 10 mm or closer to the distal end, such as at 5 mm or closer to the distal end, including at 2 mm or closer to the distal end. In some instances, the tissue modifier is located at the distal end of the elongated member.
• Tissue modifiers are components that interact with tissue in some manner to modify the tissue in a desired way. The term modify is used broadly to refer to changing in some way, including cutting the tissue, ablating the tissue, delivering an agent(s) to the tissue, freezing the tissue, etc. As such, of interest as tissue modifiers are tissue cutters, tissue ablators, tissue freezing/heating elements, agent delivery devices, etc. Tissue cutters of interest include, but are not limited to: blades, liquid jet devices, lasers and the like. Tissue ablators of interest include, but are not limited to ablation devices, such as devices for delivery ultrasonic energy (e.g., as employed in ultrasonic ablation), devices for delivering plasma energy, devices for delivering radiofrequency (RF) energy, devices for delivering microwave energy, etc. Energy transfer devices of interest include, but are not limited to: devices for modulating the temperature of tissue, e.g., freezing or heating devices, etc. In some embodiments, the tissue modifier is not a tissue modifier that achieves tissue modification by clamping, clasping or grasping of tissue such as may be accomplished by devices that trap tissue between opposing surfaces (e.g., jaw-like devices). In these embodiments, the tissue modification device is not an element that is configured to apply mechanical force to tear tissue, e.g., by trapping tissue between opposing surfaces. In some embodiments, tissue modification comprises an action other than just removal by low pressure irrigation or aspiration, for example where some other act is performed on the tissue beyond low pressure irrigation and/or aspiration. In some embodiments, the tissue modifier is distinct from a probe element or device that is configured to move tissue without any modification to the tissue other than simple displacement or repositioning, such as through retraction, atraumatic movement, etc.
• In some instances, the tissue modifier includes at least one electrode. For example, tissue modifiers of interest may include RF energy tissue modifiers, which include at least one electrode and may be configured in a variety of different ways depending on the desired configuration of the RF circuit. An RF circuit can be completed substantially entirely at target tissue location of interest (bipolar device) or by use of a second electrode attached to another portion of the patient's body (monopolar device). In either case, a controllable delivery of RF energy is achieved. Aspects of the subject tissue modification devices include a radiofrequency (RF) electrode positioned at the distal end of the elongated member. RF electrodes are devices for the delivery of radiofrequency energy, such as ultrasound, microwaves, and the like. In some instances, the RF electrode is an electrical conductor for delivering RF energy to a particular location, such as a desired target tissue. For instance, in certain cases, the RF electrode can be an RF ablation electrode. RF electrodes of the subject tissue modification devices can include a conductor, such as a metal wire, and can be dimensioned to access an intervertebral disc space. RF electrodes may be shaped in a variety of different formats, such as circular, square, rectangular, oval, etc. The dimensions of such electrodes may vary, where in some embodiments they RF electrode has a longest cross-sectional dimension that is 7 mm or less, 6 mm or less 5 mm or less, 4 mm or less, 3 mm or less or event 2 mm or less, as desired. Where the electrode includes a wire, the diameter of the wire in such embodiments may be 180 μm, such as 150 μm or less, such as 130 μm or less, such as 100 μm or less, such as 80 μm or less. A variety of different RF electrode configurations suitable for use in tissue modification and include, but are not limited to, those described in U.S. Pat. Nos. 7,449,019; 7,137,981; 6,997,941; 6,837,887; 6,241,727; 6,112,123; 6,607,529; 5,334,183. RF electrode systems or components thereof may be adapted for use in devices of the present invention (when coupled with guidance provided by the present specification) and, as such, the disclosures of the RF electrode configurations in these patents are herein incorporated by reference. Specific RF electrode configurations of interest are further described in connection with the figures, below.
• In some instances, the tissue modifier is supplied with current from an RF energy source. The voltage signal driving the current to the tissue modifier may be definable as a sine, square, saw-tooth, triangle, pulse, non-standard, complex, or irregular waveform, or the like, with a well-defined operating frequency. For example, the operating frequency can range from 1 KHz to 50 MHz, such as from 100 KHz to 25 MHz, and including from 250 KHz to 10 MHz. In some embodiments, the RF voltage signal is a sine wave withoperating frequency 460 kHz. Furthermore, the tissue modifier's operating frequency can be modulated by a modulation waveform. By “modulated” is meant attenuated in amplitude by a second waveform, such as a periodic signal waveform. The modulation waveform may be definable as a sine, square, saw-tooth, triangle, pulse, non-standard, complex, or irregular waveform, or the like, with a well-defined modulation frequency. For example, the modulation frequency can range from 1 Hz to 10 kHz, such as from 1 Hz to 500 Hz, and including from 10 Hz to 100 Hz. In some embodiments, the modulation waveform is a square wave with modulation frequency 70 Hz.
• In some embodiments, a RF tuner is included as part of the RF energy source. The RF tuner includes basic electrical elements (e.g., capacitors and inductors) which serve to tailor the output impedance of the RF energy source. The term “tailor” is intended here to have a broad interpretation, including affecting an electrical response that achieves maximum power delivery, affecting an electrical response that achieves constant power (or voltage) level under different loading conditions, affecting an electrical response that achieves different power (or voltage) levels under different loading conditions, etc. Furthermore, the elements of the RF tuner can be chosen so that the output impedance is dynamically tailored, meaning the RF tuner self-adjusts according to the load impedance encountered at the electrode tip. For instance, the elements may be selected so that the electrode has adequate voltage to develop a plasma corona when the electrode is placed in a saline solution (with saline solution grounded to return electrode), but then may self-adjust the voltage level to a lower threshold when the electrode contacts tissue (with tissue also grounded to return electrode, for example through the saline solution), thus dynamically maintaining the plasma corona at the electrode tip while minimizing the power delivered to the tissue and the thermal impact to surrounding tissue. RF tuners, when present, can provide a number of advantages. For example, delivering RF energy to target tissue through the distal tip of the electrode is challenging since RF energy experiences attenuation and reflection along the length of the conductive path from the RF energy source to the electrode tip, which can result in insertion loss. Inclusion of a RF tuner, e.g., as described above, can help to minimize and control insertion loss.
• Devices of the invention may include a linear mechanical actuator for linearly translating a distal end element of the device, such as the tissue modifier (e.g., a RF electrode) relative to the distal end of the elongate member. By “linearly translating” is meant moving the tissue modifier along a substantially straight path. As used herein, the term “linear” also encompasses movement of the tissue modifier in a non-straight (i.e., curved) path. For instance, the path of movement of the tissue modifier can be deflected from a substantially straight path if the electrode encounters a tissue of a different density (such as, cartilage, bone, etc.), or if the conformation of the tissue the electrode is passing through is not straight, etc.
• When actuated by a linear mechanical actuator, the tissue modifier is cyclically displaced from a “neutral” position along its axial extension to positions displaced distally or proximally from the neutral position, with maximum displacement from the neutral position corresponding to the vibratory amplitude. Thus, the linear mechanical actuator actuates the tissue modifier through a distance equal to twice the vibratory amplitude and ranging from a distal extreme position to a proximal extreme position. In certain embodiments, the tissue modifier can be extended by the linear mechanical actuator from the distal end of the elongated member by 0.1 mm or more, such as 0.5 mm or more, including 1 mm or more, for instance 2 mm or more, such as 5 mm or more. This back and forth movement of the tissue modifier relative to the distal end of the elongated member that is implemented by the linear mechanical actuator is described herein in terms of linear translation frequency. It is noted that the above described distal and proximal extreme positions refer to those positions implemented solely by the linear mechanical actuator. In some embodiments,.the linear mechanical actuator may be the only means for translating the electrode. In other embodiments, e.g., as described in greater detail below, the linear mechanical actuator may provide vibratory amplitude that is superimposed on another independent control over electrode translation which moves the electrode over a distance significantly greater than the vibratory amplitude, e.g. 10 mm or more, such as 20 mm or more, including 30 mm or more, for instance 40 mm or more. In this case, the tissue modifier may be extended beyond the range defined by the above described linear mechanical actuator distal and proximal extreme positions. For example, a manual control (e.g., a thumbwheel or analogous structure) may be provided on the device which permits a user to move the tissue modifier relative to the distal end in a movement that is distinct from that provided by the linear mechanical actuator.
• Accordingly, devices of the invention may include a linear mechanical actuator configured to linearly translate the tissue modifier relative to the distal end at linear translation frequency. The linear mechanical actuator can be any of a variety of actuators convenient for use in the subject devices for linearly translating the tissue modifier relative to the distal end of the elongated member. For instance, the linear mechanical actuator can be a voice coil motor (VCM), solenoid, pneumatic actuator, electric motor, etc. The linear mechanical actuator is operatively coupled to the tissue modifier. By “operatively coupled” is meant that the linear mechanical actuator is connected to the tissue modifier such that linear movement by the actuator is transferred to the tissue modifier thereby extending the tissue modifier from the distal end of the elongated member or retracting the tissue modifier towards the distal end of the elongated member depending on the direction of movement by the linear actuator.
• When present, the linear actuator provides for linear translation of the tissue modifier at a linear translation frequency. In some instances, the linear translation frequency is 10 Hz or greater, such as 25 Hz or greater, including 50 Hz or greater, such as 100 Hz or greater. In some embodiments, the linear translation frequency is 70 Hz. In certain cases, the translation of the tissue modifier between the distal and proximal extreme positions occurs with a predetermined linear translation frequency while in other embodiments the linear translation frequency may not be predetermined. The translation frequency (whether or not predetermined) may depend on various factors, such as but not limited to, the type of tissue being modified, the amount of tissue being modified, the location of the tissue, the proximity of surrounding tissues, the conformation of the tissue, the type of procedure being performed, the nature of the linear mechanical actuator, the DC voltage applied to the actuator, the amplitude of the AC voltage applied to the actuator, etc. For example, in certain embodiments, the linear translation frequency is definable as a standard waveform, such as a sine waveform. In some cases, the sine waveform is an Hz sine waveform, such that the linear translation frequency ranges from 1 Hz to 500 Hz, such as from 1 Hz to 250 Hz, and including from 10 Hz to 100 Hz. In other cases, the linear translation frequency is definable as a non-standard, complex, or irregular waveform, or the like. For example, the linear translation frequency can be definable as a waveform comprising periods that have varying frequencies, a waveform comprising periods that have varying amplitudes, a waveform comprising periods that have varying frequencies and varying amplitudes, a superposition of two or more waveforms, and the like.
• In some embodiments, the tissue modification device is configured to synchronize the linear mechanical actuation with the modulated RF waveform. By “synchronize” is meant that two or more events are timed to operate in a coordinated manner. For example, two or more waveforms can be timed to operate in a coordinated manner. In some embodiments, the modulation frequency equals the linear translation frequency, and the modulation waveform is phase-shifted relative to the linear translation waveform. Synchronization of these waveforms may be achieved using a variety of different protocols and may implement one or more controllers of different formats, including hardware, software, and combinations thereof. For instance, a single common controller may generate two waveforms that are phase-shifted; alternatively, separate controllers can be arranged in a master-slave configuration to generate two waveforms that are phase-shifted, alternatively, one controller can generate a waveform, hardware (e.g., an opto-electronic encoder, a mechanical encoder, a hall sensor, or the like) can be used to trigger on a physical embodiment (such as mechanical rotation) of that waveform, and a second controller can generate a second waveform with adjustable phase shift from the trigger signal. The phase shift of the modulation waveform relative to the linear translation waveform can be positive (phase lead) or negative (phase lag), and can have magnitude 0° to 360° or more, such as 0° to 180°, including 60° to 120°. In certain embodiments of the invention, the modulation waveform lags the linear translation waveform by 90°.
• As discussed above, the tissue modifier (e.g., a RF electrode) has distal and proximal extreme positions of its cyclic linear translation. In certain embodiments, the tissue modifier is configured to deliver RF energy to an internal target tissue while at a position other than the distal extreme position. Thus, in these cases, the modulation waveform is synchronized with the linear translation waveform such that the tissue modifier is energized when the tissue modifier is at a position other than the distal extreme position, such as while the tissue modifier is at or near the proximal extreme position. For example, as discussed above, the modulating waveform may be phase-shifted relative to the linear translation waveform.
• Cyclic linear translation of the tissue modification device can facilitate a variety of functions with multiple benefits. For instance, cyclic linear translation of the tissue modifier at a fast rate relative to manually controlled translation (e.g., at a frequency greater than 10 Hz) will tend to physically advance the tissue modifier into soft tissue due to the compliance of the soft tissue, while hard tissue will resist deformation and will thus not allow the tissue modifier to physically advance into the hard tissue. Consequently, the electrode will push back against the elongated body as it encounters hard tissue, thus producing tactile feedback to the user. In some embodiments, synchronization of the tissue modifier's modulation waveform with its linear translation waveform provides additional benefits. For instance, rapid retraction of the electrode from hard tissue that it encounters will leave the tissue modifier physically separated from the hard tissue by a gap as the tissue modifier approaches the proximal extreme position. In some embodiments, the tissue modifier tip is activated only when the tissue modifier is at or near the proximal extreme position, as mentioned above. This has the effect of preferentially delivering the tissue modification energy to soft, compliant tissue as opposed to hard, stiff tissue. Stated otherwise, this provides tissue discrimination based on elastic modulus. In the case of spinal surgery applications requiring removal of nuclear material, such as fusion, total disc replacement, and partial disc replacement, synchronization of the modulation waveform with the linear translation waveform facilitates the delivery of tissue modification energy to the nucleus pulposus (soft, compliant tissue) while minimizing the delivery of tissue modification energy to the disc annulus (hard, stiff tissue) and the endplates of the vertebral bodies (hard, stiff tissue). In addition, cyclic linear translation of the tissue modifier helps to prevent a condition where the electrode sticks to tissue as it ablates it, resulting in increased thermal effects to the surrounding tissue, ineffective or discontinuous tissue dissection, buildup of charred or otherwise modified tissue on the tissue modifier tip, or a combination thereof. Additionally, cyclic linear translation of the tissue modifier helps chop the dissected tissue into smaller pieces, thus facilitating aspiration of the dissected tissue.
• Depending on the nature of the tissue modifier, the devices will include proximal end connectors for operatively connecting the device and tissue modifier to extra-corporeal elements required for operability of the tissue modifier, such as extra-corporeal RF controllers, mechanical tissue cutter controllers, liquid jet controllers, etc.
• In some embodiments, an integrated articulation mechanism that imparts steerability to at least one of the visualization sensor, the tissue modifier and the distal end of the elongated member is also present in the device. By “steerability” is meant the ability to maneuver or orient the visualization sensor, tissue modifier and/or distal end of the elongated member as desired during a procedure, e.g., by using controls positioned at the proximal end of the device. In these embodiments, the devices include a steerability mechanism (or one or more elements located at the distal end of the elongated member) which renders the desired distal end component maneuverable as desired through proximal end control. As such, the term “steerability”, as used herein, refers to a mechanism that provides a user steering functionality, such as the ability to change direction in a desired manner, such as by moving left, right, up or down relative to the initial direction. The steering functionality can be provided by a variety of different mechanisms. Examples of suitable mechanisms include, but are not limited to one or more wires, tubes, plates, meshes or combinations thereof, made from appropriate materials, such as shape memory materials, music wire, etc. In some instances, the distal end of the elongated member is provided with a distinct, additional capability that allows it to be independently rotated about its longitudinal axis when a significant portion of the operating handle is maintained in a fixed position, as discussed in greater detail below. The extent of distal component articulations of the invention may vary, such as from −180 to +180°; e.g., −90 to +90°. Alternatively, the distal probe tip articulations may range from 0 to 360°, such as 0 to +180°, and including 0 to +90°, with provisions for rotating the entire probe about its axis so that the full range of angles is accessible on either side of the axis of the probe, e.g., as described in greater detail below. Articulation mechanisms of interest are further described in published PCT Application Publication Nos. WO 2009029639; WO 2008/094444; WO 2008/094439 and WO 2008/094436; the disclosures of which are herein incorporated by reference. Specific articulation configurations of interest are further described in connection with the figures, below.
• In certain embodiments, devices of the invention may further include an irrigator and aspirator configured to flush an internal target tissue site and/or a component of the device, such as a lens of the visualization sensor. As such, the elongated member may further include one or more lumens that run at least the substantial length of the device, e.g., for performing a variety of different functions, as summarized above. In certain embodiments where it is desired to flush (i.e., wash) the target tissue site at the distal end of the elongated member (e.g. to remove ablated tissue from the location, etc.), the elongated member may include both irrigation lumens and aspiration lumens. Thus, the tissue modification device can comprise an irrigation lumen located at the distal end of the elongated member, and the tissue modification device can include an aspiration lumen located at the distal end of the elongated member. During use, the irrigation lumen is operatively connected to a fluid source (e.g., a physiologically acceptable fluid, such as saline) at the proximal end of the device, where the fluid source is configured to introduce fluid into the lumen under positive pressure, e.g., at a pressure ranging from 0 psi to 60 psi, so that fluid is conveyed along the irrigation lumen and out the distal end. While the dimensions of the irrigation lumen may vary, in certain embodiments the longest cross-sectional dimension of the irrigation lumen ranges from 0.5 mm to 5 mm, such as 0.5 mm to 3 mm, including 0.5 mm to 1.5 mm. During use, the aspiration lumen is operatively connected to a source of negative pressure (e.g., a vacuum source) at the proximal end of the device. While the dimensions of the aspiration lumen may vary, in certain embodiments the longest cross-sectional dimension of the aspiration lumen ranges from 1 mm to 7 mm, such as 1 mm to 6 mm, including 1 mm to 5 mm. In some embodiments, the aspirator comprises a port having a cross-sectional area that is 33% or more, such as 50% or more, including 66% or more, of the cross-sectional area of the distal end of the elongated member. In some instances, the negative pressure source is configured to draw fluid and/or tissue from the target tissue site at the distal end into the aspiration lumen under negative pressure, e.g., at a negative pressure ranging from 300 to 600 mmHg, such as 550 mmHg, so that fluid and/or tissue is removed from the tissue site and conveyed along the aspiration lumen and out the proximal end, e.g., into a waste reservoir. In certain embodiments, the irrigation lumen and aspiration lumen may be separate lumens, while in other embodiments, the irrigation lumen and the aspiration lumen can be included in a single lumen, for example as concentric tubes with the inner tube providing for aspiration and the outer tube providing for irrigation. When present, the lumen or lumens of the flushing functionality of the device may be operatively coupled to extra-corporeal irrigation devices, such as a source of fluid, positive and negative pressure, etc. Where desired, irrigators and/or aspirators may be steerable, as described above.
• Where desired, the devices may include a control structure, such as a handle, operably connected to the proximal end of the elongated member. By “operably connected” is meant that one structure is in communication (for example, mechanical, electrical, optical connection, or the like) with another structure. When present, the control structure (e.g., handle) is located at the proximal end of the device. The handle may have any convenient configuration, such as a hand-held wand with one or more control buttons, as a hand-held gun with a trigger, etc., where examples of suitable handle configurations are further provided below.
• In some embodiments, the distal end of the elongated member is rotatable about its longitudinal axis when a significant portion of the operating handle is maintained in a fixed position. As such, at least the distal end of the elongated member can turn by some degree while the handle attached to the proximal end of the elongated member stays in a fixed position. The degree of rotation in a given device may vary, and may range from 0 to 360°, such as 0 to 270°, including 0 to 180°.
• Devices of the invention may be disposable or reusable. As such, devices of the invention may be entirely reusable (e.g., be multi-use devices) or be entirely disposable (e.g., where all components of the device are single-use). In some instances, the device can be entirely reposable (e.g., where all components can be reused a limited number of times). Each of the components of the device may individually be single-use, of limited reusability, or indefinitely reusable, resulting in an overall device or system comprised of components having differing usability parameters.
• Devices of the invention may be fabricated using any convenient materials or combination thereof, including but not limited to: metallic materials such as tungsten, stainless steel alloys, platinum or its alloys, titanium or its alloys, molybdenum or its alloys, and nickel or its alloys, etc; polymeric materials, such as polytetrafluoroethylene, polyimide, PEEK, and the like; ceramics, such as alumina (e.g., STEATITE™ alumina, MAECOR™ alumina), etc.
• Various aspects of device embodiments of the invention have been described in varying detail above. Device embodiments will now be described in further detail in terms of figures.FIGS. 1A and 1B provide two different side views of adevice100 according to one embodiment of the invention.Device100 includes anelongated member110 and anoperating handle120 at the proximal end of theelongated member110. The operating handle has a gun configuration and includes atrigger125 andthumbwheel130 which provide a user with manual operation over certain functions of the device, e.g., RF electrode positioning and extension. Located at the distal end of the elongated member is anintegrated visualization sensor140 andtissue modifier150. Control elements160 (which may include aspiration and irrigation lumens, control/power wires, etc.) exit thehandle120 at thedistal end region170, whichregion170 is rotatable relative to the remainder of thehandle120. A variety of additional components may be present at the distal end of the elongated member, which additional elements may include irrigators, aspirators, articulation mechanisms, etc. as described generally above. More details regarding the distal end ofelongate member140 may be seen inFIG. 6D.
• FIGS. 2A to 2C provide cross-sectional views of the distal ends of elongated members according to three different embodiments of the device. Each of these views shows how the visualization sensor and tissue modifier may be integrated at the distal end despite the limited size of the distal end.
• FIG. 2A shows an example cross-section of thedistal end200 of an elongated member of a device according one embodiment of the invention.Distal end200 includes an integratedCMOS visualization sensor210, which has a 2.5 mm diameter. Also shown are guide-wires215 which have a 1 mm diameter and provide for articulation of the distal end of the device. Integratedmechanical cutter230 has a 1.58 mm diameter.Light source240 has a 1.33 mm diameter. Also shown is lumen250 which provides for aspiration and irrigation.FIG. 2A is drawn to scale, demonstrating that integrated visualization, tissue modification, illumination and irrigation can be positioned at the distal end of an elongated member that has a 5.00 mm outer diameter.
• FIG. 2B shows the cross-section of a distal end of elongated member that is analogous to that shown inFIG. 2A, with the exception that smaller diameter guidewires (0.80 mm) are employed. As a result,light source240 may have a 1.50 mm diameter andmechanical cutter230 may have a 1.92 mm diameter. Like the embodiment shown inFIG. 2A,FIG. 2B is drawn to scale, demonstrating that integrated visualization, tissue modification, illumination and irrigation can be positioned at the distal end of an elongated member that has a 5.00 mm outer diameter.
• FIG. 2C shows the cross-section of a distal end of elongated member that is analogous to that shown inFIG. 2A, with the exception that smaller non-circular cross-section guidewires (1.20 mm×0.60 mm) are present. As a result,light source240 may have a 1.63 mm diameter andmechanical cutter230 may have a 2.22 mm diameter. Like the embodiment shown inFIG. 2A,FIG. 2C is drawn to scale, demonstrating that integrated visualization, tissue modification, illumination and irrigation can be positioned at the distal end of an elongated member that has a 5.00 mm outer diameter.
• FIG. 3A shows an example cross-section a distal end of a device according to an embodiment of the invention.FIG. 3A illustrates the distal end of adevice300 having a distal end outer diameter of 6.6 mm, where the drawing is to scale. The distal end ofdevice300 includes an integrated camera320 (e.g., a CMOS sensor) having an outer diameter of 2.8 mm and two fiber opticlight sources330 each having an outer diameter of 1.3 mm. Also integrated at the distal end are electrode cutters340 (having dimensions of 2.0 mm×0.7 mm) each associated with an irrigation lumen350 (having dimensions of 1.2 mm×0.8 mm). In addition, the distal end includescentral aspiration lumen360 which has a rectangular configuration and dimensions of 5.0 mm×1.8 mm. InFIG. 3A, theintegrated camera320 is overlapping with other elements, which illustrates how the camera cross-section only occupies space at the most distal portion of thedevice300. Overlapping portions of cross sections of other components, including theaspiration lumen360, would be terminated or diverted laterally before reaching the proximal end of the camera. During use of the device for removal of tissue from a target tissue location, the following steps may be performed. First thedistal end300 of the device is introduced into the target tissue dissection region throughaccess device310.Access device310 may be any convenient device, such as a conventional retractor tube.Access device310 as shown inFIG. 3A has an inner diameter of 7.0 mm and an outer diameter of 9.5 mm. At this stage, orientation ofcamera320 is biased to one side (left side in figure). During insertion, theelectrode340 on the side opposite the viewing field of the camera (right side in figure) is distally translated so that it emerges distally from the distal tip of thedevice300. Also during insertion, the distally translatedelectrode340 is activated by supplying RF current and irrigating conducting fluid, resulting in tissue dissection during insertion of the device. For further tissue dissection on the side to which the camera is biased (left side in figure), theelectrode340 on the same side as the viewing field of the camera (left side in figure) is distally translated so that it emerges laterally from the endoscope probe on the proximal side of the camera. While being translated, the same electrode (left side in figure) is activated by supplying RF current and irrigating conducting fluid, resulting in tissue dissection. At this point, the entire end of thedevice300 may be translated proximally and distally until the desired tissue dissection is obtained. When finished with tissue dissection at the first location, the device may be rotated 180 degrees and further tissue removed using the steps described above.
• FIG. 3B shows an example cross-section of the distal end of adevice300 similar to that inFIG. 3A, except that it includes additional irrigation lumens370 (outer diameter 1.2 mm) in addition to the irrigation lumens350 (dimensions of 1.5 mm×0.9 mm) associated with the electrodes340 (dimensions 2.5 mm×1.1 mm). Also, the geometry of the aspiration tube is hexagonal rather than rectangular to maximize use of space for this geometry (dimensions 4.2 mm×2.3 mm). The drawing is to scale, and shows another example of what can be integrated at the distal end of a device having a 6.6 mm outer. As shown, the cross section of thecamera320 is overlapping with other elements as inFIG. 3A, which shows how the camera cross-section only occupies space at the most distal portion of the device. Overlapping portions of other cross sections, including the light sources, one of the electrodes, and the aspiration tube, would be terminated or diverted laterally before reaching the proximal end of the camera. Operating this device may include the same steps as described above in connection with the device ofFIG. 3A, except that additional irrigation could be used to help flush out dissected tissue and to clean the camera lens using theadditional irrigation lumens370.
• FIG. 3C shows an example cross-section of thedistal end300 of a device similar to that inFIG. 3B, except that the orientation one of theelectrodes340 is reversed and the geometry of theaspiration tube360 is trapezoidal rather than hexagonal to maximize use of space for this geometry. The drawing is to scale, and shows another example of components that can be integrated into a 6.6 mm outer diameter device distal end. InFIG. 3C, the dimensions of the components are the same as that ofFIG. 3B, with the exception thatirrigation lumens370 have an outer diameter of 1.1 mm, the dimensions ofaspiration lumen360 are 4.2 mm×2.7 mm, the dimensions ofelectrodes340 are 2.5 mm×1.1 mm and the dimensions ofelectrode irrigation lumens350 are 1.5 mm×0.9 mm. As in the devices shown inFIGS. 3A and 3B, the camera cross section is overlapping with other elements, which shows how thecamera cross-section320 only occupies space at the most distal portion of the probe. Overlapping portions of other cross sections, including the light sources, one of the electrodes, and the aspiration tube, would be terminated or diverted laterally before reaching the proximal end of thecamera320. Operating this device may include the same steps as described above in connection with the device ofFIGS. 3A and 3B.
• FIG. 3D shows an example cross-section of thedistal end300 of a device that is similar to that inFIG. 3C, except that only one electrode340 (dimensions 5.4 mm diameter×0.35 mm thick) is used and it is much larger than the electrode present in the device shown inFIG. 3C. The electrode irrigation lumen is also dimensioned differently, having dimensions of 1.5 mm×0.6 mm. InFIG. 3C,integrated camera320 is shown with camera cables380 (having dimensions of (1.5 mm×0.8 mm). Also, the geometry of the aspiration lumen is a semi-circular rather than trapezoidal to maximize use of space for this geometry, where the dimensions of the aspiration lumen are 3.4 mm×2.1 mm. The drawing is to scale, and shows an example of the components that can be integrated at the distal end of a device that has a 6.6 mm outer diameter. The device is shown present in an access tube having a 7.2 mm inner diameter and a 9.5 mm outer diameter. InFIG. 3D, thecamera320 cross section is overlapping with other elements as inFIGS. 3A to 3C, demonstrating that thecamera320 cross-section only occupies space at the most distal portion of the probe. Overlapping portions of other cross sections, including the light sources and the aspiration tube, would be terminated or diverted laterally before reaching the proximal end of the camera. Operating this device may include the same steps as described above in connection with the device ofFIGS. 3A to 3C, except that the single electrode serves the function of both electrodes inFIGS. 3A to 3C. The electrode is distally translated only a short distance for distal cutting, and then it is distally translated farther to cause it to extend laterally to the side viewed by the camera for tissue dissection on that side.
• FIG. 3E shows an example cross-section of the distal probe tip similar to that inFIG. 3D, except that one of the irrigation channels is replaced by aprobe tool390, having an outer diameter of 1.2 mm, which is employed to manipulate tissue and expose target tissue regions for visualization and/or modification by a tissue modifier, such as theelectrode device340. The drawing is to scale, and shows another example of components that can be integrated at the distal end of a device having a 6.6 mm outer diameter. Operating this device may include the same steps as described above in connection with the device ofFIGS. 3A to 3D, except that the probe is also available for probing the tissue dissection region and for assisting in desired tissue dissection.
• FIG. 4 provides a side view of a device according to an embodiment of the invention, where the device includes a side-viewing integrated camera at its distal end. InFIG. 4,device400 includesintegrated camera410 having a side-viewing orbiased lens420, which provides a field of view which includes components from both the forward and side views of the device. As shown, the side-viewing camera is angled at a degree ranging from 15 to 65° relative to the longitudinal axis of theelongated member Device400 also includes an integrated tissue cutter430 (e.g., in the form of an RF electrode) and integratedlight source435.Device400 is shown in relation tointervertebral disc440, where the distal end of thedevice400 extends through theannulus fibrosis450 into thenucleus pulposus460.
• FIG. 5 provides a side view of adevice500 according to an embodiment of the invention, where the device includes a side-viewingintegrated camera510 at its distal end and twosteerable electrodes520 and525. InFIG. 4,device500 includesintegrated camera510 having a side-viewing orbiased lens520.Device500 also includes anintegrated electrodes530 and535 which are steerable (erg., being fabricated from a shape-memory material) and integratedlight source540.Device500 is shown in relation tointervertebral disc540, where the distal end of thedevice500 extends through theannulus fibrosis450 into thenucleus pulposus460.
• FIGS. 6A and 6B are isometric views of an embodiment of the distal end of a tissue modification device illustrating the invention inserted into the intervertebral disc space. Thetissue modification device600 includes anelongated member610 inserted through thedisc annulus620 into the nucleus pulposus630 of the intervertebral disc space. Thetissue modification device600 also includes anRF electrode640 extended from the distal end ofguidetubes650, which are extended from the distal end of theelongated member610. Theguidetubes650 are extended from the distal end of theelongated member610 and have a curved shape, which facilitates access of theRF electrode640 to the entire intervertebral disc space. Thetissue modification device600 also includes an integrated CMOS visualization-element660 at the distal end of theelongated member610.
• FIGS. 6A and 6B provide views of an RF electrode that is steerable at its distal end. In the embodiment depicted inFIGS. 6A and 6B, the steering functionality of the RF electrode is provided by a shape-memory element in conjunction with a guidetube. The term “shape-memory” as used herein refers to a material that can return to its original shape after being deformed. In certain embodiments, the shape-memory element comprises a shape-memory alloy, such as, but not limited to, a nickel-titanium (e.g., NITINOL) alloy, a copper-zinc-aluminum-nickel alloy, a copper-aluminum-nickel alloy, or the like. For example, the steering functionality of the RF electrode can be provided by wires comprising a shape-memory alloy. The shape-memory wires can be attached to the RF electrode such that when the RF electrode is extended from the distal end of the elongated member, the shape-memory wires take on a predetermined conformation, thus moving the RF electrode into substantially the same conformation. In certain cases, the shape-memory element is provided in conjunction with a guidetube. The guidetube can be a tube (i.e., a cylinder with a hollow central lumen) provided within the elongated member for housing the RF electrode and for guiding the direction of the RF electrode. Thus, the RF electrode can be provided within the central lumen of the guidetube. The guidetube can be composed of any convenient biocompatible material, such as plastic, rubber, metal, and the like. The guidetube can be provided with one or more shape-memory elements, such as wires comprising a shape-memory alloy, as described above. In certain embodiments, the guidetube is a shape-memory guidetube, such as a guidetube comprising a shape-memory alloy.
• In some cases, the guidetube is slidably positioned in the elongated member, and may be extended from the distal end of the elongated member. In some cases, the shape-memory guidetube has a curved shape when extended from the distal end of the elongated member, such that the guidetube extends at an angle from the longitudinal axis of the elongated member. For example, when the guidetube is fully extended from the distal end of the elongated member, the guidetube may form an arc shape where the guidetube comprises an arc of 1° to 360°, such as 30° to 180°, including 60° to 120°. As described above, the guidetube can be provided with an RF electrode in the central lumen of the guidetube. In some instances, the guidetube is configured to facilitate the RF electrode's access to the entire intervertebral disc space. In certain instances, accessibility to the entire IVD space is facilitated by articulation of one or more of the RF electrode, the guidetube, and the elongated member. In addition, the RF electrode can be slidably positioned in the guidetube, and may be extended from the distal end of the guidetube. The elongated member, the RF electrode and/or the guidetube can be independently rotated, providing additional accessibility within the IVD space.
• In certain embodiments, the tissue modification device includes two or more guidetubes, where the guidetubes are slideably translateable with respect to the elongated member. In some cases, the guidetubes are slideably translateable with respect to each other, which facilitates extending the RF electrode at an angle from the longitudinal axis of the elongated member or deforming the electrode tip into a new shape or configuration. Thus, one guidetube can be extended or retracted with respect to the distal end of the elongated member independent of the other guidetube(s). For instance, the movement of each guidetube can be controlled by the user, such that the user can extend, retract or steer each guidetube individually.
• In some cases, the RF electrode comprises a wire slidably positioned in a shape-memory guidetube that is slidably positioned in the elongated member. In certain instances, the RF electrode comprises an exposed portion positioned between first and second ends, where the first and second ends are each positioned in a shape-memory guidetube. By “exposed” is meant that a portion of the RF electrode is able to make electrical contact with the desired target tissue. In these cases, the first and second ends are linearly translatable, where the first and second ends are translatable in unison, such that the first and second ends can be extended and retracted from the distal end of the elongated member at the same rate. In other instances, the first and second ends are linearly translatable with respect to each other, such that the first and second ends can be extended and retracted from the distal end of the elongated member at different rates or to different positions of extension from the distal end of the elongated member. This facilitates the movement of the exposed portion of the RF electrode at an angle from the longitudinal axis of the elongated member. For example, when the RF electrode is extended from the distal end of the elongated member, the angle between the RF electrode and the longitudinal axis of the elongated member can be from 1° to 270°, such as 30° to 180°, including 60° to 120°.
• As shown inFIGS. 6A and 6B, theRF electrode640 is a U-shaped structure that includes a distal cutting end (the exposed region), bounded on each side by a ceramic member. This U-shaped configuration is further illustrated inFIG. 6E. Theceramic members617 flanking each side of thedistal cutting end619 may be joined (e.g., such that they have a cross-bar configuration as shown inFIGS. 6A and 68) or be separate component from each other (e.g., as shown inFIG. 6E). These components may be fabricated from any convenient ceramic material, including but not limited to alumina, such as STEATITE™ alumina, MAECOR™ alumina, and the like. InFIG. 6E, the extended length ofregion619 may vary, ranging from 2 to 20 mm, such as 2 to 10 mm and including 2 to 6 mm. The diameter of the wire making upregion619 may vary, and in certain embodiments is 180 μm, such as 150 μm or less, such as 130 μm or less, such as 100 μm or less, such as 80 μm or less. While the distal cutting end orregion619 may be fabricated from a variety of materials, in some instances this portion of the electrode is fabricated from a material that is different from the material of theelectrode wires621. Materials of interest from which thedistal cutting end619 may be fabricated include, but are not limited to tungsten, tungsten alloys, e.g., tungsten rhenium, steel, tungsten coated with noble metals, such as Pt, Au, etc., and the like.
• FIG. 6C provides a view of the distal end of device that is analogous to that shown inFIGS. 6A and 6B.FIG. 6C shows how a variety of components including an integratedCMOS visualization sensor660,irrigation lumens665,aspiration lumen670, andsteerable RF electrode640 can be incorporated into the distal end of an elongated member having an outer diameter that is 7.0 mm or less, such as 6.5 mm or less.Electrode640 is made up of electrode wires extending fromelectrode guidetubes650. Separating the electrode wires from thedistal cutting end690 are ceramicelectrode crimp elements680.Electrode wires640 andguidetubes650 are shown in an extended configuration inFIG. 6C but each independently may be fabricated from a shape memory material so as to assume a curved configuration (as shown inFIGS. 6A and6B) and therefore impart steerability to the RF electrode. As shown inFIG. 6C,aspiration lumen670 opens to the side of thedevice600 and is positioned just proximal of theCMOS visualization sensor660 so that all of the disparate components may be integrated at the distal end of the device.
• FIG. 6D provides a three-dimensional view of one embodiment of a distal end of tissue modification device600 (having a 6.5 mm outer dimension) of the invention. InFIG. 6D, the distal end of the device includes and integrated circularCMOS visualization sensor605 andintegrated LED610. Also shown is a first forward facingirrigation lumen615 and asecond irrigation lumen617 which is slightly extended from the distal end and is side facing so that fluid emitted fromlumen617 is flowed acrossCMOS visualization sensor605 to clean the sensor of debris, when needed. Also shown is anaspiration lumen625 positioned proximal theirrigation lumens615 and617 and integratedCMOS visualization sensor605, where theaspiration lumen605 is configured to aspirate fluid and tissue debris from a target tissue site during use. The distal end further includes an integrated steerableRF electrode assembly655.RF electrode assembly655 includes NITINOL shape memory guide tubes645 extending from insulated (e.g., RF shielded) guidelumens642. The RF electrode further includes atungsten cutting wire665 joined at each end to a NITINOL shapememory electrode wire663 by aceramic arc stop675. As shown, the diameter of thecutting wire665 is smaller than the diameter of theelectrode wires663, where the difference in size may vary and may range from 100 to 500 μm, such as 300 to 400 μm.
• FIGS. 1A and 1B, reviewed above, provide different views of a device according to an embodiment of the invention, where the device includes a distal end as shown inFIG. 6D.FIG. 7 provides a cutaway view of the devices shown inFIGS. 1A and 1B. As shown inFIG. 7, the device includestrigger element125 which translates the guidetubes relative to the distal end of the elongated member. Also shown is thumbwheel130 which provides for manual movement of the electrode relative to the distal end. The cutaway view ofFIG. 7 showsmechanical actuator180 which provides for linear translation of electrode190 positioned at the distal end of the elongated member.
• Tissue modification devices of the invention are configured to be hand-held. Accordingly, in certain instances the tissue modification devices have a mass that is 1.5 kg or less, such as 1 kg or less, including 0.5 kg or less, e.g., 0.25 kg or less.
Systems
• Aspects of the subject invention include tissue modification systems, where the systems include a tissue modification device, e.g., as described above, operatively connected to one or more extra-corporeal control units (i.e., extra-corporeal controllers). Extra-corporeal control units may include a number of different components, such as power sources, irrigation sources, aspiration sources, image data processing components, image display components (such as monitors, printers, and the like), data processors, e.g., in the form of computers, data storage devices, e.g., floppy disks, hard drives, CD-ROM, DVD, flash memory, etc., device and system controls, etc.
• An example of a system according to an embodiment of the invention is shown inFIG. 8. InFIG. 8 the system includes hand-heldtissue modification device800 andextra-corporeal control unit850. Hand-helddevice800 includesdistal end810 and handle820 configured to be held in the hand of an operator. Positioned at thedistal end810 are the integrated visualization and tissue modification components (as well as other components), as shown bycross-section830.Extra-corporeal control unit850 includes image display860 (e.g., a liquid crystal display monitor), videodigital signal processor870, energy source880 (e.g., configured to operate an RF tissue modification member) and irrigation/aspiration system890. The hand-helddevice800 andextra-corporeal control unit850 are operatively connected to each other by a cable.
• FIG. 9 provides a diagrammatic view of the architecture of a system according to one embodiment of the invention and how the various components of the system may interact with a user, such as a surgeon, during use. InFIG. 9,extra-corporeal control unit910 includes avideo processing unit911, an RFelectrode power source912, anirrigation source913 and anaspiration source914. Each of these components is operatively connected to electrical controls915, with which the user990 may interact to operate the system as desired. Also shown is tissue modification device950 which includes anintegrated visualization sensor951, anRF electrode952, anirrigation lumen953, anaspiration lumen954 and anarticulation mechanism955. The tissue modification device950 provides a number of functionalities960, including tissue dissection961, tissue removal962, tissue discrimination963 and accessibility964. The system provides numeroususer interface opportunities930; includingimage display931,tactile feedback932 andmechanical controls933.
• Within a given system, the integrated distal end visualization sub-system may have a variety of different configurations.FIG. 10 provides an example of an embodiment of an integrated visualization sub-system that includes a distal end CMOS visualization sensor. As shown inFIG. 10,visualization sub-system1000 includes distal endCMOS visualization sensor1010 that includeslens housing1015 component operatively coupled tointegrated circuit component1020. As shown in the figure,lens housing1015 includes alens set1016. Also shown at the distal end is LED1018 which provides illumination for a target tissue location during use.Integrated circuit component1020 includes CMOS sensor integrated circuit1021 and rigid printedcircuit board1022. The sub-components of lens housing/light source component1015 are operatively coupled toflexible cable1030 which provides for operative connection of the CMOS visualization system at the distal end of the device via the handle.1040 to thevideo processing sub-system1050. In thehandle1040 the flexible cable operatively connects to a shieldedcable1052 which provides for RF isolation. As shown inFIG. 10, the various components are shielded from RF, e.g., by coating the elements with a conductive material which is then connected to a ground. For example,lens housing1015 andcable1030 are RF shielded. RF shieldedcable1052 connects tovideo processing sub-system1050 which includes a variety of functional blocks, such as host controller1051 (coupled to PC1061), digital signal processor1052 (coupled to LCD1062) and CMOSvisualization sensor bridge1053. As shown inFIG. 10,video processing sub-system1050 is ground toearth1072 by connection tometal case1070.
• Systems of the invention may include a number of additional components in addition to the tissue modification devices and extra-corporeal control units, as described above. Additional components may include access port devices; root retractors; retractor devices, system component fixation devices; and the like; etc. Of interest are systems that further access devices as described in co-pending U.S. application Ser. Nos. 12/269,770; 12/269,772; and 12/269,775; the disclosures of which are herein incorporated by reference.
Methods
• Aspects of the subject invention also include methods of imaging and/or modifying an internal target tissue of a subject. Accordingly, aspects of the invention further include methods of imaging an internal tissue site with tissue modification devices of the invention. A-variety of internal tissue sites can be imaged with devices of the invention. In certain embodiments, the methods are methods of imaging an intervertebral disc in a minimally invasive manner. For ease of description, the methods are now primarily described further in terms of imaging IVD target tissue sites. However, the invention is not so limited, as the devices may be used to image a variety of distinct target tissue sites.
• With respect to imaging an intervertebral disc or portion thereof, e.g., exterior of the disc, nucleus pulposus, etc., embodiments of such methods include positioning a distal end of a minimally invasive intervertebral disc imaging device of the invention in viewing relationship to an intervertebral disc or portion of there, e.g., nucleus pulposus, internal site of nucleus pulposus, etc. By viewing relationship is meant that the distal end is positioned within 40 mm, such as within 10 mm, including within 5 mm of the target tissue site of interest. Positioning the distal end in viewing device in relation to the desired target tissue may be accomplished using any convenient approach, including through use of an access device, such as a cannula or retractor tube, which may or may not be fitted with a trocar, as desired. Following positioning of the distal end of the imaging device in viewing relationship to the target tissue, the target tissue, erg., intervertebral disc or portion thereof, is imaged through use of the illumination and visualization elements to obtain image data. Image data obtained according to the methods of the invention is output to a user in the form of an image, e.g., using a monitor or other convenient medium as a display means. In certain embodiments, the image is a still image, while in other embodiments the image may be a video.
• In certain embodiments, the methods include a step of tissue modification in addition to the tissue viewing. For example, the methods may include a step of tissue removal, e.g., using a combination of tissue cutting and irrigation or flushing. For example, the methods may include cutting a least a portion of the tissue and then removing the cut tissue from the site, e.g., by flushing at least a portion of the imaged tissue location using a fluid introduced by an irrigation lumen and removed by an aspiration lumen.
• The internal target tissue site may vary widely. Internal target tissue sites of interest include, but are not limited to, cardiac locations, vascular locations, orthopedic joints, central nervous system locations, etc. In certain cases, the internal target tissue site comprises spinal tissue.
• The subject methods are suitable for use with a variety of mammals. Mammals of interest include, but are not limited to: race animals, e.g. horses, dogs, etc., work animals, e.g. horses, oxen etc., and humans. In some embodiments, the mammals on which the subject methods are practiced are humans.
• An example of a method which employs the device depicted inFIG. 3A includes the following steps. First thedistal end300 of the device is introduced into the target tissue dissection region throughaccess device310.Access device310 may be any convenient device, such as a conventional retractor tube.Access device310 as shown inFIG. 3A has an inner diameter of 7.0 mm and an outer diameter of 9.5 mm. At this stage, orientation ofcamera320 is biased to one side (left side in figure). During insertion, theelectrode340 on the side opposite the viewing field of the camera (right side in figure) is distally translated so that it emerges distally from the distal tip of thedevice300. Also during insertion, the distally translatedelectrode340 is activated by supplying RF current and irrigating conducting fluid, resulting in tissue dissection during insertion of the device. For further tissue dissection on the side to which the camera is biased (left side in figure), theelectrode340 on the same side as the viewing field of the camera (left side in figure) is distally translated so that it emerges laterally from the endoscope probe on the proximal side of the camera. While being translated, the same electrode (left side in figure) is activated by supplying RF current and irrigating conducting fluid, resulting in tissue dissection. At this point, the entire end of thedevice300 may be translated proximally and distally until the desired tissue dissection is obtained. When finished with tissue dissection at the first location, the device may be rotated 180 degrees and further tissue removed using the steps described above.
Utility
• The subject tissue modification devices and methods find use in a variety of different applications where it is desirable to image and/or modify an internal target tissue of a subject while minimizing damage to the surrounding tissue. The subject devices and methods find use in many applications, such as but not limited to surgical procedures, where a variety of different types of tissues may be removed, including but not limited to; soft tissue, cartilage, bone, ligament, etc. Specific procedures of interest include, but are not limited to, spinal fusion (such as Transforaminal Lumbar Interbody Fusion (TLIF)), total disc replacement (TDR), partial disc replacement (PDR), procedures in which all or part of the nucleus pulposus is removed from the intervertebral disc (IVD) space, arthroplasty, and the like. As such, methods of the invention also include treatment methods, e.g., where a disc is modified in some manner to treat an existing medical condition. Treatment methods of interest include, but are not limited to: annulotomy, nucleotomy, discectomy, annulus replacement, nucleus replacement, and decompression due to a bulging or extruded disc. Additional methods in which the imaging devices find use include those described in United States Published Application No. 20080255563.
• In certain embodiments, the subject devices and methods facilitate the dissection of the nucleus pulposus while minimizing thermal damage to the surrounding tissue. In addition, the subject devices and methods can facilitate the surgeon's accessibility to the entire region interior to the outer shell, or annulus, of the IVD, while minimizing the risk of cutting or otherwise causing damage to the annulus or other adjacent structures (such as nerve roots) in the process of dissecting and removing the nucleus pulposus.
• Furthermore, the subject devices and methods may find use in other procedures, such as but not limited to ablation procedures, including high-intensity focused ultrasound (HIFU) surgical ablation, cardiac tissue ablation, neoplastic tissue ablation (e.g. carcinoma tissue ablation, sarcoma tissue ablation, etc.), microwave ablation procedures, and the like. Yet additional applications of interest include, but are not limited to: orthopedic applications, e.g., fracture repair, bone remodeling, etc., sports medicine applications, e.g., ligament repair, cartilage removal, etc., neurosurgical applications, and the like.
• Devices of the invention may provide variable tactile feedback to the operator depending on tissue type. For example, in embodiments where a distal end structure, such as a tissue modifier (e.g., a RF electrode) is linearly translated by a mechanical linear actuator (e.g., as described above), the operator may experience different tactile properties depending on the type of tissue that is being contacted by the linearly translating distal end structure. These different tactile properties may then be employed by the user to differentiate between different types of tissue. In other words, devices of invention may provide different sensations to an operator, such as a surgeon, during use depending on the nature of the tissue with the distal end of the device is in contact. As such, devices and methods of the invention also find use in tissue discrimination applications, where the devices are employed to determine the particular nature of the internal tissue with which the distal end of the device is in contact, e.g., whether the distal end of the device is in contact with soft tissue, cartilage, bone, etc.
• As reviewed above, in some embodiments synchronization of the tissue modifier's modulation waveform with its linear translation waveform provides additional benefits. For instance, rapid retraction of the electrode from hard tissue that it encounters will leave the tissue modifier physically separated from the hard tissue by a gap as the tissue modifier approaches the proximal extreme position. In some embodiments, the tissue modifier tip is activated only when the tissue modifier is at or near the proximal extreme position, as mentioned above. This has the effect of preferentially delivering the tissue modification energy to soft, compliant tissue as opposed to hard, stiff tissue. Stated otherwise, this provides tissue discrimination based on elastic modulus. In the case of spinal surgery applications requiring removal of nuclear material, such as fusion, total disc replacement, and partial disc replacement, synchronization of the modulation waveform with the linear translation waveform facilitates the delivery of tissue modification energy to the nucleus pulposus (soft, compliant tissue) while minimizing the delivery of tissue modification energy to the disc annulus (hard, stiff tissue) and the endplates of the vertebral bodies (hard, stiff tissue). In addition, cyclic linear translation of the tissue modifier helps to prevent a condition where the electrode sticks to tissue as it ablates it, resulting in increased thermal effects to the surrounding tissue, ineffective or discontinuous tissue dissection, buildup of charred or otherwise modified tissue on the tissue modifier tip, or a combination thereof. Additionally, cyclic linear translation of the tissue modifier helps chop the dissected tissue into smaller pieces, thus facilitating aspiration of the dissected tissue.
Kits
• Also provided are kits for use in practicing the subject methods, where the kits may include one or more of the above devices, and/or components of the subject systems, as described above. The kit may further include other components, e.g., guidewires, access devices, fluid sources, etc., which may find use in practicing the subject methods. Various components may be packaged as desired, e.g., together or separately.
• In addition to above mentioned components, the subject kits may further include instructions for using the components of the kit to practice the subject methods. The instructions for practicing the subject methods are generally recorded on a suitable recording medium. For example, the instructions may be printed on a substrate, such as paper or plastic, etc. As such, the instructions may be present in the kits as a package insert, in the labeling of the container of the kit or components thereof (i.e., associated with the packaging or subpackaging) etc. In other embodiments, the instructions are present as an electronic storage data file present on a suitable computer readable storage medium, e.g. CD-ROM, diskette, etc. In yet other embodiments, the actual instructions are not present in the kit, but means for obtaining the instructions from a remote source, e.g. via the internet, are provided. An example of this embodiment is a kit that includes a web address where the instructions can be viewed and/or from which the instructions can be downloaded. As with the instructions, this means for obtaining the instructions is recorded on a suitable substrate.
• Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims.
• Accordingly, the preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. The scope of the present invention, therefore, is not intended to be limited to the exemplary embodiments shown and described herein. Rather, the scope and spirit of present invention is embodied by the appended claims.

Claims (28)

1. A tissue modification device comprising:

an elongated member having a distal end dimensioned to be passed through a minimally invasive body opening, wherein the distal end comprises an integrated visualization sensor and tissue modifier.

2. The tissue modification device according toclaim 1, wherein the integrated visualization sensor comprises a lens and an integrated circuit.

3. The tissue modification device according toclaim 2, wherein the visualization sensor is a CMOS device.

4. The tissue modification device according toclaim 2, wherein the visualization sensor is a CCD device

5. The tissue modification device according toclaim 1, wherein the device further comprises an integrated articulation mechanism that imparts steerability to at least one of the visualization sensor, the tissue modifier and the distal end of the elongated member.

6. The tissue modification device according toclaim 1, wherein the distal end of the elongate member is dimensioned to be passed through a Cambin's triangle.

7. The tissue modification device according toclaim 6, wherein the distal end of the elongate member has an outer diameter of 7.5 mm or less.

8. The tissue modification device according toclaim 7, wherein the distal end of the elongate member has an outer diameter of 7.0 mm or less.

9. The tissue modification device according ofclaim 8, wherein the distal end of the elongate member has an outer diameter of 5.0 mm or less.

10. The tissue modification device according toclaim 1, wherein the distal end of the elongate member further comprises an integrated illuminator.

11. The tissue modification device according toclaim 10, wherein the illuminator is a fiber-optic illuminator.

12. The tissue modification device according toclaim 10, wherein the illuminator is a light emitting diode.

13. The tissue modification device according toclaim 1, wherein the tissue modifier comprises an electrode.

14. The tissue modification device according toclaim 1, wherein at least one of the visualization sensor and tissue modifier are moveable relative to the distal end of the elongate member.

15. The tissue modification device according toclaim 1, wherein the distal end of the elongate member further comprises an irrigator and an aspirator.

16. The tissue modification device according toclaim 15, wherein the aspirator is located proximal of the integrated visualization sensor.

17. The tissue modification device according toclaim 15, wherein the aspirator comprises a port having a cross-sectional area that is 33% or more of the cross-sectional area of the distal end of the elongate member.

18. The tissue modification device according toclaim 1, wherein the elongated member is rigid.

19. The tissue modification device according toclaim 1, wherein the tissue modification device is configured to modify an intervertebral disc tissue.

20. The tissue modification device according toclaim 1, wherein the device is configured as a disposable.

21. The tissue modification device according toclaim 1, wherein the device comprises an operating handle positioned at the proximal end.

22. The tissue modification device according toclaim 21, wherein the distal end of the elongated member is rotatable about its longitudinal axis when a significant portion of the operating handle is maintained in a fixed position.

23. A system comprising:

(a) an elongated member having a distal end dimensioned to be passed through a minimally invasive body opening, wherein the distal end comprises an integrated visualization sensor and tissue modifier; and

(b) an extracorporeal controller operatively coupled to the proximal end of the elongated member.

24. The system according toclaim 23, wherein the system further comprises an image displayer for displaying to a user images obtained by the visualization sensor.

25. The system according toclaim 23, wherein the system further comprises a minimally invasive access tube.

26. A method of modifying an internal target tissue of a subject, the method comprising:

(a) positioning distal end of a tissue modification device comprising an elongated member having a distal end dimensioned to be passed through a minimally invasive body opening, wherein the distal end comprises an integrated visualization sensor and tissue modifier in operable relation to the internal target tissue; and

(b) modifying the internal target tissue with the tissue modifier.

27. The method according toclaim 26, wherein the internal target tissue site comprises spinal tissue.

28. The method according toclaim 26, wherein the method is a method of removing nucleus pulposus tissue from an intervertebral disc.

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