Abstract:
The present disclosure describes an apparatus for tissue resection. At least one embodiment described herein provides a tissue resection system that includes a cutter that includes a blade system and a guide bar. The blade system is configured to be slidably coupled to said guide bar to permit said blade system to move relative to the guide bar, and said blade system comprises a chain of a plurality of links hingedly coupled together, wherein at least one said link comprising a cutting portion to cut tissue. The blade system has a thickness configured to generate a recessed pocket in the tissue. Of course, many alternatives, variations and modifications are possible without departing from this disclosure.

Description:
[0001]     This application claims the benefit under 35 USC 119(e) of U.S. Provisional Application Ser. No. 60/807,538, filed Jul. 17, 2006, the teachings of which are hereby incorporated by reference in their entirety. 
     
    
     FIELD  
       [0002]     The present disclosure describes a system and method for resecting tissue, for example, to create an implant site for an orthopedic repair component.  
       BACKGROUND  
       [0003]     One approach to repairing a damaged articular joint may involve resecting at least a portion of one or more damaged articular surfaces so that they may receive a repair component that may replace a portion, or all, of the articular joint. The repair component may be a prosthetic or a biological repair. Various tools and systems have been employed for resecting bone to create an implant site having a desired size and shape that may receive the repair component. Cutting tools, such as blade saws, burrs, osteotomes, and rotary drills may be used for resecting the desired portions of bone. These cutting tools may be used in conjunction with associated guides and templates, to create the desired implant sites.  
         [0004]     Creating relatively complicated implant sites may often require multiple cuts, which may require a variety of angles of approach. The conventional cutting tools may have limitations in terms of geometric capability. The various cuts that may be made to achieve a final desired implant site are properly aligned with respect to relevant anatomical structures, as well as with respect to the other cuts. Multiple cuts from varying angles of approach may require a larger access incision, or multiple large access incisions. Additionally, implementation and coordination of the various cutting guides and instruments may often be extremely complicated, requiring a high level of skill in the clinician and increasing the chance of error. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0005]     Features and advantages of the claimed subject matter will be apparent from the following detailed description of exemplary embodiments consistent therewith, which description should be considered with reference to the accompanying exemplary drawings, wherein:  
         [0006]      FIG. 1  schematically depicts an exemplary embodiment of a cutter consistent with the present disclosure;  
         [0007]      FIG. 2  schematically depicts an exemplary embodiment of a cutting guide consistent with the present disclosure;  
         [0008]      FIG. 3  shows another exemplary embodiment of a cutter and a cutting guide consistent with the present disclosure;  
         [0009]      FIG. 4  shows the exemplary cutter of  FIG. 3  including an exemplary drill as an external power source;  
         [0010]      FIG. 5  is a close-up view showing the coupling between the drill and the exemplary cutter of  FIG. 4 ;  
         [0011]      FIG. 6  depicts the exemplary cutter of  FIG. 3  in exemplary operation resecting a portion of a model of a tibial articular surface and adjacent bone;  
         [0012]      FIG. 7  is another view of the exemplary cutter of  FIG. 3  in exemplary operation resecting a portion of a model of a tibial articular surface and adjacent bone;  
         [0013]      FIG. 8  depicts the exemplary resected slot created in the model of the tibia using the exemplary cutter of  FIG. 3 ;  
         [0014]      FIG. 9  depicts an exemplary embodiment of a positioning system which may be used in connection with a resection system according to the present disclosure;  
         [0015]      FIGS. 10 and 11  depict the use of exemplary guide pins that may be used to establish an orientation and position relative to tissue to be resected;  
         [0016]      FIGS. 12 through 16  depict an exemplary cutting guide and the exemplary use thereof for resecting tissue; and  
         [0017]      FIG. 17  depicts an exemplary resected pocket created according to an exemplary embodiment of the system of the present disclosure. 
     
    
     DETAILED DESCRIPTION  
       [0018]     Generally, this disclosure describes a system and method that may be used for resecting tissue, for example, bone, cartilage, or other tissue. While this disclosure is generally set forth in the context of resecting an articular surface and adjacent bone, e.g., to create a pocket or recess for receiving a repair component implant, such as a prosthetic articular surface implant or biological repair, it should be understood that the system and method herein may be applicable to resecting any bone, cartilage, or other tissue, and should not be limited to the context of creating an implant site for a repair component replacing at least a portion of an articular surface.  
         [0019]      FIGS. 1 and 2  depict an exemplary tissue resection system according to one embodiment of this disclosure. The system may include a cutter  10  ( FIG. 1 ) and an exemplary cutting guide  12  ( FIG. 2 ). The cutting guide  12  may be removably secured relative to an anatomical feature. The cutter  10  may be slidably coupled to the cutting guide  12  to orient the cutter  10  with respect to tissue to be resected. Generally, the cutter  10  may be introduced along a path into an articular surface and/or surrounding bone or other tissue, and may be configured to resect or mill a slot in the articular surface and/or the surrounding or adjacent bone and/or other tissue. The path of the cutter  10  may be controlled, at least in part, by the cutting guide  12 . For example, the cutting guide  12  may control the position, orientation, and depth of the slot that may be created (milled) in the articular surface and/or bone or tissue.  
         [0020]     As shown in  FIG. 1 , the cutter  10  may include a blade system  14  for removing articular cartilage, bone, and/or other tissue, and a guide bar  16  at least partially supporting the blade system  14 . The blade system  14  may be slidably coupled to the guide bar  16  to permit the blade system  14  to move relative to the guide bar  16 . The blade system  14  may include a plurality of links, e.g.,  18   a,    18   b,  with each link  18   a,    18   b  being coupled to adjacent links to form an endless loop that may be flexible in at least one plane (to permit, for example, the links to rotate about the guide  16 ). For example, each of the plurality of links  18   a,    18   b  may be hingedly coupled to adjacent links having parallel hinge axes. At least a portion of the plurality of links  18   a,    18   b  may include an outwardly facing cutting portion  20  to cut the tissue to be resected. The cutting portions  20  may include one or more teeth, which may have sharpened and/or abrasive portions. According to an embodiment, the blade system  14  may be generally reminiscent of aspects of a chain saw and/or mortise saw chain. Alternatively, the blade system  14  may include an endless loop of flexible material, e.g., rubber, fabric, metal, etc., such as, for example, a belt, which may include at least one cutting portion  20 .  
         [0021]     The guide bar  16  may support the blade system  14  around at least a portion of the periphery  22  of the guide bar  16 . For example, the guide bar  16  may include a protruding rib  24  disposed around at least a portion of the periphery of the guide bar  16 . At least a portion of the rib  24  may be received in a complementary groove  26 , indicated by broken line, or recess in at least one link  18   a,    18   b  of the blade system  14 . In other embodiments, the guide bar  16  may include a peripheral groove or channel extending around at least a portion of the guide bar  16 . At least a portion of the blade system  14 , e.g., at least a portion of one or more links  18   a,    18   b,  including the link itself or a protrusion or portion thereof, may be at least partially disposed in the groove.  
         [0022]     The cutter  10  may include a drive mechanism  28  to drive the blade system  14  to travel around the perimeter of the guide bar  16 . The drive mechanism  28  may include a sprocket, drive wheel, etc., configured to engage at least a portion of the plurality of links  18   a,    18   b.  In one embodiment, the drive mechanism  28  may be configured for rotation about an axis generally perpendicular to a plane of the guide bar  16 . A drive axle  29  may be associated with the drive mechanism  28  so that an external power source, such as a drive motor, hand drill, etc., may be coupled to and may rotatably drive the drive mechanism  28 . Alternatively, the cutter  10  may include an integral power source for rotating the drive to drive the blade system  14  around the perimeter of the guide bar  16 .  
         [0023]     In other embodiments, the blade system  14  may not be formed as an endless loop traveling around the guide bar  16 . For example, the blade system  14  may include a flexible member having respective opposed ends and including at least one cutting portion  20 . The flexible member may be disposed around at least a portion of the perimeter of the guide bar  16  and may be configured for oscillating, or back-and-forth, movement around at least a portion of the perimeter of the guide bar  16 , rather than movement in only a single direction. Of course, a blade system configured as an endless loop may also be susceptible to an oscillating mode of operation. Various other configurations may also be suitably employed in connection with a cutter  10  of the present disclosure. The cutter  10  may also include, for example, a tensioning screw  30  for controlling the tension of the blade system  14 , a lubricating systems (not shown), a gear train (not shown—e.g., associated with the drive portion  28 , etc.).  
         [0024]     As shown in  FIG. 2 , the cutting guide  12  may include a longitudinal member  39  and a locating member  38 . The locating member  38  may be disposed at an angle relative to the longitudinal member  39 , to provide orientation of the longitudinal member  39  with respect to tissue to be resected. To this end, the cutting guide  12  may be configured to be positioned relative to an articular surface, or tissue, to be resected and to constrain or control the movement of the cutter  10  relative to the articular surface, or tissue, to be resected. In this embodiment, the cutting guide  12  may be oriented relative to the articular surface, or bone/tissue, to be resected using the screws  32 ,  34  to maintain the cutting guide  12  in selected orientation. The cutting guide  12  may be removably affixed relative to the articular surface, or bone, using at least one screw  32  and/or  34  that may be coupled to the locating member  38 .  
         [0025]     The cutting guide  12  may include one or more guide portions configured to control the movement of the cutter  10  relative to the cutting guide  12 . As shown in  FIG. 2 , the guide portions may include at least one protrusion, such as bosses  40 ,  42 , that may be positioned along the longitudinal member  39 . The bosses  40 ,  42  may be configured to be at least partially received in a complementary slot  44  defined in the guide bar  16  and may slidably couple the guide bar  16  to the longitudinal member  39 . The interaction of the bosses  40 ,  42  of the cutting guide  12  and the slot  44  in the guide bar  16  may control the path of the cutter  10  and the depth of the resection. For example, when the two bosses  40 ,  42  are at least partially received in the slot  44 , the trajectory, or path of movement, of the cutter  10  may be constrained to an axis of the slot  44 . Similarly, the travel of the cutter  10 , i.e., the depth of resection, may be constrained by the length of the slot  44  relative to the spacing of the bosses  40 ,  42 . The length of the slot  44  relative to the spacing of the bosses  40 ,  42  may be adjustable to allow the depth of resection to be varied. For example, an adjustable obstruction, e.g., a screw, may be disposed relative to the slot  44  to control the travel of the cutter  10  relative to the cutting guide  12 . Additionally, the cutter  10  may be biased toward a retracted position, i.e., a position away from the tissue to be resected, e.g., by a spring  46  disposed in the slot  44 .  
         [0026]      FIGS. 3-8  depict another exemplary embodiment of a resection system consistent with the present disclosure. Similar to the previous embodiment, the cutter  102  may generally include a blade system that may be the form of a linked cutting chain  106  in which at least a portion of the links may include teeth  108 . The blade system may be configured to be slidably coupled to the guide bar  110  to permit the blade system to move relative to the guide bar  110 . The cutting chain  106  may be disposed around at least a portion of a guide bar  110 . The guide bar  110  may include a peripherally extending rib  112  which may be received in a cooperating groove defined in at least a portion of the links that may make up the cutting chain  106 . The cutting chain  106  may be driven around the guide bar  110  by a drive sprocket  114 , which may engage the cutting chain  106 . The cutter  102  may further include a base member  121  that may be coupled to the guide bar  110 . The cutter  102  may further include a handle  116 , which may facilitate moving the cutter  102 , e.g., for advancing the cutter  102  into tissue to be resected, such as cartilage, bone or other tissue.  
         [0027]     The cutting guide  104  may include an alignment portion such as a longitudinal member  120  and may further include a locating member  118  that may be disposed at an angle to the longitudinal member  120 . The locating member  118  may be used to orient the longitudinal member  120  relative to tissue to be resected. According to an embodiment, the cutting guide  104  may be removably secured to a bone, e.g., a portion of which is to be resected. For example, the locating member  118  may be clamped, or temporarily screwed, to the bone being resected. The longitudinal member  120 , which may be directly or indirectly coupled to the cutter  102 , may, at least in part, guide the movement of the cutter  102  relative to the tissue to be resected. For example, the longitudinal member  120  may be slidably coupled to the base member  121  to position the cutter  102  relative to the tissue to be resected.  
         [0028]     In an embodiment, the cutter  102  may be slidably coupled to the cutting guide  104 , e.g., via the longitudinal member  120 . For example, the longitudinal member  120  may be at least partially received in a slot, e.g., slot  119  in  FIG. 5 , or other aspect, of a base member of the cutter  102 , e.g., base member  121  of  FIG. 5 . In such an embodiment, the cutter  104  may travel along the path, or trajectory, defined by the longitudinal member  120 . The cutter  102  may be restrained against movement other than axial movement along the axis defined by the longitudinal member  120 . For example, the cutter  102  may be prevented from one or more of moving transversely, rotating, or yawing relative to the longitudinal member  120 . As used herein, rotating relative to the longitudinal member  120  may be understood to mean rotation about the axis defined by the longitudinal member  120 , and yawing may be understood to mean rotation in any plane that contains the axis defined by the longitudinal member  120 . In other embodiments, the cutter  102  may be provided with greater freedom of movement than simple axial displacement along the axis of the longitudinal member  120 . For example, the cutter  102  may be permitted to experience at least some degree of transverse translation, rotation, and/or yaw. In related embodiments, the greater freedom of movement may be, at least in part, restricted to a defined range of movement.  
         [0029]     As shown, for example, in  FIGS. 4 and 5 , the cutting chain  106  of the cutter  102  may be driven by an external power source, such as an electric motor, e.g., in the form of a drill  122 . As shown, the drill  122  may be coupled to the sprocket  114  by inserting a drive axle  124  into the drill chuck. The drill  122  may rotatably drive the sprocket  114 , and thereby drive the cutting chain  106  around the guide bar  110 . The cutter  102  may, in this manner, be powered by a drill  122 , which may be commonly available in a clinical environment, thereby reducing the size, weight, and complexity of the cutter  102 . Other external power sources, e.g., pneumatic, hydraulic, etc., may also suitably be employed for driving the cutting chain  106 . Furthermore, the power source may be provided as an integrated portion of the cutter assembly, rather than as a separate element.  
         [0030]     As shown, for example, in  FIGS. 6 and 7 , tissue  126 , such as a portion of a tibial articular surface and/or adjacent bone or other tissue, may be resected by advancing the cutter  102  into the tissue  126  as the cutting chain  106  may be driven around the guide bar  110  to provide a continuous cutting action around the perimeter of the cutter  102 . The cutter  102  may be advanced into the tissue  126  resecting the tissue  126  along the path of the cutter  102 . While not shown, as previously discussed the path of the cutter  102  may be controlled by the cutting guide. Similarly, the cutting guide  110  may be configured to control the depth of penetration of the cutter  102  into the tissue  126 .  
         [0031]     As shown in  FIG. 6 , placement and trajectory of the cutter  102  may be controlled so that a portion of tissue  126  may be resected while preserving neighboring structures. For example, as shown, the cutter  102  may resect a portion of a tibia, which may include a portion of the tibial articular surface, without damaging an adjacent feature, e.g., a femoral condyle  130 . Similarly, resection of a portion of the tibia may also be accomplished without damaging other adjacent structures, such as the anterior cruciate ligament or the meniscus, thereby minimizing the collateral damage. This may minimize, or eliminate, the need to make additional incisions to protect adjacent nervo-vascular structures. Furthermore, the resection of a portion of the tibial articular surface may be accomplished with minimal, or no, dislocation of the joint. Of course, as with all aspects of the present disclosure, this aspect may be similarly applicable to other parts of the anatomy.  
         [0032]     As shown, for example, in  FIG. 8 , the cutter  102  may create a resected slot  128  having a specific shape and volume. A resected pocket may generally have the shape of a slot bounded by a full radius at the closed end of the slot. The rounded geometric shape of the resected slot may reduce the occurrence of stress concentration, as may result from a hard angle. Additional cutting, grinding, etc., operations may be employed to remove any overhanging margins around the slot, etc., or to further alter the resected slot.  
         [0033]     The size and shape of the slot  128  may be based, at least in part, on the size and geometry of the cutter  102 . For example, the height and geometry of the resected pocket may be based, at least in part, on the height, e.g., thickness, of the cutting chain  106 , the geometry of the guide bar  110 , configuration of the cutting chain  106 , e.g., link pitch, tooth pattern, etc., as well as the cut trajectory and depth. More than one intersecting, or at least partially overlapping, cutting passes may be employed to achieve resected pockets having still other heights and geometries. The forgoing attributes of the cutter may be chosen to facilitate creating resected pockets having specific or general desired characteristics.  
         [0034]     A resected slot may be created using a single cut along a single trajectory. As such, the procedure may be performed with reduced access to the resection site. The resected slot may be created from a single access point without exposing a substantial portion of the tibial surface. A procedure consistent with the foregoing may generally be considered less invasive than traditional procedures. Depending upon the size parameters of the cutter, a desired resection may be accomplished via incisions as small as about two inches, although this should not be construed as limiting the present disclosure.  
         [0035]      FIGS. 9 through 17  depict yet another exemplary embodiment of a resection system consistent with the present disclosure. Turning first to  FIGS. 9 through 11 , according to one aspect of this embodiment, a cutting path may be established relative to an anatomical feature to be resected, e.g., a portion of a tibia  200 . An aiming device  202  may be located relative to the tibia  200 . The aiming device  202  may include an aiming portion  204 , which may be located relative to, or contact, the tibia  200 , e.g., the tibial articular surface. For example, the aiming portion  204  may contact a portion of the articular surface of the tibia  200  to be removed during the resection. The aiming device  202  may further include an alignment portion, such as alignment portion  206 . The alignment portion  206  may cooperate with a locating device  208  for establishing one or more axes relative to the tibia  200 . The aiming device  202  may include indicia for indicating a position of the locating device  208  relative to the aiming device  202 . In one embodiment, the alignment portion  206  may be received in a cooperating channel or trough  210  in the locating device  208 . The aiming device  202  and the locating device  208  may be slidably coupled and releasably securable to one another to maintain a desired relationship between the aiming device  202  and the locating device  208  and relative to the tissue to be resected. In other embodiments, the aiming device  202  and the locating device  208  may comprise a single instrument, etc.  
         [0036]     In addition to cooperating with the aiming device  202 , the locating device  208  may include one or more elements for establishing working axes relative to the tibia  200 . As shown, for example, in  FIGS. 10 and 11 , the locating device  208  may include at least one aperture, e.g., cannulated member  212  and/or  214 , oriented along respective working axes. At least one guide pin  216  and/or  218  may be at least partially received through the cannulated member  212  and/or  214  and may engage the tibia  200 . In this way, the locating device  208  may orient the one or more guide pins  216 ,  218  relative to the tissue to be resected. For example, the at least one guide pin  216  and/or  218  may be drilled into, or otherwise inserted, extending at least partially into the tibia  200 . The at least one guide pin  216  and/or  218  may establish a trajectory and an orientation relative to the tibia  200 . Once the at least one guide pin  216  and/or  218  has engaged the tibia  200  to define respective axes, the aiming device  202  and the locating device  208  may be removed.  
         [0037]     Turning to  FIGS. 12 through 16 , the axes provided by the at least one guide pin  216  and/or  218  may be used to guide the resection of a portion of the tibia  200 .  FIG. 12  depicts a cutting guide  220  according to this embodiment. The cutting guide  220  of this embodiment includes a guide device  221  and at least one guide pin  216  and/or  218 . The at least one guide pin  216  and/or  218  may be secured to at least one anatomical feature to define an axis relative to tissue to be resected. The guide device  221  may cooperate with the at least one guide pin  216  and/or  218  and may assume an alignment and orientation based on the axes of the at least one guide pin  216  and/or  218 . For example, the guide device  221  may be slidably coupled to the at least one guide pin  216  and/or  218  and may position the guide device  221  relative to the tissue to be resected along an axis defined by the at least one guide pin  216  and/or  218 . For example, the guide device  221  may include apertures  222 ,  224  configured to at least partially receive the at least one guide pin  216  and/or  218  therethrough.  
         [0038]     The guide device  221  may be slidably coupled to a cutter  230  to position the cutter  230  relative to tissue to be resected. The guide device  221  may include a guide portion, such as a dovetail rail  226 . The dovetail rail  226  may constrain the movement of the cutter  230  along the axis defined by the at least one guide pin  216  and/or  218 . Various other guide portions may also be employed in connection with the present disclosure, such as ribs, rails, rods, beaded ribs, grooves, etc. Referring briefly to  FIGS. 13-16 , a cooperating guide portion on a cutter  230 , such as a complementary dovetail groove  228 , or other portion capable of cooperating with the guide portion of the guide device, may interact with the dovetail rail  226  to guide the movement of the cutter  230  relative to the cutting guide  220 . The cutter  230  shown in  FIGS. 13-16  is a representational depiction which does not show any particular cutters and drive mechanisms. Suitable cutters and drive mechanisms may be consistent with the previously described cutter, e.g., shown in  FIGS. 1 , and  3 - 7 . Various other embodiments of a cutter may also suitably be employed in connection with the present disclosure.  
         [0039]     As shown, for example, in  FIGS. 14 through 16 , the cutter  230  may be advanced into the tibia  200  along a path defined by, at least in part, the dovetail rail  226 . Consistent with the disclosure relative to  FIGS. 1 , and  3 - 7 , the cutter  230  may include a blade system for resecting material as the cutter  230  may be advanced into the tibia  200 . The depth of the resection may be controlled, at least in part, by the cutting guide  220 . In one embodiment, and referring specifically to  FIG. 14 , the guide device  221  may include indicia  232  which may indicate position, e.g., depth of advancement of the cutter  230 , relative to the guide device  221 . Movement of the cutter  230  relative to the indicia  232  may facilitate controlling the depth of advancement of the cutter  230  into the tibia  200 . In other embodiments, stops may be associated with the cutter and/or with the guide device  221  to limit the range of advancement of the cutter  230  relative to the guide device  221 , and therein relative to the tibia, in order to control the depth of resection.  
         [0040]     As depicted, for example, in  FIG. 17 , and consistent with the foregoing description, advancing the cutter  230  into, and withdrawing the cutter  230  from, the tibia, as shown in  FIGS. 14-16 , may provide a resected pocket  234  or slot in the tibia  200 . The shape of the pocket  234  may be based on, at least in part, the geometry of the cutter  230 , the path of travel of the cutter  230 , as controlled by the guide device  221  and the arrangement of the guide pins  216 ,  218 . For example, in the illustrated embodiment, the cutter  230  may include a rounded distal end, which may produce a radiused interior end  235  of the pocket  234 . Alternatively or additionally, the shape of the cutting portion of the links of the blade system (as depicted in  FIG. 1 , for example) may be selected to generate a desired geometry of the pocket  234 . In other embodiments the cutter  230  may have a flatter, or squared-off, distal end, producing a corresponding pocket geometry. Additionally, more than one resection cut may be carried out to create various pocket geometries, such as undercuts, dovetails, eccentric pockets, etc. Further, while the embodiment described herein depict the cutting guide as directly attached to a anatomical structure (via, for example, screws or guide pins) it is equally contemplated herein that the cutting guide may be attached to the anatomical structure in a less-invasive manner, for example, using straps or brackets that may stabilize the position of the cutting guide with respect to the tissue to be resected.  
         [0041]     The cutter described in any of the embodiments herein may generally have a thickness that is greater than a conventional tissue cutting instrument. Thus, the pocket  234  generated by the cutter described herein may include defined sidewall surfaces  250 A and  250 B. The sidewall surfaces  250 A and/or  250 B may be generally normal to the top and bottom surfaces  252  and  254 , respectively. Advantageously, the pocket  234  including sidewall surfaces  250 A and/or  2150 B generated by the cutter described herein may have sufficient height to accommodate a variety of implants without the need for additional cutting.  
         [0042]     Advantageously, consistent with the present disclosure, it may, therefore, be possible create a clean and precise cavity, e.g., for receiving an implant. For example, in at least one embodiment described herein, a cutter is slidably coupled to a cutting guide. The cutting guide may be This The controllability of the size and shape of the resected slot may, in some instances, lend itself to the use of standard size implants. The controllability of the cutting system may also allow the resection of a desired area and volume of material using a minimally invasive procedure along a single approach. Additionally, the system herein may have lower demands of dexterity and experience to create the resected site than may be required using convention freehand techniques.  
         [0043]     Various elements, aspects, and embodiments have been described herein. The elements, aspects, and embodiments are susceptible to combination with one another as well as to variation and modification, as will be understood by those having skill in the art. The present disclosure should, therefore, be considered to encompass such combinations, variations and modifications.