Abstract:
A dual function arthroscopic blade provides multiple cutting surfaces of differing cut aggressiveness for selective engagement of the desired cutting blade without retracting the instrument for changing cutting members to apply a different set of cutting edges, or blade. An inner rotating member within a stationary outer cutting member provide cutting edges defined by cutting windows on the inner and outer cutting members, and a rotational drive applies an oscillating rotation such that one of the cutting windows, corresponding to one of the sets of cutting edges, engages an extraction region such as tissue or bone. The use of different sized cutting windows allows variance in the aggressiveness of the cut, and allows selection of another cutting window by rotating the cutting member to align the selected cutting edges without requiring extraction and reinsertion in order to attach a different blade with a different cut aggressiveness.

Description:
BACKGROUND 
       [0001]    Powered arthroscopic surgical instruments typically include a rigid, stationary outer tube within which a rigid inner tube is rotated by a motor. A cutting implement, such as a blade or abrading burr, is disposed on the distal end of the inner tube. Tissue or bone is exposed to the cutting implement through an opening in the distal end of the outer tube, and tissue or bone fragments cut by the rotating blade or burr are drawn through the interior of the inner tube along with irrigating fluid by the use of suction applied at the proximal end of the instrument. 
         [0002]    A motorized attachment engages a hub, typically on the inner tube, and rotates the inner tube within the outer tube for providing cutting movement and force. The attachment also incorporates a suction attachment for evacuating cut matter from a surgical extraction site through the hollow tubes. Several surgical instruments of various complementary functions are often employed in a surgical field within a patient for performing surgical operations at the surgical site, one function of which is the controlled cutting and evacuation of tissue and bone fragments. 
       SUMMARY 
       [0003]    A dual function arthroscopic blade provides multiple cutting surfaces of differing cut aggressiveness for selective engagement of the desired cutting blade without retracting the instrument for changing cutting members to apply a different set of cutting edges, or blade. An inner rotating member within a stationary outer cutting member provide cutting edges defined by cutting windows on the inner and outer cutting members, and a rotational drive applies an oscillating rotation such that one of the cutting windows, corresponding to one of the sets of cutting edges, engages an extraction region such as tissue or bone. The use of different sized cutting windows allows variance in the aggressiveness of the cut, and allows selection of another cutting window by rotating the cutting member to align the selected cutting window with the cutting edges on the other (inner or outer cutting member) for engagement with the extraction area. 
         [0004]    Unfortunately, conventional approaches to arthroscopic extraction and control suffer from the shortcoming that conventional cutting instruments employ only a single blade or cutting surface engaged in a continuous rotary motion, thus applying the same cutting edge repeatedly on each rotation. Configurations herein are based, in part, on the observation that conventional cutting instruments employ only a single blade on each cutting member, therefore requiring extraction and reinsertion in order to attach a different blade with a different cut aggressiveness. It would be beneficial, therefore, to provide a dual set of separately engageable blades or cutting edges on the same instrument to avoid the need to withdraw an already inserted instrument and change cutting members to achieve a different cutting function. 
         [0005]    Accordingly, configurations herein substantially overcome the shortcoming of repetitive instrument extraction and changeover by employing a cutting member having dual cutting functions from multiple sets of cutting edges engageable in an oscillating manner such that only one of the sets of cutting edges is active. The disclosed approach includes a method and apparatus to provide a resecting device using a standard rotary shaving system that combines effective resection of tough tissue (e.g. meniscus) with less aggressive resection for smoothing and debridement. Such a dual function arthroscopic blade as discussed below combines aggressive resection capability with less aggressive smoothing and debridement abilities within one single rotary shaving device. 
         [0006]    In an example arrangement, two cutting windows on either the inner or outer cutting member each define a pair of cutting edges for slideably engaging a cutting window on the other cutting member for shearing engagement of the cutting edges. The rotation causes the two blade edges to pass in close tolerance with a shearing action, similar to a pair of scissors blades absent a pivoting hinge point. Each of the cutting windows therefore defines a pair of opposed cutting edges for engagement with the cutting edges on the other concentric cutting member. A drive mechanism applies oscillatory rotation sufficient to alternately engage the opposed cutting edges on each side of the cutting window with corresponding edges on the other cutting member, typically around a half revolution depending on the width of the respective cutting windows. In contrast, conventional approaches perform unidirectional rotation of at least a plurality of revolutions, thus repeatedly engaging a single cutting edge repeatedly before engaging the opposed edge, therefore permitting only a single cutting window and corresponding set of opposed cutting edges on a particular instrument. 
         [0007]    Conventional arthroscopic cutting blade arrangements therefore suffer from the shortcoming that oscillatory or periodic rotation includes a plurality of complete rotations in one direction before reversing, thus permitting only a single cutting window and associated pair of cutting edges. In conventional approaches, the use of multiple cutting windows would cause each to be engaged upon each revolution, obviating selectivity of multiple windows. In the example arrangement, a more aggressive cut provided by a wider cutting window, and a less aggressive cut provided by a narrower cutting window allow alternate extraction of, for example, bone and soft tissue, using the same instrument without extraction and reinsertion. Selection of an alternate cut provided by another cutting window occurs by rotating the selected cutting window slightly more than a half rotation (in the case of a dual window) to bring the selected cutting window into alignment and simultaneously rotate the previously engaged cutting window to a dormant side away from the extraction area. 
         [0008]    Typically, at least one of the inner and outer cutting members employs a single cutting window for focusing suction toward the extraction area without permitting stray suction through unused cutting windows. Further, having greater than two cutting windows tends to limit the cutting window size, and corresponding oscillatory motion range permitted by the different windows. For example, a third cutting window would allow each only approximately ⅓ of a revolution range of motion, therefore limiting the size of the corresponding cutting windows. 
         [0009]    In further detail, the disclosed arthroscopic cutting instrument includes elongated cylindrical members including an inner member concentrically disposed within an outer member and adapted for rotation therewithin, such that each of the cylindrical members has a proximate end for engaging a drive mechanism and a distal end having at least one cutting edge. Each cutting edge is responsive to the rotation for causing slideable engagement with a cutting edge on the other cylindrical member (e.g. inner or outer), and in which at least one of the cylindrical members includes multiple cutting edges. Each of the multiple cutting edges is responsive to the oscillatory rotation for engagement with a selected subset of the multiple cutting edges during a particular oscillatory cycle. The oscillatory rotation disposes the cutting edges of the selected subset through a cutting range to repeatedly engage a cutting edge on the other member without engagement by cutting edges of an unselected subset, thus the unselected subset is defined by the cutting edges of the multiple cutting edges not in the selected subset, as now described further below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    The foregoing and other objects, features and advantages of the invention will be apparent from the following description of particular embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. 
           [0011]      FIG. 1  is a perspective view of an arthroscopic instrument as disclosed herein; 
           [0012]      FIG. 2  is a side view of the arthroscopic instrument of  FIG. 1 ; 
           [0013]      FIG. 3  shows the cutting windows of the inner and outer cutting members in the instrument of  FIG. 2 ; 
           [0014]      FIG. 4  shows the inner and outer cutting members in the instrument of  FIG. 3 ; 
           [0015]      FIG. 5  shows an exploded view of the inner and outer cutting members of  FIG. 4 ; 
           [0016]      FIG. 6  shows an assembled view of the inner and outer cutting members of  FIG. 5 ; 
           [0017]      FIG. 7  shows a cutaway view of the operation of the inner and outer cutting members of  FIG. 6 ; 
           [0018]      FIGS. 8 and 9  show a flowchart of selection and control of the dual function arthroscopic instrument of  FIG. 7 ; 
           [0019]      FIG. 10  shows an alternate configuration having a dual window on the outer cutting member; 
           [0020]      FIG. 11  shows an alternate configuration extending the cutting window on an inner or outer cutting member as in  FIG. 3 ; 
           [0021]      FIG. 12  shows an alternate configuration of the closed end of the inner or outer cutting member as in  FIG. 3 ; 
           [0022]      FIGS. 13   a - 13   i  show views of a dual inner window configuration; 
           [0023]      FIG. 13   a  shows a perspective view of the inner cutting member; 
           [0024]      FIG. 13   b  shows an end view of the inner cutting member; 
           [0025]      FIG. 13   c  shows a top view of the inner cutting member; 
           [0026]      FIG. 13   d  shows a bottom or opposed view of the inner cutting member of  FIG. 13   c;    
           [0027]      FIG. 13   e  shows a perspective view of the outer cutting member; 
           [0028]      FIG. 13   f  shows a side view of the outer cutting member; 
           [0029]      FIG. 13   g  shows an end view of the outer cutting member; 
           [0030]      FIG. 13   h  shows a top view of  FIG. 13   f;    
           [0031]      FIG. 13   i  shows a perspective cutaway view of the inner cutting member disposed within the outer cutting member; 
           [0032]      FIGS. 14   a - 14   i  show views of a dual outer window configuration; 
           [0033]      FIG. 14   a  shows a perspective view of the inner cutting member; 
           [0034]      FIG. 14   b  shows an end view of the inner cutting member; 
           [0035]      FIG. 14   c  shows a top view of the inner cutting member; 
           [0036]      FIG. 14   d  shows a side view of the inner cutting member; 
           [0037]      FIG. 14   e  shows a perspective view of the outer cutting member; 
           [0038]      FIG. 14   f  shows an end view of the outer cutting member; 
           [0039]      FIG. 14   g  shows a top view of the outer cutting member; 
           [0040]      FIG. 14   h  shows a bottom or opposed view of the outer cutting member of  FIG. 14   g ; and 
           [0041]      FIG. 14   i  shows a perspective cutaway view of the inner cutting member disposed within the outer cutting member. 
       
    
    
     DETAILED DESCRIPTION 
       [0042]    Depicted below is an example configuration of the arthroscopic instrument as disclosed and claimed herein. Configurations of the disclosed approach employ a concentric two tube construction without a rotatable shield and knob, thus reducing the cost, complexity and outside diameter of the precedent design. Functionality is enabled via selective oscillatory motion over a partial revolution of the inner member. In the disclosed arrangement, the arthroscopic instrument includes a pair of rotationally opposed cutting edges on each of an inner cutting member and an outer cutting member, such that the inner cutting member is disposed within the outer cutting member for rotational movement therewithin. The arthroscopic instrument is operable as a rotary shaving device having two different sized windows located on either the inner or outer blade combined with a single window located on the opposite blade (cutting member). The device is insertable into a motor drive unit which is controlled such that it oscillates substantially within a 180 degree operating range for oscillatory rotation such that only one of the cutting windows is employed within a particular oscillation pattern about half a rotation, depending on the size of the active cutting window. The semicircular oscillatory mode alternates rotation in substantially 180 degree increments and applies only one of multiple cutting windows on the cutting member. 
         [0043]      FIG. 1  is a perspective view of an arthroscopic instrument as disclosed herein, and  FIG. 2  is a side view of the arthroscopic instrument of  FIG. 1 . Referring to  FIGS. 1 and 2 , the arthroscopic surgical instrument  10  (instrument) includes a rigid, stationary outer cutting member  12 , within which rotates a rigid inner cutting member  14  (shown partly in dotted lines in  FIG. 2 ), and a dual function cutting portion, or blade  16 , also formed as part of the inner cutting member  14 . The distal end of the outer cutting member  12  defines at least one opening  18  through which the blade  16  is exposed. At least one other opening  20  is defined in the blade  16 . The cutting edges  22  of the blade opening  20  cooperate with cutting edges  24  of the outer tube opening  18  to shear tissue and bone during operation of the instrument. In addition, the blade opening  20  aligns with the outer tube opening  18  periodically as the inner cutting member  14  rotates, thereby admitting tissue and bone fragments into the interior of the blade  16  and connected inner cutting member  14 . These fragments are then removed by suction through a central opening  26  in the inner cutting member  14 . 
         [0044]    The instrument  10  further includes a hub  30  and a rotatable drive shaft  34 . The proximal end of the outer cutting member  12  is rigidly mounted to the hub  30  at a sealed joint  36 , while the proximal end of the inner cutting member  14  is mounted and sealed to the drive shaft  34 , which rotates within the hub  30 . The hub  30  and drive shaft  34  are secured in rotational communication by any suitable manner, such as short threaded portions  40  and  42 , respectively, which, after being engaged and screwed past each other, serve as abutments to prevent the drive shaft from sliding back out of the cutting member. A snap fit or frictional resilient arrangement may be used instead of the threads to accomplish the same goal. 
         [0045]      FIG. 3  shows cutting windows  112 ,  114 ,  114 ′ of the inner  14  and outer  12  cutting members in the instrument  10  of  FIG. 2 . Referring to  FIG. 3 , both the inner cutting member  14  and the outer cutting member  12  have a cutting window  112  and  114 , and at least one of the cutting members  12 , 14  has at least one other cutting window  114 ′ (shown on the inner cutting member  14  in  FIG. 3 ). Each of the cutting windows  112 ,  114 ,  114 ′ define opposed cutting edges  122 - 1 ,  122 - 2  ( 122  generally) and  124 - 1 ,  124 - 2  ( 124  generally) formed parallel to an axis  110  of rotation, as well as alternate cutting window  114 ′, having cutting edges  124 ′- 1 ,  124 ′- 2  ( 124 ′ generally). Each of the cutting windows  122 ,  124  and  124 ′ are formed as generally rectangular oriented lengthwise along the axis  110  so as to maximize the cutting edges  122 ,  124  and are formed by any suitable method, such as by cutouts from a closed tube along lines parallel and perpendicular to the axis  110 . In alternate arrangements, discussed further below, the cutting windows  122 ,  124  and  124 ′ may extend to a closed end  130 - 1 ,  130 - 2  ( 130  generally). 
         [0046]      FIG. 4  shows the inner and outer cutting members in the instrument of  FIG. 3 . Referring to  FIGS. 3 and 4 , the inner  14  and outer  12  cutting members extend from the drive shaft  34  and hub  30 , respectively for rotational communication. The drive shaft  34  engages a drive mechanism for oscillating rotation within the hub  30 , thus rotating the inner cutting member  14  within the outer cutting member  12 . Rotation of the drive shaft  34  causes the cutting edges  124 ,  124 ′ of the inner cutting member  14  to engage the cutting edges  122  of the outer cutting member in a slideable or shearing manner for cutting tissue and/or bone at an extraction area defined by placement of the window  112  of the outer cutting member  12  in a surgical field. 
         [0047]    Upon rotational movement by the inner cutting member  14 , a first cutting edge  124 - 1  of the inner cutting member  14  engages a first cutting edge  122 - 2  of the outer cutting member  12 , and a second cutting edge  124 - 2  of the inner cutting member  14  engages the second cutting edge  122 - 1  of the outer cutting member  12  in an alternating manner. An oscillatory drive pattern of substantially 180 degrees drives the alternating manner of cutting in which only one of the dual cutout windows  114 ,  114 ′ is employed as a cutting member during the semirotational oscillation of substantially about 180 degrees. Such semicircular rotation ensures that only one cutting window  114  and associated pair of cutting edges  124  engages the extraction area. 
         [0048]    In one conventional approach, U.S. Pat. No. 4,834,729 (&#39;729), assigned to the assignee of the present application, an arthroscopic surgical instrument includes an outer stationary member having a distal aperture, the wall of the outer member defining a first cutting edge at the aperture, and an internal movable member disposed within the outer member, adapted to be power driven and having a second cutting edge arranged to move toward and closely past the first cutting edge in rapid, repetitive fashion to sever tissue. However, the &#39;729 disclosure employs unidirectional rotary motion, thus engaging the extraction surface from a single direction, in contrast to the oscillatory rotation disclosed herein. 
         [0049]    Another conventional approach is discussed in U.S. Publication No. 2007/0282361 (&#39;361), which suggests that a cutting instrument can be used in both directions of rotation and oscillating, however no further clarification of oscillatory drive are disclosed or claimed. There is no disclosure of an oscillation mode which alternates rotational movement in increments substantially less than a full rotation, such as 180 degrees, or rotation that alternately engages opposes cutting members of the same window, as conventional methods typically oscillate multiple full rotations in one direction before reversing, thereby engaging cutting members of one side of a window multiple times before engaging the opposed side. 
         [0050]    Further, the &#39;361 publication shows a welded forward tip, rather than unitary composition with the tubular member, and has an angular cutaway that defines a cutaway opening extending at an angle from the annular surface parallel to the axis of rotation to a point substantially around the center of the head, or tip. In the present application, in contrast, the cutting surfaces are formed from a cutting window defined by a cut parallel to the axis of rotation, rather than angular toward the tip. 
         [0051]    U.S. Pat. No. 5,766,199 suggests a dual window structure of an inner member, however a corresponding cutting edge of an outer member extends through the rotational axis. Further, the disclosed curvilinear window periphery has edges of differing included angles, and employs cutting windows that extend through the cutting member causing discontinuity at the tip because the cutting windows open at the distal tip thereby producing a distal end slot having adjacent finger ends with low included angle cutting edges. In contrast, the claimed approach defines the cutting edges substantially parallel to the rotational axis, and the cutting windows do not extend through the axis nor through the tip to form a discontinuous surface with “finger ends,” in a so-called “open mouth” arrangement. 
         [0052]      FIG. 5  shows an exploded view of the inner and outer cutting members of  FIG. 4 . Referring to  FIGS. 4 and 5 , the inner cutting member  14  has a slightly smaller diameter Di that diameter Do of the outer cutting member  12  such that it is adapted for slideable insertion and rotation within the outer cutting member  12  within a sufficiently close tolerance that slideable engagement during rotation causes a shearing action as the cutting edges  122 ,  124  engage. 
         [0053]      FIG. 6  shows an assembled view of the inner  14  and outer  12  cutting members of  FIG. 5 . Referring to  FIGS. 5 and 6 , upon insertion of the inner cutting member  14  concentrically into the outer cutting member  12 , the cutting window  114  aligns with the cutting window  112 , such that oscillatory rotation of the inner cutting member  114  causes the cutting edges  124 - 1  and  124 - 2  to slideably engage the cutting edges  122 - 1  and  122 - 2 . Further, upon rotation of the inner cutting member  14  about half a revolution, the cutting window  114 ′ aligns with the cutting window  112 , such that further oscillation causes the cutting edges  124 ′- 1  and  124 ′- 2  to engage the cutting edges  122 - 1  and  122 - 2 . Varying a width  115 ,  115 ′ of the cutting windows  114 ,  114 ′ effects the aggressiveness of the cut resulting from oscillating, with a larger width generally resulting in a more aggressive cut. Sharpening or modifying (such as by serrations or “teeth”) of the cutting edges  122 ,  124  also effects the cut. 
         [0054]      FIG. 7  shows a cutaway view of the operation of the inner  14  and outer  12  cutting members of  FIG. 6 . Referring to  FIGS. 6 and 7 , an oscillatory cycle of oscillatory rotation of the inner cutting member  14  of  FIG. 6  is shown in  FIG. 7 . A stationary axis position  140  (normal to cut axis  110 ) shows the inner cutting member  14  at rest with the cutting window  114  aligned with the cutting window  112 , and the cutting window  114 ′ opposed, as shown by the stationary (rest) axis position  140 . Upon an idle or stationary state, the cutting edges  122 - 1  and  122 - 1  (on outer cutting member  12 ) align substantially with and parallel to the cutting edges  124 - 1  and  124 - 2  (inner cutting member  14 ). Rotating along the cutting axis 180 degrees results in similar alignment with respect to cutting edges  124 ′- 1 ,  124 ′- 2 . 
         [0055]    During oscillation, rotation of the inner cutting member  14  as shown by arrows  143  and  145  through a oscillation range defined by a set of range limits  142  and  144 , shown by arrows  143  and  145  respectively, disposes the cutting edge  124 - 2  to engage the cutting edge  122 - 1  from rotation substantially around the range limit  142 , and on a reverse oscillation ( 145 ) to engage the cutting edge  124 - 1  with the cutting edge  122 - 2 . Selection of cutting window  124 ′ includes rotation to align the cutting window  114 ′ with  112 , and oscillation of cutting edges  124 ′- 1  with  122 - 1  and  124 ′- 2  with  122 - 2 . 
         [0056]      FIGS. 8 and 9  show a flowchart of selection and control of the dual function arthroscopic instrument of  FIG. 7 . Referring to  FIGS. 4-9 , the drive shaft  34  imparts oscillation and selection control to the inner cutting member  14 . Accordingly, the method for controlling a surgical cutting instrument  10  as disclosed herein includes independently rotating a plurality of elongated cylindrical members  12 ,  14 , the cylindrical members including an inner member  14  concentrically disposed within an outer member  12  and adapted for rotation therewithin, such that each of the cylindrical members  12 ,  14  has a proximate end for engaging a rotating drive mechanism and a distal end  130  having at least one cutting edge  122 ,  124 , as depicted at step  300 . The cutting edges  122 ,  124  form cutting windows  112 ,  112 ′ ( FIG. 10  below),  114  and  114 ′ defined by the opposed edges on each of the cylindrical members  12 ,  14 , as disclosed at step  301 . In the example arrangement, the cutting windows  112 ,  114  are defined by the cutout in the annular surface of the cutting members  12 ,  14 , such that the cutting windows each  112 ,  114  have a pair of opposed cutting edges  122 - 1 ,  122 - 2 ,  124 - 1 ,  124 - 2  substantially along an line parallel to the axis of rotation  110 , in which the cutting windows  112 ,  114  are configured for opening and closing in an alternating manner along the opposed cutting edges  122 ,  124 , as depicted at step  302 . At least one of the cylindrical members  12 ,  14  has a plurality of cutting windows  114 ,  114 ′, such that the cutting windows  114 ,  114 ′ are selectable by rotation of the inner cutting member  14 , as shown at step  303 . Rotating in this manner includes rotating at least one cutting edge  122 ,  124  for causing slideable engagement with a cutting edge  122 ,  124  on the other cylindrical member  12  or  14 , and further including oscillating at least one of the cylindrical members  12 ,  14  including multiple cutting edges, in which each of the multiple cutting edges  122 ,  124  is responsive to oscillatory rotation for engagement with a selected subset of the multiple cutting edges  122 ,  124 , as depicted at step  304 . In the example shown in  FIG. 4 , the selected subset is either  124 - 1 ,  124 - 1 , or  124 ′- 1 ,  124 ′- 2 , depending on which cutting window  114  or  114 ′ is aligned with the cutting window  112  on the outer cutting member  12 . 
         [0057]    In the example arrangement, the arthroscopic cutting blade is inserted to an extraction area of a surgical site, typically as one of several instruments similarly suited for surgical activity. The drive shaft  34  rotates to dispose a first cutting edge  124 - 2  of the inner cutting member  14  to engage a first cutting edge  122 - 1  of the outer cutting member  12 , and disposes a second cutting edge  124 - 1  of the inner cutting member  14  to engage the second cutting edge  122 - 2  of the outer cutting member in an alternating manner, as disclosed at step  305 . Upon initial insertion, rotation of the drive shaft  34  determines the selected subset (e.g.  114  or  114 ′) by a degree of rotational oscillation and an angular position of the cutting edge  124 ,  124 ′ on an annular surface of the cylindrical members  14 , as depicted at step  306 . Initial rotation will bring the cutting member having the multiple cutting windows ( 14  shown) into alignment with the other cutting member having a single window ( 12  in the example shown). Thus, at least one of the cylindrical members  14  includes a plurality of opposed pairs ( 124 - 1 ,  124 - 2  and  124 ′- 1 ,  124 ′- 2 ) of the cutting edges defined by a cutout  114  and  114 ′ in an annular surface of the cylindrical member  14 , such that the cutout is longitudinally parallel to the rotational axis  110  forming a substantially parallel pair of cutting edges defined by the rectangular cutout, as shown at step  307 . This orientation provides that the cutting edges  124  are substantially parallel to the axis of rotation  110 , in which the oscillatory rotation causes repeated opposed engagement of the selected subset in a shearing manner while avoiding cutting engagement of the cutting edges not within the selected subset, as depicted at step  308 . 
         [0058]    Following initial selection of the cutting window  124  or  124 ′, the drive shaft  34  rotates in an oscillatory manner through the cutting range  142 ,  144  to dispose the cutting edges  124  of the selected subset to repeatedly engage a cutting edge  122  on the other member  12  without engagement by cutting edges of an unselected subset such that the unselected subset is defined by the cutting edges of the multiple cutting edges not in the selected subset, e.g. the complement of the set  124  or  124 ′, as depicted at step  309 . Oscillation includes rotating the inner member  14  to align the selected subset of cutting edges  124 ,  124 ′ proximate to the cutting edge  122  on the outer member  12  and proximate to an extraction area, as disclosed at step  310 . In the example arrangement shown, the cutting edges further comprise a pair of rotationally opposed cutting edges  124 ,  122  on each of an inner cutting member  14  and an outer cutting member  12 , such that the inner cutting member  14  is disposed within the outer cutting member  12  for rotational movement therewithin, as depicted at step  311 . The oscillating by the hub  34  therefore repeatedly engages the cutting edges  124  of the selected window  114  (or edges  124 ′ when cutting window  114 ′ is selected) with the cutting edges on the other (e.g. outer  12 ) member in a shearing manner for cutting bone and tissue while the unselected (e.g.  124 ′) window remains unengaged from the edges  122  of cutting window  112  during the oscillation. 
         [0059]    Oscillation continues until selection of an alternate cutting window  114 ′ and associated cutting edges  124 ′ (blade), as shown at step  312 . In response to operator control, the drive shaft  34  selects an unselected subset ( 124 ′ in the example shown) of cutting edges by rotating the cutting edges  124 ′ into proximate alignment with the cutting edge  122  of the other cylindrical member  12 , the alignment such that subsequent oscillation provides slideable engagement of the previously unselected subset with the cutting edge  122  on the other cylindrical member  12 , as depicted at step  313 . This includes selecting the multiple cutting edges  124  or  124 ′ by rotating of the concentric cylindrical member  14  relative to the other concentric cylindrical member  12 , such that a degree of rotation for the oscillatory rotation is less than a degree of rotation for selecting the cutting edges, as shown at step  314  and  FIG. 7 . An oscillatory rotation causes the inner member  14  to travel through the range defined by limits  142 , 144 , while a blade selection (as in step  312 ) rotates the cutting window  114 ′ substantially in alignment with the cutting window  112 , for continued oscillation using the newly selected cutting edges  124 ′. Thus, rotation for oscillatory rotation is substantially around a half revolution and the rotating for selection of the unselected window  114 ′ is substantially around one revolution from a range limit ( 142  or  144 ) of the previously selected window  114 , as depicted at step  315 . 
         [0060]      FIG. 10  shows an alternate configuration having a dual window on the outer cutting member  12  and a single cutting window  114  on the inner cutting member  14 . A plurality of cutting windows  112 ,  112 ′ on the outer cutting member  12  provides that selection of the cutting window occurs by rotating the outer cutting member  12 , typically the cutting member affixed to the base  30 . Alternatively, an opposed surface of an extraction area may be accessed more readily from the second cutting window  112 ′. As with the dual window on the inner cutting member, different sized windows  112 ,  112 ′ allows varying aggressiveness of cut by invoking different windows. It should be noted that by having a single window  112  or  114  on at least one of the cutting members  12 ,  14 , suction applied via the base  30  is focused only on the extraction site for evacuating cut tissue or bone. Multiple windows on each of the inner  14  and outer cutting member  12  would result in the extractive suction force being directed to both openings. 
         [0061]      FIG. 11  shows an alternate configuration extending the cutting window on an inner  14  or outer cutting member  12  as in  FIG. 3 . Referring to  FIGS. 3 and 11 , the substantially rectangular cutting windows  112  and  114  may be formed by a cut extended to the tip  130  of the cutting member  12 ,  14 . Similarly,  FIG. 12  shows an alternate configuration of the closed end of the inner or outer cutting member as in  FIG. 3 . Referring to  FIG. 12 , the tip  130  may be squared off  130 ′ or may be formed in various combinations of flattened or convex formations. As with the aperture formed by the cutting windows  112 ,  114 , a closed end  130 ,  130 ′ allows suctional force to focus on the windows for extracting cut material. 
         [0062]      FIGS. 13   a - 13   i  show views of a dual inner window configuration as depicted in  FIGS. 3-7 . Referring to  FIGS. 6 and 13   a - 13   i ,  FIG. 13   a  shows a perspective view of the inner cutting member  14  having dual cutting windows  114  and  114 ′ of varying widths  115  and  115 ′ respectively. The cutting window  114  defines cutting edges  124 - 1  and  124 - 2 , and the smaller cutting window  114 ′ defines cutting edges  124 ′- 1  and  124 ′- 2 . 
         [0063]      FIG. 13   b  shows an end view of the inner cutting member  14  having cutting windows  114 ,  114 ′ and cutting edges  124 - 1 ,  124 - 2 ,  124 ′- 1 ,  124 ′- 2 . The tip  130  is defined by a concave end as in  FIG. 11  and linear cutaway extending to the tip  130 .  FIG. 13   c  shows a top view of the inner cutting member  14  with cutting window  114 ′ in above cutting window  114  and obscuring the cutting edges  124 - 1 ,  124 - 2  of the larger cutting window  114 .  FIG. 13   d  shows a bottom or opposed view of the inner cutting member of  FIG. 13   c , such that cutting edges  124 - 1  and  124 - 2  of window  114  are visible in the foreground and cutting edges  124 ′- 1  and  124 ′- 2  beyond. 
         [0064]      FIG. 13   e  shows a perspective view of the outer cutting member  12  having a single cutting window  112  defining cutting edges  122 - 1  and  122 - 2 .  FIG. 13   f  shows a side view of the outer cutting member  12  with a reducing section  13  for altering the diameter for rotational communication with the inner portion  14 . The reducing section may also represent a welded or attachment section for securing a separately fabricated windowed portion. Alternatively, unitary construction may be employed. The view shows the cutting window  112  and cutting edge  122 - 2  in the foreground obscuring distal cutting edge  122 - 1 . 
         [0065]      FIG. 13   g  shows an end view of the outer cutting member  12  with the cutting edges  122 - 1  and  122 - 2  defined by a concave cutout extending to the tip  130 - 1  as in  FIG. 11  to define the cutting window  112 .  FIG. 13   h  shows a top view of  FIG. 13   f , and  FIG. 13   i  shows a perspective cutaway view of the inner cutting member disposed within the outer cutting member  12  and the inner cutting member  14  rotated approximately ¼ turn out if alignment of the cutting windows  112  and  114 . 
         [0066]      FIGS. 14   a - 14   i  show views of a dual outer window configuration as in  FIG. 10 . Referring to  FIGS. 6 and 14   a - 14   i ,  FIG. 14   a  shows a perspective view of the inner cutting member  14  having a single cutting window  114  and cutting edges  124 - 1 ,  124 - 1 .  FIG. 14   b  shows an end view of the inner cutting member  14  and cutting edges  124 - 1 ,  124 - 2 .  FIG. 14   c  shows a top view of the inner cutting member  14  and single cutting window  114 .  FIG. 14   d  shows a side view of the inner cutting member  14  defined by a cutaway forming cutting edges  124 - 1 ,  124 - 2  extending to the tip  130 . 
         [0067]      FIG. 14   e  shows a perspective view of the outer cutting member  12  having dual outer cutting windows  112  and  112 ′ defining cutting edges  122 - 1 ,  122 - 2  and  122 ′- 1 ,  122 ′- 2 , respectively. A reducing section  13  specializes adjustment or attachment of the cutting portion for rotation of the inner cutting member  14  therewithin.  FIG. 14   f  shows an end view of the outer cutting member  12 , and  FIG. 14   g  shows a top view of the outer cutting member  12 . The smaller width  115 ′ cutting window  112 ′ is visible through the larger width  115  cutting window  112 , as are the cutting edges  122 ′- 1 ,  122 ′- 2 , as well as cutting edges  122 - 1  and  122 - 2 .  FIG. 14   h  shows a bottom or opposed view of the outer cutting member of  FIG. 14   g , showing cutting window  112 ′ and cutting edges  122 ′- 1 ,  122 ′- 2  obscuring distal cutting edges  122 - 1 ,  122 - 2  defined by cutting window  112 .  FIG. 14   i  shows a perspective cutaway view of the inner cutting  14  member disposed within the outer cutting member  12  and adapted for rotational communication therewithin. Upon oscillating rotation as disclosed above, the cutting edges  122 - 1 ,  122 - 2  or  122 ′- 1 ,  122 ′- 2  alternately engage the cutting edges  124 - 1 ,  124 - 2  in a shearing action for extraction of bone and tissue fragments. 
         [0068]    While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present application as defined by the appended claims. Such variations are intended to be covered by the scope of this present application. As such, the foregoing description of embodiments of the present application is not intended to be limiting, the full scope rather being conveyed by the appended claims.