Patent Publication Number: US-2017354431-A1

Title: Surgical instrument with internal irrigation

Description:
CROSS REFERENCE 
     This Application is a Continuation of U.S. patent application Ser. No. 12/109,713, filed Apr. 25, 2008, entitled SURGICAL INSTRUMENT WITH INTERNAL IRRIGATION, and is incorporated herein by reference. 
    
    
     BACKGROUND 
     Powered surgical instruments have been developed for use in many ear-nose-throat (ENT) operations as well as other operations in and around the skull. One type of cutting instrument includes a bur supported by an inner tubular member that is rotatable with respect to an outer tubular member. The bur is used to debride a target tissue of a treatment site. In many instances, the bur and/or treatment site are irrigated to facilitate lubrication of the treatment site as well as to cool the bur. In other instances, aspiration is applied to the treatment site to remove debrided tissue as well as to remove excess fluid. However, conventional cutting instruments that include an aspiration mechanism and/or an irrigation mechanism do so by externally attaching an aspiration tube or an irrigation tube that extends along a length of an outer surface of the cutting instrument. While the additional functions of aspiration and irrigation are gained, this added functionality comes at a high price because these external aspiration/irrigation tubes substantially increase a cross-sectional profile of the cutting instrument. This increased cross-sectional profile can reduce the number and/or type of treatment sites accessible by the conventional cutting instrument. Moreover, a distal end of these external aspiration/irrigation tubes increase the likelihood of the cutting instrument catching on soft tissues and bony structures encountered along the entry pathway of the cutting instrument to the treatment site. 
     Accordingly, conventional surgical instruments including external irrigation pathways can reduce the effectiveness of micro-burring instruments by hampering access through narrow entryways and into small treatment sites. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is perspective view of a system including a surgical debriding instrument, in accordance with principles of the present disclosure; 
         FIG. 2  is as assembly view of the instrument, in accordance with principles of the present disclosure; 
         FIG. 3  is an enlarged partial cross-sectional view of the instrument of  FIG. 2 ; 
         FIG. 4  is a schematic illustration of irrigating a treatment site using a debriding instrument, in accordance with principles of the present disclosure. 
         FIG. 5  is a top plan view of an outer portion of an outer tubular member of a debriding instrument, in accordance with principles of the present disclosure; 
         FIG. 6  is a cross-sectional view of the instrument as taken along lines  6 - 6  of  FIG. 5 ; 
         FIG. 7  is an enlarged partial cross-sectional view of a proximal portion of the instrument of  FIG. 5  as secured within an outer hub, in accordance with principles of the present disclosure; 
         FIG. 8  is a top plan view of an inner portion of the outer tubular member of the debriding instrument, in accordance with principles of the present disclosure; 
         FIG. 9  is a cross-sectional view of the instrument as taken along lines  9 - 9  of  FIG. 8 ; 
         FIG. 10  is a perspective view of the outer tubular member illustrating the interior passages of the side wall of the outer tubular member, in accordance with principles of the present disclosure; 
         FIG. 11  is a cross-sectional view of the outer tubular member as taken along lines  11 - 11  of  FIG. 10 . 
         FIG. 12  is a top plan view of an instrument including an angled distal portion, in accordance with principles of the present disclosure; 
         FIG. 13  is a perspective view of an instrument and a handpiece, in accordance with principles of the present disclosure; 
         FIG. 14  is a side plan view of an instrument, in accordance with principles of the present disclosure; and 
         FIG. 15  is schematic illustration of irrigating a treatment site using a debriding instrument including an internal aspiration pathway, in accordance with principles of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure are directed to cutting instruments having a low cross-sectional profile to enable their application in smaller treatment sites and/or to facilitate their access to a treatment site through narrow passageways. 
     In one embodiment, the cutting instrument includes an inner tubular member rotatably received within an outer tubular member and which includes a bur at its distal end. The inner tubular member and the outer tubular member each include a hub to facilitate their rotational relationship and their control by a handpiece that further supports both the inner tubular member and the outer tubular member. Rotation of the bur via rotation of inner tubular member causes debriding of the target tissue at a treatment site. 
     The outer tubular member includes a side wall defining an interior passage that acts as an irrigation pathway to supply an irrigation fluid to the treatment site adjacent to the bur. Because the irrigation pathway is incorporated internally and not provided through an external tube (as in conventional cutting instruments), the cutting instrument has a low cross-sectional profile. This smaller cross-sectional profile enables insertion of distal cutting end of the instrument into smaller treatment sites and facilitates introduction of the distal cutting end through narrow and/or curved passageways that provide access to the treatment site. In another aspect, by providing the irrigation pathway within a sidewall of the outer tubular member, interaction of the irrigation fluid with the inner tubular member (or other components internal to cutting instrument) is avoided. 
     In some embodiments, the bur and the inner tubular member further define an aspiration pathway through an interior of the bur (and the inner tubular member) to avoid the conventional arrangement of an external aspiration tube of the types typically used in conventional instruments. In the embodiments, the inner tubular member has a length so that the aspiration pathway may extend continuously through a hub assembly of both the inner tubular member and the outer tubular member. Accordingly, with this arrangement, the internally incorporated aspiration pathway further maintains the low cross-sectional profile that is achieved via arranging the irrigation pathway within a side wall of the outer tubular member, as described above. 
     Surgical instruments embodying principles of the present disclosure can be employed in various types of surgery including, but not limited to, various sinus procedures, skull base tumor removal (such as pituitary tumors, clivus chordomas, etc.), mastoidectomy, temporal bone tumor removal, craniotomy, a modified Lothrop procedure, spinal diseases, and the like. 
     These and other embodiments are described more fully in association with  FIGS. 1-15 . 
     One preferred embodiment of a surgical micro-burring instrument  10  is illustrated in  FIGS. 1-2 . The instrument  10  includes an outer tubular assembly  12  and an inner tubular assembly  14  (referenced generally in  FIG. 1 ). With particular reference to  FIG. 2 , the outer tubular assembly  12  includes an outer hub  16  and an outer tubular member  18 , whereas the inner tubular assembly  14  includes an inner hub  20  and an inner tubular member  22 . The inner tubular member  22  is sized to be coaxially received within the outer tubular member  18  and forms a bur  24 . The inner tubular member  22  includes a proximal section  142  with end  143  and a distal section  145 . In some embodiments, inner tubular member  22  additionally comprises a spring section  26  positioned proximal to bur  24  at distal section  145 . In one aspect, an inner surface of inner tubular member  22  defines a lumen  147 . As described in greater detail below, the micro-burring instrument  10  is configured to optimally perform a surgical procedure, such as a sinus procedure or one of the other procedures noted above. 
     As illustrated in  FIG. 1 , the outer tubular member  18  extends distally from the outer hub  16 . To this end, the outer hub  16  can assume a wide variety of forms known in the art. In some embodiments, outer hub  16  comprises an irrigation port  30  configured for fluid communication via tubing (not shown) with a fluid source  32  controlled by controller  34 . 
     As illustrated in  FIG. 1  and with additional reference to  FIG. 3 , the inner tubular member  22  extends distally from inner hub  20 . With continued reference to  FIG. 1 , in some embodiments, inner hub  20  is configured to be engaged by a handpiece  36  (or handpiece  236  in  FIG. 13 ) for handling instrument  10 . In particular, rotational controller  38  (via a connection between handpiece  36  and inner hub  20 ) enables selective rotational control over inner tubular member  22  to cause high-speed rotation of bur  24  for debriding or otherwise cutting a target tissue. 
     With reference to  FIG. 2 , the outer tubular member  18  is an elongated tubular body defining a proximal section  40  with proximal end  41  ( FIG. 5 ), an intermediate section  42 , a distal section  44  with distal end  45  ( FIG. 5 ), and a central lumen  46 . The central lumen  46  extends from the proximal section  40  to the distal section  44 . In this regard, and as described in greater detail below, the distal section  44  is open at a distal end  45  thereof to enable the inner tubular member  22  to extend distally beyond the distal end  45  of outer tubular member  18 . Similarly, the proximal section  40  is open at a proximal end  41  thereof to facilitate positioning of the inner tubular member  22  within the central lumen  46 . Moreover, with additional reference to  FIGS. 3, 5, and 7 , proximal section  40  comprises a proximal window  47  located distally of proximal end  41 . In some embodiments, proximal section  40  additionally comprises a knurled portion  49  located on a surface of proximal section  40  and that surrounds the proximal window  47 . In one aspect, knurled portion  49  facilitates securing proximal section  40  to an inner portion of outer hub  16 , as illustrated in  FIGS. 3 and 7 . 
     In one suitable configuration, as illustrated in  FIG. 7 , the proximal portion  40  is inserted into a lumen  93  of outer hub  16  to secure knurled portion  49  within the distal section  92  and intermediate section  91  of outer hub  16 . While better seen in  FIG. 3 , the proximal section  40  is advanced proximally within lumen  93  of outer hub  16  until window  47  is aligned underneath a bottom opening  31  of irrigation port  30 , and then secured in this position to maintain fluid communication between irrigation port  30  and proximal window  47 . In addition, in this configuration, proximal end  41  is open to lumen  93  of outer hub  16 . Accordingly, in one aspect, the proximal section  40  has an outer diameter adapted to receive the outer hub  16  thereon. 
     However, the remainder of the outer tubular member  18  preferably provides a relatively uniform outer diameter (as represented by reference numeral  74  in  FIG. 6 ) selected to perform the desired sinus procedure and a relatively uniform inner diameter (as represented by reference numeral  75  in  FIG. 6 ) selected to rotatably receive the inner tubular member  22 . For example, in one embodiment, the intermediate section  42 , as well as the distal section  44  to permit use of the inner tubular member  22 /burr  24  as part of a sinus procedure. 
     Returning to  FIG. 2 , the inner tubular member  22  extends from the inner hub  20 . In one preferred embodiment, the inner hub  20  is configured for selective attachment to handpiece  36  (and as also described in association with  FIG. 13 ) that can be operated to automatically rotate the inner tubular member  22  during use. 
     As previously described, the inner tubular member  22  forms bur  24  at a distal end thereof. In general terms, bur  24  is a solid member that can assume a variety of forms and is adapted with an abrasive or rough surface to cut or abrade bodily tissue upon rotation thereof. In some embodiments, the bur  24  forms a cutting surface including one or more cutting elements. While a spherical bur configuration is shown, it will be appreciated that other configurations can be used including, but not limited to, cylindrical, hemispherical, ellipsoidal, and pear-shaped configurations. 
     With reference to  FIGS. 1-3 , the micro-burring instrument  10  is assembled by coaxially positioning the inner tubular member  22  within the outer tubular member  18  via the central lumen  46 . With particular reference to  FIG. 3 , a seal portion  52  of the inner hub  20  (at distal end  95  of inner hub  20 ) abuts against a seal portion  50  of the outer hub  16 . With this in mind, the inner tubular member  22  and inner hub  20  of inner assembly  14  is rotatable relative to the outer tubular member  18  and outer hub  16  of outer assembly  12 . To this end, a distance of separation between the inner hub  20  and the bur  24  is greater than a distance of separation between the outer hub  16  and the distal end  45  of outer tubular member  18 , thereby dictating that a desired position of the bur  24  will be exposed relative to the outer tubular member  18 , as best shown in  FIGS. 1 and 4 . In particular, the inner tubular member  22  is coaxially disposed within the outer tubular member  18  such that the distal end  45  of the outer tubular member  18  is proximal to the bur  24  and to the distal end  145  of inner tubular member  22 . 
     As illustrated by  FIGS. 1-2  and with additional reference to  FIG. 4 , once bur  24  is positioned at treatment site  80  to debride target tissue  82 , fluid  58  supplied from fluid source  32  flows through an interior passage  64  of side wall  60  of outer tubular member  18  to irrigate bur  24  and/or the treatment site  80 . In one aspect, this arrangement enables flooding the treatment site  80  with fluid  58  (and as further represented by arrows F), as appropriate to the procedure, while the bur  24  is rotating to cut the target tissue  82 . In some embodiments, the fluid  58  irrigates the treatment site  80  before and/or after the bur  24  rotates to cut the target tissue  82 . While side wall  60  can take many forms, one particular embodiment is illustrated in  FIGS. 6-12 , as described in more detail hereafter. 
     With further reference to  FIG. 4 , bur  24  includes a shaft  71  extending distally from (and secured relative to) distal section  44  of inner tubular member  22  and a tip  70  shaped to debride the target tissue  82 . In one aspect, proximal end  73  of bur  24  blocks lumen  147  of inner tubular member  22  to prevent any fluid or other substances from entering lumen  147  near bur  24 . Moreover, while tip  70  is shown as having a generally spherical shape in  FIG. 4 , bur  24  can take other forms, as previously described in association with  FIGS. 1-2 . 
     While outer tubular member  18  was previously described in association with  FIGS. 1-2 , outer tubular member  18  can take many forms to achieve the configuration of a side wall  60  that defines an interior passageway  64  configured to provide fluid to cool bur  24  and/or lubricate treatment site  80 , as previously described in association with  FIG. 4 . Nevertheless, in one configuration, outer tubular member  18  comprises an assembly  100  formed from an outer portion  102  shown in  FIGS. 5-7  and an inner portion  104 , as shown in  FIGS. 8-9 . Outer portion  102  and inner portion  104  comprise two separate members that are joined together to produce an assembly  100  having the form shown in  FIGS. 10-11 . For the sake of illustrative clarity, each of the inner portion  102  and the outer portion  104  will be further described separately. 
       FIG. 6  is a cross-sectional view of outer portion  102  of outer tubular member  18  and illustrates outer portion  102  defining a hollow sleeve. In one aspect, an outer surface of outer portion  102  of outer tubular member  18  comprises substantially the same features and attributes that were previously described in association with  FIGS. 3, 5, and 7  for outer tubular member  18  as a whole. In one aspect,  FIG. 6  further illustrates outer portion  102  including an inner surface  75  that defines a diameter sized and adapted to receive inner portion  104 . Outer portion  102  also defines an outer surface  74  which forms the outer surface of outer tubular member  18  and which provides a generally uniform and generally smooth outer diameter. 
       FIG. 8  is a side plan view of inner portion  104  of outer tubular member  18  and  FIG. 9  is a cross-sectional view of inner portion  104 , according to principles of the present disclosure. While inner portion  104  can take many forms, in the one configuration shown in  FIGS. 8-9 , inner portion  104  defines an inner surface  120  and an outer surface  122 . The inner surface  120  defines a generally uniform diameter and is generally uniformly smooth from the proximal section  40 , through the intermediate section  42 , to the distal section  44 . However, the outer surface  122  defines an array  128  of elongate recesses  130  extending from the distal section  44 , along intermediate section  42 , and through at least a portion of proximal section  40 . In one embodiment, the elongate recesses  130  extend along a majority of the length of inner portion  104  (and therefore a majority of a length of outer tubular member  18 ) before terminating adjacent a circular recess  140  that extends transversely to the elongate recesses  130 . In one aspect, circular recess  140  forms a ring extending about a circumference of outer surface of inner portion  104 . The circular recess  140  is in fluid communication simultaneously with each of the elongate recesses, as will be further illustrated later in  FIG. 10 . 
     As illustrated in  FIG. 8 , in one aspect, outer surface  122  of inner portion  104  further defines a non-recess portion  142  proximal to circular recess  140 . This non-recess portion  142  is sized and adapted to be sealingly secured to an inner surface  75  of outer portion  102 . In one embodiment, non-recess portion  142  is laser welded relative to inner surface  75  of outer portion  102 . This arrangement secures the inner portion  104  to outer portion  102  at proximal section  40  of outer tubular member  18  (located proximal to proximal window  47  shown in  FIGS. 5 and 7 ) while simultaneously defining a terminal end of the fluid communication pathway that extends generally within sidewall  60  of outer tubular member  18 . Accordingly, fluid flowing into outer tubular member  18  at proximal section  40  (from port  30  and fluid source  32 ) will enter through proximal window  47  of outer tubular member  18 , and flow through circular recess  130  ( FIGS. 3, 5, and 7 ) just distal to non-recess portion  142  of inner portion  104  before proceeding into recesses  130 . 
     As best seen in  FIG. 9 , the elongate recesses  130  of inner portion  104  (of outer tubular member  18 ) form an array  128  of recesses  130  uniformly spaced apart about the circumference of inner portion  104  with each elongate recess  130  being defined between an adjacent pair of raised protrusions  150  formed on outer surface  122  of inner portion  104 . In the one configuration shown in  FIG. 9 , array  128  includes six elongate recesses  130  that are spaced apart uniformly (i.e., equidistant from each other) about the circumference of outer surface  122  of inner portion  104 . Of course, in other configurations, there can be greater or fewer than six elongate recesses  130 . Nevertheless, at least one recess  130  is provided to form interior passageway  64  in side wall  60  of outer tubular member  18 . Configurations with a greater number of recesses (instead of fewer recesses) spaced apart uniformly about the circumference of the inner portion (and consequently about the circumference of the outer tubular member  18 ) provide more balance to the fluid flow through side wall  60 . This arrangement enables outer tubular member  18  to have a smaller thickness of the side wall because each recess  130  can have a smaller thickness or height (as represented by H in  FIG. 11 ) while enabling generally the same volume of fluid to flow within the side wall  60  of the outer tubular member  18 . 
     While a variety of techniques may be used to form the inner portion  104 , in one embodiment inner portion  104  is formed by providing a generally tubular sleeve (not shown) having a first thickness and then cutting an outer surface of the sleeve (corresponding to outer surface  122 ) to create each elongate recess  130 . Accordingly, with reference to  FIG. 9 , the protrusions  150  generally define the original, first thickness (as represented by T 1 ) of the sleeve while the recesses  130  extending between the respective protrusions  150  comprise a second thickness (as represented by T 2 ) substantially less than the first thickness. The difference between the first thickness and the second thickness will then define a height of the recess  130 , as best seen in  FIG. 11 . In one aspect, the height of each recess  130  (as represented by H, the difference between T 1  and T 2 ), the width of each recess  130  (as represented by W), and the number of recesses defines the cross-sectional area available to send fluid through the interior passageway  64  within the sidewall  60  of outer tubular member  18 . 
       FIG. 10  is a perspective view of assembly  100  of outer tubular member  18  showing inner portion  104  and outer portion  102  in an assembled state to form outer tubular member  18 .  FIG. 11  is cross-sectional view of assembly  100  of  FIG. 10  that further illustrates the relationship between inner portion  104  and outer portion  102  of assembly  100  of outer tubular member  18 . 
     As seen in  FIGS. 10-11 , after slidably inserting inner portion  104  within outer portion  102 , inner portion  104  becomes coaxially disposed within outer portion  102 . With this arrangement, the protrusions  150  contact inner surface  75  of outer portion  102 , thereby forming separate conduits  160  between each of the elongate recesses  130  and inner surface  75  of outer portion  102 . Accordingly, in one aspect, each adjacent pair of protrusions  150  defines the side walls of each respective conduit  160 . The conduits  160  extend a majority of a length (represented by L 1  in  FIG. 8 ) of the outer tubular member  18  to provide a fluid communication pathway from a proximal section  40  (at which fluid  58  is supplied from irrigation port  30  via proximal window  47  ( FIG. 5 ) and via circular recess  140 ) to the distal section  44 . In one aspect, a surface  141  of circular recess  140  (also seen in  FIG. 9 ) and a bottom portion of each recess  130  have substantially the same elevation at junction  155  (between circular recess  150  and the respective recesses  130 ) to provide a generally seamless transition therebetween. 
     Accordingly, one or more conduits  160  shown in  FIGS. 10-11  correspond to (and define just one configuration of) interior passage  64  of side wall  60  of outer tubular member  18  that was previously described in association with  FIG. 4 . Therefore, conduits  160  define a fluid flow pathway internally within side wall  60  of outer tubular member  18  to deliver fluid  58  (from fluid source  32 ) to bur  24  and target tissue  82  at treatment site  80 . As previously noted, this delivered fluid will flood the treatment site  80  to cool the bur  24  during rotation and/or to lubricate the target tissue  82 , thereby increasing the effectiveness of the debriding action of the bur  24 . 
     Moreover, because the irrigation fluid pathway is contained internally within the sidewall  60  of the outer tubular member  18 , the outer tubular member  18  has a smaller overall cross-sectional profile. In another aspect, the outer surface  74  of the outer tubular member  18  is generally uniform and generally smooth without significant protrusions, such as the protrusion(s) that would otherwise be formed by an irrigation tube externally attached to instrument as seen in conventional instruments. With this in mind, this smaller cross-sectional profile provides instrument  10  with greater maneuverability to enable distal section  44  of instrument  10  to pass through various soft tissues and bony structures with less likelihood of the instrument  10  catching on soft tissues and bony structures encountered along a path to a treatment site at which rotation of bur  24  is deployed. 
     While the micro-burring instrument  10  of the present disclosure has been illustrated as being relatively straight (e.g., relative to the view of  FIG. 1 , the outer tubular member  18  is relatively straight), other configurations can be employed to facilitate a desired procedure. For example,  FIG. 12  illustrates an alternative embodiment micro-burring instrument  210  highly useful for a sinus procedure that again includes an outer tubular assembly  212  and an inner tubular assembly  214  (illustrated generally). The outer and inner tubular assemblies  212 ,  214  comprise, in one embodiment, substantially the same features and attributes as the outer and inner tubular assemblies  12 ,  14  (respectively) as previously described in association with  FIGS. 1-11 . However, with the alternative embodiment instrument  210  of  FIG. 12 , the outer and inner tubular members  212 ,  214  define a slight bend, as referenced generally by  250 , at a junction between a distal end portion  260  and an intermediate portion  270  of the instrument  210 . In one embodiment, the bend  250  is configured to cause the a central axis (as represented by dashed line A) of the distal end portion  260  to define an angle a in the range of 10°-70°, relative to a central axis (as represented by dashed line B) of the intermediate portion  270  and proximal portion  272  of the instrument  210 . Among other uses, this bend is particularly useful in properly positioning the distal end portion  260  during a skull-based procedure, among other surgical procedures favoring a bend  250  in distal end portion  260 . To facilitate necessary rotation of the inner tubular assembly  214  in the region of the bend  250  (such as for rotating the bur  24  at a distal end thereof), an inner tubular member (hidden in the view of  FIG. 12 , but akin to the inner tubular member  22  of  FIG. 2 ) is preferably flexible and formed of an appropriate material such as spiral wrap technology. Alternatively, other constructions can be employed. 
     Regardless of exact form, the micro-burring instrument  10 ,  210 , of the present invention is useful in performing various sinus operations and other procedures. By way of example, and with reference to the one embodiment of  FIGS. 1 and 2 , the assembled instrument  10  is deployed to the target site. For example, in a surgical procedure, the instrument  10  is maneuvered to the treatment site  80  and the bur  24  is positioned against the bone or other target tissue  82 , as illustrated in  FIG. 4 . Other related surgical techniques may be performed before, during, or after application of instrument  10 . 
     Next, the inner tubular member  22  is then rotated relative to the outer tubular member  18 , such that the bur  24  burs (e.g., cuts or abrades) the contacted cartilage and/or bone. As best seen in  FIG. 4 , the bur  24 , and thus the target site  82 , are periodically or continuously flushed with an irrigation fluid via the interior passage  64  (for example, the irrigation conduits  160 ) extending within the side wall  60  of the outer tubular member  18 . 
     In addition to the surgical procedure described above, the micro-burring instrument  10 ,  210  of the present disclosure can be used to perform a variety of other surgical procedures in which hard tissue is debrided or cut while flooding the treatment site with fluid to irrigate the bur and the target tissue. 
     In one embodiment, the micro-burring instrument  10 ,  210 , is attached to a powered handpiece  236  as shown in  FIG. 13 . The handpiece  236  can assume a variety of forms known in the art, and in one preferred embodiment comprises a StraightShot® powered handpiece, marketed by Medtronic-Xomed. In some embodiments in which a surgical instrument supports aspiration, and as illustrated in  FIG. 13 , handpiece  236  supports aspiration tubing  281  which forms part of an aspiration pathway  280  that extends distally through an interior of handpiece  236  (for fluid communication with an aspiration lumen associated with the instrument) and which extends proximally to be in fluid communication with negative pressure source  359 . 
     In one particular embodiment, instrument  10  takes a modified form as an instrument  310  illustrated and described in association with  FIGS. 14-15 . For example,  FIGS. 14-15  illustrate another alternative embodiment micro-burring instrument  310  highly useful for a surgical procedure that again includes an outer tubular assembly  312  and an inner tubular assembly  314  (illustrated generally). The outer and inner tubular assemblies  312 ,  314  include, in one embodiment, substantially the same features and attributes as the outer and inner tubular assemblies  12 ,  14  (and  212 ,  214 ) previously described in association with  FIGS. 1-13 . However, with the alternative embodiment instrument  310  of  FIGS. 14-15 , the inner tubular assembly  314  defines an aspiration pathway  380  extending through a central lumen  347  of an inner tubular member  322  and inner hub  320  for connection to and fluid communication with negative pressure source  359  (via handpiece  36  or  236 ). 
     With additional reference to  FIG. 15 , a distal end  350  of the bur  324  forms a conduit  352  that extends through shaft  354  of bur  324  and which is open to the central lumen  347  defined by inner tubular member  322 . By forming conduit  352  to extend through bur  324 , a smaller overall, cross-sectional profile of instrument  310  is maintained in accordance with the smaller cross-sectional profile achieved via providing an irrigation pathway  280  within interior passage  64  (for example, the conduits  160  of  FIGS. 10-11 ) of side wall  60  of outer tubular member  318 . Regardless, the central lumen  347  serves as an aspiration conduit for the micro-burring instrument  310  ( FIG. 1 ). Further, with reference to  FIG. 15 , when instrument  310  including aspiration pathway  280  including central lumen  347  is applied to treat a target site  82  ( FIG. 4 ) the conduit  352  extending through bur  324  enables periodic or continuous aspiration (as represented by arrow V) via the central lumen  347  of the inner tubular member  22  to remove abraded tissue from the target site  82 . 
     Nevertheless, it is understood that an alternative embodiment can be formed by modifying the embodiment of instrument  10  ( FIGS. 1-12 ) to include an exteriorly extending aspiration passage proximal the bur  24  that is otherwise fluidly connected to the central lumen  147 . This arrangement provides an externally-located aspiration mechanism in combination with the internally located irrigation mechanism formed in accordance with principles of the present disclosure and that was previously described in association with  FIGS. 1-12 . 
     As familiar to those skilled in the art, the outer tubular member  18  and the inner tubular member  22  are formed from biocompatible metallic materials, such as stainless steel, titanium alloys, and the like. Accordingly, at least the outer tubular member  18  defines a generally rigid member. 
     Embodiments of the present disclosure facilitate surgery involving narrow access to treatment sites within a body. For example, with respect to sinus surgeries and other skull-related surgical procedures, a micro-burring instrument having a low cross-sectional profile, in accordance with principles of the present disclosure, provides a distinct advantage over currently-accepted techniques employing external irrigation tubes which increase the cross-sectional profile of the instrument and which increase the likelihood of the instrument getting caught during use. 
     Although the present disclosure has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes can be made in form and detail without departing from the spirit and scope of the present disclosure.