Mechanical tissue modification devices and methods

A device for modifying one or more tissues in a patient's spine may include: an elongate, at least partially flexible body having a proximal portion and a distal portion, wherein at least the distal portion has dimensions that allow it to be passed into an epidural space and between target and non-target tissues of the spine; at least one movable blade disposed along one side of the elongate body; at least one actuator coupled with the at least one blade and disposed at or near the proximal or distal portion of the body for moving the blade(s) to modify one or more target tissues, wherein the at least one actuator is configured to move the blade(s) without significantly translating the elongate body proximally or distally; and means at or near the proximal and distal portions of the elongate body for facilitating application of at least one of anchoring force and tensioning force to the body to urge the at least one blade against the target tissue.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to methods and apparatus for modifying tissue in a patient.

Many pathological conditions in the human body may be caused by enlargement, movement, displacement and/or a variety of other changes of bodily tissue, causing the tissue to press against (or “impinge on”) one or more otherwise normal tissues or organs. For example, a cancerous tumor may press against an adjacent organ and adversely affect the functioning and/or the health of that organ. In other cases, bony growths (or “bone spurs”), arthritic changes in bone and/or soft tissue, redundant soft tissue, or other hypertrophic bone or soft tissue conditions may impinge on nearby nerve and/or vascular tissues and compromise functioning of one or more nerves, reduce blood flow through a blood vessel, or both. Other examples of tissues which may grow or move to press against adjacent tissues include ligaments, tendons, cysts, cartilage, scar tissue, blood vessels, adipose tissue, tumor, hematoma, and inflammatory tissue.

One specific example of a condition caused by tissue impingement is spinal stenosis. Spinal stenosis occurs when neural tissue and/or vascular tissue in the spine become impinged by one or more structures pressing against them (“neural and/or neurovascular impingement”), causing one or more symptoms. This impingement of tissue may occur in one or more of several different areas in the spine, such as in the central spinal canal (the vertical passage through which the spinal cord and cauda equina extends), the lateral recesses of the spinal canal, or one or more intervertebral foramina (the openings through which nerve roots branching from the spinal cord pass).

For explanatory purposes,FIG. 1is offered to show an approximate top view of a vertebra (one of the bones of the spinal column) with the cauda equina (the horsetail-shaped bundle of nerves that extends from the base of the spinal cord through the central spinal canal) shown in cross section and two nerve roots exiting the central spinal canal and extending through intervertebral foramina on either side of the vertebra. (FIG. 1is not drawn to exact scale and is intended for exemplary purposes only. It should be emphasized here that the drawing figures appended to this application are not intended to be precisely anatomically correct and are provided for exemplary purposes to facilitate description.) The spinal cord and cauda equina run vertically along the spine through the central spinal canal, while nerve roots branch off of the spinal cord and cauda equina between adjacent vertebrae and extend through the intervertebral foramina.

One common cause of spinal stenosis is buckling and thickening of the ligamentum flavum (one of the ligaments attached to and connecting the vertebrae), as shown inFIG. 1. Buckling or thickening of the ligamentum flavum may impinge on one or more neurovascular structures, dorsal root ganglia, nerve roots and/or the spinal cord itself. Another common cause of neural and neurovascular compression within the spine is disease of one or more of the intervertebral discs (the malleable discs between adjacent vertebrae), which may lead to collapse, bulging or herniation of the disc. InFIG. 1, an intervertebral disc is shown with three solid-tipped arrows demonstrating how the disc might bulge or herniate into the central spinal canal to impinge upon the spinal cord, cauda equina and/or individual nerve roots. Other causes of neural and neurovascular impingement in the spine include: hypertrophy of one or more facet joints (also known as zygapophysial joints, facet joints provide articulation between adjacent vertebrae—two vertebral facet superior articular processes are shown inFIG. 1); formation of osteophytes (bony growths or “bone spurs”) on vertebrae; spondylolisthesis (sliding of one vertebra relative to an adjacent vertebra); and (facet joint) synovial cysts. Disc, bone, ligament or other tissue may impinge on the spinal cord, the cauda equina, branching spinal nerves and/or blood vessels in the spine to cause loss of function, ischemia (shortage of blood supply) and even permanent damage of neural or neurovascular tissue. In a patient, this may manifest as pain, impaired sensation and/or loss of strength or mobility.

In the United States, spinal stenosis occurs with an incidence of between 4% and 6% of adults aged 50 and older and is the most frequent reason cited for back surgery in patients aged 60 and older. Conservative approaches to the treatment of symptoms of spinal stensosis include systemic medications and physical therapy. Epidural steroid injections may also be utilized, but they do not provide long lasting benefits. When these approaches are inadequate, current treatment for spinal stenosis is generally limited to invasive surgical procedures to remove vertebral ligament, cartilage, bone spurs, synovial cysts, cartilage, and bone to provide increased room for neural and neurovascular tissue. The standard surgical procedure for spinal stenosis treatment includes laminectomy (complete removal of the lamina (seeFIG. 1) of one or more vertebrae) or laminotomy (partial removal of the lamina), followed by removal (or “resection”) of the ligamentum flavum. In addition, the surgery often includes partial or occasionally complete facetectomy (removal of all or part of one or more facet joints between vertebrae). In cases where a bulging intervertebral disc contributes to neural impingement, disc material may be removed surgically in a discectomy procedure.

Removal of vertebral bone, as occurs in laminectomy and facetectomy, often leaves the effected area of the spine very unstable, leading to a need for an additional highly invasive fusion procedure that puts extra demands on the patient's vertebrae and limits the patient's ability to move. In a spinal fusion procedure, the vertebrae are attached together with some kind of support mechanism to prevent them from moving relative to one another and to allow adjacent vertebral bones to fuse together. Unfortunately, a surgical spine fusion results in a loss of ability to move the fused section of the back, diminishing the patient's range of motion and causing stress on the discs and facet joints of adjacent vertebral segments.

While laminectomy, facetectomy, discectomy, and spinal fusion frequently improve symptoms of neural and neurovascular impingement in the short term, these procedures are highly invasive, diminish spinal function, drastically disrupt normal anatomy, and increase long-term morbidity above levels seen in untreated patients.

Therefore, it would be desirable to have less invasive methods and devices for addressing neural and neurovascular impingement in a spine. Ideally, methods and devices for addressing impingement in spine would treat one or more target tissues while preventing unwanted effects on adjacent or nearby non-target tissues. Also ideally, such methods and devices would be minimally invasive and reduce impingement without removing significant amounts of vertebral bone, joint, or other spinal support structures, thereby avoiding the need for spinal fusion and, ideally, reducing the long-term morbidity levels resulting from currently available surgical treatments. It may also be advantageous to have less invasive methods and devices for modifying target tissues in parts of the body other than the spine while preventing modification of non-target tissues. At least some of these objectives will be met by the present invention.

2. Description of Background Art

Flexible wire saws and chain saws, such as threadwire saws (T-saws) and Gigli saws, have been used since the late 1800s to saw through or file/abrade bone and other tissue in the human body. See, for example, Brunori A et al., “Celebrating the Centenial (1894-1994): Leonardo Gigli and His Wire Saw,” J Neurosurg 82:1086-1090, 1995. An example of one such saw is described in U.S. Pat. No. 8250, issued to P. A. Stohlmann on Nov. 28, 1876. A description of using a T-saw to cut vertebral bone is provided in Kawahara N et al., “Recapping T-Saw Laminoplasty for Spinal Cord Tumors,” SPINE Volume 24, Number 13, pp. 1363-1370.

A method and apparatus for treating spinal stenosis is described in PCT Patent Application Pub. No. WO 01/08571. A surgical instrument for removing cartilage from a knee cavity is described in U.S. Pat. No. 3,835,859.

SUMMARY OF THE INVENTION

In various embodiments, the present invention provides methods, apparatus and systems for modifying tissue in a patient. Generally, the methods, apparatus and systems may involve using an elongate, at least partially flexible tissue modification device having one or more tissue modifying members to modify one or more target tissues. The tissue modification device may be configured such that when the tissue modification member (or members) is in a position for modifying target tissue, one or more sides, surfaces or portions of the tissue modification device configured to avoid or prevent damage to non-target tissue will face non-target tissue. In various embodiments, during a tissue modification procedure, an anchoring force may be applied at or near either a distal portion or a proximal portion of the tissue modification device, either inside or outside the patient. Pulling or tensioning force may also be applied to the unanchored end of the device to urge the tissue modifying member(s) against target tissue. The tissue modifying members may then be activated to modify tissue while being prevented from extending significantly beyond the target tissue in a proximal or distal direction. In some embodiments, the tissue modifying members may be generally disposed along a length of the tissue modification device that approximates a length of target tissue to be modified.

By “applying an anchoring force,” it is meant that a force is applied to maintain a portion of a device, or the device as a whole, substantially stable or motion-free. Applying an anchoring force is, therefore, not limited to preventing all movement of a device, and in fact, a device to which an anchoring force is applied may actually move in one or more directions in some embodiments. In other embodiments, an anchoring force is applied to maintain a portion of a device substantially stable, while another portion of the device is allowed to move more freely. As will be described in further detail below, applying an anchoring force in one embodiment involves a user of a device grasping the device at or near one of its ends. In other embodiments, devices may use one or more anchoring members to apply an anchoring force. In a number of embodiments, an anchoring force may be applied with or against one or more tissues of a patient's body, and the tissue(s) may often move even as they apply (or help apply) the force. Thus, again, applying an anchoring force to a device does not necessarily mean that all motion of the device is eliminated. Of course, in some embodiments, it may be possible and desirable to eliminate all movement or substantially all movement of a device (or portion of a device), and in some embodiments anchoring force may be used to do so.

Methods, apparatus and systems of aspects of the present invention generally provide for tissue modification while preventing unwanted modification of, or damage to, surrounding tissues. Tensioning the tissue modification device by applying anchoring force at or near one end and applying tensioning or pulling force at or near the opposite end may enhance the ability of tissue modification members of the device to work effectively within a limited treatment space. Applying tensioning force to a predominantly flexible device may also allow the device to have a relatively small profile, thus facilitating its use in less invasive procedures and in other procedures in which alternative approaches to target tissue may be advantageous.

In some embodiments, the described methods, apparatus and systems may be used to modify tissue in a spine, such as for treating neural impingement, neurovascular impingement and/or spinal stenosis. In alternative embodiments, target tissues in other parts of the body may be modified.

In one aspect of the present invention, a device for modifying one or more tissues in a patient's spine may include: an elongate, at least partially flexible body having a proximal portion and a distal portion, wherein at least the distal portion has dimensions that allow it to be passed into an epidural space and between target and non-target tissues of the spine; at least one movable blade disposed along one side of the elongate body; at least one actuator coupled with the at least one blade and disposed at or near the proximal or distal portion of the body for moving the blade(s) to modify one or more target tissues, wherein the at least one actuator is configured to move the blade(s) without significantly translating the elongate body proximally or distally; and means at or near the proximal and distal portions of the elongate body for facilitating application of at least one of anchoring force and tensioning force to the body to urge the at least one blade against the target tissue.

In another aspect of the present invention, a device for modifying one or more tissues in a patient may include: an elongate, flexible body having a proximal portion and a distal portion; at least one blade disposed along one side of the elongate body; and means at or near the proximal and distal portions of the elongate body for facilitating application of at least one of anchoring force and tensioning force to the body to urge the at least one blade against the target tissue.

In another aspect of the present invention, a method for modifying tissue in a patient may involve: advancing at least a distal portion of at least one elongate, at least partially flexible tissue modification device into a patient and between one or more target tissues and one or more non-target tissues; positioning at least one blade of the tissue modification device adjacent the target tissue such that the blade(s) face the target tissue and do not face the non-target tissue; applying at least one of anchoring and tensioning force to the tissue modification device at or near its proximal and distal portions to urge the blade(s) against the target tissue; and moving the at least one blade to cut the target tissue.

These and other aspects and embodiments are described more fully below in the Detailed Description, with reference to the attached Drawings.

DETAILED DESCRIPTION OF THE INVENTION

Methods, apparatus and systems for modifying tissue in a patient are provided. Although the following description and accompanying drawing figures generally focus on tissue modification in spine, in various alternative embodiments any of a number of tissues in any of a number of anatomical locations in a patient may be modified.

Referring toFIG. 2, in one embodiment a tissue modification device102may include an elongate body108having a proximal portion107and a distal portion109, a handle104with an actuator106coupled with proximal portion107, one or more tissue modifying members110, and one or more protective surfaces112. In various embodiments, some of which are described further below, modification device102may be introduced into an area for performing a treatment, such as a spine, using any of a number of different introduction methods, devices and systems100. InFIG. 2, for example, modification device102extends through an introducer device114placed through a first incision240on the patient's back and into the central spinal canal. Modification device102is advanced along a guide member116, which extends through introducer member114, through the intervertebral foramen between two adjacent vertebrae (only part of one vertebra is shown inFIG. 2), and out a second (or “distal”) incision242on the back. In some embodiments, as shown, guide member has a beveled distal tip117for facilitating advancement of guide member116through tissue.

Generally, tissue modification device102may be advanced to a position in the spine such that tissue modifying member110faces target tissue to be modified, such as buckled, thickened or otherwise impinging ligamentum flavum tissue as shown inFIG. 2. Modification device102is configured such that when tissue modifying member110faces the target tissue, protective surface(s)112face non-target tissue. Protective surface112may be simply a length of elongate body108or may have one or more protective features, such as a widened diameter, protective or lubricious coating, extendable barrier, drug-eluting coating or ports, or the like. In some instances, protective surface(s)112may act as “non-tissue-modifying” surfaces, in that they may not substantially modify the non-target tissue. In alternative embodiments, protective surface(s)112may affect non-target tissue by protecting it in some active way, such as by administering one or more protective drugs, applying one or more forms of energy, providing a physical barrier, or the like.

In some embodiments, once tissue modification device102is positioned such that tissue modifying member110faces target tissue and protective surface112faces non-target tissue, an anchoring force may be applied at or near distal portion109of elongate body108, either inside or outside the patient's body. A tensioning force may also be applied at or near proximal portion107of elongate body108, such as by pulling on handle104(one-directional arrows), and actuator106may be used (two-headed arrow) to activate tissue modifying member(s)110to modify target tissue. In the example shown, anchoring force is applied near distal portion109by a user's hand244, and handle104is pulled proximally (arrows) to apply tensioning force. In an alternative embodiment, hand244may grasp guide member116at or near its distal portion117and thus apply anchoring force to it, thus also applying anchoring force to elongate body108. In one variation of such an embodiment, elongate body108or handle104may optionally be adjustably clamped to guide member116to further enhance or facilitate application of anchoring force to elongate body108. Tissue modification via tissue modifying members110may include cutting, ablating, dissecting, repairing, reducing blood flow in, shrinking, shaving, burring, biting, remodeling, biopsying, debriding, lysing, debulking, sanding, filing, planing, heating, cooling, vaporizing, delivering a drug to, and/or retracting the target tissue. Once tissue has been modified, tissue modification device102and any introducer devices114, guide members116or other devices may be removed from the patient.

In various embodiments of the apparatus, tissue modifying member(s)110may be disposed along any suitable length of body108. In one embodiment, for example, such as an embodiment of the device to be used in a spinal treatment, tissue modifying members110may be disposed along a length of the device measuring no longer than 10 cm, and preferably no more than 6 cm, and even more preferably no more than 3 cm. In various embodiments, tissue modifying member(s)110may include a rongeur, a curette, a scalpel, one or more cutting blades, a scissors, a forceps, a probe, a rasp, a file, an abrasive element, one or more small planes, an electrosurgical device, a bipolar electrode, a unipolar electrode, a thermal electrode, a rotary powered mechanical shaver, a reciprocating powered mechanical shaver, a powered mechanical burr, a laser, an ultrasound crystal, a cryogenic probe, a pressurized water jet, a drug dispensing element, a needle, a needle electrode, or some combination thereof. In various embodiments, all tissue modifying members110may be mobile relative to the elongate body, all may be static, or some may be mobile and some may be static. These and other aspects and embodiments are described further below.

Turning now toFIG. 3A-3I, more detailed figures of one embodiment of tissue modification device102are shown. Referring toFIG. 3A, tissue modification device102may include elongate body108having proximal portion107and distal portion109, a window111disposed along elongate body108, two tissue modifying blades110exposed through window111, and handle104with actuator106coupled with proximal portion107. In the embodiment shown, the tissue modifying members comprise blades110, although in alternative embodiments other tissue modifying members may be added or substituted.

In various embodiments, elongate body108may have any number of dimensions, shapes, profiles and amounts of flexibility. For example, distal portion109is shown having a curved shape to demonstrate that at least a portion of elongate body108may be flexible. In various embodiments, elongate body108may have one or more of a round, ovoid, ellipsoid, flat, cambered flat, rectangular, square, triangular, symmetric or asymmetric cross-sectional shape. As shown inFIGS. 3C and 3D, in the pictured embodiment, elongate body108has a relatively flat configuration, which may facilitate placement of body108between target and non-target tissues. Distal portion109of body108may be tapered, to facilitate its passage into or through narrow spaces as well as through small incisions on a patient's skin. Body108may also include a slightly widened portion around the area of window111and blades. In one embodiment, such as an embodiment used for modifying tissue in a spine, body108may have a small profile, such as having a height of not more than 10 mm at any point along its length and a width of not more than 20 mm at any point along its length, or more preferably a height not more than 5 mm at any point along its length and a width of not more than 10 mm at any point along its length, or even more preferably a height not more than 2 mm at any point along its length and a width of not more than 4 mm at any point along its length. Body108may be long enough to extend through a first incision on a patient, between target and non-target tissue, and out a second incision on a patient. Alternatively, body108may be long enough to extend through a first incision, between the target and non-target tissue, and to an anchoring location within the patient. In another alternative embodiment, body108may be long enough to extend through a first incision, between the target and non-target tissue, to a location nearby but distal to the target tissue within the patient, with some portion of tissue modification device102anchored to guide member116. In some embodiments, elongate body108includes at least one feature for allowing passage of the body over a guidewire or other guide member or to allow passage of one or more guide members over or through body108. For example, in various embodiments body108may include one or more guidewire lumens, rails, tracks, lengthwise impressions or some combination thereof.

In one embodiment, elongate body108is predominantly flexible along its length and comprises any suitable flexible material, such as thin, flexible metals, plastics, fabrics or the like. In some embodiments, it may be advantageous to include one or more rigid sections in elongate body108, such as to impart pushability to a portion of body108or to facilitate application of force to tissue modification members110without causing unwanted bending or kinking of elongate body108. In such embodiments, rigidity may be conferred by using additional materials in body108or by making the rigid portions thicker or wider or of a different shape.

Handle104may have any suitable configuration according to various embodiments. Similarly, actuator106may include any of a number of actuation devices in various embodiments. In the embodiment shown inFIG. 3A, actuator106comprises a trigger or moving handle portion, which is grasped by a user and pulled or squeezed toward handle164to bring blades110together to cut tissue. In an alternative embodiment, actuator106instead may include a switch or button for activating a radiofrequency surgical ablation tissue modifying member. In yet another embodiment, actuator106may include a combination trigger and switch, one or more pull wires, any suitable form of lever and/or some combination thereof.

FIGS. 3B-3Dshow in greater detail a portion of tissue modification device102. In these figures, window111and blades110are more clearly seen. In one embodiment, at least a portion of elongate body108and blades110may have a slightly curved configuration. In alternative embodiments, at least a portion of elongate body108and blades110may be flat. In other alternative embodiments, tissue modification members such as blades110may be proud to elongate body108.

Blades110include a distal110aand a proximal blade110bthat reside at the distal and proximal edges, respectively, of window111of elongate body108. Window111of body108may accommodate both soft and hard tissue when the device is forcibly applied to the surface of a target tissue site. The top view of the distal portion of elongate body108, shown inFIG. 3C, depicts the angled edges of distal blade110aand proximal blade110b, which facilitate shearing of target tissue. In alternative embodiments, blades110may have any of a number of alternative shapes and configurations. The distal portion of body108may have a very low profile (height compared to width), as shown in side viewFIG. 3D, where only blades110protrude from the top surface of the elongate body108. In one embodiment, also as shown inFIG. 3D, a guidewire tube120(or lumen) may extend from (or be coupled with) a lower surface of elongate body108. The lower surface of elongate body108is an example of a protective or non-tissue-modifying surface.

In one embodiment, distal blade110ais coupled with two pull-wires118, as seen inFIGS. 3C,3E and3F. Pull-wires118coupled to and translated by actuator106on handle104may be used to drive distal blade110aproximally to contact the cutting edge of proximal blade110b, thus cutting tissue. Other alternative mechanisms for driving blades110, such as gears, ribbons or belts, magnets, electrically powered, shape memory alloy, electro magnetic solenoids and/or the like, coupled to suitable actuators, may be used in alternative embodiments. As mentioned, in one embodiment distal blade110aand/or proximal blade110bmay have an outwardly curvilinear shape along its cutting edge. Alternatively, distal blade110amay have a different blade shape, including flat, rectilinear, v-shaped, and inwardly curvilinear (concave vs. convex). The cutting edge of either blade110may have a sharp edge formed by a simple bevel or chamfer. Alternatively or in addition, a cutting edge may have tooth-like elements that interlock with a cutting edge of an opposing blade, or may have corrugated ridges, serrations, rasp-like features, or the like. In various embodiments, both blades110may be of equal sharpness, or alternatively one blade110may be sharp and the other substantially flat to provide a surface against which the sharp blade110may cut. Alternately or in addition, both cutting edges may be equally hard, or a first cutting edge may be harder than a second, the latter of which deflects under force from the first harder edge to facilitate shearing of the target tissue.

FIGS. 3E and 3Fshow cross-sectional views through elongate body at lines A-A and B-B, respectively, ofFIG. 3C. In some embodiments, all or a portion of elongate body108, such as the lower surface shown inFIG. 3E, may include a lubricious surface for facilitating manipulation of the tool in the surgical space and at the anatomical site. The lubricious lower surface also provides a barrier between blades110and non-target tissue in the surgical space. The lower surface may include a guide member lumen120to accommodate a guidewire or other access device or rail.FIG. 3Eshows distal blade110coupled with pull wires118.FIG. 3Fshows proximal blade110b, which is not coupled with pull wires118but rather fixed to body108. In various alternative embodiments, proximal blade110bmay be movable distally while distal blade110ais static, both blades may be moved toward one another, or a different number of blades may be used, such as one blade drawn toward a backstop or more than two blades, one or more of which may be mobile. In various alternative embodiments, guide member lumen120may be accommodated on a side surface or more centrally within elongate body108. In further alternative embodiments, the one or more guide member lumens120may comprise one or more various cross sectional shapes, for example substantially round, substantially oval, or substantially rectabular, to accommodate alternative guide members, for example flat or rectangular guidewires, needles or rails. In still other alternative embodiments guide member lumen120may be adjustably coupled with the elongate body108to enable manipulation of the location of the elongate body108and therefore the tissue modifying members110relative to the guiding member.

Referring now toFIGS. 3G-3I, blades110are shown in their closed position. In one embodiment, when distal blade110ais drawn proximally to cut tissue, at least some of the cut tissue is captured in a hollow interior portion of elongate body108. Various embodiments may further include a cover, a cut tissue housing portion and/or the like for collecting cut tissue and/or other tissue debris. Such collected tissue and debris may then be removed from the patient during or after a tissue modification procedure. During a given tissue modification procedure, distal blade110amay be drawn proximally to cut tissue, allowed to retract distally, and drawn proximally again to further cut tissue as many times as desired to achieve a desired amount of tissue cutting.

Blades110may be made from any suitable metal, polymer, ceramic, or combination thereof. Suitable metals, for example, may include but are not limited to stainless steel, nickel-titanium alloy, tungsten carbide alloy, or cobalt-chromium alloy, for example, Elgiloy™ (Elgin Specialty Metals, Elgin, Ill., USA), Conichrome™ (Carpenter Technology, Reading, Pa., USA), or Phynox™ (Imphy SA, Paris, France). In some embodiments, materials for the blades or for portions or coatings of the blades may be chosen for their electrically conductive or thermally resistive properties. Suitable polymers include but are not limited to nylon, polyester, Dacron™, polyethylene, acetal, Delrin™ (DuPont, Wilmington, Del.), polycarbonate, nylon, polyetheretherketone (PEEK), and polyetherketoneketone (PEKK). In some embodiments, polymers may be glass-filled to add strength and stiffness. Ceramics may include but are not limited to aluminas, zirconias, and carbides. In various embodiments, blades110may be manufactured using metal injection molding (MIM), CNC machining, injection molding, grinding and/or the like. Pull wires118be made from metal or polymer and may have circular, oval, rectangular, square or braided cross-sections. In some embodiments, a diameter of a pull wire118may range from about 0.001″-0.050″, and more preferably from about 0.010″-0.020″.

Depending on the tissue to be treated or modified, activating blades110(or other tissue modifying members in alternative embodiments) may cause them to modify target tissue along an area having any of a number of suitable lengths. In use, it may also be advantageous to limit the extent of action of blades110or other tissue modifying members to a desired length of tissue, thus not allowing blades110to affect tissue beyond that length. In so limiting the effect of blades, unwanted modification of, or damage to, surrounding tissues and structures may be limited or even eliminated. In one embodiment, for example, where the tissue modification device is used to modify tissue in a spine, blades110may operate along a length of target tissue of no more than 10 cm, and preferably no more than 6 cm, and even more preferably no more than 3 cm. Of course, in other parts of the body and to address other tissues, different tissue modification devices may be used and tissue modifying members may have many different lengths of activity. In one embodiment, to facilitate proper location of tissue modifying members, such as blades110, relative to target tissue, the tissue modifying members and/or the elongate body and/or one or more additional features intended for just such a purpose may be composed of a material readily identifiable via x-ray, fluoroscopic, magnetic resonance or ultrasound imaging techniques.

In various embodiments, a number of different techniques may be used to prevent blades110(or other tissue modifying members) from extending significantly beyond the target tissue. In one embodiment, for example, preventing blades110from extending significantly beyond the target tissue involves holding tissue modification device102as a whole predominantly stable to prevent device102from translating in a direction toward its proximal portion or toward its distal portion while activating blades110. Holding device102stable is achieved by anchoring one end of the device and applying tensioning force at or near the other end, as described further below.

In the embodiment shown inFIGS. 3A-3I, pull wires118are retracted proximally by squeezing actuator106proximally. In an alternative embodiment, squeezing actuator106may cause both blades110to translate inward so that they meet approximately in the middle of window111. In a further embodiment, distal blade110amay be returned to it's starting position by a pulling force generated from the distal end of device102, for example by using a distal actuator that is attached to distal wires, or by pulling on the distal guide member which is attached to distal blade110a. In yet another alternative embodiment, proximal blade110bmay be moved to cut by a pulling force generated from the distal end of device102, for example by using a distal actuator that is attached to distal wires, or by pulling on the distal guide member which is attached to proximal blade110b. In yet another embodiment, squeezing actuator106may cause proximal blade110bto move distally while distal blade110astays fixed. In other alternative embodiments, one or more blades110may move side-to-side, one or more blades110may pop, slide or bow up out of window111when activated, or one or more blades110may expand through window. In another embodiment, one or more blades110and/or other tissue modifying members of device102may be powered devices configured to cut, shave, grind, abrade and/or resect target tissue. In other embodiments, one or more blades may be coupled with an energy transmission device, such as a radiofrequency (RF) or thermal resistive device, to provide energy to blade(s)110for cutting, ablating, shrinking, dissecting, coagulating or heating and thus enhancing tissue modification. In another embodiment, a rasp or file may be used in conjunction with or coupled with one or more blades. In any of these embodiments, use of actuator106and one or more moving blades110provides for tissue modification with relatively little overall translation or other movement of tissue modification device102. Thus, target tissue may be modified without extending blades110or other tissue modification members significantly beyond an area of target tissue to be treated.

Referring now toFIGS. 4A-4C, in an alternative embodiment, a tissue modification device202may include an elongate body208having a proximal portion and a distal portion209, a handle204and actuator206coupled with proximal portion, and a window211and tissue modifying member210disposed near distal portion209. As seen more clearly inFIGS. 4B and 4C, in the embodiment shown, tissue modifying member210comprises an RF electrode wire loop. Wire loop210may comprise any suitable RF electrode, such as those commonly used and known in the electrosurgical arts, and may be powered by an internal or external RF generator, such as the RF generators provided by Gyrus Medical, Inc. (Maple Grove, Minn.). Any of a number of different ranges of radio frequency may be used, according to various embodiments. For example, some embodiments may use RF energy in a range of between about 70 hertz and about 5 megahertz. In some embodiments, the power range for RF energy may be between about 0.5 Watts and about 200 Watts. Additionally, in various embodiments, RF current may be delivered directly into conductive tissue or may be delivered to a conductive medium, such as saline or Lactate Ringers solution, which may in some embodiments be heated or vaporized or converted to plasma that in turn modifies target tissue. Distal portion209includes a tapered tip, similar to that described above, to facilitate passage of elongate body208into narrow anatomical sites. Handle204and actuator206are similar to those described above, although in the embodiment ofFIGS. 4A-4C, actuator206may be used to change the diameter of the wire loop210. Using actuator206, wire loop210may be caused to extend out of window211, expand, retract, translate and/or the like. Some embodiments may optionally include a second actuator (not shown), such as a foot switch for activating an RF generator to delivery RF current to an electrode.

Elongate body208may be fabricated from any suitable material and have any of a number of configurations. In one embodiment, body208comprises a metal tube with a full-thickness slit (to unfold the tube into a flat form--not shown) or stiffening element (not shown). The split tube provides for a simple manufacturing process as well as a conductive pathway for bi-polar RF operation. The tube may include a waist region220.

Referring toFIG. 4C, insulators222may be disposed around a portion of wire loop210so that only a desired portion of wire loop210may transfer RF current into the tissue for tissue modifying capability. Wire loop210, covered with insulators222may extend proximally into support tubes218. In various alternative embodiments, an electrode tissue modifying member (of which wire loop210is but one example) may be bipolar or monopolar. For example, as shown inFIG. 4C, a sleeve224housed toward the distal portion of window211may act as a return electrode for wire loop210in a bipolar device. Wire loop electrodes210may be made from various conductive metals such as stainless steel alloys, nickel titanium alloys, titanium alloys, tungsten alloys and the like. Insulators222may be made from a thermally and electrically stable polymer, such as polyimide, polyetheretherketone (PEEK), polytetrafluoroethylene (PTFE), polyamide-imide, or the like, and may optionally be fiber reinforced or contain a braid for additional stiffness and strength. In alternative embodiments, insulators222may be composed of a ceramic-based material.

In one embodiment, wire loop210may be housed within elongate body208during delivery of tissue modification device202into a patient, and then caused to extend up out of window211, relative to the rest of body208, to remove tissue. Wire loop210may also be flexible so that it may pop or bow up out of window211and may deflect when it encounters hard tissue surfaces. Wire loop210may have any of a number of shapes, such as curved, flat, spiral or ridged. Wire loop210may have a diameter similar to the width of body208, while in alternative embodiments it may expand when extended out of window211to have a smaller or larger diameter than that of body208. Pull wires (not shown) may be retracted proximally, in a manner similar to that described above, in order to collapse wire loop210, decrease the diameter and lower the profile of the wire loop210, and/or pull wire loop210proximally to remove tissue or be housed within body208. The low profile of the collapsed wire loop210, facilitates insertion and removal of tissue modification device202prior to and after tissue modification. As the wire loop210diameter is reduced, support tubes218deflect toward the center of elongate body208.

In an alternative embodiment (not shown), tissue modification device202may include multiple RF wire loops210or other RF members. In another embodiment, device202may include one or more blades as well as RF wire loop210. In such an embodiment, wire loop210may be used to remove or otherwise modify soft tissues, such as ligamentum flavum, or to provide hemostasis, and blades may be used to modify hard tissues, such as bone. In other embodiments, as described further below, two separate tissue modification devices (or more than two devices) may be used in one procedure to modify different types of tissue, enhance modification of one type of tissue or the like.

In other alternative embodiments, tissue modification devices202may include tissue modifying members such as a rongeur, a curette, a scalpel, a scissors, a forceps, a probe, a rasp, a file, an abrasive element, one or more small planes, a rotary powered mechanical shaver, a reciprocating powered mechanical shaver, a powered mechanical burr, a laser, an ultrasound crystal a cryogenic probe, a pressurized water jet, a drug dispensing element, a needle, a needle electrode, or some combination thereof. In some embodiments, for example, it may be advantageous to have one or more tissue modifying members that stabilize target tissue, such as by grasping the tissue or using tissue restraints such as barbs, hooks, compressive members or the like. In one embodiment, soft tissue may be stabilized by applying a contained, low-temperature substance (for example, in the cryo-range of temperatures) that hardens the tissue, thus facilitating resection of the tissue by a blade, rasp or other device. In another embodiment, one or more stiffening substances or members may be applied to tissue, such as bioabsorbable rods.

Referring now toFIGS. 5A-5D, one embodiment of a method for modifying tissue in a spine is demonstrated in simplified, diagrammatic, cross-sectional views of a portion of a patient's back and spine.FIG. 5Ashows a portion of the patient's back in cross section, with a portion of a vertebra, the spinal cord with branching nerve roots, and target tissue, which in this illustration is the ligamentum flavum and possibly a portion of the facet capsule. The target tissue is typically impinging directly on one or more of the group including nerve roots, neurovascular structures, dorsal root ganglia, cauda equina, or individual nerves.

InFIG. 5B, tissue modification device102has been positioned in the patient's back to perform a tissue modification procedure. Various methods, devices and systems for introducing device102into the patient and advancing it to the position for modifying tissue are described in further detail below. Generally, device102may be positioned via a percutaneous or open surgical procedure, according to various embodiments. In one embodiment, device102may be inserted into the patient through a first incision240, advanced into the spine and between target tissue and non-target tissue (such as spinal cord, nerve roots, nerves and/or neurovascular tissue), and further advanced so a distal portion of elongate body108exits a second (or distal) incision242to reside outside the patient. In positioning device102, one or more tissue modifying members (not shown) are positioned to face the target tissue, while one or more protective portions of elongate body108face non-target tissue.

Referring toFIG. 5C, once device102is positioned in a desired location, anchoring force may be applied at or near the distal portion of elongate body108. In one embodiment, applying anchoring force involves a user244grasping body108at or near its distal portion. In alternative embodiments, as described further below, anchoring force may be applied by deploying one or more anchor members disposed at or near the distal portion of body108, or by grasping a guidewire or other guide member extending through at least part of body108. Once the anchoring force is applied, proximally-directed tensioning force may be applied to device102, such as by pulling proximally on handle104(one-directional, diagonal arrows). This tensioning force, when applied to the substantially anchored device102, may help urge the tissue modifying member(s) against the target tissue (one-directional, vertical arrows near target tissue), thus enhancing contact with the target tissue and facilitating its modification. With the tissue modifying member(s) contacting the target tissue, actuator106may be squeezed or pulled (two-headed arrow) to cause the tissue modifying member(s) to modify tissue. (Alternative actuators may be activated in different ways in alternative embodiments.)

In various alternative embodiments, certain of the above-described steps may be carried out in different order. For example, in one embodiment the distal portion of elongate body108may be anchored within or outside the patient before the tissue modifying members are positioned adjacent the target tissue. In another alternative embodiment, the proximal portion of device102may be anchored, and the tensioning force may be applied to the distal portion of device102. In yet another embodiment, tensioning force may be applied to both ends of the device. In yet another embodiment, a second handle and actuator may be coupled with the distal end of body108after it exits the patient's back, allowing tensioning forces as well as tissue modifying actuation to occur at both the proximal and distal portions of device102. By anchoring one end of device102and applying tensioning force to the opposite end, contact of the tissue modifying members with the target tissue is enhanced, thus reducing or eliminating the need for translating or otherwise moving device102as a whole and reducing the overall profile and the resulting access pathway required to position the device. Reducing movement and profile of device102and using tissue modifying members confined to a relatively small area of device102helps facilitate target tissue modification while minimizing or eliminating damage to surrounding tissues or structures.

As mentioned above, tissue may be modified using one tissue modification device or multiple devices, according to various embodiments. In one embodiment, for example, an RF electrosurgical tissue modification device may be used in the patient to remove soft tissue such as ligament, and a bladed tissue modification device such as a rongeur may then be used to remove additional soft tissue, calcified soft tissue, or hard tissue such as bone. In some embodiments, such multiple devices may be inserted, used and removed serially, while in alternative embodiments such devices may be inserted into the patient at the same time to be used in combination.

Referring toFIG. 5D, using one or more tissue modification devices102, a desired amount of target tissue may be removed from more than one area in the spine.FIGS. 5A-5Cdemonstrate removal of target tissue on one side of the spine, and that method or a similar method may also be used to remove target tissue on an opposite side of the spine, as shown inFIG. 5D, where target tissue has been removed from both sides. That the desired amount of tissue has been removed may be confirmed by tactile feedback from the device or from a separate device, by testing nerve conduction through one or more previously impinged nerves, by testing blood flow through one or more previously impinged blood vessels, by passing (independently or over the guide member) a measurement probe or sound through the treated portion, through one or more radiographic tests, through some combination thereof, or by any other reasonable means.

Referring now toFIG. 6A, tissue modification device102is shown with one embodiment of a distal anchoring member250deployed at the patient's skin. In various embodiments, anchoring members may include but are not limited to one or more handles, barbs, hooks, screws, toggle bolts, needles, inflatable balloons, meshes, stents, wires, lassos, backstops or the like. In some embodiments, anchoring members250may be disposed at the extreme distal portion109of elongate body108, while in other embodiments anchoring members250may be located more proximally. In the embodiment shown, anchoring members250are deployed at the patient's skin. In an alternative embodiment, anchoring may be achieved outside the patient by deploying one or more anchoring members250above the skin and having a user grasp the anchoring members250. In an alternative embodiment, anchoring may be achieved outside the patient by deploying one or more anchoring members250above the skin and having a user grasp anchoring members250, after tissue modification device102has been anchored to the guide member. In another alternative embodiment, anchoring may be achieved outside the patient by attaching anchoring member250to an external device, for example one that is mounted on the patient or on the procedure table. In a further alternative embodiment, anchoring may be achieved outside the patient by attaching the guide member to an external device, for example one that is mounted to on the patient or on the procedure table, after tissue modification device102has been anchored to the guide member. Anchoring members250generally are deployable from a first, contracted configuration to facilitate delivery of device102, to a second, expanded configuration to facilitate anchoring. This change in configuration may be achieved, for example, by using shape memory or super-elastic materials, by spring loading anchoring members250into body108or the like. In most embodiments, anchoring members250may also be collapsed down into the first, contracted configuration after a tissue modification procedure has been performed, to facilitate withdrawal of device102from the patient. In an alternative embodiment, anchoring members250may detach from body108and may be easily removable from the patient's skin.

FIG. 6Bshows tissue modification device102with an alternative embodiment of a distal anchoring member260. Here, distal anchoring member260includes multiple hooks or barbs extended out the distal portion109of elongate body108within the patient's back. In using such an embodiment, it may not be necessary to pass guide member117through a second, distal incision on the patient, although in some embodiments guide member117may extend significantly beyond distal portion109. Anchoring member(s)260, according to various embodiments, may be deployed so as to anchor to bone, ligament, tendon, capsule, cartilage, muscle, or any other suitable tissue of the patient. They may be deployed into vertebral bone or other suitable tissue immediately adjacent an intervertebral foramen or at a location more distant from the intervertebral foramen. When a tissue modification procedure is complete, anchoring members260are retracted within elongate body for removal of device102from the patient.

Referring now toFIGS. 7A-7S, a system and method for introducing a tissue modification device into a spine is demonstrated. This system and method may be referred to as an “access system” or “access method,” in that they provide or facilitate gaining access to a target tissue to be modified. Of course, the embodiment shown is merely one exemplary embodiment, and any of a number of other suitable methods, devices or systems may be used to introduce one or more devices for modifying tissue in spine. For example, in one alternative embodiment a spinal tissue modification procedure may be carried out through an open surgical approach. Therefore, the following description is provided primarily for exemplary purposes and should not be interpreted to limit the scope of the invention as it is defined in the claims.

Referring toFIG. 7A, in one embodiment a device delivery method first involves advancing an introducer cannula300coupled with a stylet302into the patient's back. Cannula300and stylet302are then passed between adjacent vertebrae and into the ligamentum flavum or an adjacent spinal ligament, as shown further inFIG. 7B. As shown inFIG. 7C, when the distal tip of cannula is positioned as desired, stylet302is removed. Referring toFIGS. 7D and 7E, a loss of resistance syringe304including a plunger310, barrel308and fluid and/or air306, is coupled with the proximal portion of cannula300. The distal portion of cannula300is advanced through the ligamentum flavum until it enters the central spinal canal where a loss of resistance to pressure placed on plunger310is encountered, and fluid and/or air306is injected into central spinal canal to confirm correct placement of cannula300as shown inFIG. 7E. Syringe304is then removed, as inFIG. 7F, and a guidewire312with a non-rigid, atraumatic tip is advanced through cannula300into the central spinal canal, as inFIG. 7G. Next, cannula300is removed, as inFIG. 7H, leaving behind guidewire312. As shown inFIGS. 7I and 7J, an introducer sheath114, coupled with a dilator314, is then advanced over guidewire312to position a distal portion of sheath114at a desired location within the spine. Dilator314and guidewire312are then removed, as inFIG. 7K.

Once introducer sheath114is in place, one or more curved or steerable guide devices318may be advanced through it to desired positions in and/or through the spine, as shown inFIGS. 7L and 7M. One or more guide members116, may then be advanced through the guide device318, as shown inFIGS. 7N-7P. Finally, guide device318may be removed, as inFIG. 7Q, and elongate body108of tissue modification device102may be advanced over guide member116and through introducer sheath114to a desired position in the spine, as inFIG. 7R. As shown inFIG. 7S, elongate body108may be tensioned to urge tissue modifying members110against target tissue, as shown with arrows at opposite ends of device102, while distal portion109is anchored, in this case by hand244. In an alternative embodiment, guide member116may be tensioned to urge tissue modifying members110against target tissue as shown inFIG. 7R.

Once tissue modification device102is in a desired position, tissues which may be modified in various embodiments include, but are not limited to, ligament, tendon, tumor, cyst, cartilage, scar, “bone spurs,” inflammatory and bone tissue. In some embodiments, modifying the target tissue reduces impingement of the tissue on a spinal cord, a branching nerve or nerve root, a dorsal root ganglia, and/or vascular tissue in the spine. Actuator106on handle104is activated to modify target tissue using tissue modification member(s)110, while elongate body108is held relatively stable by hand244and by tension force applied to handle104.

In various embodiments, the system and method described immediately above may include additional features or steps, may have fewer features or steps, may have an alternate order of implementation of steps, or may have different features or steps. For example, in some embodiments placement of device102will be performed in a medial-to-lateral direction (relative to the patient), while in alternative embodiments device placement will be performed lateral-to-medial. In some embodiments, one or more components of the system described may be anchored to the patient, such as guide member116or introducer sheath114. In various embodiments, one or more guide members116may include one or more wires, rails or tracks and may be inserted through guide device318, introducer sheath114without guide device318, cannula300, an epidural needle, a lumen of an endoscope, a lumen of a tissue shield or barrier device, a curved guide device318placed through a lumen of an endoscope, or the like. In other embodiments, for example, guide device318may be placed through introducer cannula300and then introducer sheath114may be passed over guide device318. Tissue modification device102may similarly be inserted with or without using any of these devices or components in various combinations. Various guidewires312, guide devices318and/or guide members116may be pre-shaped to have one or more curves, may be steerable, and/or may include one or more rails, tracks, grooves, lumens, slots, partial lumens, or some combination thereof.

In some embodiments, tissue modification device102is inserted through one or more hollow devices as described above (such as introducer sheath114, as shown, or cannula300in an alternative embodiment) in such a way that device102expands upon extending out of a distal portion of the hollow delivery device thereby assuming a wider profile for modifying a greater amount of target tissue from a single location. In an alternative embodiment, device102retains the same overall profile during insertion and during use. In some embodiments, one or more delivery devices will remain in the patient during use of tissue modification device102, while in alternative embodiments all delivery devices are removed from the patient when tissue modification device102is operating. In some embodiments, tissue modification device102may be slidably coupled with one or more delivery devices during delivery and/or during use. In one embodiment, tissue modification device102is advanced through introducer sheath114and sheath114is used as an irrigation and evacuation lumen to irrigate the area of the target tissue and evacuate removed tissue and other debris, typically by applying a vacuum. In alternative embodiments, tissue modification device102may include an irrigation and/or evacuation lumen to irrigate an area of the target tissue and evacuate removed tissue and other debris.

Some embodiments of an access system for facilitating tissue modification may further include one or more visualization devices (not shown). Such devices may be used to facilitate placement of the access system for introducing the tissue modification device, to facilitate tissue modification itself, or any combination of these functions. Examples of visualization devices that may be used include flexible, partially flexible, or rigid fiber optic scopes, rigid rod and lens-endoscopes, CCD or CMOS chips at the distal portion of rigid or flexible probes, LED illumination, fibers or transmission of an external light source for illumination or the like. Such devices may be slidably couplable with one or more components of an access system or may be slidably or fixedly coupled with a tissue modification device. In other embodiments, additional or alternative devices for helping position, use or assess the effect of a tissue modification device may be included. Examples of other such devices may include one or more neural stimulation electrodes with EMG or SSEP monitoring, ultrasound imaging transducers external or internal to the patient, a computed tomography (CT) scanner, a magnetic resonance imaging (MRI) scanner, a reflectance spectrophotometry device, and a tissue impedance monitor disposed across a bipolar electrode tissue modification member or disposed elsewhere on a tissue modification device or disposed on the access system.

Referring now toFIGS. 8A-8E, in an alternative embodiment, a tissue modification device and optionally one or more introduction/access devices may be positioned in a patient using an open surgical technique. As shown inFIG. 8A, for example, in one embodiment an open surgical incision is made on a patient's back, and two retractors402are used to expose a portion of the patient's vertebra. As shown inFIG. 8B, an introducer sheath414may then be inserted through the incision, between retractors402. As inFIG. 8C, a curved guide device418may then be inserted through introducer sheath414. Guide device418extends into the epidural space and through the intervertebral foramen as shown inFIG. 8D.

In some embodiments, a curved and cannulated thin, blunt probe may be placed directly through the open incision into the epidural space of the spine, or alternatively may be placed through introducer sheath414. The probe tip may be advanced to or through a neural foramen. Such a probe may be similar in shape, for example, to a Woodson elevator, Penfield 3, hockey stick probe, ball tipped probe, or the like. In alternative embodiments, probes that may be manually bent to change their shapes, or probes with articulating tips, or probes with shape lock portions, and/or probes having grooves instead of cannulas may be used.

As shown inFIGS. 8D-8E, a substantially straight, flexible guidewire420with a sharp tip422may then be inserted through curved. guide device418and advanced so that its distal portion with sharp tip422extends outside the patient's back at a location separate from the open incision (FIG. 8E). Guide device418may then be removed, as inFIG. 8F, and in subsequent steps a tissue modification device may be inserted over guide wire420and through introducer sheath414and used to modify tissue as described in more detail above. In an alternative embodiment, a curved, flexible cannula may be inserted through the curved guide device, until it extends lateral to the neural foramen, after which a substantially straight, flexible guidewire with a sharp tip may then be inserted through curved cannula and advanced so that its distal portion with sharp tip extends outside the patient's back.

Referring now toFIGS. 9A and 9B, another alternative open surgical access method is shown. InFIG. 9A, a curved guide device446is shown in place through the epidural space and intervertebral foramen, and a guidewire440with a beveled distal tip442is about to be advanced through guide device446. As shown inFIG. 9B, in this embodiment, guidewire440is directed by guide device446back through the open incision through which the various access devices are introduced. In such an embodiment, then, only one incision is created and the proximal and distal portions of one or more devices extend out of the patient's back through the same incision.

In various alternative embodiments, open surgical access may be through exposure down to a vertebral lamina, through ligamentum flavum without lamina removal, through ligamentum flavum with partial or complete lamina removal, through ligamentum flavum with or without lamina removal with partial or complete medial facet joint removal, through open exposure and out through skin laterally, through open exposure and back out through the open exposure, or through a lateral open exposure that accesses the neural foramen from the lateral side. One or more visualization devices may be used with open surgical access procedures as well as with percutaneous or other less invasive procedures. In another alternative embodiment (not shown), a tissue modification device may be placed in the patient directly, without any introduction devices.

Referring now toFIGS. 10A-10E, in the embodiments described above, the tissue modification devices102,202include at least one non-tissue-modifying (or “protective”) portion, side or surface. The non-tissue-modifying portion is located on tissue modification device102,202so as to be positioned adjacent non-target tissue when tissue modifying members110,210are facing the target tissue. The non-tissue-modification surface of the device is configured so as to not modify or damage tissue, and thus the non-target tissue is protected from unwanted modification or damage during a tissue modification procedure. Alternatively, in some embodiments, a protective surface or portion of tissue modification device102,202may actually modify non-target tissue in a protective manner, such as by delivering a protective drug, coating, fluid, energy or the like to the non-target tissue.

Optionally, in some embodiments, tissue modification devices or systems may further include one or more tissue barriers (or “shields”) for further protecting non-target tissues. Such barriers may be slidably coupled with, fixedly coupled with, or separate from the tissue modification devices with which they are used. In various embodiments, a barrier may be delivered between target and non-target tissues before delivering the tissue modification device, may be delivered along with the tissue modification device, or may be delivered after delivery of the tissue modification device but before the device is activated or otherwise used to modify target tissue. Generally, such a barrier may be interposed between the non-target tissue and one or more tissue modification devices to prevent unwanted damage of the non-target tissue.

FIG. 10Ashows a distal portion of an introducer device514through which a barrier may be introduced.FIGS. 10B and 10Cshow one embodiment of a barrier500partially deployed and in cross-section, respectively. Typically, barrier500will have a first, small-profile configuration for delivery to an area near non-target tissue and a second, expanded configuration for protecting the non target tissue. In various embodiments, some of which are described more fully below, barrier500may be configured as one piece of super-elastic or shape-memory material, as a scaffold with material draped between the scaffolding, as a series of expandable wires or tubes, as a semicircular stent-like device, as one or more expandable balloons or bladders, as a fan or spring-loaded device, or as any of a number of different devices configured to expand upon release from delivery device514to protect tissue. As shown inFIGS. 10B and 10C, barrier500may comprise a sheet of material disposed with a first end502aabutting a second end502bwithin introducer device514and unfurling upon delivery. In an alternative embodiment, as shown inFIGS. 10D and 10E, opposite ends522aand522bof a barrier520may overlap in introducer device514. Generally, barrier500,520may be introduced via introducer device514in one embodiment or, alternatively, may be introduced via any of the various means for introducing the tissue modification device, such as those described in conjunction withFIGS. 7A-7S,8A-8F and9A-9B. In some embodiments, barrier500,520may be fixedly coupled with or an extension of a tissue modification device. Barrier500,520may also include one or more lumens, rails, passages or the like for passing a guidewire or other guide member, for introducing, removing or exchanging any of a variety of tissue modification, drug delivery, or diagnostic devices, for passing a visualization device, for providing irrigation fluid at the tissue modification site, and or the like. In some embodiments, barrier500,520is advanced over multiple guidewires and the guidewires remain in place during a tissue modification procedure to enhance the stability and/or maintain positioning of barrier500,520.

Referring now toFIGS. 11A and 11B, an alternative embodiment of a tissue modification device suitably includes an elongate body1005having a distal portion1007, a distal cutting blade1008a, and a proximal cutting blade1008b, each blade1008having a cutting edge1008c,1008d. In this embodiment, distal cutting blade1008aand proximal cutting blade1008bmay be rotated away from elongate body1005to further expose cutting edges1008c,1008d. The height of cutting edges1008c,1008drelative to the elongate body1005may be used, for example, to control the depth of the cut into hard and/or soft target tissue.

The embodiment shown inFIGS. 11A and 11B, as well as many of the embodiments described below, include two movable, opposing blades1008a,1008b, which may be moved toward one another to cut tissue. Alternative embodiments, however, may include two immobile blades, one movable blade and one immobile blade, one movable blade, one immobile blade, more than two immobile blades facing in one direction, more that two immobile blades facing in different directions, a movable blade and a backstop against which the blade may be driven, or any other suitable combination of movable and/or immobile blades. Furthermore, any blade of any given embodiment may have any suitable shape, size and overall configuration. In some embodiments, blades may be flat, while in others they may be curved, squared off, ridged, bent or the like. Blades may be long or short, multiple blades may be aligned closely one after the other, such as in a typical multi-blade razor used for shaving a face, multiple blades may be disposed apart from one another by several millimeters or even centimeters, and/or the like. Blades may have any suitable amount of sharpness or dullness, and in some embodiment a combination of sharper and duller blades may be used. Therefore, although exemplary embodiments of blades are described in detail above and below, any other suitable blades or combinations of blades may be substituted in various embodiments, without departing from the scope of the present invention.

In the embodiments described previously or in any other embodiments described herein, blades may be fabricated from metals, polymers, ceramics, composites or any other suitable material or combination of materials. According to various embodiments, suitable metals for blades may include, but are not limited to, stainless steel, nickel-titanium alloy, or cobalt-chromium alloy, for example, Elgiloy™ (Elgin Specialty Metals, Elgin, Ill., USA), Conichrome™ (Carpenter Technology, Reading, Pa., USA), or Phynox™ (Imphy S A, Paris, France). Polymer materials include nylon, polyester, Dacron™ , polyethylene, acetal, Delrin™ (DuPont), polycarbonate, nylon, polyetheretherketone (PEEK), and polyetherketoneketone (PEKK). In some embodiments where polymers are used, such polymers may be glass-filled or carbon-filled to add strength and stiffness. Ceramics may include, but are not limited to, aluminas, zirconias, and carbides. Blades may be manufactured using skills known in the art, for example, metal injection molding (MIM), CNC machining, injection molding, grinding, electrodischarge madhining (EDM), sheet metal bending, etching, electrodeposition, or the like. Pull wires1011may similarly be fabricated from any suitable material and may have any of a number of suitable shapes and dimension. In some embodiments, for example, pull wires1011may be made from metal or polymer and may have substantially circular, oval, rectangular or square cross sections, although this is by no means a comprehensive list. In some embodiments, pull wires1011may range in diameter from about 0.001 inches to about 0.10 inches, and more preferably between about 0.010 inches and 0.020 inches. Other portions of a tissue modification device, such as a cover over one or more blades or other features, may be made of any suitable material now known or hereafter discovered. A blade cover, for example, may be fabricated in various embodiments of one or more polymeric materials, such as nylon, silicone, polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polytetrafluoroethylene (PTFE), polyurethane (Tecothane,), Pebax (co, USA), polycarbonate, Delrin (co, USA), high-density polyethylene (HDPE), low-density polyethylene (LDPE), HMWPE, UHMWPE, or the like. In some embodiments, one or more materials may be chosen for their compatibility with one or more imaging techniques or systems, such as magnetic resonance imaging (MRI), for example.

In various embodiments, elongate body1005may include one or more hollow chambers (not shown) at or near a distal portion of body1005. Such hollow chamber(s) may serve any of a number of suitable functions. In some embodiments, for example, a chamber may be located distal and/or proximal to one or more blades1008a,1008band may serve to collect removed tissue during and/or after a tissue modification procedure. In some embodiments, one or more blades1008a,1008bmay help push removed tissue into such a chamber or chambers. In some embodiments, one or more chambers may house one or more blades1008a,1008b, such that blades1008a,1008bare housed within the chamber(s) while elongate body1005is passed into a patient and between target and non-target tissues. Once elongate body1005is in a desired position, blades1008a,1008bmay then be deployed out of one or more windows or similar openings in the chamber(s) to remove or otherwise modify tissue. Such chambers may include, in various embodiments, a hollow distal portion or nosecone of elongate body1005, a hollow portion of elongate body1005just proximal to proximal cutting blade1008b, and/or the like.

Another embodiment, as shown inFIGS. 12A and 12B, suitably includes a thin distal cutting blade1010aand a thin proximal cutting blade1010b, each blade1010having a cutting edge1010c,1010dand both blades1010being attached to two parallel pull wires1011. InFIG. 12A, blades1010a,1010bare shown their flat configuration. In one embodiment, as shown inFIG. 12B, when a load is applied that is planar to pull wires1011and normal to the long axis of pull wires1011, thin blades1010a,1010bflex or bow out of plane to increase the height of the cutting edges1010c,1010d.

Referring now toFIGS. 13A and 13B, another alternative embodiment of a blade1012that changes shape as it translates along a device is shown. Blade1012includes multiple flat members1024joined at edges1025, which may form bends, creases, folds, or hinges that allow blade1012to widen (FIG. 13A) and contract (FIG. 13B). Blade1012includes a cutting edge1014, which may be formed using methods known in the art, for example, grinding, molding, cutting, EDM machining, etching, laser cutting, electropolishing, electrodeposition, etc. In various embodiments, blade1012may be made from metal, polymer, or a combination of both. In some embodiments, blade1012may be translated along a central member23that causes blade1012to widen and contract at various locations along central member23. When blade1012is located over a wider section of central member, as inFIG. 13A, blade1012has a flatter, wider configuration. When blade1012slides or otherwise translates along central member1023to a narrower section, as inFIG. 13B, blade1012assumes a taller, narrower configuration. Such a taller configuration may facilitate cutting tissue with blade edge1014, in some embodiments. Edges1025of blade1012allow it to change shape more readily between the wider and narrower configurations, and the bends or ridges formed in blade1012in the narrower configuration (FIG. 13B) may help limit the amount of material that is removed with each pass of blade1014along a surface of target tissue.

Referring now toFIGS. 14A-14D, one embodiment of a blade system for a tissue modification device is shown.FIG. 14Ais a side view showing distal cutting blade1008aand proximal cutting blade1008b, each of which is free to pivot about an external pin1031that may be rigidly fixed to an external support block1026that is free to slide along a pull wire1011. An internal pin1032may be contained within an angled slot1033(shown inFIG. 14D) in an internal support block1028that freely slides along pull wire1011. A wire stop1030is securely fixed to the end of pull wire1011to prevent pull wire1011from pulling through distal external support block1026as axial force is applied to pull wire1011. In various embodiments, wire stop1030may include but is not limited to a mechanical squeeze-type clamp, a ball formed at the end using a laser, TIG welder, or torch, a crimped hypo-tube, a sleeve with a set-screw, a loop, bend or twist in the wire, or the like. A pair of external springs1027may maintain blades1008a, b in a low-profile (or “flat”) configuration. An internal spring1029may act to separate blades1008a,1008b.

FIG. 14Bprovides a cross-sectional view along the line A-A inFIG. 14A. Proximal cutting blade1008bis shown to have a curved profile, and centrally located pull wire1011and internal spring1029are also shown. Internal support block1028and external support block1026remain within the profile of proximal cutting blade1008b. Cutting blade edge1008cis positioned in a low profile configuration.

As shown inFIG. 14C, in one embodiment, the width of distal blade1008aand proximal blade1008bmay be approximately the same as the width of external support block1026. Pull wire1011may be centrally located to facilitate uniform movement of the cutting blade1008aand therefore uniform cutting with cutting blade edge1008c.

In the cross-sectional view ofFIG. 14D, an angled slot1033is shown that constrains internal pin1032that controls the height of blades1008a,1008bat a given. axial displacement of internal support block1028relative to external support block1026. In some embodiments, a baffle1034may be used as a one-way mechanism for debris transport down the open channel of blade1008a,1008b.

Referring now toFIGS. 15A-15D, in one embodiment, as proximal external support block1026is driven distally towards wire stop1030, external springs1027compress to increase the height of the proximal and distal cutting blades1008a,1008b, as shown in side view inFIG. 15A. External springs1027may have a lower spring rate (lb./in.) than that of internal spring1029, such that external springs1027displace more readily than internal spring1029during the initial loading of the mechanism in order to preferentially drive blades1008a,1008bupward. This increase in blade height may help control the amount of tissue material that will be removed during a cutting cycle. The blade height can be adjusted by adjusting the length, angle, and endpoint positions for angled slot1033. To help support blades1008a,1008bduring the cuffing process, blades1008a,1008bmay stop at the limits of the angled slot1033and may also be limited by the angled cut on the sides of external support blocks1026near external pin1031.

With reference now toFIGS. 16A-16C, in one embodiment blades1008a,1008bmay be made to rotate to a desired height, such as their maximum height, and may then be driven toward one another by applying an additional load to further compress internal spring1029, as depicted in side-view inFIG. 16A. In some embodiments, blades1008a,1008bare driven together until cutting blade edges1008ccontact each other to complete a cutting cycle. In some embodiments, relative spring rates for external spring1027and internal spring1029may be customized/selected to provide a desired cutting action and penetration behavior for blades1008a,1008binto target tissue. After a cutting cycle is complete, blades1008a,1008bmay be driven apart and further pushed into a low profile state by internal spring1029and external springs1027. Baffle1034may be displaced as debris is driven into the blade channel, and baffle1034then may return to its original position to hold the debris in place. In some embodiments, for example, baffle1034may include a metal tab or a polymer flap molded into blade1008a,1008b. An alternative debris capture mechanism is shown in the cross-sectional view of blade1008depicted inFIG. 17F. Multiple ramps1034aand stops1034ballow debris to slide away from cutting edge1008cbut prevent the debris from sliding back.

Referring toFIG. 17A, in one embodiment, to prevent a cutting blade1008afrom rotating about the axis of a single pull wire1011and/or to allow for more force or more distributed force along cutting edge1008c, multiple pull wires1011may be used to actuate the blade mechanism. In addition, external support block1026may optionally include ridge features1035that slidably engage with a track1036that may serve as an anti-rotation mechanism and may also provide additional strength and stiffness along the length of the blade mechanism. In various embodiments, orientation of such ridge features1035may be varied. For example, ridge feature1035may be folded inward as inFIG. 17B, flat as inFIG. 17Cor folded outward as inFIG. 17D. In various embodiments, ridge feature1035have any suitable shape or configuration, such as but not limited to a round, square, dove-tailed, rectangular, or triangular cross-sectional shape.

With reference now toFIGS. 18A and 18B, in various embodiments the cutting edges of blades1008a,1008bmay have teeth1037that facilitate engagement with a smooth, curved, and/or hard target tissue, such as bone. One embodiment, as inFIG. 18A, may include pointed teeth1036, while an alternative embodiment, as inFIG. 18B, may include rounded teeth1037. Of course, any other suitable configuration may be substituted in various alternative embodiments.

Referring now toFIGS. 18C-18G, in various embodiments, the interaction of cutting edges of two blades or one blade and a backstop may effectively modify tissue with any number of different actions.FIG. 18Cdepicts the cross section of two opposing blades1118a,1118b, which are slightly offset with their respective bevels angled opposite of each other. This may create a shearing action when blades1118a,1118bare brought together and pass each other as shown in the lower portion of theFIG. 18C. InFIG. 18Dtwo blades1148a,1148bare in plane with similar bevels. The cutting edges of these blades1148a,1148bcome in contact to bite tissue when blades1148a,1148bare brought together. In another embodiment, as inFIG. 18E, one blade1158may be brought into contact with a backstop1160, which in one embodiment comprises a hard flat plane.FIG. 18Fdepicts a single blade1162brought into contact with a compliant flat plane backstop1164. Contact of blade1162with such a backstop1164may create both a pinching and a shearing effect on tissue. In yet another embodiment, as inFIG. 18G, a single blade1166may be brought against the a backstop1168having a concave pocket1169. This may also create both a shearing and a pinching action on targeted tissue.

Referring toFIGS. 19A and 19B, in one embodiment, distal cutting blade1008aand proximal cutting blade1008b(or external support blocks1026that in turn are fitted with blades that pivot about the external pin1031) may be slidably engaged in a track1036, two pull wires1011may be mounted in opposite directions, and wire-stops1030may be located on the outside of opposite blades1008a,1008b, as shown in top-view inFIG. 19A. By applying a force to the pull wires1011, blades1008a,1008bare drawn toward the center of track1036, as depicted inFIG. 19B.

In an alternative embodiment, as inFIGS. 20A and 20B, two pull wires1011may be actuated from one end of a tissue modification device. In such an embodiment, a pulley1038(or capstan) may be used to redirect one of the wires1011, as shown in top-view inFIG. 20A, so that the two pull wires1011are aligned. As depicted inFIG. 20B, actuating pull wires1011from the one end causes blades1008a,1008bto move toward the center of track1036.

In one alternative embodiment (not pictured), similar to that inFIGS. 20A and 20B, a first pull wire may be constrained on one side of a blade by a wire stop to provide a closing motion of the blade toward a stationary blade. A second pull wire may be constrained on an opposite side of the blade by a wire stop and guided around a pulley or capstan to direct the pull wire in the same direction as the first pull wire. This second pull wire may be used to provide an opening motion of the blade away from stationary blade.

Referring now toFIGS. 21A and 21B, in another alternative embodiment, to balance or distribute the applied load on blades1008a,1008bmore evenly (to prevent blades1008a,1008bfrom binding while sliding with or without the track) and still have pull wires1011actuate from one end of the device, the two pull wires1011may both be redirected around a double grooved pulley1038(or capstan), as shown in top-view inFIG. 21A. Two additional wire stops1030may be added to an edge of each blade1008a,1008b. Applying force to the pull wires1011causes blades1008a,1008bto move toward one another.

As depicted inFIGS. 22A-22C, in another embodiment, distal cutting blades1008aand proximal cutting blades1008bmay be housed within an enclosure1039that has an opening1041and a ramp1042to facilitate deployment of blades1008a,1008bout of window. Blades1008a,1008bare shown in their undeployed positions inFIG. 22A. InFIG. 22B, as blades1008a,1008bare driven inward by an applied force via one or more wires, flexures, or mechanisms, blades1008a,1008brotate about a base pivot1040and are driven through opening1041along ramp1042and are exposed out of enclosure1039.FIG. 12Cshows blades1008a,1008bin contact with one another as enclosures1039are driven inward to complete a cutting cycle. In some embodiments, springs (not shown) may be used to drive the mechanism apart, similar to the mechanism described inFIG. 4A, such that blades1008a,1008bwould lay flush within enclosure1039once the applied force is removed.

In some embodiments, as inFIGS. 23A and 23B, blades1008a,1008bmay also be directed to translate along an axis normal to pull wire1011by having pull wire1011change its applied direction by 90 degrees by means of a pulley1038(or capstan).

Referring toFIGS. 24A and 24B, in one embodiment, a tissue modification device1001may include endcaps1043on each end of an elongate body1005, which endcaps1043are attached to pull wires1011in order to actuate the distal and proximal cutting blades1008a,1008b. In addition, as depicted inFIG. 14B, elongate body1005, in some embodiments, may be partially flexible at various locations along its length or, in some embodiments, along its entire length. The embodiment depicted inFIG. 14Bshows two flexion points where elongate body1005may be flexed to bend around anatomical structures. In some embodiments, encaps1043may be tapered to facilitate passage of device1001through a small incision. Encaps1043and elongate body1005may also optionally be configured to accommodate a guidewire for over-the-wire advancement to target tissue.

In one embodiment, and with reference now toFIGS. 25A and 25B, endcaps1043may nest within a simple T-handle mechanism1044that is fitted within a handgrip1045, as demonstrated inFIG. 25A. T-handle mechanism1044may be displaced to pull endcap1043that is in turn connected to pull wire1011, as handgrip1045provides counter-traction to elongate body1005. Other quickly attached and separated handle mechanisms that allow tensioning and wire actuation and/or wire constraint may alternately be used.

Referring now toFIGS. 26A and 26B, some embodiments may optionally provide for lateral movement and/or control of lateral movement of one or more cutting blades. As shown in front-view inFIG. 26A, in one embodiment a cam1046may be rigidly fixed to a rotatable control rod1048that freely rotates within a support block1049. Support block1049has raised features1047that constrain cam1046. Support rods1050prevent axial displacement of support block1049while allowing it to translate from side to side. A support frame1051may contain the mechanism and may be fitted to the body of the tissue modification device. Support block1049may translate to the left, for example, as depicted inFIG. 26B, as control rod1048is rotated counter-clockwise. According to various embodiments, any of the previously disclosed cutting mechanisms may be fitted to support block1049to facilitate controlled lateral displacement of the cutting mechanism as actuated by control rod1048for cutting tissue.

FIGS. 27A and 27Bshow an alternative embodiment including a rotatable control rod1048that freely rotates within support frame1051. Control rod1048is rigidly fixed to a fork or yoke1052that captures a positioning pin1053. As yoke1052is rotated counterclockwise, for example, support block1049may be displaced to the right, as depicted inFIG. 27B.

Referring to top-viewFIGS. 28A and 28B, in one alternative embodiment, instead of rotating a rod about the long axis of a tissue modification device, control wires1011may be secured to a base pulley1054that is rigidly fixed to a control linkage1055. By pulling on a control wire1011, support block1049may be translated to the left, as inFIG. 28B, or to the right, as inFIG. 28A.

With reference now toFIGS. 29A-29C, in some embodiments it may be advantageous to include one or more guiding or steering features on an elongate body of a tissue modification device, to facilitate guiding or steering of the body and/or one or more tissue modification members. In some embodiments, such guiding or steering features may be located adjacent or near tissue modifying members and may facilitate moving such members laterally back and forth or in any of a number of directions and/or may facilitate urging the tissue modifying members into target tissue. In other embodiments, guiding or steering members may be located along an elongate body at one or more locations distant from the tissue modifying members.

As shown inFIGS. 29A-29C, in one embodiment, a tissue modifying portion1056, such as a blade mechanism, may be coupled with a deployable wire loop1058that may facilitate guiding or directing portion1056by bowing outward to press against tissue. A top-view depicted inFIG. 29Ashows tissue modifying portion1056(possibly polymer or hypotube), which may contain a push wire1057constrained at the distal end. When a force is applied to push wire1057, the portion of the wire contained in tissue modifying portion1056bows out to create a side-loop1058, as depicted inFIG. 29B. A small feature on the end of the wire like a formed ball (or clamp)1059can be constrained at distal end of tissue modifying portion1056. Alternately, as inFIG. 29C, wire1057may be pulled to bow out a portion of side loop1058. In either case, side loop1058may push against tissue on one side to force tissue modifying portion1056laterally to the other side.

Referring toFIGS. 30A and 30B, in some embodiments, side-loop1058may be toggled from side to side by means of a distal tip1060to facilitate control and/or steering of tissue modifying portion1056.

In yet another embodiment, as depicted inFIGS. 31A and 31B, a mechanism to provide lateral position control of a cutting blade mechanism1063may include a track (or monorail)1061fixed to a backing plate1062. Cutting blade mechanism1063may be advanced and retraced along track1061to provide different lateral positions, as depicted in top view inFIG. 31A.FIG. 31Bshows a cross-sectional view of track1061and backing plate1062.

In an alternative embodiment, as shown inFIG. 32, a track1061may include a junction, which may facilitate directing cutting blade mechanism1063from one side to another of backing plate1062.

Top-viewFIGS. 33A-33Cfurther demonstrate one embodiment of a tissue modifying portion1056(here a cutting blade mechanism). These figures show how using push wires1057and side-loop wires1058on opposite sides of tissue modifying portion1056, a user may move, guide or steer tissue modifying portion1056from side to side (FIGS. 33B and 33C).

In yet another embodiment, as shown in end-on views inFIGS. 34A-34C, lateral displacement control of a tissue modification device may use one or more fillable bladders1063, which may be filled or emptied of water, saline, air, or other fluid or gaseous medium to direct one or more components of a tissue modification device to one side or another. In one embodiment, for example, bladders1063may be aligned on either side of a track1061, as depicted inFIG. 34A. As shown inFIGS. 34B and 34C, one bladder1063may be deflated or emptied while the other bladder1063is filled to move track1061to one side, and then the emptied bladder1063may be filled and the filled bladder1063emptied to move track1061to the opposite side.

In yet another embodiment, and with reference now toFIGS. 35A and 35B, a track1061is fixed to proximal and distal ends of a backing plate1062, and the position of track1061in between the proximal and distal ends is controlled by a lateral displacer1064, as shown in top-view inFIG. 35A. When force is applied to move lateral displacer1064, track1061may be shifted relative to backing plate1062, as shown inFIG. 35B. A cutting blade mechanism advanced or retracted along track1061may be controllably displaced from side to side by controlling lateral displacer1064.

Although various illustrative embodiments are described above, any of a number of changes may be made to various embodiments without departing from the scope of the invention as described by the claims. For example, the order in which various described method steps are performed may often be changed in alternative embodiments, and in other alternative embodiments one or more method steps may be skipped altogether. Optional features of various device and system embodiments may be included in some embodiments and not in others. For example, in many of the embodiments described above, one or more abrasive tissue modifying members may be substituted for one or more bladed tissue modifying members or vice versa. These an many other modifications may be made to many of the described embodiments. Therefore, the foregoing description is provided primarily for exemplary purposes and should not be interpreted to limit the scope of the invention as it is set forth in the claims.