Patent Description:
Certain diagnostic and therapeutic procedures for treatment and removal of disc material require access to and/or formation of a cavity in an interior body region, including the intervertebral disc. The intervertebral disc includes a thick outer ring of elastic soft tissue material (annulus fibrosus) and an inner gel-like substance (nucleus pulposus). Healthy disc material helps maintain flexibility of the spine and acts as a shock absorber dissipating loads across the spine. When the condition of the disc material deteriorates as a result of, for example, degenerative disc disease, herniation, and/or injury, the patient may suffer deformation of the normal alignment or curvature of the affected area of the spine, as well as chronic complications and an overall adverse impact upon the quality of life.

Until recently, doctors were limited to treating such deterioration and related deformities with pain medications, bed rest, bracing or invasive spinal surgery. Surgical removal of the offending disc material can be completed (e.g., discectomy) to provide a treatment element to the disc space (e.g., bone graft, filler material, etc.) and/or fusion of adjacent vertebral bodies using metal screws/rods. Standard surgical instruments for removing and/or creating a cavity in the intervertebral disc include chisels, disc cutters, rasps, pituitary rongeurs, scrapers, curettes, cobb elevators, sizers, broaches or the like. The surgical procedure for accessing the disc may depend upon patient anatomy and/or disc/vertebral condition.

A common drawback of most systems for removing disc material is that they require significant dissection and muscle retraction to accommodate the multitude tools needed for creating the cavity, leading to longer recovery time for the patient. Accordingly, there remains a need in the art to provide a safe and effective apparatus and method for minimally invasive disc tissue detachment and removal.

<CIT> discloses tissue-removal devices and methods for treating spinal diseases using such devices. The tissue-removal devices may comprise a cable and/or extendable elements with a retracted and a deployed configuration. The cable and/or extendable elements may be distally supported and restrained by a support element such that the support element may be pushed transversely away when the extendable element is distally extended into its deployed configuration. An annular cutting element may be provided about the distal end of the extendable element or the support element. Various configurations of the extendable and support elements are described, as well as methods of using tissue-removal devices with extendable and support elements coupled by an annular cutting element for treating spinal diseases.

<CIT> discloses a tissue removal device comprising a handheld housing, a motor, and a tissue removal mechanism coupled to the handheld housing. The tissue removal mechanism may comprise a tissue collection chamber coupled to a distal portion of the handheld housing, a jaw member comprising first and second jaw portions, where the first jaw portion is coupled to a first elongated member and the second jaw portion is coupled to a second elongated member configured to actuate the second jaw portion, a rotatable shaft disposed within a lumen of the first elongated member, a helical member disposed around at least a portion of the rotatable shaft, and an impeller coupled to at least one of a distal end of the helical member and a distal end of the rotatable shaft. Rotation of the rotatable shaft may effect rotation of the helical member and the impeller.

<CIT> discloses a surgical instrument which includes a cannula shaft terminating in a cutting window at the distal end of the cannula shaft. The proximal end of the cannula shaft is supported by a handle having an axial bore extending therethrough. A flexible drive shaft, connected at one end to an external drive mechanism, extends through the handle and the cannula shaft. A cutting head is mounted to the distal end of the drive shaft and positioned for cooperative cutting action with the cutting window of the cannula shaft. A non-rotating idler shaft is journaled about the drive shaft. Severed tissue is removed or evacuated from the surgical site through an annular passage formed by the cannula and idler shafts.

<CIT> discloses methods of fusing a facet joint that include inserting a cannula with a first end of the cannula at the facet joint and a second end positioned away from the facet joint. One or more tools may be inserted through the cannula to contact against and treat one or both vertebral members to enlarge the facet joint. An osteogenic material is then inserted into the enlarged facet joint to facilitate fusion of the first and second vertebral members.

According to one aspect of the present invention there is provided a material removal instrument according to claim <NUM>. According to another aspect of the present invention there is provided a material removal instrument according to claim <NUM>. Optional features are recited in dependent claims.

Tools and methods are described for creating cavities in a body, in particular, cavities in intervertebral disc material and cancellous bone. An aspect of the present disclosure is directed to a material removal instrument. The material removal instrument includes a cannula and a rotation mechanism. The cannula includes a cannula bore and a cannula opening at a distal end of the cannula, where the cannula opening can provide access to the cannula bore. All or a portion of the cannula may be constructed from a rigid or flexible material. Flexibility can be achieved based on the material properties of the cannula, structural properties and/or modifications to the cannula, and/or a linkage with another portion of the material removal instrument. The rotation mechanism is disposed at least partially within the cannula. The rotation mechanism includes an elongated shaft having a central bore and an opening at a distal end of the elongated shaft providing access to the central bore. The central bore of the elongated shaft may be used to provide irrigation to the cutting area. The central bore of the elongated shaft may be sized and configured to receive a guide wire to direct placement of the rotation mechanism. All or a portion of the rotation mechanism, including the elongated shaft, may be constructed from a rigid or flexible material. Flexibility can be achieved based on the material properties of the rotation mechanism/elongated shaft, structural properties and/or modifications to the rotation mechanism/elongated shaft, and/or a linkage with another portion of the material removal instrument. Flexibility of the cannula and/or the rotation mechanism can be used to provide steering/directional control when accessing the target area and during removal of tissue. The elongated shaft includes a central bore.

In one aspect, the rotation mechanism includes projections extending from a portion of the elongated shaft and a blade extending from another portion of the elongated shaft. The blade may be used for dislocating material from a target area. At least a portion of the blade extends from the cannula opening. The rotation mechanism may be rotated within the cannula to cause the blade to dislocate material from the target area. The dislocated material may be drawn from the target area through the cannula bore.

Another aspect of the present disclosure is directed to a material removal instrument that includes a cannula and a rotation mechanism. The cannula includes a cannula bore and a cannula opening at a distal end of the cannula. The cannula opening provides access to the cannula bore. The rotation mechanism is disposed at least partially within the cannula. The rotation mechanism includes an elongated shaft and a thread extending from a portion of the elongated shaft. The thread may be used for dislocating material from a target area. The thread includes a flank having a leading side and a trailing side. The trailing side has a flank angle less than <NUM>° with respect to a longitudinal axis of the rotation mechanism. At least a portion of the rotation mechanism extends from the cannula opening. The rotation mechanism may be rotated within the cannula to cause the thread to impact and dislocate material from the target area.

An example of a material removal instrument that may include a cannula and a rotation mechanism is described, the description of which is useful as background information to the disclosure. In this example, the cannula may include a cannula bore and a cannula opening at a distal end of the cannula. The cannula opening may provide access to the cannula bore. The rotation mechanism may be disposed at least partially within and rotatable within the cannula. The rotation mechanism may include an elongated shaft, a connection element, and a mass element. The connection element may be fixed to the elongated shaft. The mass element may be used for dislocating material from a target area. The mass element may be fixed to the connection element. Rotation of the rotation mechanism may cause the connection element to move in a direction away from a longitudinal axis of the rotation mechanism. Rotation of the rotation mechanism may also cause the mass element to rotate about the longitudinal axis of the rotation mechanism at a distance from the longitudinal axis. Rotation of the mass element may cause the mass element to impact and dislocate material from the target area.

Another example of a material removal instrument that may include a cannula and a cutting element is described, the description of which is useful as background information to the disclosure. In this example, the cannula may include a cannula bore and a cannula opening at a distal end of the cannula. The cannula opening may provide access to the cannula bore. The cutting element may be disposed at least partially within the cannula and attached to an inner element. The cutting element may expand radially from the cannula opening upon movement of the inner element from a first position to a second position in a direction along a longitudinal axis of the cannula. The rotation of the cannula with the cutting element in the expanded position may cause the cutting element to impact and dislocate material from a target area.

The device is explained in even greater detail in the following drawings. The drawings are merely examples to illustrate the structure of preferred devices and certain features that may be used singularly or in combination with other features. The invention should not be limited to the examples shown.

Certain terminology is used in the following description for convenience only and is not limiting. The words "right", "left", "lower", and "upper" designate direction in the drawings to which reference is made. The words "inner", "outer" refer to directions toward and away from, respectively, the geometric center of the described feature or device. The words "distal" and "proximal" refer to directions taken in context of the item described and, with regard to the instruments herein described, are typically based on the perspective of the surgeon using such instruments. The words "anterior", "posterior", "superior", "inferior", "medial", "lateral", and related words and/or phrases designate preferred positions and orientation in the human body to which reference is made. The terminology includes the above-listed words, derivatives thereof, and words of similar import.

In addition, various components may be described herein as extending horizontally along a longitudinal direction "L" and lateral direction "A", and vertically along a transverse direction "T". Unless otherwise specified herein, the terms "lateral", "longitudinal", and "transverse" are used to describe the orthogonal directional components of various items. It should be appreciated that while the longitudinal and lateral directions are illustrated as extending along a horizontal plane, and that the transverse direction is illustrated as extending along a vertical plane, the planes that encompass the various directions may differ during use. Accordingly, the directional terms "vertical" and "horizontal" are used to describe the components merely for the purposes of clarity and illustration and are not meant to be limiting.

Certain examples of the invention will now be described with reference to the drawings. In general, such embodiments relate to a material removal instrument for cavities in intervertebral disc material and cancellous bone.

<FIG> provide perspective views of example material removal instruments <NUM>. The example material removal instrument <NUM> can include a cannula <NUM> and a rotation mechanism <NUM>. The rotation mechanism <NUM> can include a shaft <NUM>. The shaft <NUM> can define an elongated cylindrical structure. In another example (not shown), the shaft <NUM> can define an elongated structure with a cross-section having any suitable shape including, for example, elliptical, square, rectangular, or any other regular or irregular shape. The shaft <NUM> can be constructed from a flexible material (e.g., polymers, Nitinol) or a rigid material. An example shaft <NUM> constructed from a stiff and/or rigid material can include structural modification (e.g., geometric cutouts or shapes) that provide an overall flexible behavior regarding cross forces. The flexibility of the shaft <NUM> can also be achieved by a linkage (not shown) between the cutting surface <NUM> and the flanks <NUM>.

The shaft <NUM> can include a blade <NUM> extending from the outer surface of the shaft <NUM> body. The blade <NUM> can extend in a radial direction from the outer surface of the shaft <NUM> along a length of the shaft <NUM> in the longitudinal direction. Likewise, the blade <NUM> can extend from the distal end <NUM> of the shaft <NUM>. An example blade <NUM> can have a length along the longitudinal axis of the shaft <NUM> of about <NUM> to about <NUM>. An example blade <NUM> can have a thickness ranging from about <NUM> to about <NUM>.

The blade <NUM> can include a cutting surface <NUM> along the outer perimeter of the blade <NUM>. The cutting surface <NUM> can be used for dislocating material from a target area within the intervertebral disc (e.g., nucleus and/or annulus material) and/or cancellous bone. The cutting surface <NUM> can define a continuous edge as provided in <FIG>. The cutting surface <NUM> can also define an interrupted edge. For example, as illustrated in <FIG>, <FIG> and <FIG>, the cutting surface <NUM> can include a plurality of grooves <NUM> to aid in removal of material as the cutting surface <NUM> moves along/impacts the target area. The grooves <NUM> can break/cut the material into smaller fragments thereby making them easier to transport away from the target area and out of the body of the patient. <FIG>, provide an axial cross-section view of example blades <NUM>. As illustrated in <FIG>, the cutting surface <NUM> can include a curved or rounded surface terminating at a sharpened point/edge. As illustrated in <FIG>, the cutting surface <NUM> can include an angled or chamfered surface terminating at a sharpened point/edge.

The blade <NUM> can also include a portion that is rotated around the longitudinal axis of the rotation mechanism <NUM>. For example, as illustrated in <FIG>, <FIG> and <FIG>, the blade <NUM> can form a helical surface rotating around the longitudinal axis of the shaft <NUM>. The angle of rotation/twist of the blade <NUM> can be determined to prevent a hammering effect on the interior disc/bone surface when the blade <NUM> is rotated. The hammering effect occurs when disc/bone material is impacted as a result of the height of the cavity created by the blade <NUM> varying during blade rotation. As a result, the angle of rotation/twist of the blade <NUM> can be determined such that the width/height defined by the rotated blade <NUM> generally constant.

<FIG> provides an illustration of an example blade <NUM> rotated/twisted at various angles. Row A provides an example blade <NUM> with <NUM>° of blade twist. From left to right in <FIG>, the blade <NUM> is shown at various orientations. As the entire blade <NUM> is rotated between <NUM>°, <NUM>°, and <NUM>°, the height defined by the blade <NUM>, when viewed from the side, varies significantly. For example, Row A provides an example blade <NUM> having <NUM>° of blade twist. At a <NUM>° orientation, the blade <NUM> has a narrow height profile. The height profile increases drastically as the entire blade <NUM> is rotated through <NUM>° and <NUM>° orientation. It can be estimated that a blade <NUM> with <NUM>° of blade twist can have a blade height that varies approximately <NUM>%. Such a drastic variation in blade height can cause a hammering effect on opposing disk surfaces during rotation of the blade <NUM>.

Row B provides an example blade <NUM> having approximately <NUM>° if blade twist. From left to right in <FIG>, as the entire blade <NUM> is rotated between <NUM>°, <NUM>°, and <NUM>°, the height defined by the blade <NUM>, when viewed from the side, can vary approximately <NUM>%. This blade height variation can also cause a hammering effect on opposing disk surfaces during rotation of the blade <NUM>.

Row C provides an example blade having approximately <NUM>° of blade twist. From left to right in <FIG>, as the entire blade <NUM> is rotated between <NUM>°, <NUM>°, and <NUM>°, the change in height defined by the blade <NUM>, when viewed from the side, is minimal (approximately null). As a result, the hammering effect is minimal.

Accordingly, in the present disclosure, an example blade <NUM> can have a blade twist less than about <NUM>°. Another example blade <NUM> can have a blade twist of at least about <NUM>°. Another example blade <NUM> can have a blade twist of at least about <NUM>°. In a further example, the blade <NUM> can have a blade twist greater than about <NUM>°.

The pre-twist/blank shape of the blade <NUM> can define any suitable regular or irregular shape. <FIG> provides an illustration of example blades <NUM> with various blank (pre-twist) shapes (Column <NUM>). For example, Row A provides an example blade <NUM> having a blank defining a rectangular shape with convex side edges that curve and extend radially. Row B provides an example blade <NUM> with a blank defining a rectangular shape with square corners and straight side edges. Row C provides an example blade <NUM> with a blank defining a rectangular shape with concave side edges that curve inward radially. The blank shape of the blade <NUM> can also be designed to maximize the contact of the cutting surface <NUM> with the target area. <FIG> illustrates the twisted blades <NUM> at an initial position (Column <NUM>) and the twisted blades <NUM> rotated <NUM>° (Column <NUM>). As illustrated in Column <NUM>, the amount of cutting surface <NUM> contacting the target area at a <NUM>° rotation is greatest with the blade <NUM> design provided in Row C, a rectangular shape with concave side edges.

As illustrated in <FIG>, <FIG>, <FIG>, <FIG> and <FIG>, the shaft <NUM> can also include projections <NUM> extending from the outer surface of the shaft <NUM> body. The projections <NUM> can form a helical (or spiral) surface extending around the shaft <NUM>. The height of the projections <NUM> can be configured such that the rotation mechanism <NUM> is rotatable within the cannula <NUM>. When rotated within the cannula <NUM>, the shaft <NUM>/projections <NUM> can act as a conveyor (or screw pump) for moving dislocated material from the target area and through the cannula bore <NUM>. The projections <NUM> can include a plurality of flanks <NUM>. When the flanks <NUM> come into contact with the dislocated material, rotation of the shaft <NUM>/flanks <NUM> generates a force in the axial direction on the material.

As explained in more detail below with respect to <FIG>, the pitch between various flanks <NUM> of the projections <NUM> can vary along the length of the shaft <NUM> to provide for different efficiency in removing dislocated material and/or help control the axial forces on the rotation mechanism <NUM>. The pitch can be adjusted to define the rate of material removal as well as the particle size of the dislocated material capable of being transported through the cannula <NUM>. In an example rotation mechanism <NUM> the pitch is uniform along the length of the shaft <NUM>. In another example, the pitch varies between various flanks <NUM>. Similarly, the length of the projections <NUM> along the longitudinal axis of the shaft <NUM> can be adjusted to provide for different efficiency in removing dislocated material and/or help control the axial forces on the rotation mechanism <NUM>. In an example rotation mechanism <NUM>, the projections <NUM> can extend from the shaft <NUM> along a portion of the shaft <NUM>. In another example (not shown), the projections <NUM> can extend along the entire length of the shaft <NUM>.

Another example rotation mechanism <NUM>, illustrated in <FIG>, can include a plurality of blades <NUM> rotated around the longitudinal axis of the rotation mechanism <NUM> to form a plurality of helical surfaces. During operation, the blades <NUM> rotate around the longitudinal axis of the shaft <NUM>. The blades <NUM> originate at a first terminal <NUM> and terminate at a second terminal <NUM>. The first and second terminals <NUM>, <NUM> can be operatively coupled to the elongated shaft <NUM>. As outlined in more detail below, the rotation mechanism <NUM> and/or the cannula <NUM> can be formed from a flexible or rigid material to aid in direction and placement of the rotation mechanism at the target area.

The shaft <NUM> can include a central bore <NUM> and an opening <NUM> providing access to the central bore <NUM>. The opening <NUM> can be located at the end of the shaft <NUM>, as illustrated in <FIG>. In another example (not shown), the opening <NUM> can be located on a lateral surface of the shaft <NUM>. The opening <NUM> can define any suitable shape including, for example, circular, elliptical, square, rectangular, or any other regular or irregular shape. An example rotation mechanism <NUM> may include multiple bore openings <NUM>. For example, a bore opening <NUM> can be provided on each side of the blade <NUM>. It is contemplated that the bore <NUM> can be used to provide irrigation to the target cutting area. The proximal end of the bore <NUM> can be operatively coupled to an irrigation source for providing irrigation at the bore opening <NUM>. The irrigation can dissipate heat generated between the rotation mechanism <NUM> and the target area and/or heat generated between the rotation mechanism <NUM> and the cannula <NUM>. The irrigation can also prevent dislocated material (e.g., soft tissue, bone, blood, or other interstitial fluid/materials) from adhering to the blade <NUM>, projections <NUM>, or inner surface of the cannula bore <NUM>. The irrigation also aids in the flow of the dislocated material from the target area through the cannula <NUM>. It is further contemplated that the bore <NUM> can be sized and configured to receive a guide wire to direct placement of the rotation mechanism <NUM>. In another example (not shown), the shaft <NUM> can include a solid structure, without including a bore <NUM>.

As illustrated in <FIG> and <FIG>, the rotation mechanism <NUM> can be disposed within a cannula <NUM>. The cannula <NUM> is sized and configured to permit rotation of the rotation mechanism <NUM>. The cannula <NUM> can also function as a torque transmission element with respect to dislocated material passing through the cannula bore <NUM> and/or the rotation mechanism <NUM>. In an example rotation mechanism <NUM>, rotational movement of the cannula <NUM> can be fixed. In another example, the cannula <NUM> can rotate in the same or opposite direction of the rotation mechanism <NUM>. The cannula <NUM> can define an elongated cylindrical structure. The cannula <NUM> can be constructed from a flexible material (e.g., polymers, Nitinol) or a rigid material. An example cannula <NUM> constructed from a stiff and/or rigid material can include structural modification (e.g., geometric cutouts or shapes) that provide an overall flexible behavior regarding cross forces.

An example cannula <NUM> can have an outer diameter ranging from about <NUM> to about <NUM>. In another example, the cannula <NUM> can have an outer diameter ranging from about <NUM> to about <NUM>. In a further example, the cannula <NUM> can have an outer diameter of about <NUM>. The cannula <NUM> can include a central bore <NUM> sized and configured to accommodate the rotation mechanism <NUM>. The inner diameter of the central bore <NUM> can range from about <NUM> to about <NUM>. The cannula <NUM> can also include an opening <NUM> providing access to the central bore <NUM>. The opening <NUM> can be located on the rotation mechanism <NUM> such that at least a portion of the blade <NUM> is provided access to the target area when the material removal instrument <NUM> is located within the patient. The opening <NUM> can be located at the end of the cannula <NUM>, as illustrated in <FIG> and <FIG>. In this example, the rotation mechanism <NUM>, including at least a portion of the blade <NUM>, can extend from the cannula opening <NUM>. In another example (not shown), the opening <NUM> can be located on a lateral surface of the cannula <NUM>. In this example, the cannula opening <NUM> can be sized and located such that at least a portion of the rotation mechanism <NUM>, including at least a portion of the blade <NUM>, extends from the cannula opening <NUM>. The opening <NUM> can define any suitable shape including, for example, circular, elliptical, square, rectangular, or any other regular or irregular shape.

In use, the material removal instrument <NUM> can remove bony material and/or disc material between adjacent and/or within vertebrae. When used for removal of disc material (e.g., discectomy), disc access can be gained via a posterior and/or posterolateral percutaneous, extrapedicular approach. If a guide wire is used, it can be inserted into the disc. As provided in <FIG>, an introducer cannula <NUM> can be slid over the guide wire and introduced into the disc space. An example introducer cannula <NUM> can have an outer diameter of about <NUM> to about <NUM>. The cannula <NUM> and rotation mechanism <NUM> can then be provided into the disc space via the introducer cannula <NUM>. The material removal instrument <NUM> (cannula <NUM> and rotation mechanism <NUM>) can be located such that the cannula opening <NUM> is proximate the target area within the disc. Once positioned at the target area, the rotation mechanism <NUM> can be rotated within the cannula <NUM> causing the blade <NUM> to contact and dislocate disc material at the target area and thereby create a cavity, e.g., within the disc space. In an example material removal instrument <NUM>, the proximal end <NUM> of the rotation mechanism <NUM> can be operatively coupled to a source of rotation energy.

The dislocated material can be drawn into the cannula opening <NUM> and through the cannula bore <NUM>. As outlined above, rotation of the rotation mechanism <NUM> can create pumping action that urges the dislocated tissue into the cannula opening <NUM> and through the cannula bore <NUM> without the use of supplemental aspiration/suction. In another example, the proximal end of the cannula bore <NUM> can be operatively coupled to a suction device to aid in removal of the dislocated material from the target area and/or the cannula bore <NUM>.

The material removal instrument <NUM> can be withdrawn from the cavity and a treatment element can be provided to the disc space. The treatment element can include, for example, a filler material and/or an inflatable body, such as those used for kyphoplasty. The filler material can include, for example, bone cement, bone chips, demineralized bone, and/or an implant.

<FIG> provide side cross-section views of another example material removal instruments <NUM>. The example material removal instrument <NUM> can include a cannula <NUM> and a rotation mechanism <NUM>. The rotation mechanism <NUM> can include a shaft <NUM>. The shaft <NUM> can define an elongated cylindrical structure. In another example (not shown), the shaft <NUM> can define an elongated structure with a cross-section having any suitable shape including, for example, elliptical, square, rectangular, or any other regular or irregular shape. As outlined above with respect to shaft <NUM>, the shaft <NUM> can be constructed from a flexible material (e.g., polymers, Nitinol) or a rigid material. An example shaft <NUM> constructed from a stiff and/or rigid material can include structural modification (e.g., geometric cutouts or shapes) that provide an overall flexible behavior regarding cross forces. The flexibility of the shaft <NUM> can also be achieved by a linkage (not shown) between the cutting surface <NUM> and the flanks <NUM>.

The shaft <NUM> can include a central bore <NUM> and an opening <NUM> providing access to the central bore <NUM>. The opening <NUM> can be located at the end of the shaft <NUM>, as illustrated in <FIG>. In another example (not shown), the opening <NUM> can be located on a lateral surface of the shaft <NUM>. The opening <NUM> can define any suitable shape including, for example, circular, elliptical, square, rectangular, or any other regular or irregular shape. An example rotation mechanism <NUM> may include multiple bore openings <NUM>. It is contemplated that the bore <NUM> can be used to provide irrigation to the target cutting area. The proximal end of the bore <NUM> can be operatively coupled to an irrigation source for providing irrigation at the bore opening <NUM>. The irrigation can dissipate heat generated between the rotation mechanism <NUM> and the target area and/or heat generated between the rotation mechanism <NUM> and the cannula <NUM>. The irrigation can also prevent dislocated material (e.g., soft tissue, bone, blood, or other interstitial fluid/materials) from adhering to the threads <NUM> or inner surface of the cannula bore <NUM>. The irrigation also aids in the flow of the dislocated material from the target area through the cannula <NUM>. It is further contemplated that the bore <NUM> can be sized and configured to receive a guide wire to direct placement of the rotation mechanism <NUM>. In another example (not shown), the shaft <NUM> can include a solid structure, without including a bore <NUM>.

The shaft <NUM> can include a thread <NUM> extending from the outer surface of the shaft <NUM> body. The thread <NUM> can form a helical (or spiral) surface extending around the shaft <NUM>. The thread <NUM> can extend from the shaft <NUM> along the entire length of the shaft <NUM>. In another example, the thread <NUM> can extend along only a portion of the length of the shaft <NUM>. The thread <NUM> can include a cutting surface <NUM> along the outer perimeter of the thread <NUM> for dislocating material from the target area within the intervertebral disc (e.g., nucleus and/or annulus material) and/or cancellous bone. As illustrated in <FIG>, the cutting surface <NUM> can include an edge extending towards the proximal end <NUM> of the shaft <NUM>. The example cutting surface <NUM> can be used to dislocate material from the target area and help to retain the dislocated material behind the flanks <NUM> for during rotation of the shaft <NUM>.

Rotation of the shaft <NUM> can cause the cutting surface <NUM> to contact and dislocate material in the target area. Similarly, rotation of the shaft <NUM> can cause the thread <NUM> to act as a conveyor for moving the dislocated material <NUM> from the target area towards the proximal end <NUM> of the shaft <NUM> (similar to the projections <NUM> included in the rotation mechanism <NUM>).

The thread <NUM> can include a plurality of flanks <NUM>. In another example (not shown), the thread <NUM> can include a single flank <NUM>. Each flank <NUM> can include a leading side <NUM> and a trailing side <NUM>. Each flank <NUM> can define a flank angle (α). For the purpose of this application, the flank angle (α) will be defined with respect to the trailing side <NUM> of the flank <NUM> and a reference plane parallel with the longitudinal axis of the shaft <NUM>. In the example rotation mechanism <NUM> illustrated in <FIG>, the flank angle (α) defined by the flank <NUM> is approximately <NUM>°. A thread <NUM> having a <NUM>° flank angle (α) provides a single cutting direction perpendicular to the longitudinal axis of the shaft <NUM>, a radial component (as represented by Arrow A). To provide a cutting direction in the parallel to the longitudinal axis of the shaft <NUM> (an axial component), the rotation mechanism <NUM> can include a cannula <NUM> that functions as a shearing sleeve. As the dislocated material <NUM> is transported towards the proximal end <NUM> of the shaft <NUM> and the cannula <NUM>, the interface between the flank <NUM> and the cannula <NUM> can detach the material from the target location and/or rupture the material into smaller pieces. Because the interface between the flank <NUM> and the cannula <NUM> provides an additional dislocation point for the material, it is not necessary that the cutting surface <NUM> of the thread <NUM> be as sharp as when the cannula <NUM> is not used as a shearing sleeve.

In another example, illustrated in <FIG>, the flank angle (α) can be an angle less than <NUM>°. For example, the flank angle (α) range between about <NUM>° and less than about <NUM>°. In another example, the flank angle (α) can range between about <NUM>° and less than about <NUM>°. In a further example, the flank angle (α) can be about <NUM>°. With a flank angle (α) less than <NUM>° can result in better retention and transport of dislocated material <NUM> via rotation of the thread <NUM>. In another example (not shown), an example rotation mechanism <NUM> with a flank angle (α) less than <NUM>° can include a cannula <NUM> functioning as a shearing sleeve, as described above with respect to <FIG>.

During rotation, a thread <NUM> having a flank angle (α) less than <NUM>° provides a cutting directions perpendicular to the longitudinal axis of the shaft <NUM>, a radial cutting component (represented by Arrow A), and a cutting direction parallel to the longitudinal axis of the shaft <NUM>, an axial cutting component (as represented by Arrow B). <FIG> provides a perspective view of the example rotation mechanism <NUM> illustrating the radial (Arrow A) and axial (Arrow B) cutting components when the shaft <NUM> is rotated (Arrow Z). A third cutting direction can be provided by moving the shaft <NUM> in the lateral (side-to-side) or vertical (up-an-down) direction. As illustrated in <FIG>, rotation of the rotation mechanism <NUM> (Arrow Z), provides a radial cutting component (Arrow A) and an axial cutting component (Arrow B). Movement of the distal end rotation mechanism <NUM> in the vertical direction (Arrow Y) provides a lateral cutting component (Arrow C).

As outlined above with respect to the rotation mechanism <NUM> works to remove dislocated material from the target by rotation of the threads <NUM> (similar to rotations mechanism <NUM> and projections <NUM>). As the rotation mechanism <NUM>/threads <NUM> urge the dislocated material towards the proximal end <NUM> of the shaft <NUM>, forces in the opposite direction direct ("pull") the rotation mechanism <NUM> in the direction towards the distal end <NUM>. That is, consistent with Newton's third law of motion, when the rotation mechanism <NUM>/threads <NUM> exert a force (F1) on the material in the target area, the material simultaneously exerts a force (F2) on the rotation mechanism <NUM>. These forces are generally equal in magnitude and opposite in direction. This force on the rotation mechanism <NUM> causes the shaft <NUM> to "crawl" forward in the target area making control of the rotation mechanism <NUM> challenging.

Varying the pitch between various flanks <NUM> of the thread <NUM> along the length of the shaft <NUM> can help control the resultant axial forces on the rotation mechanism <NUM> (including the forward force) and can control the efficiency in removing dislocated material. That is, the pitch width can be adjusted to adjust the force in the axial direction on the material (e.g., the thrust effect on the dislocated material particles) and thereby dissipate the forward force on the rotation mechanism <NUM>. The pitch can also be adjusted to define the rate of material removal as well as the particle size of the dislocated material capable of being transported from the target area. As provided in <FIG>, the pitch between various flanks <NUM> can vary. For example, the pitch (P1) between a first set of flanks can be less than the pitch (P2) between a second set of flanks. In another example rotation mechanism <NUM>, illustrated for example in <FIG>, the pitch between various flanks <NUM> is uniform along the length of the shaft <NUM>.

Varying the height of the flanks <NUM> along the length of the shaft <NUM> can also be adjusted to control the resultant axial forces on the rotation mechanism <NUM> and provide for different efficiency in removing dislocated material. In general, the height of the flanks <NUM> is configured such that the rotation mechanism <NUM> can pass through and rotate within the cannula <NUM>. <FIG> provides a partial side view of an example rotation mechanism <NUM> located within the disc space between the adjacent vertebral bodies. As illustrated in <FIG>, the height of various flanks <NUM> can vary along the length of the shaft <NUM>. For example, the height of the first flank 258A can be less than the height of the second flank 258B, and the overall flank height (H) progressively increases from the distal end <NUM> towards the proximal end <NUM>. The flank height can be configured such that the flanks <NUM> located towards the proximal end <NUM> of the shaft <NUM> are proximate the surface of the superior and/or inferior vertebral body while the flanks <NUM> at the distal end <NUM> of the shaft <NUM> can impact and dislocate material without coming into contact with bony components. In another example rotation mechanism illustrated in <FIG>, the height of the flanks <NUM> can remain constant along the length of the shaft <NUM>.

Varying the length of the thread <NUM> along the longitudinal axis of the shaft <NUM> can also be adjusted to control the resultant axial forces on the rotation mechanism <NUM> and provide for different efficiency in removing dislocated material. In the example rotation mechanism <NUM> illustrated in <FIG>, the thread <NUM> can extend from the shaft <NUM> along a portion of the shaft <NUM>. In another example illustrated in <FIG> and <FIG>, the projections <NUM> can extend along the entire length of the shaft <NUM>.

The axial forces on the rotation mechanism <NUM> can also be controlled by the use of a housing surrounding a portion of the rotation mechanism <NUM>. As illustrated in <FIG>, the housing can include a sleeve <NUM> that partially covers the shaft <NUM> and the threads <NUM>. The shaft <NUM> can rotate within the sleeve <NUM>. The sleeve <NUM> can include a first arm <NUM> and a second arm <NUM> and a distal end <NUM>. The shaft <NUM> can matingly engage the distal end <NUM>. In another example, the shaft <NUM> is independent of the distal end <NUM>. The open space between the first arm <NUM> and the second arm <NUM> can provide the threads <NUM> access to material at the target area. In the example rotation mechanism <NUM>, when inserted into an intervetebral space, the first arm <NUM> and the second arm <NUM> can protect material adjacent to and/or associated with the superior and inferior vertebra, while providing cutting windows in the posterior and anterior direction.

The rotation mechanism <NUM> can be disposed within a cannula <NUM>. The cannula <NUM> can be similar in form and function to cannula <NUM>. The cannula <NUM> is sized and configured to permit rotation of the rotation mechanism <NUM>. The cannula <NUM> can be constructed from a flexible material (e.g., polymers, Nitinol) or rigid material. An example cannula <NUM> constructed from a stiff and/or rigid material can include structural modification (e.g., geometric cutouts or shapes) that provide an overall flexible behavior regarding cross forces. As outlined above, the cannula <NUM> can also function as a torque transmission element with respect to dislocated material passing through the cannula bore <NUM> and/or the rotation mechanism <NUM>.

The cannula <NUM> can define an elongated cylindrical structure having an outer diameter ranging from about <NUM> to about <NUM>. In another example, the cannula <NUM> can have an outer diameter ranging from about <NUM> to about <NUM>. In a further example, the cannula <NUM> can have an outer diameter of about <NUM>. The cannula <NUM> can include a central bore <NUM> sized and configured to accommodate rotation of the rotation mechanism <NUM>. The inner diameter of the bore <NUM> can range from about <NUM> to about <NUM>. The cannula <NUM> can also include an opening <NUM> providing access to the central bore <NUM>. The opening <NUM> can be located with respect to the rotation mechanism <NUM> such that at least a portion of the threads <NUM> is provided access to the target area when the material removal instrument <NUM> is located within the patient.

As illustrated in <FIG>, the opening <NUM> can be located on a lateral surface of the cannula <NUM>. In this example, the cannula opening <NUM> can be sized and located such that at least a portion of the rotation mechanism <NUM>, including at least a portion of the threads <NUM>, extends from the cannula opening <NUM>, thereby limiting cutting in the direction of the opening <NUM>. The opening <NUM> can define any suitable shape including, for example, circular, elliptical, square, rectangular, or any other regular or irregular shape. The cannula <NUM> can include a single opening <NUM> or a plurality of openings <NUM> (not shown). In another example (not shown), the opening <NUM> can be located at the end of the cannula <NUM> and the rotation mechanism <NUM>, including at least a portion of the threads <NUM> can extend from the cannula opening <NUM>.

The cannula <NUM> can also be used to control the axial forces on the rotation mechanism <NUM>. As illustrated in <FIG>, the cannula <NUM> partially covers the shaft <NUM> and the threads <NUM>. As provided in <FIG>, the opening <NUM> can be located on a lateral surface of the cannula and can define an elongated opening extending in both the longitudinal and radial surfaces of the cannula <NUM>. By providing an opening <NUM>, only those portions of the thread <NUM> proximate the opening <NUM> come in contact with material at the target area with a corresponding other portion of the thread <NUM> are not in contact with the material, thereby the axial forces resulting from rotation of the shaft <NUM> and contact with material at the target area are reduced. The cannula <NUM> can cover the distal end <NUM> of the rotation mechanism <NUM>. By covering the distal end of the rotation mechanism <NUM>, the cannula <NUM> helps prevent axial force on the rotation mechanism <NUM> from driving the rotation mechanism <NUM> forward. Covering the distal end <NUM> of the rotation mechanism <NUM> also helps prevent unintentionally removing excess material and/or damaging unintended tissue.

In use, the material removal instrument <NUM> can remove bony material and/or disc material between adjacent vertebrae. The cannula <NUM> and rotation mechanism <NUM> can be provided into the disc/bone space. The material removal instrument <NUM> (cannula <NUM> and rotation mechanism <NUM>) can be located such that the cannula opening <NUM> is proximate the target area within the disc. Once positioned at the target location and the rotation mechanism <NUM> operatively coupled to a source of rotation energy, the rotation mechanism <NUM> can be rotated within the cannula <NUM> causing the threads <NUM> to contact and dislocate disc material at the target location and create a cavity within the disc space.

The dislocated material can be drawn into the cannula opening <NUM> and through the cannula bore <NUM>. As outlined above, rotation of the rotation mechanism <NUM> and threads <NUM> can act as a conveyor (or screw pump) for moving dislocated material from the target area and through the cannula bore <NUM> without the use of supplemental aspiration/suction. In another example, the proximal end of the cannula bore <NUM> can be operatively coupled to a suction device to aid in removal of the dislocated material from the target area and/or the cannula bore <NUM>.

<FIG> provide partial views of another example material removal instrument <NUM>. The example material removal instrument <NUM> can include a cannula <NUM> and a rotation mechanism <NUM>. The rotation mechanism <NUM> can include a shaft <NUM>. The shaft <NUM> can define an elongated cylindrical structure. In another example (not shown), the shaft <NUM> can define an elongated structure with a cross-section having any suitable shape including, for example, elliptical, square, rectangular, or any other regular or irregular shape. As provided in <FIG>, the shaft <NUM> can define a first portion <NUM> having a first diameter and a second portion <NUM> having a second diameter. In another example rotation mechanism <NUM>, the diameter of the shaft <NUM> can be constant along the longitudinal length of the shaft <NUM>. In a further example, the shaft <NUM> can include cutouts and/or hinges to accommodate the mass element <NUM> during delivery through the cannula bore <NUM>.

The rotation mechanism <NUM> can also include a connection element <NUM> fixed to the shaft <NUM> and a mass element <NUM> fixed to the connection element <NUM>. The connection element <NUM> can comprise a flexible member for connecting the mass element <NUM> to the shaft <NUM>. Example connection elements <NUM> can include wires, threads, and/or sheets formed from a flexible material. Other example connection elements <NUM> can include pre-shaped highly elastic materials including, for example, Nitinol (NiTi) strips. The pre-shaped connection element <NUM> can be stressed in a deformed shape while within the cannula <NUM>. Upon removal from the cannula <NUM>, the pre-shaped connection element <NUM> can be restored to its original, undeformed shape.

As illustrated in <FIG>, the mass element <NUM> can have a round/spherical shape. In another example the mass element <NUM> can define any suitable shape including, for example, spherical, ellipsoid, cube, torus, cylindrical, or square, rectangular, or any other regular or irregular shape. The mass element <NUM> can include a cutting surface <NUM> on the perimeter or surface of the mass element <NUM> for dislocating material from a target area within the intervertebral disc (e.g., nucleus and/or annulus material) and/or cancellous bone. The cutting surface <NUM> can include sharp edges, a roughened surface, a blasted surface, and/or any other form of abrasive surface and/or feature formed on or attached to the mass element <NUM>. For example, as illustrated in <FIG>, the mass element <NUM> can include a round/cylindrical mass having an abrasive surface for dislocating material from the target area. The mass element <NUM> can have a weight less than about <NUM> gram. In another example, the mass element <NUM> can have a weight of about <NUM> gram. In a further example, the mass element <NUM> can have a weight greater than about <NUM> gram. An example mass element <NUM> has uniform weight distribution. In another example, the mass distribution of the mass element <NUM> is concentrated at the cutting surface <NUM>.

As illustrated in <FIG>, the mass element <NUM> can be attached to the shaft <NUM> via the connection element <NUM> such that the rotation mechanism <NUM> (shaft <NUM>, connection element <NUM>, mass element <NUM>) can be inserted into the body/target area via the cannula <NUM>.

The rotation mechanism <NUM> can extend from an opening <NUM> in the cannula <NUM>. Rotation of the shaft <NUM> can cause the connection element <NUM> and the mass element <NUM> to move in a direction away from the shaft <NUM>. As illustrated in <FIG>, during rotation of the shaft <NUM>, the connection element <NUM> extends in a direction away from the longitudinal axis of the shaft <NUM>. As the mass element <NUM> rotates around the longitudinal axis of the shaft <NUM>, it impacts and dislocates material from the target area. The length of the connection element <NUM> and dimensions of the mass element <NUM> can be adjusted to define the maximum excavation diameter (D) created by rotation of the shaft <NUM>. As illustrated in <FIG>, the maximum excavation diameter (D) can be greater than the outer and/or inner diameter of the cannula <NUM>.

The shaft <NUM> can be constructed from a flexible material (e.g., polymers, Nitinol) or a rigid material. An example shaft <NUM> constructed from a stiff and/or rigid material can include structural modification (e.g., geometric cutouts or shapes) that provide an overall flexible behavior regarding cross forces. The example rotation mechanism illustrated in <FIG> includes a shaft <NUM> constructed from a flexible material. An example shaft <NUM> constructed from a stiff and/or rigid material can include geometric cutouts or shapes that provide an overall flexible behavior regarding cross forces (e.g. spring). As provided in <FIG>, the mass element <NUM> can be attached directly to the flexible shaft <NUM> without the use of a connecting element <NUM>. In the example rotation mechanism <NUM> illustrated in <FIG>, the excentric center of mass of the shaft <NUM> and mass element <NUM> can result in an imbalance when rotating the shaft <NUM>. If the surface of the elongated shaft <NUM> also includes a cutting surface <NUM> such that the elongated shaft <NUM> (in addition to the mass element <NUM>) can impact and dislocate material, the imbalanced center of mass can create a cone shaped cavity at the target area.

Depending on the desired application and patient anatomy, it may be desirable to vary the shape of the cavity. When using a flexible shaft <NUM>, the shape of the cavity can be varied by changing the shape of the cannula opening <NUM>. For example, the shape of the opening <NUM> can be varied as illustrated in <FIG>. The opening <NUM> can include a recessed portion <NUM> and a protruding portion <NUM> where the shape of the opening defines the rotation/path of the flexible shaft <NUM> and the mass element <NUM>. In particular, the recessed portion <NUM> permits the shaft <NUM> to rotate to a diameter (X<NUM>) and the protruding portion permits the shaft <NUM> to rotate to a diameter (X<NUM>), where X<NUM> is greater than X<NUM>.

In another example material removal instrument <NUM> illustrated in <FIG>, the connection element <NUM> can include a flexible strip of material having a mass element <NUM> attached to a portion of the strip. In the example rotation mechanism <NUM>, the mass element <NUM> is integrally formed on the connection element <NUM>. For example, the mass element <NUM> can be formed at a folded portion of the connection element <NUM>. The mass element <NUM> can be located at a position on the connection element <NUM> that defines the greatest distance from the longitudinal axis of the shaft <NUM> when the connection element <NUM> and mass element <NUM> are in a deployed position (e.g., when the shaft <NUM> is rotating and the connection element <NUM> is extended from the shaft <NUM>). The lighter, thinner, and/or more flexible portions of the folded connection element <NUM> can be located between the mass element <NUM> and the shaft <NUM>. It is also contemplated that the mass element <NUM> can be located at a position on the connection element <NUM> that defines the greatest distance from the longitudinal axis of the shaft <NUM> when the connection element <NUM> and mass element <NUM> are in an undeployed position. When the center of mass of the mass element <NUM> can also define the greatest distance from the longitudinal axis of the shaft <NUM> and the resulting force that moves the mass element <NUM> away from the rotation axis is higher. That is, applying Newton's second law (F=ma), the centripetal force (F) on the mass element <NUM> can be determined using the following formula F=mω<NUM>r, where m is the mass of the mass element <NUM>, ω is the rotational speed of the mass element <NUM>, and r is the radius of rotation (distance between the mass element <NUM> and the rotation axis).

Another example material removal instrument <NUM> is illustrated in <FIG> and <FIG>. The connection element <NUM> is a flat strip of flexible material capable of being wrapped around the shaft <NUM>. The mass element <NUM> can include a sharpened spike or other edge/projection formed on and/or fixed to the surface of the connection element <NUM>. The connection element <NUM> is shown in an undeployed configuration in <FIG>. As the shaft <NUM> is rotated, centrifugal forces urge the connection element <NUM>/mass element <NUM> outwards with regard to the rotation axis of the shaft <NUM>, as illustrated in <FIG>. Because the properties of the connection element <NUM> (width, thickness, material, pre-shaping, etc.) can alter the centrifugal forces on the mass element <NUM> and/or the rotational speed of the shaft <NUM>, the excavation diameter of the cavity can be adjusted.

Another example material removal instrument <NUM> is illustrated in <FIG> and <FIG>. To increase the cutting performance of the rotation mechanism <NUM> (i.e., amount of cut or detached material per unit of time), the rotation mechanism <NUM> can including a plurality of mass elements <NUM>. When only one mass element <NUM> is used, a disc-like cavity is created (see <FIG>). To enlarge the cavity, the rotation mechanism <NUM> must be moved in the axial direction (distance "a" in <FIG>), thereby creating a cylindrically-shaped cavity. When multiple mass elements <NUM> are used, the same amount of axial movement (distance "a" in <FIG>), results in larger cavity than the single mass element <NUM> cavity. Moreover, if a single mass element <NUM> detaches disc material at a certain rate (e.g., grams per second), multiple mass elements <NUM> can detach more disc material at a greater rate (assuming that the source of rotational energy driving the rotation mechanism <NUM> can maintain a constant turning speed).

As illustrated in <FIG>, mass elements <NUM> can be provided at shifted/offset locations along opposite sides of the length of the shaft <NUM>. In another example (not shown), the mass elements <NUM>/connection elements <NUM> can extend from the shaft <NUM> at mirrored positions along the length of the shaft <NUM>. In another example illustrated in <FIG>, multiple mass elements <NUM> extend from one side of the shaft <NUM>. In a further example, a plurality of mass elements <NUM> can extend from any location around the perimeter (diameter) of the shaft <NUM>. The rotation mechanism <NUM> can include an even or odd number of mass elements <NUM>. The mass of each of the mass elements <NUM> can vary, or the mass can be constant for each of the plurality of mass elements <NUM>. The size and/or shape of each of the mass elements <NUM> and connection elements <NUM> can vary, or the size and/or shape can be constant for each of the plurality of mass elements <NUM>.

The rotation mechanism <NUM> can be disposed within a cannula <NUM>. The cannula <NUM> can be similar in form and function to cannula <NUM> and cannula <NUM>, as outlined above. The cannula <NUM> can include a central bore (not shown) sized and configured to accommodate rotation of the rotation mechanism <NUM>. The cannula <NUM> can also include an opening <NUM> providing access to the central bore <NUM>. The opening <NUM> can be located on the cannula <NUM> such that the rotation mechanism <NUM> (including the mass elements <NUM>) is provided access to the target area when the material removal instrument <NUM> is located within the patient. The cannula <NUM> can be constructed from a flexible material (e.g., polymers, Nitinol) or a rigid material. An example cannula <NUM> constructed from a stiff and/or rigid material can include structural modification (e.g., geometric cutouts or shapes) that provide an overall flexible behavior regarding cross forces.

In use, the material removal instrument <NUM> can remove bony material and/or disc material between adjacent vertebrae. As illustrated in <FIG>, the cannula <NUM> and rotation mechanism <NUM> can be provided into the disc/bone space in an undeployed configuration. The cannula opening <NUM> is proximate the target area within the disc/bony material. As provided in <FIG>, the rotation mechanism <NUM> can be adjusted to extend from the cannula opening <NUM> at the target location. The rotation mechanism <NUM>/shaft <NUM> can be operatively coupled to a source of rotation energy causing the rotation mechanism <NUM> rotate. An example rotation mechanism can rotate at speed raging from about <NUM>,<NUM> rpm to about <NUM>,<NUM> rpm. Centrifugal forces resulting from the rotation of the shaft <NUM> force the mass element <NUM> and the connection element <NUM> in a direction away from the axis of rotation (i.e., the longitudinal axis of the shaft <NUM>). The rotation of the shaft <NUM> also causes the mass element <NUM> to rotate about the longitudinal axis of the shaft <NUM> at an angular velocity and in a generally circular trajectory. As the mass element <NUM> is rotated about the axis of the shaft <NUM>, the inertia and trajectory of the mass element <NUM> cause the cutting surface <NUM> to contact and dislocate disc material from the target location. The required rotational speed can be determined based on the weight of the mass element <NUM> and the distance between the center of the mass element and the axis of rotation.

As illustrated in <FIG>, the rotating mass element <NUM> can define a diameter (D) of rotation that determines the size of the cavity. The diameter (D) can be defined by the length of the connection element <NUM> and the size of the mass element <NUM>. The flexibility/resistance of the connection element <NUM> can also influence the diameter (D). For example, a flexible connection element <NUM> can fully expand into the disc space along the length of the connection element <NUM>. In another example using a semi-flexible connection element <NUM>, the resistance of the connection element <NUM> can resist full expansion during rotation. The length and/or flexibility of the connection element <NUM> and the size of the mass element <NUM> can be provided such that the diameter (D) of rotation is similar to the maximum disc height between superior and inferior vertebral bodies. Likewise, the length and/or flexibility of the connection element <NUM> and the size of the mass element <NUM> can be provided such that the diameter (D) of rotation is greater than the outer diameter of the cannula <NUM>.

As illustrated in <FIG>, the shaft <NUM> can be moved in the axial direction to cause the mass element <NUM> to advance within the disc material and thereby remove additional material, enlarging the cavity. Likewise, the shaft <NUM> and/or cannula <NUM> can be moved in the lateral and/or vertical direction to remove to cause the mass element <NUM> to impact additional disc material and enlarge the cavity in the lateral and/or vertical directions.

<FIG> provide partial side views of other example material removal instruments <NUM>. The example material removal instrument <NUM> can include a cannula <NUM>, a cutting element <NUM>, and an inner element attached to the cutting element <NUM>. The cutting element <NUM> can be disposed within the cannula <NUM>. The cannula <NUM> can be similar in form and function to cannula <NUM>, cannula <NUM>, and cannula <NUM>, as outlined above. The cannula <NUM> can be constructed from a flexible or rigid material. The cannula <NUM> can include a central bore (not shown) sized and configured to accommodate the cutting element <NUM> and inner element (not shown). The cannula <NUM> can also include an opening <NUM> providing access to the central bore. The opening <NUM> can be located such that at least a portion of the cutting element <NUM> is provided access to the target area when the material removal instrument <NUM> is located within the patient.

As illustrated in <FIG> and <FIG>, the cannula <NUM> can include a single opening <NUM>. In another example, the cannula <NUM> can include a plurality of openings <NUM> located around the around the outer surface of the cannula <NUM>. For example, as illustrated in <FIG>, the cannula <NUM> can include two openings <NUM> provided on opposite sides of the cannula <NUM>. The opening <NUM> can be located on a lateral surface of the cannula <NUM>.

In another example illustrated in <FIG>, the opening <NUM> can be located on the end surface at the distal end <NUM> of the cannula <NUM>. The opening <NUM> can define any suitable shape including, for example, circular, elliptical, square, rectangular, or any other regular or irregular shape.

The cutting element <NUM> can include a flexible blade and/or wire. A portion of the cutting element <NUM> can be fixed to the inner element such that movement of the inner element expands the cutting element <NUM> radially through the cannula opening <NUM>. The expanded cutting element <NUM> can define an outer diameter greater than the outer diameter of the cannula <NUM>. For example, the expanded cutting element <NUM> can define an outer diameter greater than the outer diameter of the cannula <NUM> by about <NUM> to about <NUM>. That is, the cutting element <NUM> can expand radially from the outer surface of the cannula <NUM> from about <NUM> to about <NUM>.

In an example material removal instrument <NUM>, movement of the inner element in the direction along the longitudinal axis of the cannula <NUM> applies a force on the cutting element <NUM> expanding the cutting element <NUM> radially through opening <NUM>. In one example illustrated in <FIG>, the proximal end of the cutting element <NUM> can be fixed to the inner element such that movement of the inner element in a direction towards the distal end <NUM> (Arrows A in <FIG>) of the cannula <NUM> expands the cutting element <NUM> radially through the opening <NUM>.

In another example illustrated in <FIG>, radial expansion of the cutting <NUM> can be controlled by changing the geometry of the cutting element <NUM>. For example, the profile of the cutting element <NUM> can be narrowed in the portions where deformation/radial expansion is desired. As illustrated in <FIG>, the profile of the cutting element <NUM> can be narrowed by including recesses <NUM> on the side portions of the cutting element <NUM>. It is contemplated that the recesses <NUM> can have a square, curved, or any regular or irregular shape.

In another example illustrated in <FIG>, the inner element includes a central shaft <NUM> and end cap <NUM>. The proximal end of the cutting element <NUM> can be coupled to the cannula <NUM> and the distal end of the cutting element <NUM> can be coupled to the end cap <NUM>. Movement of the central shaft <NUM> in a direction towards the proximal end <NUM> of the cannula <NUM> applies a force on the cutting element <NUM> expanding the cutting element <NUM> radially through opening <NUM>. In a further example illustrated in <FIG>, the central shaft <NUM> and/or end cap <NUM> can be rotated around the longitudinal axis of the central shaft <NUM>. The proximal end of the cutting element <NUM> can be coupled to cannula <NUM> and the distal end of the cutting element <NUM> can be coupled to the end cap <NUM> such that rotation of the central shaft <NUM>/end cap <NUM> causes the cutting element <NUM> to rotate around the central shaft <NUM> and form a helical cutting surface.

As outlined above, the cannula <NUM> and the elongated shaft <NUM> can both be constructed from a flexible material (or a material exhibiting flexible response). A cannula <NUM> and/or shaft <NUM> constructed from a flexible material allows for steering when accessing the target area. Flexibility can also increase the range of motion of the material removal instrument <NUM>.

In use, the material removal instrument <NUM> can remove bony material and/or disc material between adjacent vertebrae. The cannula <NUM>, including the cutting element <NUM>, can be provided into the disc/bone space such that the cannula opening <NUM> is proximate the target area. Once positioned at the target area, the cutting element <NUM> can be expanded radially from the opening <NUM>. The cannula <NUM> can be operatively coupled to a source of rotation energy. Rotation of the cannula <NUM> causes the expanded cutting element <NUM> to contact and dislocate disc material at the target location and create a cavity within the disc space. The cavity can be expanded by moving the rotating cannula <NUM>/cutting element <NUM> axially, laterally, and/or vertically within the disc space.

It should be noted that specific features of the various embodiments disclosed herein can be performed manually by user-applied forces or, alternately, utilizing specialized motors/power sources. For example, rotation of the various components of the rotation mechanism <NUM>, <NUM>, <NUM> and/or cannula <NUM> can be performed manually by a surgeon. Conversely, rotation of the various components of the rotation mechanism <NUM>, <NUM>, <NUM> and/or cannula <NUM> can be performed by motorized components that may utilize, in certain implementations, microprocessors or other guidance systems to coordinate the rotation speed and location of the cutting surface to optimally form the cavity within the target body.

It is contemplated that each of the rotation mechanisms <NUM>, <NUM>, <NUM> and cannula <NUM> can each include a central bore. The central bore can be used to provide irrigation to the cutting area. The central bore can be operatively coupled to an irrigation source for providing irrigation to bore openings provided at the distal ends of the rotation mechanisms <NUM>, <NUM>, <NUM> and/or cannula <NUM>. The irrigation can be provided to dissipate heat generated between the rotation mechanism <NUM>, <NUM>, <NUM> and/or cannula <NUM> and the target area. The irrigation can also dissipate heat generated between the rotation mechanism <NUM>, <NUM>, <NUM> and/or cannula <NUM> and the cannula <NUM>, <NUM>, <NUM> and/or the introducer cannula <NUM>. The irrigation can also prevent dislocated material (e.g., soft tissue, bone, blood, or other interstitial fluid/materials) from adhering to the blade, projections, threads, cutting surface, mass element, cutting surface, and/or inner surface of the cannula bore and/or introducer cannual included in any one of the material removal instruments <NUM>, <NUM>, <NUM>, <NUM>. The irrigation can also aid the flow of the dislocated material from the target area through the cannula <NUM>, <NUM>, <NUM>, <NUM>. It is further contemplated that the bore included in each of the rotation mechanisms <NUM>, <NUM>, <NUM> and cannula <NUM> can be sized and configured to receive a guide wire to direct placement of the rotation mechanism <NUM>, <NUM>, <NUM>/cannula <NUM>. An example guide wire can include a Kirschner wire (K-wire).

It is also contemplated that the cannula <NUM>, <NUM>, <NUM>, <NUM> for each of the described material removal instruments <NUM>, <NUM>, <NUM>, <NUM> can exhibit flexible behavior. All or a portion of the cannula <NUM>, <NUM>, <NUM>, <NUM> may be constructed from a rigid or flexible material. Flexibility can be achieved based on the material properties of the cannula <NUM>, <NUM>, <NUM>, <NUM>, structural properties and/or modifications to the cannula <NUM>, <NUM>, <NUM>, <NUM>, and/or a linkage with another portion of the material removal instrument. Similarly, all or a portion of the rotation mechanisms <NUM>, <NUM>, <NUM> for each of the described material removal instruments <NUM>, <NUM>, <NUM>, <NUM> can also exhibit flexible behavior. In particular, the elongated shaft <NUM>, <NUM>, <NUM> may be constructed from a rigid or flexible material. Flexibility can be achieved based on the material properties of the rotation mechanism <NUM>, <NUM>, <NUM>/elongated shaft <NUM>, <NUM>, <NUM>, structural properties and/or modifications to the rotation mechanism <NUM>, <NUM>, <NUM>/elongated shaft <NUM>, <NUM>, <NUM>, and/or a linkage with another portion of the material removal instrument <NUM>, <NUM>, <NUM>, <NUM>. Flexibility of the cannula <NUM>, <NUM>, <NUM>, <NUM> and/or the rotation mechanism <NUM>, <NUM>, <NUM> can be used to provide steering/directional control when accessing the target area and during removal of tissue.

One or more components of the material removal instrument <NUM>, <NUM>, <NUM>, <NUM> may be made from any biocompatible material known including, for example, metals such as titanium, titanium alloys, stainless steel and cobalt chromium, cobalt chromium molybdenum (CoCrMo), or other metals. Other materials include, for example, composites, polymers, or ceramics. In one example, one or more components of the material removal instrument <NUM>, <NUM>, <NUM>, <NUM> can be constructed from a radiopaque material including, for example, stainless steel such as <NUM>-4PH stainless steel. Likewise, one or more components described herein can be constructed from a radiolucent material to enhance visibility of the assembly during radiographic imaging. Example radiolucent materials can include "life science" grade PEEK (Ketron <NUM> PEEK). Life science grade PEEK can improve wear and abrasion characteristics as well as provide high yield strength. A coating may be added or applied to the various components described herein to improve physical or chemical properties, such as a plasma-sprayed titanium coating or Hydroxypatite. Moreover, skilled artisans will also appreciate that the various components herein described can be constructed with any dimensions desirable for implantation and cavity creation.

While the foregoing description and drawings represent the preferred embodiment of the present invention, it will be understood that various additions, modifications, combinations and/or substitutions may be made therein without departing from the scope of the present invention as defined in the accompanying claims. In particular, it will be clear to those skilled in the art that the present invention may be embodied in other specific forms, structures, arrangements, proportions, and with other elements, materials, and components, without departing from the scope of the claims. One skilled in the art will appreciate that the invention may be used with many modifications of structure, arrangement, proportions, materials, and components and otherwise, used in the practice of the invention, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present invention as defined in the accompanying claims. In addition, features described herein may be used singularly or in combination with other features, as defined in the accompanying claims. The presently disclosed embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims and not limited to the foregoing description.

It will be appreciated by those skilled in the art that changes could be made to the embodiments described above without departing from the scope of the claims. It is understood, therefore, that this invention is not limited to the particular embodiments disclosed, but it is intended to cover modifications within the scope of the present invention, as defined by the following claims.

Claim 1:
A material removal instrument (<NUM>), comprising,
a cannula (<NUM>) including:
a cannula bore (<NUM>); and
a cannula opening (<NUM>) at a distal end of the cannula (<NUM>), the cannula opening providing access to the cannula bore (<NUM>); and
a rotation mechanism (<NUM>) disposed at least partially within the cannula (<NUM>), the rotation mechanism (<NUM>) including:
an elongated shaft (<NUM>) having a central bore (<NUM>) extending therethrough and a shaft opening (<NUM>) at a distal end of the elongated shaft (<NUM>) providing access to the central bore (<NUM>);
projections (<NUM>; <NUM>)) extending from an outer surface of the elongated shaft (<NUM>) along a portion of the elongated shaft (<NUM>);
a blade (<NUM>) extending from the outer surface of the elongated shaft (<NUM>) along another portion of the elongated shaft (<NUM>) proximate the distal end for dislocating material from a target area, at least a portion of the blade (<NUM>) extends distal of the shaft opening (<NUM>) and extends from the cannula opening (<NUM>);
wherein the rotation mechanism (<NUM>) is rotatable within the cannula (<NUM>) to cause the blade (<NUM>) to dislocate material from the target area,
wherein the rotation mechanism (<NUM>) is configured to draw the dislocated material from the target area through the cannula bore (<NUM>).