Patent Abstract:
A surgical instrument includes a cutting member with an implement for cutting tissue, and a drive coupled to the cutting member to simultaneously rotate and translate the cutting member in response to a force applied to the drive. A method of cutting tissue includes positioning an outer member such that tissue is located within the outer member, engaging the tissue with an inner member, and simultaneously rotating 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 the tissue. The inner member is mechanically driven to undergo simultaneous rotation and translation.

Full Description:
TECHNICAL FIELD 
     This invention relates to rotary cutting surgical instruments, and more particularly, to a reciprocating rotary surgical instrument for cutting semi-rigid tissue. 
     BACKGROUND 
     Conventional arthroscopic surgical instruments 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. This type of cutting is generally used to cut soft tissue, such as muscle, ligaments, and tendons. 
     SUMMARY 
     In one aspect, a surgical instrument includes a cutting member with an implement for cutting tissue, and a drive coupled to the cutting member to simultaneously rotate and translate the cutting member in response to a force applied to the drive. 
     One or more of the following features may be included in the surgical instrument. The drive is configured such that the cutting member reciprocates. The drive includes a drive member attached to the cutting member. The drive member includes a helical groove. The drive includes a translation piece disposed in the groove such that rotary driving of the drive member results in simultaneous reciprocation of the drive member relative to the translation piece. 
     In the illustrated embodiment, the drive includes an inner drive hub coupled to the drive member. The inner drive hub defines a slot and the drive member includes a key received in the slot rotary coupling the drive member to the inner drive hub such that the drive member rotates with the inner drive hub while being free to translate relative to the inner drive hub. The helical groove includes a left-hand threaded helical channel. The helical groove includes a right-hand threaded helical channel. The cutting member is attached to the drive member to move rotatably and axially with the member. 
     The implement is a chamfered cutting edge at a distal end of the cutting member. The chamfered edge is a straight cutting edge. Alternatively, the chamfered edge is an angled cutting edge. 
     The instrument includes an outer tubular member. The cutting member is received within the outer member. The outer member includes a cutting window disposed proximate to a tip of the outer member. The cutting window is an opening in the outer member exposing the cutting member to tissue. The cutting window has a U-shaped proximal end and a saddle-shaped distal end. The saddle-shaped distal end of the cutting window includes a hook. 
     The translation piece includes a follower received within the groove and a sealing cap 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 drive member such that the translation piece is disposed in the helical groove and swivels to follow the helical groove as the drive member rotates. 
     In another aspect, a method of cutting tissue includes positioning an outer member such that tissue is located within the outer member, engaging the tissue with an inner member received within the outer member, and simultaneously rotating and translating the inner member to cut the tissue. One or more of the following features may be included. The translating is reciprocating. The outer member is oriented tangentially to the tissue. 
     In another aspect, a method of cutting tissue includes providing a surgical instrument having an outer member and an inner member received within the outer member for movement relative to the outer member, and applying a tangential cutting force to the tissue with the inner member to mechanically cut the tissue. 
     In another aspect, a method of cutting tissue includes applying a tangential cutting force to tissue with a member, and mechanically driving the member to undergo simultaneous rotation and translation. The method may include that the translation is reciprocation. 
     The cutting edge of conventional arthroscopic surgical instruments, such as rotary shears, have difficulty initiating a cut into semi-rigid tissue tend to bounce away from the tissue. Toothed edge geometry somewhat ameliorates this problem because the “teeth” attempt to pierce the tissue to initiate a cut. However, the efficiency of using “teeth” is limited and the limitations are more evident when cutting large volumes of semi-rigid tissue, such as meniscus or intrauterine fibroid tissue. The simultaneous rotating and reciprocating inner member of the surgical instrument of the invention overcomes these difficulties. The tangential approach to the tissue in the method of the invention limits the tendency of the instrument to bounce away from the tissue. In particular, the instrument and method provide a higher resection rate to shorten procedure length, during, e.g., fibroid and polyp resection. 
     The details of one or more implementations are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1A  is a side view and  1 B is a cross-sectional view taken along  1 B— 1 B in  FIG. 1A  of a reciprocating rotary surgical instrument. 
         FIG. 2A  is a top view,  FIG. 2B  is a cross-sectional view taken along  2 B— 2 B in  FIG. 2A ,  FIG. 2C  is a distal end view, and  FIG. 2D  is a proximal end view of the inner drive hub of the reciprocating rotary surgical instrument of  FIG. 1 . 
         FIG. 3A  is a top view,  FIG. 3B  is a side view,  FIG. 3C  is a cross-sectional view taken along  3 C— 3 C in  FIG. 3A , and  FIG. 3D  is a proximal end view of the helical member of the reciprocating rotary surgical instrument of  FIG. 1 . 
         FIG. 4A  is a top view,  FIG. 4B  is a cross-sectional view taken along  4 B— 4 B in  FIG. 4A , and  FIG. 4C  is a distal end of the outer hub of the reciprocating rotary surgical instrument of  FIG. 1 . 
         FIG. 5A  is an exploded view,  FIG. 5B  is a partial cutaway view, and  FIGS. 5C and 5D  are side views of the translation piece and the helical member of the surgical instrument of  FIG. 1 . 
         FIG. 6A  is a side view,  FIG. 6B  is a cross-sectional view taken along  6 B— 6 B in  FIG. 6A , and  FIG. 6C  is a top view of the follower of the translation piece of the reciprocating rotary surgical instrument of  FIG. 1 . 
         FIG. 7A  is a top view and  FIG. 7B  is a cross-sectional view taken along  7 B— 7 B of  FIG. 7A  of the cap for the follower of the translation piece of the reciprocating rotary surgical instrument of  FIG. 1 . 
         FIG. 8A  is a top view and  FIG. 8B  is a side view of the outer member of the reciprocating rotary surgical instrument of  FIG. 1 . 
         FIG. 9  is a side view of the inner member of the reciprocating rotary surgical instrument of  FIG. 1 . 
         FIG. 10  illustrates a reciprocating rotary surgical instrument of  FIG. 1  in use to cut tissue. 
         FIG. 11  is a side view of an alternate implementation of the inner member of a reciprocating surgical instrument. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     As shown in  FIGS. 1A and 1B , a cutting device  100  includes a driving end  110  and a cutting end  190 . The driving end  110  is located at the proximal end of the cutting device  100 . The cutting end  190  is located at the distal end of the cutting device  100 . 
     At the driving end  110 , there is an inner drive hub  130  with a drive coupler  120 , and an outer hub  140 . The drive coupler  120  mounts into a rotary driver (not shown), which turns the drive coupler  120  causing a helical member  150  and the inner drive hub  130  to rotate. For instance, the rotary driver is Dyonics Power Handpiece, No. 725355. The inner drive hub  130  with the drive coupler  120  is, for example, a component of Smith &amp; Nephew disposable arthroscopic surgical instrument, No. 7205306. The helical member  150  is located within the inner drive hub  120  and the outer hub  140 . The helical member  150  and a translation piece  145  are coupled together such that rotation of the helical member  150  causes linear translation of the helical member  150 , as described further below. 
     The cutting device  100  includes an elongated inner member  185  and an elongated outer member  186 , as shown in  FIG. 1B . The inner member  185  is tubular with a hollow interior  184 . The inner member  185  is fixed to the helical member  150  for axial and rotary motion therewith. 
     The outer member  186  is also tubular with a hollow interior  187 . The inner member  185  is received inside the outer member  186 . The outer member  186  is fixed to the outer hub  140  and does not move. The outer member  186  includes a tip  188 , which is blunt, i.e., the corners are rounded. At the cutting end  190 , the outer member  186  defines a cutting window  170  through a wall  186   a  of the outer member  186 . 
     Referring to  FIGS. 2A–2D , the inner drive hub  130  includes the drive coupler  120 , a lumen  136 , an aspiration opening  132 , and a slot  134 . The drive coupler  120  extends from the proximal end of the inner drive hub  130  and mounts in the rotary driver. Debris from the cutting end  190  of the cutting device  100  is aspirated through the aspiration opening  132 . The slot  134  is disposed in a wall  131  of the inner drive hub  130 . The slot  134  is like a track along one side of the inner drive hub  130 . The slot  134  of the inner drive hub  130  is coupled with a key  152  of the helical member  150  (see  FIG. 4B ) so that rotation of the inner drive hub  130  causes the helical member  150  to rotate while allowing the helical member  150  to move axially relative to the inner drive hub  130 , e.g., the key  152  axially slides along the slot  134 . 
     Referring to  FIGS. 3A–3D , the helical member  150  of the cutting device  100  is formed of a lubricious material in a tubular shape with a through lumen  159 . The inner member  185  is disposed within the helical member  150  and fixed therein, for example, by epoxy, injection-molded, or over-molded plastic. 
     The helical member  150  includes the key  152  and two helical channels  156 ,  158  disposed thereon. As shown in  FIG. 3B , the key  152  is shaped like a fin and is located at the proximal end of the helical member  150 . The key  152  mates with the slot  134  of the inner drive hub  130 . 
     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 the helical channels may be different or the same. The length of the distal portion of the helical member  150  with helical channels  156 ,  158  is longer than the length of the cutting window  170 . 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 at each end of the distal portion of the helical member  150 . 
     The helical member  150  and the inner drive hub  130  are mechanically driven by the rotary driver. The helical member  150  also moves in an axial direction, e.g., reciprocates, as a result of the interaction of the translation piece  145  with the helical channels  156 ,  158 , as described below. 
     Referring to  FIGS. 4A–4C , the outer hub  140  of the cutting device  100  is formed of hard plastic and does not move. An example of an outer hub is a component of Smith &amp; Nephew disposable arthroscopic surgical instrument, No. 7205306, modified with a cutout  144  for receiving the translation piece  145 . The cutout  144  is disposed within a wall of the outer hub  140 , for example, centrally, as in  FIG. 4B , and aligned with the helical member. The translation piece  145  is located in the cutout  144  of the outer hub  140 . 
     As shown in  FIG. 1B , the outer member  186  is disposed within the outer hub  140  and fixed therein by a coupling  144  using, for example, epoxy, glue, insert molding, or spin-welding. 
     Referring to  FIG. 5A , the translation piece  145  includes a follower  145   a  and a cap  145   b . Having the two helical channels  156 ,  158  in conjunction with the slot/key  134 ,  152  coupling of the inner drive hub  130  and the helical member  150 , the rotary driver only needs to rotate in one direction and does not require reversal of the rotational direction upon the translation piece  145  reaching the end of one of the helical channels  156 ,  158 . 
     Referring to  FIGS. 6A–6C , the follower  145   a  includes a cylindrical head  145   a   1  and two legs  145   a   2 . As shown in  FIGS. 5B–5D , the legs  145   a   2  form an arch and rest in the channels of the double helix  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 . 
     Referring particularly to  FIGS. 5C and 5D , as the helical member  150  and the inner drive hub  130  are mechanically driven by the rotary driver (not shown), the follower  145   a  follows the helical channels  156 ,  158 , swiveling as the follower  145   a  smoothly transitions from helical channel to helical channel  156 ,  158  at the ends 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 also translate. Thus, the inner member  185  simultaneously rotates and reciprocates to cut the tissue. 
     Referring to  FIGS. 7A and 7B , 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   b  to swivel. 
     As shown in  FIGS. 8A and 8B , the outer member cutting window  170  has a generally oblong shape. The proximal end  172  of the cutting window  170  is U-shaped and the distal end  173  has a saddle shape that forms a hook  174 . The distal end  173  is chamfered to provide a sharp edge. The hook  174  pierces the targeted tissue to hold the tissue as the inner member  185  cuts. Also, the shape of the cutting window  170  eliminates galling between the inner and outer members  185 ,  186 , and dulling of the cutting edge of the inner member  185 . 
     The cutting window  170  is disposed proximate to the tip  188  of the outer member  186 . The cutting window  170  exposes the inner member  185  over a length L. 
       FIG. 9  shows that the inner member  185  is generally tubular with hollow interior  187 . Aspiration of debris occurs through the hollow interior  187  of the inner member  185 , and through the lumen of the helical member to the aspiration opening  132  of the inner drive hub  130 . The distal end  183  of the inner member  185  is chamfered to a sharp edge  187  for cutting. The inner member  185  simultaneously rotates about its axis and translates along its axis to cut tissue. The cutting surface of the distal end  183  of the inner member  185  shears the tissue. For example, referring to  FIG. 10 , the cutting device  100  is placed tangentially against the targeted tissue such that the cutting window  170  exposes the inner member  185  to the tissue. As the inner member  185  rotates and translates, as shown by the arrows, the tissue within the cutting window catches on the hook  174  to initiate the cut and then the cutting edge  183  of the inner member  185  shears the tissue as the inner member  185  advances to cut the tissue. The cut is completed as the cutting edge  183  of the inner member  185  advances beyond the hook  174  of the cutting window  170  within the outer member  186 . 
       FIG. 11  shows an alternative implementation of the inner member. The distal end  283  of the inner member  285  may be angled to a chamfered point so that the cut in the targeted tissue is initiated on one side and then extends across the width of the tissue. Similarly, when the cutting device is placed tangentially against the targeted tissue, the rotating and translating inner member  285  shears the tissue to be cut. 
     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.

Technology Classification (CPC): 0