Patent Description:
Angled cutting instruments for surgery facilitate treatment of anatomy not otherwise accessible to straight instrumentation. The angled cutting instruments typically include a drive shaft or inner tube rotatably disposed within an outer tube, and require transmission of torque along or about a bend. Angled shavers may provide for aspiration, often through an aspiration lumen defined by the inner tube. Yet the geometries often necessary to facilitate the transmission of torque about the bend render the aspiration lumen suspectable to undesirable ingress or egress of fluid through the geometries. One such cutting instrument is an angled shaver described in <CIT>, in which a heat shrunk sleeve is disposed over a continuous helical cut of an inner tube. The heat shrunk sleeve is susceptible to wear when rotated at high speed in a journal bearing arrangement with the outer tube. Another known angled shaver is described in <CIT>, in which a portion of the inner tube is replaced with a length of flexible coupling. The arrangement undesirably requires complex means of fabrication to effectively overmold the flexible coupling with lap joints of adjacent components. Further, the capacity for the flexible coupling to effectively transmit torques required of certain cutting operations is suspect. Still further, certain flexible couplings may tend to kink when bent, or alternatively those being sufficiently study are typically too large for most desired surgical applications. Therefore, there is a need in the art for an improved cutting assembly that provides for irrigation and aspiration and about a bend.

<CIT> discloses a surgical cutting accessory for attachment to a powered surgical handpiece having a cutting element for cooperation with a drive member of the handpiece, a distal end defining a cutting element, and an elongate tube disposed between the proximal and distal ends. The tube of the cutting element has a flexible portion defined by a continuous cut disposed in the tube and extending in a helical manner generally axially, and a tubular liner is disposed within the tube axially adjacent the flexible portion. Tire accessory additionally having an outer tube housing in which the cutting element is disposed, the outer tube having a bent portion.

<CIT> describes tissue removal probes comprising an elongated member, a drive shaft rotatably disposed within the member, and a rotatably tissue removal element mounted to the distal end of the drive shaft. One tissue removal element comprises a plurality of tissue-cutting filaments affixed at proximal and distal ends of the tissue removal element.

<CIT> describes a tissue disintegrator adapted for use with an endoscope for the surgical removal of tissue. The disintegrator comprises a cutter blade mounted at the end of an elongated drive shaft the other end of which is connected to means for rotating the drive shaft. The drive shaft is supported for rotation in a hollow sheath and a suction path parallel to the drive shaft leads from the cutter blade to an attachment for connection to a source of suction, so that disintegrated tissue can be removed by suction from the region in which the cutter blade operates. In Order to prevent the cutter blade from binding on the tissue, the region in which the cutter blade operates may be flushed with a physiologically acceptable Irrigation liquid or a reciprocating motion may be imparted to the drive shaft.

Claim <NUM> defines the invention and dependent claims disclose embodiments. No surgical methods are claimed. A cutting assembly may include an aspiration path for suctioning resected tissue and other surgical debris, and an irrigation path for irrigating the surgical site. A movable or rotatable inner tube may define at least a portion of the aspiration path, and the irrigation path may be external to the inner tube. The cutting assembly includes means for preventing ingress of fluid from within the irrigation path to within the aspiration path, thereby maximizing irrigation and suction capabilities. The cutting assembly may include a tube assembly that is straight or angled. The means for preventing ingress of the fluid may be particularly well suited for angled cutting assemblies. The cutting assembly may be a shaver, a bur, or other tissue manipulating device in which suction and irrigation is incorporated. Alternatively, the means for preventing fluid ingress may also be used on instruments with irrigation but no suction, or with suction but no irrigation.

The cutting assembly includes a housing hub, and the tube assembly is coupled to the housing hub. The tube assembly includes at least an outer tube, and the inner tube is movably or rotatably disposed within the outer tube. A drive hub is rigidly coupled to the inner tube and includes keys and other features configured to releasably engage complementary components of a motor and capital equipment. The drive hub and the inner tube may define an aspiration lumen in fluid communication with a cutting tip disposed at a distal end of the tube assembly. The aspiration lumen may define the aspiration path. The resected tissue and other debris and fluids are drawn through the cutting tip. In certain implementations, the materials being aspirated through the inner tube traverse a bend of the tube assembly to pass through the housing hub for collection through the capital equipment. The housing hub defines an irrigation cavity or lumen. A seal may be coupled to the housing hub and defines an opening in fluid communication with the irrigation cavity. The seal is configured to be positioned in a sealing relationship with a complementary feature of the capital equipment to prevent egress of fluid during irrigation being supplied through the surgical instrument. The tube assembly extends distally from the housing hub. The outer tube may be rigidly coupled to the housing hub. The inner tube is rotatable within the outer tube, and thus is rotatable relative to the housing hub. With the drive hub of the cutting assembly coupled to the capital equipment, relative axial movement between the inner and outer tubes is prevented.

In certain implementations, the cutting tip defines a cutting window such that the cutting assembly is a shaver. The cutting assembly may include an outer tip. portion and an inner tip portion. The outer tip portion is rigidly coupled to the outer tube. The outer tip portion includes a collar configured to be welded to the outer tube. Distal and relative to an outer diameter of the collar, the outer tip portion may include a thinned region. The thinned region has an outer diameter less of that than the collar. The thinned region may be formed through a plunge grind or other suitable manufacturing technique. The thinned region may be tapered, for example, in a direction towards an outer window defined by the outer tip portion.

Cutting teeth may be disposed adjacent the outer window. The inner tip portion is rigidly coupled to the inner tube. The inner tip portion defines an inner window, and cutting teeth may be disposed adjacent the inner window. Disposed within the inner tip portion may be an element for minimizing clogging of the cutting assembly. A gap may be defined between the outer tip portion and the inner tip portion. The gap provides clearance not only for the inner tip portion to rotate within the outer tip portion, but also for the irrigation to discharge from the cutting assembly at the surgical site. The fluid may be directed through the gap, and discharged through a periphery of the outer window.

The bend of the tube assembly may include a bend of the outer tube, and a flexible region of the inner tube. The outer tube may be rigid or malleable. Another tube may be coaxially disposed over the outer tube with the resulting arrangement providing for rotation of the cutting window independently of the bend of the tube assembly. The flexible region may define slots. In one example, the flexible region includes segments interlocked with one another to define the slots. The segments may be castellated as shown, and other interlocking geometries are contemplated. The segments may be present for an entirety of the inner tube, or present for a portion of the inner tube at least including the flexible region. Alternatively, the inner tube may include helical, T-slots, windings, braids, or the like, to transmit torque about the bend.

In certain implementations, the outer tube defines irrigation channels extending longitudinally along a length of the outer tube. The irrigation channels are in fluid communication with the irrigation cavity of the housing hub. The irrigation channels may be defined by the outer tube itself. The outer tube may be monolithic in construction and encapsulate the irrigation channels. Alternatively, the outer tube may define longitudinal slots or recesses, and a hypotube or intermediate tube may be secured within the outer tube to define the irrigation channels. The arrangement provides of the irrigation channels defining an irrigation path that is fluidly separated from the aspiration lumen. The irrigation fluid traverses the bend towards the gap without risk of being undesirably drawn into the aspiration lumen through the slots between the segments. Any number of the irrigation channels are contemplated, and the irrigation channel(s) may be located in any suitable radial arrangement.

The outer tube further defines irrigation apertures providing fluid communication between the irrigation channels and the gap defined between the inner and outer tip portions. The irrigation apertures may be slots defined by an inner surface of the outer tube. The irrigation apertures may be formed by inner thickness(es) of the outer tube terminating such that the irrigation channels effectively open into the gap. Any number of the irrigation apertures are contemplated, and the irrigation aperture(s) may be located in any suitable radial arrangement. The irrigation apertures are positioned distal to the bend. The irrigation apertures may be positioned distal to a distalmost one of the segments. The irrigation channels may be positioned near or adjacent the inner and outer tip portions. The irrigation apertures redirect the fluid from the irrigation channels to the gap distal to the bend but proximate to the cutting tip. The irrigation fluid is discharged from the cutting assembly through the cutting tip.

Fluid communication is established between the irrigation channels and the irrigation cavity of the housing hub. The housing hub may define an irrigation aperture through which the inner tube extends. The housing hub may further define recesses extending from the irrigation aperture and in rotational alignment with the irrigation channels. The arrangement provides for the irrigation fluid entering the irrigation cavity of the housing hub being further directed through the and the irrigation channels. In an alternative implementation, the recesses and/or the irrigation channels may provide for fluid communication in any rotational alignment. There may be more than four recesses, and/or the recesses and the irrigation channels may subtend larger arcs such that, in any rotational orientation between the tube assembly and/or the housing hub, at least a portion of one of the irrigation channels is in fluid communication with at least a portion of one of the recesses.

In certain implementations, the tube assembly includes an inner jacket coaxially disposed within the inner tube. The inner jacket may have an outer diameter approximate to an inner diameter of the inner tube. The inner jacket may be considered a sleeve or liner. The inner jacket has mechanical properties configured to allow the inner tube to remain flexible along the bend, and further provide a seal within the aspiration lumen to prevent aspiration of the irrigation fluid through the slots of the segments. The inner jacket may or may not facilitate the transmission of torque. The inner jacket may be a multilayered and reinforced tube. For example, the inner jacket includes braided wire disposed or sandwiched between polymeric layers. An inner layer and/or the outer layer of the inner jacket may be formed from polyether block amide, and the braided wire may be stainless steel. Alternatively, the inner jacket may be formed from polytetrafluoroethylene (PTFE). The braids may be extremely thin and ribbon-like in construction. In innermost layer may optionally be chemically etched within with the inner layer and formed from PTFE. The inner layer or the innermost layer may define a liner lumen that itself defines at least a portion of the aspiration lumen. The innermost layer being PTFE is lubricious and therefore reduces potential clogging as debris is pulled through the liner lumen.

The inner jacket includes a distal end positioned adjacent to the inner tip portion, and a proximal end coupled to the inner tube or the drive hub. The arrangement results in the inner jacket lining nearly an entirety of the aspiration lumen between the cutting tip and a proximal end of the drive hub. The inner tip portion includes a counterbore approximately sized to the thickness of the inner jacket. The distal end of the inner jacket is positioned within the counterbore. The proximal end of the inner jacket may be positioned proximal to a proximal end of the inner tube. A portion of the inner jacket proximal to the inner tube may be coupled to the drive hub with an adhesive or other suitable joining means. The proximal end and the distal end of the inner jacket are positioned opposite the flexible region of the inner tube. The inner jacket provides the seal along the bend or curve so as to prevent aspiration of the irrigation fluid through the slots of the segments.

In certain implementations, the cutting assembly may be a bur. The cutting tip may be a bur head secured to the inner tube. The outer tube may terminate at a tubular distal end, and the inner tube may extend through the tubular distal end. A neck of the cutting tip may extend from the bur head and define an aperture positioned adjacent and proximal to the bur head with the aperture in fluid communication with the aspiration lumen. The inner tube is coupled to the cutting tip. A distal end of the inner tube may be secured to a proximal end of the neck of the cutting tip. The inner jacket is coaxially disposed within the inner tube. The proximal end and the distal end of the inner jacket are configured to at least be positioned opposite the flexible region of the inner tube in which there are slots, and consequently the inner jacket assumes a complementary bend or curve. The distal end of the inner jacket may be positioned adjacent to the proximal end of the neck. The proximal end of the inner jacket may be positioned proximal to the proximal end of the inner tube. A portion of the inner jacket proximal to the inner tube may be coupled to the drive hub. The distal end of the inner jacket may or may not be coupled to the cutting tip. Implementations including the inner jacket may be combined with implementations including the irrigation channels and apertures.

The cutting assembly may further include an irrigation spacer disposed within the housing hub and distal to the drive hub. The irrigation spacer may be disposed in a distal cavity extending distally from the irrigation cavity. In one implementation, the irrigation spacer may have a hub that defines a bore through which the inner tube and the inner jacket extend, and fins extending radially away from the hub. At least one washer may be positioned between the irrigation spacer and the drive hub. The irrigation spacer provides for axial spacing of the drive hub from the irrigation aperture while also providing irrigation passageways to permit robust fluid flow through the irrigation path.

Therefore, a first aspect of the present disclosure is directed to the cutting assembly configured to be coupled to the irrigation source and the aspiration source. The cutting assembly includes the housing, the outer tube, the inner tube, and the cutting tip. The proximal end of the outer tube is coupled to the housing. The inner tube coupled to the drive hub and rotatably and coaxially disposed within the outer tube. The irrigation path is defined between the inner tube and the outer tube. The cutting tip comprising an inner tip portion is secured to the inner tube. The inner jacket is coupled to the drive hub and coaxially disposed within the inner tube. The aspiration path is defined within the inner jacket. The inner jacket is configured to provide a fluid seal between the aspiration path and the irrigation path. The cutting assembly is characterized in that the inner tip portion defines a counterbore approximately sized to a thickness of the inner jacket, and wherein the inner jacket comprises a distal end positioned within the counterbore and adjacent to the inner tip portion.

In certain implementations, the inner tube may define slots. The fluid seal provided by the inner jacket is configured to prevent ingress of irrigation fluid through the slots. The outer tube may include a bend, and the slots of the inner tube may be axially positioned along the bend. The inner jacket may be coupled to the drive hub at a position proximal to where a proximal end of the inner tube is coupled to the drive hub. The inner jacket may not be secured to the cutting tip. The inner jacket may a multilayer reinforced tube, such as a braid disposed between inner and outer layers of polymeric material. The braid may be stainless steel, and the polymeric material may be polyether block amide.

In certain implementations, the outer tube includes the outer tip portion defining the outer window, and the inner tip portion comprises the inner window such that the cutting assembly is a shaver. Alternatively, the cutting tip may be a bur head. The bur head may include a cutting element and define an aspiration port proximal to the cutting element. An irrigation spacer may be disposed within a cavity defined by the housing. The irrigation spacer may include a hub defining a bore through which the inner tube is rotatably disposed, and fins extending radially from the hub to be secured within the cavity.

According to a second aspect of the present disclosure, the cutting assembly includes the housing, the outer tube, and the inner tube. The proximal end of the outer tube is coupled to the housing and includes the outer tip portion defining an outer window. The inner tube is rotatably and coaxially disposed within the outer tube and defines the aspiration lumen configured to be in arranged in fluid communication with the aspiration source. The inner tube includes the inner tip portion defining the inner window, and a gap is defined between the inner tip portion and the outer tip portion. The outer tube defines irrigation channels extending longitudinally from near the proximal end and configured to be arranged in fluid communication with the irrigation source. The outer tube further defines irrigation apertures configured to provide fluid communication between the irrigation channels and the gap at a position proximal to the outer window and the inner window. The irrigation apertures may be positioned proximal to the outer window. The outer tube may include a bend and the inner tube may include a flexible region. The irrigation apertures may be positioned distal to the flexible region.

According to a third aspect of the present disclosure, the cutting assembly includes the housing, the outer tube, and the inner tube. The outer tube includes a distal end, and a bend to angle the distal end relative to a longitudinal axis. The inner tube is rotatably and coaxially disposed within the outer tube and includes the flexible region traversing the bend of the outer tube. The cutting tip is secured to the inner tube and angled relative to the longitudinal axis. The outer tube defines the irrigation channels configured to be in fluid communication with the irrigation source. The irrigation channels are fluidly separated from the flexible region of the inner tube. The outer tube further defines the irrigation apertures positioned distal to the flexible region and configured to provide fluid communication between the irrigation channels and the gap between the cutting tip and the outer tube.

In certain implementations, the outer tube may include the outer tip portion defining the outer window, and the cutting tip may define the inner window such that the cutting assembly is a shaver. Alternatively, the cutting tip may be a bur head. The outer tube may include the bend, and the irrigation channels may traverse the bend. The inner tube may include the segments defining the flexible region. The irrigation channels are fluidly separated from the segments. The outer tube may be monolithic, and the irrigation channels are encapsulated within the outer tube. Alternatively, a hypotube may be disposed within and coupled to the outer tube, wherein and the irrigation channels are defined between the outer tube and the hypotube. The irrigation apertures may be recesses defined at a distal end of the irrigation channels. The irrigation channels may be four irrigation channels radially spaced equally about the longitudinal axis, and the irrigation apertures may be four irrigation apertures radially spaced equally about the longitudinal axis. The housing may define an irrigation cavity, an aperture through which the inner tube extends, and recesses in fluid communication with the aperture and the irrigation channels. The c recesses of the housing may be in a cruciform or other suitable arrangement.

<FIG> shows a cutting assembly <NUM> configured to resect tissue. The cutting assembly <NUM> of <FIG> may be considered an angled shaver. The cutting assembly <NUM> is configured to be removably coupled to capital equipment (not shown) that may include one or more of a motor, an irrigation source, and an aspiration source. Whereas the capital equipment may be reused in multiple procedures, the cutting assembly <NUM> may be a disposable component. One exemplary capital equipment suitable for the present application is sold under the tradename ESSx Microdebrider manufactured by the Stryker Corporation (Kalamazoo, Mich. ), and/or disclosed in commonly-owned <CIT>, and International Publication No. <CIT>.

The cutting assembly <NUM> includes a housing hub <NUM>, and a tube assembly <NUM> coupled to the housing hub <NUM>. The tube assembly <NUM> includes at least an outer tube <NUM>, and an inner tube <NUM> rotatably disposed within the outer tube <NUM>. The inner tube <NUM> is configured to be coupled to the motor of the capital equipment, and further configured to be rotated within the outer tube <NUM> by the motor. A drive hub <NUM> is rigidly coupled to the inner tube <NUM> and includes keys <NUM> and other features configured to releasably engage complementary components of the capital equipment.

The drive hub <NUM> and the inner tube <NUM> may define an aspiration lumen <NUM> in fluid communication with a cutting tip <NUM> disposed at a distal end of the tube assembly <NUM>. The aspiration lumen <NUM> may define an aspiration path. With the cutting assembly <NUM> removably coupled with the capital equipment, the aspiration path is configured to be arranged in fluid communication with the aspiration source. The tissue resected by relative rotation of the inner and outer tubes <NUM>, <NUM> is drawn through the cutting tip <NUM>, and other debris and fluids may similarly be aspirated from the surgical site. The materials being aspirated through the inner tube <NUM> traverse a bend <NUM> of the tube assembly <NUM> to pass through the housing hub <NUM> for collection through the capital equipment. As to be further described, aspirating fluids through a bend of a rotatable tube - and further providing irrigation through the tube assembly - is associated with technical challenges overcome with the cutting assembly <NUM> of the present disclosure.

The housing hub <NUM> defines an irrigation cavity <NUM> or lumen. A seal <NUM> may be coupled to the housing hub <NUM> and defines an opening <NUM> in fluid communication with the irrigation cavity <NUM>. One seal suitable for the present application is disclosed in the aforementioned International Publication No. <CIT>. The seal <NUM> is configured to be positioned in a sealing relationship with a complementary feature of the capital equipment to prevent egress of fluid during irrigation being supplied through the surgical instrument.

The tube assembly <NUM> extends distally from the housing hub <NUM>. The outer tube <NUM> may be rigidly coupled to the housing hub <NUM>. The inner tube <NUM> is rotatable within the outer tube <NUM>, and thus is rotatable relative to the housing hub <NUM>. With the drive hub <NUM> of the cutting assembly <NUM> coupled to the capital equipment, relative axial movement between the inner and outer tubes <NUM>, <NUM> is prevented. With the cutting assembly <NUM> decoupled from the capital equipment, slight relative axial movement between the inner and outer tubes <NUM>, <NUM> may be permitted.

The cutting tip <NUM> may define a cutting window such that the cutting assembly <NUM> is a shaver. With further reference to <FIG>, the cutting assembly <NUM> includes an outer tip portion <NUM> and an inner tip portion <NUM>. The outer tip portion <NUM> is rigidly coupled to the outer tube <NUM>. In one implementation, the outer tip portion <NUM> includes a collar <NUM> configured to be welded to the outer tube <NUM> (at interface shown in <FIG>). Distal and relative to the collar <NUM>, the outer tip portion <NUM> may include a thinned region <NUM>. The thinned region <NUM> has an outer diameter less than the outer diameter of the collar <NUM>. The thinned region <NUM> of the outer tip portion <NUM> provides for the cutting teeth <NUM> disposed adjacent the outer window <NUM> to be made sharper, and improve visibility of the surgeon of the cutting tip <NUM>. The thinned region <NUM> may be formed through a plunge grind or other suitable manufacturing technique. The thinned region <NUM> may be tapered, for example, in a direction towards an outer window <NUM> defined by the outer tip portion <NUM>.

The inner tip portion <NUM> is rigidly coupled to the inner tube <NUM>. The inner tip portion <NUM> defines an inner window <NUM>, and cutting teeth <NUM> may be disposed adjacent the inner window <NUM>. The inner and outer windows <NUM>, <NUM> may be considered to collectively define the cutting window of the cutting assembly <NUM>. With the inner tip portion <NUM> being rotatably disposed within the outer tip portion <NUM>, the cutting teeth <NUM>, <NUM> cross one another in a shearing action to resect the tissue. Disposed within the inner tip portion <NUM> may be an element <NUM> for minimizing clogging of the cutting assembly <NUM> as disclosed in the aformentioned International Publication No. <CIT>.

Referring now to <FIG>, the bend <NUM> of the tube assembly <NUM> may include a bend <NUM> of the outer tube <NUM>, and a flexible region <NUM> of the inner tube <NUM>. The outer tube <NUM> may be rigid or malleable, and thus the bend <NUM> of the outer tube <NUM> generally defines the angled shape of the tube assembly <NUM>. The bend <NUM> may be formed at any suitable angle, which is often indicated by the type of procedure. For example, the angle may be <NUM>°, <NUM>°, or <NUM>° or more limited only by the torque transmitting capabilities of the flexible region <NUM> of the inner tube <NUM>. It is further understood that the bend <NUM> of the tube assembly <NUM> may be disposed at any axial location between the housing hub <NUM> and the cutting tip <NUM>, and the bend <NUM> may be oriented in any radial direction relative to the housing hub <NUM> (e.g., upwards, downwards, or laterally). These parameters may also be influenced by the type of procedure. For example, a proximal bend may be indicated for a spine surgery, a medial bend may be indicated for general thoracic surgery, and a distal bend may be indicated for otolaryngological surgery. <FIG> illustrates a distal bend at an angle of approximately <NUM>° between opposing portions of the tube assembly <NUM> opposite the bend <NUM>. Still further, it is contemplated that another tube may be coaxially disposed over the outer tube <NUM> with the resulting arrangement providing for rotation of the cutting window independently of the bend <NUM> of the tube assembly <NUM>.

<FIG> best shows an exemplary implementation of the flexible region <NUM> of the inner tube <NUM>. The flexible region <NUM> may define slots. In one example, the flexible region includes segments <NUM> interlocked with one another to define the slots. The segments <NUM> may be castellated as shown, however, other interlocking geometries are contemplated. The interlocking of the segments <NUM> provide for the transmission of torque with rotation of the inner tube <NUM> by the motor of the capital equipment. Additionally or alternatively, the inner tube <NUM> may include helical, wound, or braided characteristics configured to transmit torque about the bend <NUM>. Relative to less intricate geometries, the segments <NUM> define smaller slots in which less loss of suction and/or less ingress of the irrigation fluid may occur. Despite the relatively smaller slots, improving suction performance of the cutting assembly <NUM> is of continued importance. This interest is particularly pronounced in implementations where the cutting assembly <NUM> also provide for irrigation through the tube assembly <NUM>, often simultaneously with aspiration. It is contemplated that the segments <NUM> may be present for an entirety of the inner tube <NUM>, or present for a portion of the inner tube <NUM> including the flexible region <NUM>, as shown in <FIG>. The extent to which the flexible region <NUM> forms the length of the inner tube <NUM> may be dependent on the flexural requirements of the tube assembly <NUM>. For example, greater angles of bend and/or smaller radii of curvature may require a relatively greater length of the inner tube <NUM> being formed from the flexible region <NUM>. In an exemplary implementation, the flexible region <NUM> forms less than <NUM>% of the length of the tube assembly <NUM>, and more particularly forms less than <NUM>% of the length of the inner tube <NUM>. Minimizing the distance of which the flexible region <NUM> forms of the length of the inner tube <NUM> may reduce whipping or chatter of the inner tube <NUM> when rotated at relatively high speeds. Further, a relatively smaller length of the flexible region <NUM> requires less segments <NUM>, which better preserves transmission of torque from the drive hub <NUM> to the inner window <NUM>. Despite the tolerances between the segments <NUM> being very small, cumulatively the stack up may result in some lag between the drive hub <NUM> and the inner window <NUM>. Reducing the number of segments <NUM> may reduce any lag.

A gap <NUM> may be defined between the outer tip portion <NUM> and the inner tip portion <NUM> (best shown in FIG. The gap <NUM> provides clearance not only for the inner tip portion <NUM> to rotate within the outer tip portion <NUM>, but also for the irrigation to discharge from the cutting assembly <NUM> at the surgical site. In particular, the fluid may be directed through the gap <NUM>, and discharged through a periphery of the outer window <NUM>. The gap <NUM> is configured to be placed in fluid communication with the irrigation source. With further reference to <FIG>, the outer tube <NUM> defines irrigation channels <NUM> extending longitudinally along a length of the outer tube <NUM>. The irrigation channels <NUM> are in fluid communication with the irrigation cavity <NUM> of the housing hub <NUM>, and thus in fluid communication with the irrigation source when the cutting assembly <NUM> is coupled to the capital equipment. In an exemplary implementation shown in <FIG>, the irrigation channels <NUM> are defined by the structure of the outer tube <NUM> itself. In other words, the outer tube <NUM> may be monolithic in construction and encapsulate the irrigation channels <NUM>. The outer tube <NUM> may be formed with the irrigation channels <NUM> through an extrusion process. For another example, the outer tube <NUM> may define longitudinal slots or recesses, and a hypotube (not shown) or intermediate tube may be secured within the outer tube <NUM> to define the irrigation channels <NUM> with the slots. As best shown in <FIG>, the arrangement provides of the irrigation channels <NUM> defining an irrigation path that is fluidly separated from the aspiration lumen <NUM>, particularly along the bend <NUM>. As a result, the irrigation fluid traverses the bend <NUM> towards the gap <NUM> without risk of being undesirably drawn into the aspiration lumen <NUM> through the slots between the segments <NUM>. <FIG> shows four of the irrigation channels <NUM> radially spaced equiangularly about an axis of the tube assembly <NUM>. More or less of the irrigation channels <NUM> are contemplated, and the irrigation channels <NUM> may be located in any suitable arrangement.

The outer tube <NUM> further defines irrigation apertures <NUM> providing fluid communication between the irrigation channels <NUM> and the gap <NUM> defined between the inner and outer tip portions <NUM>, <NUM>. Referring to <FIG> and <FIG>, the irrigation apertures <NUM> may be slots defined by an inner surface of the outer tube <NUM>. In the illustrated implementation, the irrigation apertures <NUM> may be effectively formed by inner thickness(es) <NUM> of the outer tube <NUM> terminating (see <FIG>) such that the irrigation channels <NUM> effectively open into the gap <NUM> as shown in <FIG>. However, it is contemplated that the irrigation apertures <NUM> may take on any suitable geometry or form so as to provide fluid communication between the irrigation channels <NUM> and the gap <NUM>. Further, the irrigation apertures <NUM> may be radially spaced equiangularly or in any suitable arrangement about an axis of the tube assembly <NUM>. Further, more or less of the irrigation channels <NUM> are contemplated.

Because the irrigation channels <NUM> traverse the bend <NUM> with the irrigation channels <NUM> being fluidly separated from the inner tube <NUM> about the bend <NUM>, the irrigation apertures <NUM> are positioned distal to the bend <NUM>. The irrigation apertures <NUM> may be positioned distal to a distalmost one of the segments <NUM> such that the likelihood of irrigation fluid being aspirated through the slots is eliminated. In certain implementations, the irrigation channels <NUM> are positioned near or adjacent the inner and outer tip portions <NUM>, <NUM>. As such, the irrigation apertures <NUM> redirects the fluid from the irrigation channels <NUM> to the gap <NUM> distal to the bend <NUM> but proximate to the cutting tip <NUM>. The irrigation fluid is discharged from the cutting assembly <NUM> through the cutting tip <NUM>.

<FIG> illustrate the fluid communication being established between the irrigation channels <NUM> and the irrigation cavity <NUM> of the housing hub <NUM>. As previously explained, the inner tube <NUM> is rotatable relative to the housing hub <NUM>, and therefore the housing hub <NUM> defines an irrigation aperture <NUM> through which the inner tube <NUM> extends (see also <FIG>). The housing hub <NUM> may further define recesses <NUM> extending from the irrigation aperture <NUM> and in alignment with the irrigation channels <NUM>, as best shown in <FIG>. More particularly, assembly of the cutting assembly <NUM> may require the outer tube <NUM> be rigidly coupled to the housing hub <NUM> in a single rotational orientation so as to rotationally align the recesses <NUM> and the irrigation channels <NUM>. The cruciform arrangement provides for the irrigation fluid entering the irrigation cavity <NUM> of the housing hub <NUM> being further directed through the recesses <NUM> and the irrigation channels <NUM>. The irrigation path being entirely fluidly separate from the aspiration path optimizes irrigation and aspiration performance, particularly in instrumentation that includes a bend. In alternative implementations, it is contemplated that the tube assembly <NUM> may be straight with remaining aspects of the cutting assembly <NUM> being as presently described herein. Such a straight implementation may not include the segments <NUM>, and the inner tube <NUM> may be a rigid in construction.

In alternative implementations, certain modifications may be provided on either the tube assembly <NUM> and/or the housing hub <NUM> to improve fluid flow between the irrigation cavity <NUM> and the irrigation channels <NUM>. For example, as opposed to the recesses <NUM> and the irrigation channels being rotationally aligned in a single rotational orientation, the recesses <NUM> and/or the irrigation channels <NUM> may provide for fluid communication in any rotational orientation. There may be more than four recesses <NUM>, and/or the recesses <NUM> may subtend larger arcs than the implementation shown in <FIG>. Additionally or alternatively, the irrigation channels <NUM>, or at least a proximal opening into the irrigation channels <NUM> may also subtend relatively larger arcs such that, in any rotational orientation between the tube assembly <NUM> and/or the housing hub <NUM>, at least a portion of one of the irrigation channels <NUM> is in fluid communication with at least a portion of one of the recesses <NUM>. For another example, a proximal end of the outer tube <NUM> may include inlet apertures (not shown) in communication with the irrigation channels <NUM>. The inlet apertures may be similar to the irrigation apertures <NUM> previously described with the inlet apertures extending radially inwardly from an outer diameter of the outer tube <NUM>. Whereas the irrigation channels <NUM> shown in <FIG> are defined within the proximal edge or end of the outer tube <NUM>, and perhaps of limited size, irrigation inlets are of greater size to permit greater flow rates of fluid from the irrigation cavity <NUM> to the irrigation channels <NUM>. For still another example, a seal (not shown) may be disposed between the inner tube <NUM> and the inner tube <NUM> near or adjacent the proximal end of the tube assembly <NUM>. The seal may be a dynamic seal configured to engage the inner tube <NUM> that is rotating. The seal prevents fluid from entering the annular space between the inner and outer tubes <NUM>, <NUM>, which may reduce the effectiveness of the irrigation fluid entering the irrigation channels <NUM>. In other words, should a fraction of the irrigating fluid otherwise enter the annular space, less fluid is entering the irrigation channels <NUM>. The seal positioned near the openings (or inlet apertures) prevents ingress of the irrigation fluid into the annular space, and therefore an entirety of the irrigation fluid is directed into the irrigation channels <NUM> for improved performance of the cutting assembly <NUM>.

<FIG> are directed to an alternative embodiment of the cutting assembly <NUM> in which the irrigation fluid is separated from potential fluid communication with the aspiration. With like numerals indicating like components, the tube assembly <NUM> includes the outer tube <NUM> having the bend <NUM>, the inner tube <NUM> having the flexible region <NUM>. The tube assembly <NUM> includes an inner jacket <NUM> coaxially disposed within the inner tube <NUM>. More particularly, the inner jacket <NUM> may have an outer diameter approximate to an inner diameter of the inner tube <NUM>. The inner jacket <NUM> may be considered a sleeve or liner.

The inner jacket <NUM> has mechanical properties configured to allow the inner tube <NUM> to remain flexible along the bend <NUM>, and further provide a seal within the aspiration lumen <NUM> to prevent aspiration of the irrigation fluid through the slots of the segments <NUM>. The inner jacket <NUM> may or may not facilitate the transmission of torque. Known thin-walled, mono-polymer may tend to kink when deployed in a bent configuration, or alternatively is too large for typical surgical instrumentation. The inner jacket <NUM> overcomes such shortcomings by being a multilayered and reinforced tube in which advantageously achieves smaller wall thickness without the aforementioned kinking. In one implementation, the inner jacket <NUM> includes braided wire disposed or sandwiched between polymeric layers. The braided wire <NUM> is shown in <FIG>. More particularly, an inner layer and/or the outer layer of the inner jacket <NUM> may be formed from polyether block amide sold under the trademark PEBAX sold by Arkema S. (Colomes, France), and the braided wire <NUM> may be stainless steel. Alternatively, the inner jacket <NUM> may be formed from polytetrafluoroethylene (PTFE). The braids may be extremely thin and ribbon-like in construction. In innermost layer may optionally be chemically etched within with the inner layer and formed from PTFE. The inner layer or the innermost layer may define a liner lumen <NUM> that itself defines at least a portion of the aspiration lumen <NUM>. The innermost layer being PTFE is lubricious and therefore reduces potential clogging as debris is pulled through the liner lumen <NUM>.

Referring now to <FIG>, the inner jacket <NUM> includes a distal end <NUM> positioned adjacent to the inner tip portion <NUM>, and a proximal end <NUM> coupled to the inner tube <NUM> or the drive hub <NUM>. The arrangement results in the inner jacket <NUM> lining nearly an entirety of the aspiration lumen <NUM> between the cutting tip <NUM> and a proximal end of the drive hub <NUM>. Owing to a thickness of the inner jacket <NUM>, the inner tip portion <NUM> includes a counterbore <NUM> approximately sized to the thickness of the inner jacket <NUM>. As shown in <FIG>, the distal end <NUM> of the inner jacket <NUM> is positioned within the counterbore <NUM>. With the distal end <NUM> disposed within the counterbore <NUM>, a smooth transition is present from an inner surface of the inner tip portion <NUM> to the inner jacket <NUM>. In other words, the arrangement prevents exposed lips or edges from the distal end <NUM> of the inner jacket <NUM> with which the aspirated material may otherwise be snagged. The proximal end <NUM> of the inner jacket <NUM> may be positioned proximal to a proximal end <NUM> of the inner tube <NUM>, as shown in <FIG>. A portion of the inner jacket <NUM> proximal to the inner tube <NUM> may be coupled to the drive hub <NUM> with an adhesive or other suitable joining means. In certain implementations, the inner jacket <NUM> may not be coupled to the inner tip portion <NUM> and/or the drive hub <NUM>, but rather free-floating in the appropriate axial position. The axial position may be maintained by the engagement between the bend of inner jacket <NUM> complementary to each of the flexible region <NUM> of the inner tube <NUM> and the bend <NUM> of the outer tube <NUM>. The proximal end <NUM> and the distal end <NUM> of the inner jacket <NUM> are positioned opposite the flexible region <NUM> of the inner tube <NUM>, and consequently the inner jacket <NUM> assumes a complementary bend or curve. The inner jacket <NUM> provides the seal along the bend or curve so as to prevent aspiration of the irrigation fluid through the slots of the segments <NUM>.

Referring now to <FIG>, the cutting assembly <NUM> may be a bur with like numerals indicating like components relative to the shaver of <FIG>. The cutting tip <NUM> may be a bur head <NUM> coupled to the inner tube <NUM>. The outer tube <NUM> may not include the outer window <NUM>, but rather terminate at a tubular distal end <NUM>. The inner tube <NUM> may extend through the tubular distal end <NUM> for the bur head <NUM> to be positioned distal to the tubular distal end <NUM>. A neck <NUM> of the cutting tip <NUM> may extend from the bur head <NUM> and define an aperture <NUM> positioned adjacent and proximal to the bur head <NUM> with the aperture <NUM> in fluid communication with the aspiration lumen <NUM>. In alternative implementations, for example endoscopic applications, a partially shielded bur head may be rotatable within a window.

Like the implementation of the shaver described with reference to <FIG>, the cutting assembly <NUM> may include the outer tube <NUM>, the inner tube <NUM>, and the inner jacket <NUM>. As best shown in <FIG>, the inner tube <NUM> is coupled to the cutting tip <NUM>, and more particularly a distal end <NUM> of the inner tube <NUM> is secured to a proximal end <NUM> of the neck <NUM> of the cutting tip <NUM>. The distal end <NUM> of the inner tube <NUM> and the proximal end <NUM> of the neck <NUM> may be secured together by welding, brazing, or any other suitable joining means. The inner jacket <NUM> is coaxially disposed within the inner tube <NUM>. The proximal end <NUM> and the distal end <NUM> of the inner jacket <NUM> are configured to at least be positioned opposite the flexible region <NUM> of the inner tube <NUM> in which there are slots defined by the segments <NUM>, and consequently the inner jacket <NUM> assumes a complementary bend or curve. In certain implementations, the distal end <NUM> of the inner jacket <NUM> may be positioned adjacent to the proximal end <NUM> of the neck <NUM>. The proximal end <NUM> of the inner jacket <NUM> may be positioned proximal to the proximal end <NUM> of the inner tube <NUM>, as shown in <FIG>. The arrangement results in the inner jacket <NUM> effectively lining nearly an entirety of the aspiration lumen <NUM> between the cutting tip <NUM> and the proximal end of the drive hub <NUM>. A portion of the inner jacket <NUM> proximal to the inner tube <NUM> may be coupled to the drive hub <NUM> with an adhesive or other suitable joining means. The inner jacket <NUM> provides the seal along the bend or curve so as to prevent aspiration of the irrigation fluid through the slots of the segments <NUM>. The distal end <NUM> of the inner jacket <NUM> may or may not be coupled to the cutting tip <NUM>.

The cutting assembly <NUM> may further include an irrigation spacer <NUM> disposed within the housing hub <NUM> and distal to the drive hub <NUM>. In implementations where the cutting assembly <NUM> is a shaver, interference between closed distal ends the outer tip portion <NUM> and the inner tip portion <NUM> prevents relative movement between the outer tube <NUM> and the inner tube <NUM>. Such a constraint may not be present on a bur, and distal movement of the drive hub <NUM> within the irrigation cavity <NUM> may limit or occlude the flow of fluid through the irrigation aperture <NUM>. The irrigation spacer <NUM> of the present implementation advantageously provides for axial spacing of the drive hub <NUM> from the irrigation aperture <NUM> while also providing irrigation passageways to permit robust fluid flow through the irrigation path. The irrigation spacer <NUM> may be disposed in a distal cavity <NUM> extending distally from the irrigation cavity <NUM>, as shown in <FIG>. In one implementation, the irrigation spacer <NUM> may have a hub that defines a bore through which the inner tube <NUM> and the inner jacket <NUM> extend, and fins extending radially away from the hub. At least one washer <NUM> may be positioned between the irrigation spacer <NUM> and the drive hub <NUM>. Further disclosure of the irrigation spacer <NUM> and related components are disclosed in the aforementioned International Publication No. <CIT>.

Claim 1:
A cutting assembly (<NUM>) configured to be coupled to an irrigation source and an aspiration source, the cutting assembly (<NUM>) comprising:
a housing (<NUM>);
an outer tube (<NUM>) comprising a proximal end coupled to the housing (<NUM>);
a drive hub (<NUM>);
an inner tube (<NUM>) coupled to the drive hub (<NUM>) and rotatably and coaxially disposed within the outer tube (<NUM>), wherein an irrigation path is defined between the inner tube (<NUM>) and the outer tube (<NUM>);
a cutting tip (<NUM>) comprising an inner tip portion (<NUM>) secured to the inner tube (<NUM>); and
an inner jacket (<NUM>) coupled to the drive hub (<NUM>) and coaxially disposed within the inner tube (<NUM>), wherein an aspiration path is defined within the inner jacket (<NUM>), and wherein the inner jacket (<NUM>) is configured to provide a fluid seal between the aspiration path and the irrigation path,
characterized in that the inner tip portion (<NUM>) defines a counterbore (<NUM>) approximately sized to a thickness of the inner jacket (<NUM>), and wherein the inner jacket (<NUM>) comprises a distal end (<NUM>) positioned within the counterbore (<NUM>) and adjacent to the inner tip portion (<NUM>).