Abstract:
An endoscopic tissue resecting system that includes a reciprocating rotary surgical instrument for cutting tissue that includes a planetary gear assembly to vary rotational speed. A method of cutting and detaching tissue includes positioning an outer member such that tissue is located within a window in the outer member, engaging the tissue with an inner member, and simultaneously rotating at an increased speed relative to a rotary driver and translating the inner member to cut the tissue. A tangential cutting force is applied to the tissue with the inner member to mechanically cut and detach the tissue.

Description:
FIELD OF THE INVENTION 
       [0001]    The present disclosure generally relates to endoscopic tissue resecting systems, and more particularly, to a reciprocating rotary surgical instrument for cutting and detaching tissue that includes a planetary gear assembly to increase or decrease rotational speed. 
       BACKGROUND 
       [0002]    Conventional surgical instruments that cut tissue generally include an outer tube and an inner member that rotates or translates axially within the outer tube. The outer tube and inner member may interact to create shear forces that cut tissue. In another variety of surgical instruments that cut tissue, the inner tube simultaneously rotates and translates axially within the outer tube. In the aforementioned prior art surgical instruments the inner tube rotates at approximately the same speed as the rotary driver. 
       SUMMARY 
       [0003]    In one aspect, an endoscopic tissue resecting system includes a reciprocating rotary surgical instrument for cutting and detaching tissue that includes a planetary gear assembly to increase or decrease rotational speed. 
         [0004]    According to some implementations, a rotary surgical instrument includes an endoscope and a resector. The resector includes a handpiece, a rotary driver (e.g. a motor), a drive assembly, and a cutting device (e.g., an elongated inner member and an elongated outer member). The rotary driver is positioned within the handpiece. The drive assembly may be positioned within the handpiece. The drive assembly is coupled at its distal end to the cutting device, and coupled at its proximal end to the rotary driver. The drive assembly is configured to cause the elongated inner member of the cutting device to rotate about an axis, move linearly along the axis in a first direction, switch directions, and move linearly back along the axis in a second direction opposite the first direction, etc. The cutting device is configured to cut and detach tissue during the rotation and the linear moving along the axis in the first direction. The drive assembly includes a helical member, a translation piece, and a planetary gear assembly. The helical member is coupled to the rotary driver (e.g., via a drive coupler and inner hub) and the planetary gear assembly. The planetary gear assembly is coupled to the cutting device. The translation piece is disposed in a groove of the helical member such that the rotary driving of the drive assembly results in the helical member moving linearly in the first direction, switching directions, moving linearly back in the second direction, switching directions back to the first direction, etc. This linear moving of the helical member occurs while the helical member is also rotating. The planetary gear assembly includes a fixed ring gear, one or more planet gears, and a sun gear. The fixed ring gear meshes with the planet gears, which in turn mesh with the sun gear. The sun gear is coupled to the elongated inner member of the cutting device such that rotary driving of the drive assembly results in the elongated inner member rotating at an increased or decreased speed relative to the rotary speed of the rotary driver. 
         [0005]    In some implementations, the planetary gear assembly (e.g., an epicyclic gearing assembly) can include a number of possible configurations of a fixed gear (e.g., a ring gear), a follower (e.g., one or more planet gears), and a driver (e.g., a sun gear) to achieve the desired. In some instances, the speed of the follower is greater than the speed of the driver. In other instances, the speed of the follower is less than the speed of the driver. Yet in other instances, the speed of the follower is equal to the speed of the driver. 
         [0006]    In one implementation, the planetary gear assembly includes a fixed ring gear, one or more planet gears (i.e., drivers) and a sun gear (i.e., follower). In another implementation, the planetary gear assembly includes a fixed sun gear, a ring gear (i.e., follower), and one or more planet gears (i.e., drivers). In yet another implementation, the planetary gear assembly includes a fixed ring gear, a sun gear (i.e., driver) and one or more planet gears (i.e., followers). In another implementation, the planetary gear assembly includes a ring gear (i.e., driver), a fixed sun gear, and one or more planet gears (i.e., followers). 
         [0007]    In some implementations, the elongated inner member rotates at a rotary speed about two times, about three times, about four times, about five times, about ten times, etc. greater than a rotary speed of the rotary driver (e.g., the motor). 
         [0008]    According to some implementations, the resector includes an inner hub and an outer hub. In such implementations, the inner hub is coupled (e.g., directly) to the rotary driver (e.g., a motor). The helical member is coupled to the inner hub and is located within the outer hub. The inner hub engages with the helical member, thereby coupling the helical member to the inner hub such that the helical member rotates with the inner hub while being free to translate (e.g., move linearly) relative to the inner hub. The helical member includes a helical groove configured to receive at least a portion of the translation piece therein. In some implementations, the helical groove includes a left-hand threaded helical channel, a right-hand threaded helical channel, or both. In some such implementations, the left-hand threaded helical channel and the right-hand threaded helical channel are blended at their ends to form a single continuous channel or groove. In some implementations, the translation piece includes a follower at least partially received within the helical groove and a sealing cap and/or clip positioned over the follower. The follower is free to swivel relative to the sealing cap. The follower has an arched bridge shape. The translation piece is coupled to the helical member such that the translation piece is at least partially disposed in the helical groove and swivels to follow the helical groove as the helical member rotates and reciprocates. 
         [0009]    According to some implementations, the outer hub houses therein the helical member and the planetary gear assembly, which is comprised of the ring gear, the planet gears, the sun gear, and a planetary gear carrier. The planet gears are rotary supported to stub shafts of the planetary gear carrier, which is coupled to the helical member such that the planetary gear carrier rotates with the helical member and the rotary driver (e.g., the motor). The cutting device is coupled to the planetary gear assembly such that the elongated inner member of the cutting device rotates and moves linearly. 
         [0010]    According to some implementations, the planetary gear assembly and helical member are not coupled. In some implementations, the planetary gear assembly and helical member may be housed in separate outer hubs. 
         [0011]    According to some implementations, the elongated inner member of the cutting device includes an implement having a chamfered cutting edge at a distal end of the elongated inner member. In some implementations, the chamfered cutting edge is a straight cutting edge. Alternatively, the chamfered edge is an angled cutting edge. 
         [0012]    According to some implementations, the cutting device includes an elongated outer member. In such implementations, the elongated inner member of the cutting device is received at least partially within the elongated outer member. The elongated outer member includes a cutting window disposed proximate to a tip of the elongated outer member. The cutting window is an opening in the elongated outer member configured to expose at least a portion of the elongated inner member to tissue. In some implementations, the cutting window has a U-shaped distal end and a saddle-shaped proximal end. The proximal or distal end of the cutting window can include a hook. 
         [0013]    The details of one or more implementations of the present disclosure are set forth in the description below and the accompanying drawings. Other features will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a perspective view of a tissue resecting system including an endoscope and a handpiece according to some implementations of the present disclosure; 
           [0015]      FIG. 2A  is an exploded perspective view of a resector of  FIG. 1 , including a drive assembly and a cutting device; 
           [0016]      FIG. 2B  is a partial assembled cross-sectional side view of the resector of  FIG. 2A ; 
           [0017]      FIG. 3A  is a partially exploded perspective view of a driving assembly of the resector of  FIGS. 2A and 2B ; 
           [0018]      FIG. 3B  is a partial cross-sectional view of a planetary gear assembly of the driving assembly of  FIGS. 2A and 2B ; 
           [0019]      FIG. 3C  is a perspective view of a planetary gear assembly of a resector in accordance with another embodiment; 
           [0020]      FIG. 3D  is a perspective view of a driving assembly of a resector in accordance with another embodiment; 
           [0021]      FIG. 4A  is a top plan view of an inner hub of the driving assembly of  FIGS. 2A and 2B ; 
           [0022]      FIG. 4B  is a cross-sectional side view of the inner hub of  FIG. 4A ; 
           [0023]      FIG. 4C  is a rear view of the inner hub of  FIG. 4A ; 
           [0024]      FIG. 4D  is front view of the inner hub of  FIG. 4A ; 
           [0025]      FIG. 5A  is a bottom plan view of a helical member of the driving assembly of  FIGS. 2A and 2B ; 
           [0026]      FIG. 5B  is a side view of the helical member of  FIG. 5A ; 
           [0027]      FIG. 5C  is a cross-sectional side view of the helical member of  FIG. 5B ; 
           [0028]      FIG. 5D  is a front view of the helical member of  FIG. 5A ; 
           [0029]      FIG. 5E  is a side view of a helical member in accordance with an another embodiment of a driving assembly. 
           [0030]      FIG. 6A  is bottom plan view of the outer drive hub of the driving assembly of  FIGS. 2A and 2B ; 
           [0031]      FIG. 6B  is a cross-sectional side view of the outer drive hub of  FIG. 6A ; 
           [0032]      FIG. 6C  is a front view of the outer drive hub of  FIG. 6A ; 
           [0033]      FIG. 7A  is a partially exploded perspective view of the driving assembly of  FIGS. 2A and 2B ; 
           [0034]      FIG. 7B  is an assembled, partial bottom plan view of the driving assembly of  FIG. 7A   
           [0035]      FIG. 7C  is a perspective view of a follower of the driving assembly of  FIGS. 2A and 2B  engaging a first helical channel; 
           [0036]      FIG. 7D  is a perspective view of the follower engaging a second helical channel; 
           [0037]      FIG. 8A  is a front view of the follower of the driving assembly of  FIGS. 2A and 2B ; 
           [0038]      FIG. 8B  is a side cross-sectional view of the follower of  FIG. 8A ; 
           [0039]      FIG. 8C  is top plan view of the follower of  FIG. 8A ; 
           [0040]      FIG. 9A  is a top plan view of a cap of the driving assembly of  FIGS. 2A and 2B ; 
           [0041]      FIG. 9B  is side cross-sectional view of the cap of  FIG. 9A ; 
           [0042]      FIG. 10A  is a partial top plan view of an elongated outer member of the cutting device of the cutting device of  FIGS. 2A and 2B ; 
           [0043]      FIG. 10B  is a partial side view of the elongated outer member of  FIG. 10A ; 
           [0044]      FIG. 10C  is a perspective view of the elongated outer member of  FIG. 10A ; 
           [0045]      FIG. 11A  is a partial top plan view of an elongated inner member of the cutting device of the cutting device of  FIGS. 2A and 2B ; 
           [0046]      FIG. 11B  is a perspective view of an elongated inner member in accordance with an another embodiment of the cutting device; 
           [0047]      FIG. 11C  is another perspective view of the elongated inner member of  FIG. 11B ; 
           [0048]      FIG. 12  is a partial side view illustrating the elongated inner member of  FIG. 11  moving relative to the elongated outer member of  FIGS. 10A and 10B  to cut and detach tissue. 
       
    
    
       [0049]    While the present disclosure is susceptible to various modifications and alternative forms, specific implementations have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that it is not intended to limit the present disclosure to the particular forms disclosed and illustrated, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit of the present disclosure. 
       DETAILED DESCRIPTION 
       [0050]    Referring to  FIG. 1 , a tissue resecting system  1  includes an endoscope  10  (e.g., a hysteroscope) and a handpiece  14 . The endoscope  10  includes an endoscope body  11  and an insert portion  12  that extends from the endoscope body  11  to a distal end of the endoscope  10 . The insert portion  12  is insertable into an organ (e.g., a uterus, a prostate, a bladder, etc.) of a patient for use in a tissue resecting procedure in the organ. The handpiece  14  includes a rotary driver  25  (e.g., motor) and a resector  13 . The handpiece  14  is received by the endoscope  10  to resect (e.g., cut, detach and remove) tissue from the organ. 
         [0051]    The endoscope  10  may also include other devices for use when conducting a tissue resecting procedure. For example, the endoscope  10  includes an observation port  16  configured to be coupled to a camera (not shown) and a light port  17  configured to be coupled to an illumination source (not shown). Together, the camera and the illumination source allow the operator to visualize and capture images from an area around the distal end of the endoscope  10 . It is understood, however, that the endoscope  10  is shown as an example, and that other similar devices (with fewer or more features) can be employed according to aspects of the present disclosure (e.g., to accommodate the resector  13 ). 
         [0052]    In some implementations, the endoscope  10  includes an inlet port  18  that receives fluid (e.g., saline, sorbitol, glycine, etc.) into the endoscope  10 . An inflow passageway  19  is formed in the endoscope  10  and extends from the inlet port  18  to an inflow opening  20  at the distal end of the endoscope  10 . The fluid flows from a fluid source (not shown), through the inlet port  18 , then the inflow passageway  19 , and then out of the inflow opening  20 , and into the organ at the distal end of the endoscope  10 . 
         [0053]    As shown in  FIG. 1 , the tissue resecting system  1  may include a footswitch  21  that activates and/or controls aspects of the handpiece  14 . For example, the footswitch  21  can be coupled to the handpiece  14 , via a flexible drive shaft  22 , to drive a pump (not shown) and/or to drive a cutting device  15  of the resector  13 . The tissue resecting system  1  may include a control unit (not shown) that activates and/or controls aspects of the handpiece  14 . For example, the control unit can be coupled to the handpiece  14 , via a cable, to drive the cutting device  15  of the resector  13 . 
         [0054]    As shown in  FIGS. 2A and 2B , the resector  13  includes the cutting device  15  and a driving assembly  100 . The driving assembly  100  includes an inner hub  130 , an outer hub  140 , a translation piece  145 , a helical member  150 , and a planetary gear assembly  205 . The handpiece  14  is disposed at a proximal end of the endoscope body  11 . The cutting device  15  of the resector  13  extends from the handpiece  14  and passes correspondingly through the endoscope body  11  and the endoscope insert portion  12 . At least a portion of the cutting device  15  is disposed beyond the distal end of the endoscope insert portion  12  to access tissue in the organ. 
         [0055]    The cutting device  15  includes an elongated outer member  310  and an elongated inner member  320  that performs tissue resection. The elongated outer member  310  is tubular with a hollow interior or lumen  311  ( FIG. 2A ). The elongated inner member  320  is tubular with a hollow interior or lumen  321  ( FIG. 2A ). As shown in  FIG. 2B , the elongated inner member  320  is at least partially received inside the hollow interior or lumen  311  of the elongated outer member  310 . In some implementations the elongated outer member  310  is attached (e.g., fixed) to the outer hub  140  via a cap  295  and/or a supporting tube  296  and does not move relative thereto. The elongated outer member  310  includes a tip  312 , which is blunt (e.g., the corners are rounded). The distal end of the outer member  310  defines a cutting window  330  through a wall  310   a  of the outer member  310 . The size (e.g., an inner diameter or an outer diameter) of outer member  310  is about 3 mm. In another embodiment, the size of the outer member  310  is about 2 mm. In another embodiment, the size of the outer member  310  is about 4 mm. For example, the size (e.g., an inner diameter or an outer diameter) of the outer member can be from about 1 mm to about 5 mm or from about 2 mm to about 4 mm. The elongated outer member  310  is sized such that it can receive the elongated inner member  320 . 
         [0056]    The inner hub  130  of the driving assembly  100  includes a drive coupler  120 . In some implementations, when the drive assembly  100  is positioned within the handpiece  14 , the drive coupler  120  couples and/or mounts to the rotary driver  25  positioned in the handpiece  14 . The rotary driver  25  ( FIG. 1 ) turns the drive coupler  120  causing the inner hub  130  and the helical member  150  to rotate about an axis (e.g., a central axis of the inner hub  130  and/or the helical member  150 ). The helical member  150  and the translation piece  145  are coupled together such that rotation of the helical member  150  causes linear movement of the helical member  150 , as described further below. 
         [0057]    As best shown in  FIG. 2B , the proximal end  151  of the helical member  150  is located within the inner hub  130  and the outer hub  140  during operation of the resector  13 . In some implementations, the distal end  152  of the helical member  150  includes a platen  153  that is located within the outer hub  140  during operation of the resector  13 . In some implementations, the platen  153  forms a multitude of receiving openings  153   a  configured to mate with a portion of the planetary gear assembly  205 . In some implementations, the platen  153  is a separate component, coupled to the helical member  150 . 
         [0058]    As best shown in  FIGS. 2A and 2B , the planetary gear assembly  205  includes a fixed ring gear  230 , planet gears  210 , a sun gear  220 , a lumen  223 , a planetary gear carrier  240 , stub shafts  245 , and platen  153 . As best shown in  FIG. 3B , the outer hub  140  includes a fixed ring gear  230  that meshes with the planet gears  210 , which then mesh with the sun gear  220 . The sun gear  220  is rotationally fixed to the lumen  223  ( FIG. 2A ), which is coupled to the elongated inner member  320  ( FIG. 3A ) such that rotation of the sun gear  220  and the lumen  223  at a first rotational speed causes rotation of elongated inner member  320  at the first rotational speed, which is increased or decreased relative to a second rotational speed of the rotary driver  25  (e.g., motor). The increased or decreased relative rotational speed is caused by the size and relationship between the fixed ring gear  230 , and the sun gear  220 . 
         [0059]    The stub shafts  245  extend between the planetary gear carrier  240  and the platen  153 . In some implementations, the stub shafts  245  are received in the receiving openings  153   a  of the platen  153 . The stub shafts  245  support the planet gears  210  in a rotational coupling such that each of the planet gears  210  can rotate about its respective stub shaft  245 . The planetary gear carrier  240  forms an opening  242  ( FIGS. 2A and 3A ) therethrough to permit the lumen  223  and/or a portion of the elongated inner member  320  to pass therethrough without significantly impacting rotation of the lumen  223  and/or the elongated inner member  320 . In some implementations, the opening  242  acts as a bearing surface for the lumen  223  to rotate. 
         [0060]    With reference to  FIGS. 3A and 3B , when the planetary gear assembly  205  is assembled and positioned within the outer hub  140 , the sun gear  220  is positioned to mesh with the planet gears  210 , which in turn mesh with the fixed ring gear  230 . As such, rotation of the helical member  150  about its central axis causes the platen  153  to rotate about the same central axis, which causes the planetary gear carrier  240  and the coupled stub shafts  245  to rotate about the same central axis. As the stub shafts  245  rotate about the central axis of the helical member  150 , the planet gears  210  (rotationally mounted to the stub shafts  245 ) and mesh with the fixed ring gear  230 , thereby causing each planet gear  210  to rotate about its respective central axis and about its respective stub shaft  245 . As the planet gears  210  are meshed with the sun gear  220 , such rotation of the planet gears  210  causes the sun gear  220  to rotate about its central axis, which coincides with the central axis of the helical member  150 . 
         [0061]    Referring to  FIG. 3C , planetary gear assembly  205 A is positioned within outer hub  140 A. Sun gear  220 A is positioned to mesh with planet gears  210 A, which in turn mesh with the fixed internal ring gear (not shown). Planet gears  210 A are connected to sluff chamber  130  (i.e., an inner hub) via stub shafts  245 A. As the stub shafts  245 A rotate about the central axis of the helical member  150 A, the planet gears  210 A (rotationally mounted to the stub shafts  245 A) and mesh with the fixed ring gear  230 A, thereby causing each planet gear  210 A to rotate about its respective central axis and about its respective stub shaft  245 A. As the planet gears  210 A are meshed with the sun gear  220 A, such rotation of the planet gears  210 A causes the sun gear  220 A to rotate about its central axis, which is part of helical member  150 A. As such, rotation of sun gear  220 A about its central axis causes the helical member  150 A to rotate about the same central axis. A follower (not shown) allows the helical member  150 A to move laterally in both directions, along the axis of rotation. 
         [0062]    Referring to  FIG. 3D , planetary gear assembly  205 B has a sluff chamber  130 A (i.e., an inner hub) and a sun gear  220 B. A helical gear  210 B is formed on the sluff chamber  130 A. The pattern on helical gear  210 B can be a reversing basis such that axial motion (e.g., lateral movement) of the sun gear  220 B connected to inner member  320 B. A wall (not shown) at the proximal and distal ends of the sluff chamber can assist the sun gear  220 B to move along the helical gear  210 B on sluff chamber  130 A. Other mechanisms, such as a cam, could be implemented in the driving assemblies described herein to create axial motion. 
         [0063]    Referring to  FIGS. 4A-4D , the inner hub  130  includes the drive coupler  120 , a lumen  136 , an aspiration opening  132 , and a flat or key  134 . The drive coupler  120  extends from the proximal end of the inner hub  130  and mounts in the rotary driver  25 . Debris from the cutting device  15  is aspirated through the aspiration opening  132 . The flat  134  is coupled with a corresponding feature or flat  154  of the helical member  150  ( FIG. 5B ) so that rotation of the inner hub  130  causes the helical member  150  to rotate while allowing the helical member  150  to move axially relative to the inner hub  130  (e.g., the non-rotational feature  154  slides axially along/against the non-rotational feature  134 ). 
         [0064]    Referring to  FIGS. 5A-5D , the helical member  150  of the driving assembly  100  is formed in a generally tubular shape with a through lumen  159 . The helical member  150  includes the non-rotational feature  154 , two helical channels  156 ,  158  disposed thereon, and the platen  153  located at the distal end  152 . In some implementations, the platen  153  is a separate component, coupled to the helical member  150 . As shown in  FIG. 5B , the flat  154  is located near the proximal end  151  of the helical member  150  to engage with the corresponding feature  134  of the inner hub  130 . 
         [0065]    The two helical channels  156 ,  158  are disposed on a distal portion of the exterior surface of the helical member  150 . One helical channel  156  is right-hand threaded; the other helical channel  158  is left-hand threaded. The pitch of each of the helical channels  156 ,  158  may be constant and/or variable, and each of the helical channels  156 ,  158  may have the same, or similar, pitch, or different pitches. In some implementations where the pitches of the helical channels  156 ,  158  are different, the helical member  150  is configured to move linearly in a first direction generally at a first linear speed and further configured to move linearly in a second opposite direction generally at a second linear speed that is different from the first linear speed. The helical channels  156 ,  158  are smoothly blended together at their ends to form a continuous groove so that there is a smooth transition from one helical channel to the other helical channel. 
         [0066]    Referring to  FIG. 5E , in an alternative implementation, the helical member  150 A is formed in a generally tubular shape with a through lumen  159 A. The helical member  150 A includes the rotational feature  154 A, one helical channel  156 A disposed thereon, and the platen  153 A located at the distal end  152 . In some implementations, the platen  153 A is a separate component, coupled to the helical member  150 A. As shown in  FIG. 5E , the rotational feature  154 A is located near the proximal end  151  of the helical member  150 A to engage with the corresponding feature  134  of the inner hub  130 . Rotational feature  154 A is essentially a helix with a one helical cut. This is an alternative embodiment to a dual pitch helical cuts embodiment. 
         [0067]    The helical member also includes a spring  190 . Spring  190  is disposed on spring mount  191  having a distal end and a proximal end. The spring  190  allows for quicker retraction of the cutting tube. At the distal end and the proximal end of the spring mount  191  are spring stops  192 ,  193 . The helical member  150 A with spring  190  can retract the helical member  150 A and the elongated inner member  320  after cutting has occurred. 
         [0068]    The follower (not shown) in this embodiment can be a ball follower that can ride in the helical groove as the tube cuts through tissue but allows the helix to quickly retract by allowing the ball follower to ride in an axial groove that connects the start and end points of the helical cut. 
         [0069]    Referring to  FIGS. 6A-6C , the outer hub  140  of the driving assembly  100  does not move relative to the handpiece  14 . The outer hub  140  encompasses the helical member  150 , the follower  145   a , the planetary gear assembly  205  and part of or the entirety of the inner hub  130 . Referring back to  FIGS. 2A and 2B , the outer hub  140  is formed of hard plastic and does not move relative to the handpiece  14 . The outer hub  140  is molded as a single monolithic component as shown in  FIG. 2A ; however, in some alternative implementations, the outer drive hub  140  comprises two or more individual parts coupled together (e.g., two parts, three parts, etc.). During operation of the resector  13 , the outer hub  140  houses therein the platen  153 , the fixed ring gear  230 , the planet gears  210  (two or more in number), the sun gear  220 , and the planetary gear carrier  240 . As shown, the fixed ring gear  230  is formed integrally with the outer drive hub  140  by molding it into the outer drive hub  140 . Alternatively, the fixed ring gear  230  can be a separate component that is coupled to the outer drive hub  140 . While three planet gears  210  are illustrated, any number of planet gears  210  can be included in the planetary gear assembly  205 , such as, for example, one, two, three, four, five, etc. 
         [0070]    Referring to  FIG. 7A , the follower  145   a  works in conjunction with the helical member  150 , which includes the two helical channels  156 ,  158  and the flats  134 ,  154  that couple the inner hub  130  and the helical member  150  in a non-rotational fashion (e.g., the inner hub  130  and the helical member  150  do not rotate relative to one another), the rotary driver  25  only needs to rotate in one direction and does not require reversal of its rotational direction upon the follower  145   a  reaching the end of one of the helical channels  156 ,  158 . Referring to  FIGS. 9A and 9B , the cap  145   b  of the translation piece  145  covers the follower  145   a  to provide a seal to allow sufficient suction to remove aspirated debris. Also, the cap  145   b  is a separate piece from the follower  145   a  in order to allow the follower  145   a  to swivel (e.g., rotate) relative to the cap  145   b.    
         [0071]    Referring to  FIGS. 8A-8C , the follower  145   a  includes a cylindrical head  145   a   1  and two legs  145   a   2 . As shown in  FIGS. 7B-7D , the legs  145   a   2  form an arch and rest in the helical channels  156 ,  158  formed in the distal portion of the exterior surface of the helical member  150 . The arch of the legs  145   a   2  is dimensionally related to the diameter described by the helical channels  156 ,  158  of the helical member  150 . 
         [0072]    Referring particularly to  FIGS. 7C and 7D , as the helical member  150  and the inner hub  130  are mechanically driven by the rotary driver  25 , the follower  145   a  ( FIGS. 8A and 8B ) follows the helical channels  156 ,  158 , swiveling as the follower  145   a  smoothly transitions from helical channel  156  to helical channel  158  at the end of the distal portion of the helical member  150  having the helical channels  156 ,  158 . The coupling of the follower  145   a  to the helical channels  156 ,  158  causes the helical member  150  to move linearly. Thus, the elongated inner member  320  of the cutting device  15 , which is coupled to the helical member  150  via the planetary gear assembly  205  and the platen  153 , also rotates and moves linearly to cut, detach and remove tissue. 
         [0073]    The planetary gear carrier  240  is formed with the opening  242  at its approximate center. The sun gear  220  is formed in a tubular shape with the through lumen  223 . The elongated inner member  320  is disposed within the distal end of the sun gear  220  and fixed therein, for example, by epoxy, injection-molded, or welding or over-molded plastic such that the elongated inner member  320  does not move relative to the sun gear  220  and/or the lumen  223 . The proximal end of the lumen  223  of the sun gear  220  is fluidly coupled to the lumen  159  of the helical member  150 , such that the sun gear  220  rotates freely from the helical member  150 , but fluid and/or tissue can be aspirated through the lumen  223  of the sun gear  220  and to the lumen  159  of the helical member  150 . The elongated outer member  310  is coupled to the cap  295  and/or the supporting tube  296  located near the distal end of the outer drive hub  140 , and may be fixed thereto using, for example, epoxy, glue, an insert molding, overmolding, etc. 
         [0074]    According to some implementations of the present disclosure, during operation of the tissue resecting system  1 , the rotary driver  25  of the handpiece  14  turns the drive coupler  120  causing the inner hub  130 , the helical member  150 , and the planetary gear carrier  240  to rotate at the same first rotational speed or at the same first rpm (e.g., a first number of revolutions per minute). As described herein, the rotation of the planetary gear carrier  240  causes the planet gears  210  to mesh with the fixed ring gear  230  and rotate about the stub shafts  245  at a second rpm that is greater or less than the first rpm of the rotary driver  25 , the inner hub  130 , the helical member  150 , and the planetary gear carrier  240 . As each planet gear  210  rotates, it meshes with the sun gear  220 , causing the sun gear  220  and the elongated inner member  320  to rotate at a third rpm that is greater or less than the second rpm. 
         [0075]    According to some implementations, the rotary driver  25  operates at about 2,500 rpm and the planetary gear assembly  205  has a gearing ratio of about 4:1. In such implementations, the sun gear  220  and the elongated inner member  320  operate at about 10,000 rpm. According to some other implementations, the rotary driver  25  operates at about 1,000 rpm and the planetary gear assembly  205  has a gearing ratio of about 4:1. In such implementations, the sun gear  220  and the elongated inner member  320  operate at about 4,000 rpm. According to yet some other implementations, the rotary driver  25  operates at about 1,000 rpm and the planetary gear assembly  205  has a gearing ratio of about 10:1. In such implementations, the sun gear  220  and the elongated inner member  320  operate at about 10,000 rpm. 
         [0076]    According to yet some further implementations, the rotary driver  25  operates at about 10,000 rpm and the planetary gear assembly  205  has a gearing ratio of about 1:4. In such implementations, the sun gear  220  and the elongated inner member  320  operate at about 2,500 rpm. According to yet some further implementations, the rotary driver  25  operates at about 10,000 rpm and the planetary gear assembly  205  has a gearing ratio of about 1:10. In such implementations, the sun gear  220  and the elongated inner member  320  operate at about 1,000 rpm. Various other speeds are contemplated wherein the gearing ratio is between about 10:1 to about 1:10. For example the gearing ratio (e.g., the ratio of the sun gear to the rotary driver (ring gear) can be about 10:1, about 9:1, about 8:1, about 7:1, about 6:1, about 5:1, about 4:1, about 3:1, about 2:1, about 1:1, about 1:2, about 1:3, about 1:4, about 1:5, about 1:6, about 1:7, about 1:8, about 1:9, or about 1:10. 
         [0077]    As best shown in  FIGS. 2A and 2B , the planetary gear assembly  205  is downstream from the helical member  150  relative to the rotary driver  25 . As such, the rotary driver  25  is able to rotate the helical member  150  at a first rotational speed and the planetary gear assembly  205  is able to gear-up or gear-down the first rotational speed to a third rotational speed of the elongated inner member  320  that is faster or slower than the first rotational speed (e.g., four times faster, six times faster, ten times faster, etc.). Further, because the helical member  150  is upstream from the planetary gear assembly  205 , the velocity and/or acceleration of the linear movement of the helical member  150  and of the elongated inner member  320  is not impacted by the planetary gear assembly  205 . That is, the linear velocity and linear acceleration of the helical member  150  is the same as the linear velocity and linear acceleration of the elongated inner member  320 . 
         [0078]    As shown in  FIGS. 10A-10C , the cutting window  330  has a generally oblong shape. The proximal end  331  of the cutting window  330  is saddle shaped that can form a hook  335  and the distal end  332  of the cutting window  330  is U-shaped that can form a hook. The distal end  332  is chamfered to provide a sharp edge. In some implementations, the hook  335  of cutting window  330  can have a sharpened edge to be used to pierce targeted tissue and hold the tissue as the elongated inner member  320  cuts the tissue The cutting window  330  has a length, L, over which the inner member  320  can be exposed. In other implementations, the entire cutting window  330  can have a sharped edge to aid in the piercing of targeted tissue. 
         [0079]      FIG. 11A  shows that the elongated inner member  320  is generally tubular with the hollow interior or lumen  321 . Aspiration of debris (e.g., cut and detached tissue and/or fluid) occurs through the hollow interior or lumen  321  of the elongated inner member  320 , through the lumen  223  of the sun gear  220 , and through the lumen  159  of the helical member  150  to the aspiration opening  132  of the inner hub  130 . The distal end  322  of the elongated inner member  320  is chamfered to a sharp cutting edge  323  for cutting tissue. The cutting surface of the distal end  322  of the elongated inner member  320  shears tissue as the elongated inner member  320  rotates and moves linearly across the length, L, of the cutting window  330  of the elongated outer member  310 . The distal end  322  or tip of the elongated inner member  320  is substantially flat. 
         [0080]    Referring to  FIGS. 11B and 11C , the distal end  322  of the elongated inner member  320  has a wave form tip. The wave form tip  322  has a sharpened edge that allows the elongated inner member  320  to hold onto target tissue while the cutting surface holds and slices through the tissue. Some embodiments have a single bevel edge. It is challenging to machine an inner bevel with a hard material such as 440C SS. This geometry can be created using wire-EDM and allow the device to have a double bevel edge. 
         [0081]    For example, referring to  FIG. 12 , the cutting device  15  is placed tangentially against targeted tissue  500  such that the cutting window  330  exposes the elongated inner member  320  to the tissue  500 . As the elongated inner member  320  rotates and moves linearly, as shown by arrows A and B, respectively, the tissue  500  within the cutting window  330  catches on the hook  335  and then the sharp cutting edge  323  of the elongated inner member  320  shears the tissue  500  as the elongated inner member  320  advances linearly in the direction of Arrow A. The cut is completed as the cutting sharp edge  323  of the elongated inner member  320  advances beyond the distal end  332  of the cutting window  330  within the elongated outer member  310 . 
         [0082]    A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made. For example, instead of a double helical channel, the helical member  150  may include a single helical channel with a retractable follower and spring, or possibly, attraction and repelling forces of magnets or a solenoid could enable the rotating and linear movements. Also, alternatively, the elongated inner and outer members  320 ,  310  may have a cross-sectional shape other than circular. Additionally, the shape of the hook  335  of the elongated outer member  310  may be modified in order to improve grasping of the tissue  500  or grasping a larger volume of tissue  500 . Accordingly, other implementations are within the spirit and scope of the present disclosure as recited in the following claims. 
         [0083]    A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made. For example, instead of a double helical channel, the helical member may include a single helical channel with a retractable follower and spring, or possibly, attraction and repelling forces of magnets or a solenoid could enable the rotating and reciprocating movements. Also, alternatively, the inner and outer members may have a cross-sectional shape other than circular. Additionally, the shape of the hook of the outer member may be modified in order to improve grasping of the tissue or grasping a larger volume of tissue. Accordingly, other implementations are within the scope of the following claims.