Patent Publication Number: US-2023134233-A1

Title: Meniscal repair delivery device

Description:
TECHNICAL FIELD 
     The present disclosure relates to devices and methods for repairing tissue. 
     BACKGROUND 
     Areas in the body where tissue can be surgically reattached to bone or can be surgically repaired when a tear forms in the tissue include, but are not limited to, the biceps tendon, the lateral collateral ligament in the knee, the medial collateral ligament in the knee, the meniscus in the knee, the popliteal ligament in the leg. Fibrous tissue wounds, such as muscle, ligament, and meniscal tears, can be repaired arthroscopically using sutures. Traditionally, to close a fibrous tissue wound, a surgeon would insert two suture needles into the tissue with sutures attached, thread the sutures across the wound, and then tie knots to fix the free ends of the sutures within the tissue. 
     To simplify the wound closure and to improve fixation, various types of devices, and tools for use in delivering the devices, have been developed. For example, some current meniscal repair devices utilize curved rigid needle tips to aid in reaching the appropriate regions of a damaged meniscus. Two implants, connected together using suture, are held by the needle. Once the desired meniscus repair location is reached, the needle is pushed through the meniscus and the first implant is deployed using a push delivery mechanism. The needle is then retracted from the meniscus, repositioned on the opposing side of the tear site, and pushed through the meniscus. The second implant is then deployed. The device is then removed, leaving a length of suture knotted in a manner to close the distance between the two implants when pulled. The knot is tightened by pulling on the length of suture and the suture is cut adjacent to the knot. 
     Typical repair devices employ a user manipulated push mechanism to move a first implant distally (push direction) out of the needle tip, followed by a passive retraction step to position the push mechanism behind a second implant, then move the second implant distally (push direction). These devices lack a means for user manipulated retraction (pull) of the push mechanism. For example, a number of all-inside technique meniscal repair devices use a push delivery mechanism that includes a push rod. The push rod is coupled to a user manipulated knob or trigger that moves the push rod distally to push out a first implant. Subsequently, the push rod must retract to a position proximal to the second implant so the implant can be subsequently pushed out when the knob or trigger is moved. The means of push rod retraction include compression springs, torsion springs, constant force springs, etc. When certain forces, such as the friction in the push mechanism, exceed the spring force, the push rod is unable to retract to a position suitable to deploy the second implant. 
     Furthermore, typical repair devices employ a rigid push rod that cannot easily conform to the curved needle tip geometry. The push rod is typically coupled to a user manipulated knob or trigger that moves the push rod distally to push out one or more implants. The push rod is typically fabricated from austenitic stainless steels, precipitation-hardening stainless steels, or nickel-titanium alloys, such as Nitinol. These materials exhibit the necessary compressive strength to withstand the compressive load needed to expel the implants. However, the mechanical properties for the common push rod materials are not optimized for compliance with needle curvature. Often, the needle curvature is altered during use by either bending the device manually prior to entering the joint space or by applying forces that flex the tip of the needle while in the joint space. The altered needle curvature can cause the push delivery mechanism to fail. Failure occurs by excessive force to push or the push rod portion of the push mechanism breaches the needle slot where the implants reside. Failure also occurs by failure of the push rod to retract so the second implant can be subsequently pushed out when the knob is advanced forward. The mechanical properties for common push rod materials have not been optimized to maintain low friction with added curvature, or a tortuous path. 
     Moreover, current techniques for pulling on the suture to close the distance between the two implants include wrapping the free suture end around the user&#39;s fingers, user&#39;s hand, or a surgical instrument, such as a pair of forceps. The suture is then pulled until a desired tension in the repair is achieved. Depending on the force required to tension the repair, tensioning the suture can be strenuous on the user and may even cause pain as the suture may constrict their fingers beyond comfort. Additionally, given the high lubricity of the material typically used in the construction of suture, the suture may slip during reduction when wrapped around a wet gloved finger. 
     SUMMARY 
     Described herein are tissue repair devices that provide a push-pull delivery mechanism that facilitates retraction of a push rod independent of spring force on the rod. The devices include a handle having a longitudinal axis and an elongated needle defining an axial bore extending from the handle, a first implant and a second implant connected by a suture and disposed at least partially within the axial bore of the needle, the second implant disposed proximal to the first implant, and an advancement assembly. The advancement assembly includes a rod portion configured to advance through the needle to expel the first and second implants, a ratchet coupled to a proximal section of the rod portion and configured to advance the rod through the needle by axial and rotational movement, and an advancement member having a linear travel axis including a first bore connected to a second bore. A diameter of the first bore is smaller than a diameter of the second bore such that the first bore and the second bore comprise a stop. The push-pull mechanism has mechanical properties optimized to both conform to needle curvature and provide sufficient compressive strength to expel implants from the devices. The disclosure also provides for a compliant push rod, or portion thereof, that allows for more reliable implant deployment via needles having various degrees of curvatures. Finally, the disclosure also provides for a suture having a bifurcated section which serves as a finger loop for ease of tensioning the suture. 
     In one aspect, the present disclosure relates to a tissue repair device. The device can include a handle having a longitudinal axis, and an elongated needle defining an axial bore extending from the handle. The needle can include a proximal end and a distal end. Further, the device includes a first implant and a second implant connected by a suture and disposed at least partially within the axial bore of the needle, the second implant disposed proximal to the first implant. In addition, the device can include an advancement assembly. The advancement assembly can include a rod portion configured to advance through the needle to expel the first and second implants from the distal end of the needle, and a ratchet coupled to a proximal section of the rod portion and configured to advance the rod through the needle by axial and rotational movement. The advancement assembly can include an advancement member, coupled to the ratchet member, having a linear travel axis including a first bore connected to a second bore. A diameter of the first bore is smaller than a diameter of the second bore such that the first bore and the second bore define a stop. Further, the advancement assembly can include a push-pull mechanism moving on the linear travel axis, including a mating rod. The first bore of the advancement member can receive a section of the mating rod. The mating rod can have a stop member including a barb on its distal end. In a first position, the push-pull mechanism engages the stop and, in a second position, the push-pull mechanism is proximal to the stop. 
     In some embodiments, the rod includes Nitinol. In some embodiments, the Nitinol is Martensitic phase Nitinol. In some embodiments, a tensile strain of the Nitinol is about 50 ksi. 
     In some embodiments, the advancement assembly includes a plunger to permit a user to engage the push-pull mechanism in order to advance the first implant and the second implant from the distal end of the needle. 
     In some embodiments, the distal end of the needle includes a slot. In some embodiments, at least one of the first implant and the second implant includes a main body having a cross-section approximating the axial bore of the needle and a protrusion mating with the slot to preclude rotation of the implant in the needle. 
     In some embodiments, the device further includes a depth tube limiting the depth that the needle may be inserted into a tissue. In some embodiments, the depth tube has a depth tube lock for locking a linear position of the depth tube. In some embodiments, the depth tube includes a tapered distal portion. 
     In some embodiments, the device further includes a needle housing coupled to the handle. In some embodiments, the depth tube lock is operatively coupled to the needle housing. 
     In some embodiments, the distal end of needle has curved geometry. In some embodiments, a curve of the curved geometry is in-line with a slot of the distal end of the needle. In some embodiments, a curve of the curved geometry is away from the slot of the distal end of the needle. 
     In some embodiments, the device further includes one or more stops configured to limit the advancement of the ratchet member at predefined increments. 
     In some embodiments, the ratchet member is configured to return to a final position proximally aligned with a starting position of the ratchet member after expelling at least one of the first and second implants. 
     In some embodiments, the suture includes a sliding knot. 
     In some embodiments, an internal surface of the advancement member includes a plurality of teeth configured to engage the ratchet member. 
     In some embodiments, the ratchet member includes two radially extending tabs configured to alternately engage and disengage with a plurality of channels positioned within the advancement member. 
     In some embodiments, the barb includes a lead-in portion configured to facilitate a press fit into the first bore of the advancement member. 
     In another aspect, the present disclosure relates to a method of tissue repair. The method can include inserting a first anchor into tissue, the tissue including a tear, the first anchor being inserted into the tissue on a first side of the tear. The method can also include inserting a second anchor on a second side of the tear, the second anchor coupled to the first anchor via a knotted flexible member having a finger-engageable bifurcated portion. The method can also include, using the bifurcated portion, pulling on the flexible member to reduce a length of the flexible member between the first and second anchors, closing the first and second sides of the tear. In some embodiments, a size of the bifurcated portion is fixed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various aspects of at least one embodiment of the present disclosure are discussed below with reference to the accompanying figures. It will be appreciated that for simplicity and clarity of illustration, elements shown in the drawings have not necessarily been drawn accurately or to scale. For example, the dimensions of some of the elements may be exaggerated relative to other elements for clarity or several physical components may be included in one functional block or element. Further, where considered appropriate, reference numerals may be repeated among the drawings to indicate corresponding or analogous elements. For purposes of clarity, not every component may be labeled in every drawing. The figures are provided for the purposes of illustration and explanation and are not intended as a definition of the limits of the invention. 
         FIGS.  1   a  and  1   b    illustrate an system for tissue repair, according to certain embodiments; 
         FIGS.  2   a  and  2   b    illustrate a ratchet mechanism of the tissue repair system, according to certain embodiments; 
         FIGS.  3  and  4    illustrate a push-pull mechanism of the tissue repair system, according to certain embodiments; 
         FIGS.  5   a - c    further illustrate the push-pull mechanism of the tissue repair system, according to certain embodiments; 
         FIGS.  6   a  and  6   b    illustrate another system for tissue repair, according to certain embodiments; and 
         FIG.  7    illustrates a suture for use with the system for tissue repair, according to certain embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. It will be understood by those of ordinary skill in the art that these embodiments may be practiced without some of these specific details. In other instances, well-known methods, procedures, components and structures may not have been described in detail so as not to obscure the described embodiments. 
     Prior to describing at least one embodiment in detail, it is to be understood that the claims are not limited in their application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description only and should not be regarded as limiting. 
       FIG.  1   a    illustrates an example of a tissue repair device  100  of this disclosure in an assembled view. The device  100  generally includes a handle  110 , a knobbed plunger  120  coupled to the handle  110 , a stationary housing  130  disposed within the knobbed plunger  120  and the handle  110 , and a needle housing  170  coupled to the stationary housing  130 . A depth tube lock  140  is disposed within the needle housing  170  and coupled to a depth tube  150 . A needle  180  extends through the depth tube  150  and houses a first implant  182  and a second implant  184  connected by a suture  186  within an axial bore  188  ( FIG.  1   b   ) for deployment from the needle  180  into tissue. The suture  186  includes a sliding knot  187  to facilitate in reducing a length of the suture  186  between the implants  182 ,  184 . The two implants  182 ,  184  reside in the distal portion of the needle  180  prior to deployment. The depth tube may include a tapered distal portion to facilitate easy entry into entry portals of tissue. The depth tube  150  and the depth tube lock  140  provide a means to limit the penetration of the needle  180 . The interface between the knobbed plunger  120  and the handle  110  is a slip fit as is the fit between the implants  182 ,  184  and the needle  180 . In use, the user would typically hold the device  100  by the handle  110  or the needle housing  170  positioned on either side of the knobbed plunger  120 . The user pushes the knobbed plunger  120  forward to deploy the first implant  182  from the distal tip of the needle  180 . After repositioning the needle on the opposing side of a tear, a second user manipulation of the knobbed plunger  120  is needed to deploy the second implant  184 . The suture  186  is then pulled or otherwise tensioned to reduce a length of the suture  186  between the implants  182 ,  184 , closing the tear. Other non-limiting examples of the handle  110 , the knobbed plunger  120 , the stationary housing  130 , the depth tube lock  140 , the depth tube  150 , the needle housing  170 , the needle  180  and the implants  182 ,  184  are disclosed in U.S. Pat. No. 8,888,798 and U.S. Publication No. 2018/0116654 to Smith &amp; Nephew, Inc., the entire contents of which are incorporated herein by reference. 
       FIG.  2   a    illustrates a portion of the tissue repair device  100  of  FIG.  1    in a cross-sectional view. As shown in  FIG.  2   a   , an internal surface of the knobbed plunger  120  includes a plurality of teeth  122 . The teeth  122  are configured to successively engage a ratchet member  124  which is rotatably and axially coupled to a push mechanism  126  to successively deploy the implants  182 ,  184 . A cylindrical rod portion  128  of the push mechanism  126  is contained within the needle  180 . A compressed spring  160  provides a linear force intended to maintain contact between the ratchet member  124  and the teeth  122  of the knobbed plunger  120 . The spring  160  also provides a retraction force for the push mechanism  126  after implant deployment. The spring  160  further facilitates rotation of the ratchet member  124  relative to the teeth  122  of the knobbed plunger  120 . The engagement of the ratchet member  124  with each successive tooth  122 , along with engagement between the sidewalls of the tabs  125  of the ratchet member  124  and the channel walls of the stationary housing  130 , provides a tactile and audible indication of a deployment of the corresponding first implant  182  or second implant  184 . 
     As shown in  FIG.  2   b   , the ratchet member  124  contains two radially extending tabs  125  that, during forward deployment, alternately engage and disengage with several channels positioned radially within the wall of the stationary housing  130 . The tabs  125  of the ratchet member  124  slide within internal channels along the axis of the stationary housing  130 , providing radial alignment prior to deployment of each implant  182 ,  184 . The push mechanism  126  moves distally along a travel axis A when the user retracts the knobbed plunger  120 . The distal tip of the push mechanism  126  is protracted linearly until the tabs  125  of the ratchet member  124  contact a first discrete stop member  136  of the stationary housing  130 , resulting in deployment of the first implant  182 . The discrete stops are in radial alignment with the inner channels of the stationary housing  130  to prevent the push mechanism  126  from advancing during deployment of the implants  182 ,  184 . 
     As shown in  FIG.  3   , the push mechanism  126  shares a common linear travel axis A with the knobbed plunger  120 . The knobbed plunger  120  has an inner bore  132  configured to receive the rod portion  128  of the push mechanism  126 . The inner bore  132  of the knobbed plunger  120 , in conjunction with the distal bore of the needle  180  ( FIG.  1   ), maintain alignment of the push mechanism  126 . The push mechanism  126  also includes a stop feature, such as an annular barb  134 . The inner bore  132  of the knobbed plunger  120  includes a proximal first portion  132   a  having an inner diameter selected to be larger than a distal second portion  132   b , creating a counter bore  138  between the first portion  132   a  and the second portion  132   b . The outer diameter of the barb  134  is selected to be larger than the second portion  132   b  of the inner bore  132 , but less than the outer diameter of first portion  132   a . When assembled, the linear position of the barb  134  is proximal to the linear position of the counter bore  138  in the knobbed plunger  120 , such that a gap  142  exists between the barb  134  and the counter bore  138 . 
       FIG.  4    shows the device  100  after the knobbed plunger  120  has been pushed distally until the tabs  125  of the ratchet member  124  contact a first discrete stop member  136 , causing deployment of the first implant  182 . The spring  160  creates a retraction force sufficient to retract the push mechanism  126  slightly. The small amount of retraction allows the ratchet member  124  to rotate and position the push mechanism  126  at an interim rest position. However, when the combined friction and bending forces between the rod portion  128  of the push mechanism  126  and the inner bore  188  of the needle  180  exceeds the spring force, the push mechanism  126  will not retract. This prevents the radial alignment of the ratchet member  124  to occur, preventing the push mechanism  126  from advancing distally to deploy the second implant  184 . 
       FIGS.  5 A and  5 B  show the relative positions of the push mechanism  126  and the knobbed plunger  120  when the user retracts the knobbed plunger  120 . As shown, retraction of the knobbed plunger  120  causes contact between the mating axial walls of the barb  134  in the push mechanism  126  with the annular counter bore  138  of the knobbed plunger  120 . Thus, the push mechanism  126  will retract with the knobbed plunger  120 , restoring device functionality that is compromised from use-related errors. As shown in  FIG.  5 C , the barb  134  of the push mechanism  126  includes a lead-in portion  134   a  to facilitate a press fit into the inner bore  132  of the knobbed plunger  120 . An annular feature  134   b  on the barb  134  provides sufficient structural strength to oppose the forces impeding proximal axial motion of the push mechanism  126 . The amount of diametric interference is sufficient to oppose the axial force impeding proximal axial motion, but not so high as to impede assembly of the two components. During retraction, the normal operating gap  142  between the barb  134  of the push mechanism  126  and the counter bore  138  is reduced until the mating faces contact. Once contact is made, the push mechanism  126  moves proximally along the travel axis A when the user advances the knobbed plunger  120 . The push mechanism  126  will retract with the knobbed plunger  120  until the knobbed plunger  120  reaches the proximal stop position. Thus, the delivery device of the present disclosure provides an alternative means to retract the push mechanism  126  and allow the ratchet member  124  to rotate to a radial position suitable for deployment of the second implant  184  when the spring force alone is insufficient to retract the push mechanism  126 . 
     In some embodiments, not shown, the annular coupling feature could be created in the knobbed plunger  120  with a corresponding undercut in the push mechanism  126 . A multi-component coupling feature could also provide equivalent functionality. For example, a retaining ring could be pressed onto the push mechanism  126  after assembly into the bore  132  of the knobbed plunger  120 . 
     As shown in  FIG.  6 A , another example of a tissue repair device  200  of this disclosure includes a needle  280  and a push mechanism  226  that share a common linear travel axis A. Two implants  282 ,  284  reside in the distal end of the needle  280 .  FIG.  6 A  also shows a needle  280  with significant curvature. In examples, the curvature of the needle  280  is in-line with the slot  290  in the distal portion of the needle  280 . The push mechanism  226  includes a rod portion  228  configured to advance through the needle  280  to expel the first and second implants  282 ,  284  from the distal end of the needle  280 . In examples, the rod portion  228  is comprised of operating-temperature, martensitic phase Nitinol. Martensitic phase Nitinol advantageously exhibits a lower elastic modulus than an austenitic material. For a given diameter of the rod portion  228 , the martensitic rod maintains a residual strain at a lower push force than an austenitic rod having the same cross-sectional area and shape. When the material is mechanically loaded at a temperature below the Martensite finish temperature (Mf), or completely martensitic, the material remains strained when subsequently unloaded. The original shape can be recovered upon heating above the austenite finish temperature (Af). In examples, the stress of the Nitinol measured at 3% strain during tensile loading is about 50 ksi. 
       FIG.  6   b    depicts the device  200  having needle curvature in a direction opposing the slot  290  (reverse curvature). This direction of curvature is a challenge, since the distal tip of the rod portion  228  is not supported while being advanced distally. Common push rod materials exhibit sufficient mechanical stiffness to deform the slot  290  and breach the needle bore  288 . When breach occurs, the push rod  228  will not expel the implant  284 . The rod portion  228  of this disclosure conforms to the reverse needle curvature by having optimized mechanical properties and deforming at a force lower than the force required to breach the bore  288  of the needle  280  in the region of the slot  290 . Proper function is maintained during distal advancement of the push mechanism  226  to expel the implants from the distal end of the needle  280 . In examples, at least one of the first implant  282  and the second implant  284  comprises a main body  292  having a cross-section approximating the axial bore  288  of the needle  280  and a protrusion  294  mating with the slot  290  to preclude rotation of the implant  282 ,  284  in the needle  280 . 
     In some embodiments, the push rod  228  could be fabricated having one or more portions having a lower flexural modulus, achieved by heat treating a portion of the push rod  228  to achieve the desired flexural strength. A multi-segment push rod  228  could comprise a distal tip portion having a first diameter and a proximal rod portion having a second diameter, said second diameter less than the first diameter. A multi-component push rod  228  could have the tip portion constructed from a different material, to decrease friction. The push rod  228  could include a distal tip portion having material removed (cuts) to increase flexibility. 
       FIG.  7    shows a suture  386  having a proximal end  386   a  and a distal end  386   b . The distal end  386   b  is configured for being coupled to implants of a tissue repair device, such as the tissue repair devices  100 ,  200  described above. The proximal end  386   a  is configured to exit a joint space and includes has a bifurcated section  386   c  and a tail  386   d . The bifurcated section  386   c  serves as a loop, allowing the user to pass a number of fingers through. In the bifurcated section  386   c , half of the fiber strands used to create the suture  386  form each segment of the loop, effectively creating a divergence and convergence of the suture  386 . The bifurcated section  386   c  is large enough to fit multiple fingers so that the user can pull the suture  386  to the desired repair tension. This bifurcated section  386   c  is of a fixed diameter and will not cause any user discomfort when under tension. In examples, stiffening techniques ensure that the bifurcated section  386   c  remains open even when wet, and is easily visible to the user. These stiffening techniques may include heat-stiffening or “shape-setting” of the suture  386  by heating the suture  386  to its glass-transition temperature and allowing it to cool around a mandrel of a specific shape and size. Other examples of stiffening techniques include providing a monofilament core in each segment of the bifurcated section  386   c . In other examples, not shown, the suture  386  may include a full loop instead of a bifurcated section  386   c  to maintain the same diameter along the entire length of the suture  386 , and not include a tail  386   d . It is further contemplated that suture  386  could contain multiple bifurcated sections  386   c  of the same or different sizes along the length of the suture  386 . 
     It is appreciated that certain features of the invention, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable sub-combination. 
     Whereas many alterations and modifications of the disclosure will no doubt become apparent to a person of ordinary skill in the art after having read the foregoing description, it is to be understood that the particular embodiments shown and described by way of illustration are in no way intended to be considered limiting. Further, the subject matter has been described with reference to particular embodiments, but variations within the spirit and scope of the disclosure will occur to those skilled in the art. It is noted that the foregoing examples have been provided merely for the purpose of explanation and are in no way to be construed as limiting of the present disclosure. 
     Although the present disclosure has been described herein with reference to particular embodiments, the present disclosure is not intended to be limited to the particulars disclosed herein; rather, the present disclosure extends to all functionally equivalent structures, methods and uses, such as are within the scope of the claims.