Patent Publication Number: US-2021169483-A1

Title: Jaw for clip applier

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 15/674,121, filed Aug. 10, 2017, entitled “Jaw for Clip Applier,” which is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD 
     Clip appliers having an improved jaw structure, and methods for using and manufacturing the same, are provided herein. 
     BACKGROUND 
     A variety of surgical procedures require application of clips to seal and/or secure tissue, requiring a surgical clip applier for ligating a blood vessel, a duct, shunt, a portion of body tissue, etc. during surgery. The jaws of most surgical clip appliers are formed through a process of metal stamping or machining, which can limit the possible geometry of the jaws. For example, rails of the jaws are designed to hold a clip in a clip track, however sufficient clearance is required in order to accommodate varying clip heights or other deformities between clips. This clearance can result in surgical clips being free to shift or wiggle in the clip tracks, which could result in clip malformation or clip fallout. 
     Accordingly, there remains a need for clip appliers having an improved structure for formation and placement of clips during surgical procedures. 
     SUMMARY 
     Clip appliers having improved jaws and methods for using and manufacturing the same are provided herein. In one embodiment, a surgical clip applier is provided and includes an elongate shaft and a jaw assembly at a distal end of the elongate shaft. The jaw assembly can include a metal frame having a proximal portion coupled to the elongate shaft and a distal portion including first and second jaws movable between open and closed positions for engaging tissue therebetween. The first and second jaws can each have an engagement feature formed thereon. The jaw assembly can also include a first outer housing around the first jaw and a second outer housing around the second jaw. The engagement feature can prevent movement of the first and second outer housings relative to the metal frame. The first and second outer housings can also have opposed inward facing surfaces, with each inward facing surface having a clip track formed therein and extending longitudinally therealong for receiving and guiding a clip into the jaws. 
     In one embodiment, the first and second outer housings can be overmolded around the first and second jaws, and in another embodiment, the first and second outer housings can be configured to be coupled to the first and second jaws through one of adhesive, welding, and mechanical engagement means. 
     In some embodiments, the first and second jaws can include opposed inward facing surfaces, and the engagement feature can be a protrusion formed on the inward facing surface. The protrusion on each of the first and second jaws can extend through the outer housing such that the protrusion is configured to contact a clip seated in the clip track. 
     The jaw assembly can be formed from various materials. In one embodiment, the first and second outer housings can be formed from a polymeric material. The metal frame can have a modulus of elasticity that is greater than a modulus of elasticity of a material forming the first and second outer housings. 
     The housings can include various features. For example, the first and second outer housings can each include a plurality of fingers protruding into the clip track for retaining a clip therein. The plurality of fingers can be flexible. The first and second outer housings can also each include upper and lower rails that define the clip track. In one embodiment, at least one cut-out can be formed in at least one of the upper and lower rails for allowing a user to view a clip seated in the clip track. In other embodiments, the first and second outer housings can each have upper and lower protrusions positioned on opposed sides of the clip track for retaining a clip seated in the clip track. 
     In another embodiment, a jaw insert for use with a clip applier device is provided and includes a metal body having a proximal portion and a distal portion with first and second arms having opposed inward facing surfaces. Each inward facing surface can have at least one protrusion formed thereon. The jaw insert can also include first and second housings on the first and second arms, respectively. The first and second housings can include opposed inward facing surfaces that each define a clip track extending therealong for seating a clip therein. The at least one protrusion on each of the first and second arms can extend through the inward facing surface of the first and second housings, respectively, such that the at least one protrusion on each of the first and second arms is configured to contact a clip seated in the clip track. 
     In one embodiment, the first and second housings can be overmolded onto the first and second arms, and in another embodiment, the first and second housings can be configured to be coupled to the first and second arms through one of adhesive, welding, and mechanical engagement means. 
     The protrusion can be configured to prevent longitudinal sliding of the first and second housings. In certain embodiments, the protrusion can be positioned at a substantial mid-portion of the clip track such that the protrusion is configured to engage a bend zone on a clip seated in the clip track. 
     The jaws can be formed from various materials. For example, the metal body can be made of a first material and the first and second housings can be made of a second material. The first material can have a modulus of elasticity that is greater than a modulus of elasticity of the second material. 
     The housings can include various other features. For example, each of the first and second housings can have a plurality of fingers protruding into the clip track configured for retaining a clip therein. In one aspect, the metal body can be made of a first material, the first and second housings can be made of a second material, and the plurality of fingers can be made of a third material. The third material can have a modulus of elasticity that is less than a modulus of elasticity of the first material and a modulus of elasticity of the second material. 
     In other embodiments, the inward facing surface of the first and second housings can include upper and lower rails that define the clip track. At least one cut-out can be formed in at least one of the upper and lower rails for allowing a user to view a clip seated in the clip track. 
     In another embodiment, a method of manufacturing a jaw assembly of a surgical clip applier is provided and can include forming a metal frame defining first and second jaws configured to grasp tissue therebetween. Each jaw can have an engagement feature thereon. The method can also include molding first and second housings around the first and second jaws, respectively, to form opposed inward facing surfaces having a clip track formed therein and extending therealong for receiving and guiding a clip into the jaws. The engagement feature can prevent sliding movement of the first and second housings relative to the first and second jaws. 
     In one embodiment, the engagement feature can be a protrusion that extends through the housing and that is configured to contact a clip seated in the clip track. Each housing can include upper and lower rails defining the clip track. At least one of the upper and lower rails can have at least one finger protruding into the clip track. The method can also include injection molding a third material into cavities formed in the clip track to form a plurality of fingers extending into the clip track. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a side view of one exemplary embodiment of a surgical clip applier; 
         FIG. 2  is an exploded view of a distal portion of the surgical clip applier of  FIG. 1 ; 
         FIG. 3  is a perspective view of a distal portion of the surgical clip applier of  FIG. 1 ; 
         FIG. 4A  is a perspective, partially transparent view of a proximal portion of the surgical clip applier of  FIG. 1 ; 
         FIG. 4B  is another perspective view of the proximal portion of the surgical clip applier of  FIG. 1 ; 
         FIG. 5  is a side, transparent view of an embodiment of a portion of a jaw assembly for use with a surgical clip applier; 
         FIG. 6  is a front, transparent view of an inward facing surface of one of the jaws of the surgical clip applier in the direction AA of  FIG. 5 ; 
         FIG. 7  is a side, transparent view of another embodiment of a portion of a jaw assembly for use with a surgical clip applier; 
         FIG. 8  is a side, transparent view of another embodiment of a portion of a jaw assembly for use with a surgical clip applier; 
         FIG. 9  is a side, transparent view of another embodiment of a portion of a jaw assembly for use with a surgical clip applier; 
         FIG. 10  is a front, transparent view of an inward facing surface of another embodiment of a jaw; 
         FIG. 11  is a front, transparent view of an inward facing surface of yet another embodiment of a jaw; 
         FIG. 12  is a cross-sectional view of another embodiment of a jaw; 
         FIG. 13  is a cross-sectional view of still another embodiment of a jaw; 
         FIG. 14  is a cross-sectional view of another embodiment of a jaw; 
         FIG. 15  is a cross-sectional view of yet another embodiment of a jaw; and 
         FIG. 16  is a cross-sectional view of still another embodiment of a jaw. 
     
    
    
     DETAILED DESCRIPTION 
     Certain exemplary embodiments will now be described to provide an overall understanding of the principles of the structure, function, manufacture, and use of the devices and methods disclosed herein. One or more examples of these embodiments are illustrated in the accompanying drawings. Those skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments and that the scope of the present invention is defined solely by the claims. The features illustrated or described in connection with one exemplary embodiment may be combined with the features of other embodiments. Such modifications and variations are intended to be included within the scope of the present invention. 
     A surgical clip applier can generally be used to apply surgical clips to a vessel, duct, shunt, etc., during a surgical procedure. An exemplary surgical clip applier can include a jaw assembly having a frame with a pair of jaws and a housing overmolded onto the jaws with various clip aligning and engaging features. For example, the overmolded housing can have inward facing surfaces that define a clip track for receiving and guiding a clip into the jaws. The outer overmolded housing can allow for a variety of different structures and geometries to better control formation and placement of surgical clips that are not possible with other surgical clip appliers, such as clip appliers having jaws formed through a stamping or machining process. 
     A surgical clip applier can generally have a variety of different forms with a variety of different jaws and clip tracks.  FIGS. 1-4B  illustrate one embodiment of a surgical clip applier  100 . A person skilled in the art will appreciate that the jaw assemblies disclosed herein can be used with any clip applier device, or with any device having jaws. The illustrated clip applier is merely one example of a device for use with the jaw assemblies disclosed herein, and it is not intended to be limiting. As shown, the surgical clip applier  100  generally includes a housing  102  having a stationary handle  104  and a movable handle or trigger  106  that is pivotally coupled to the housing  102 . An elongate shaft  108  extends distally from the housing  102  and includes a jaw assembly  110  formed on a distal end  108   d  thereof and including first and second jaws  112 ,  114  that are movable between open and closed positions. The first and second jaws  112 ,  114  include opposed inward facing surfaces and each inward facing surface has a clip track formed therealong for receiving and guiding legs of a clip into the first and second jaws  112 ,  114 . The elongate shaft  108  can be rotated with respect to the housing  102  via a rotation knob  103 . 
     As shown in  FIGS. 2 and 3 , the elongate shaft  108  can include an outer support tube  120 , an upper shroud  122  coupled distally to the outer tube  120 , and a lower shroud  124 . The outer support tube  120  and the upper and lower shrouds  122 ,  124  form an outer casing of the shaft  108 . As shown in  FIGS. 2 and 3 , a clip stack  126  including multiple surgical clips is disposed within a clip track or holder  128  of the shaft  108  proximal to the first and second jaws  112 ,  114 , and is biased distally. A floor  130  extends beneath the clip stack  126  for maintaining the clip stack  126  in alignment within the shaft  108 , and for guiding a distal-most clip  126   d  into the jaws  112 ,  114 . A lifter spring  132  is positioned just proximal to the jaws  112 ,  114  and distal to the clip stack  126  for preventing distal movement of the clip stack  126 , with the distal-most clip  126   d  disposed around the lifter spring  132 . A feeder bar  134  extends through the elongate shaft  108  for feeding the distal-most clip  126   d  into the jaws. As shown in  FIG. 3  illustrating the clip applier  100  with the upper and lower shrouds  122 ,  124  removed, a former tube  136  extends around a proximal end of the jaws  112 ,  114  and is movable distally to cam the jaws  112 ,  114  to a closed position for forming a clip  127  disposed therebetween. 
     The surgical clip applier  100  has a clip forming assembly including various components that operate together to close the jaws  112 ,  114  when the trigger  106  is activated to thereby cause a clip (e.g., clip  127 ) disposed in the jaws to be applied (formed) to the tissue. The clip forming assembly encompasses the former tube  136  and other components that are coupled to the trigger  106  configured to be activated to move the former tube  136  distally to thereby close the jaws  112 ,  114 . A clip advancing assembly of the surgical clip applier  100  includes the feeder bar  134  that is also coupled to the trigger  106 , via a link  107  extending proximally from the trigger  106 , as shown in  FIGS. 4A and 4B . In this way, when the trigger  106  is activated, the feeder bar  134  is caused to move proximally, opposite to a distal direction in which the former tube  136  is moved upon activation of the trigger  106 . 
     The clip forming and clip advancing assemblies can have any suitable configurations. For example, in the illustrated embodiment, as shown in  FIGS. 4A and 4B , the former tube  136  of the clip forming assembly is coupled, via an inner coupling  138 , to a former plate  140  in the handle  102  that is, in turn, coupled to the trigger  106  via a pin  141 , and the feeder bar  134  of the clip advancing assembly is coupled to the trigger  106  via a feeder plate  142  that is also coupled to the trigger  106 , via the link  107 . As shown in  FIG. 4A , the feeder plate  142  has arms  144   a ,  144   b  at a distal end thereof that are disposed over and mate with a proximal end of an outer coupling  146  (shown partially transparent). A connecting pin  148  at a distal end of the outer coupling  146  attaches the feeder bar  134  to the outer coupling  146 .  FIGS. 4A and 4B  illustrate the handle  102  with part of an outer casing removed, and  FIG. 4B  shows the handle  102  without the feeder plate  142 , for illustration purposes only. It should be appreciated that the surgical clip applier  100  can include various other components and assemblies that are not described herein for the sake of simplicity. 
     In use, when the trigger  106  of the handle  102  is activated (e.g., moved towards the stationary handle  104 ), the former plate  140  of the clip forming assembly is advanced distally to cause the former tube  136  to advance distally over the jaws  112 ,  114 , thereby camming the jaws  112 ,  114  to the closed position. At the same time, the feeder plate  142  of the clip advancing assembly is moved proximally, thereby pulling the feeder bar  134  proximally to position the feeder bar  134  proximal of the distal-most clip  126   d  of the clip stack  126 . Once the clip  127 , disposed in the jaws  112 ,  114  such that clip&#39;s legs are received within the clip track of each of the jaws, is fully formed, the trigger  106  is released, which causes the clip forming assembly to move proximally while the clip advancing assembly moves distally.  FIG. 2  shows the clip  127  in an original, pre-formed configuration. The proximal movement of the clip forming assembly causes the former tube  136  to retract relative to the jaws, thus allowing the jaws  112 ,  114  to move to the original open position, thereby releasing the formed clip. The distal movement of the clip advancing assembly causes the feeder bar  134  to move distally, and the feeder bar  134  thereby pushes the distal-most clip  126   d  distally, overcoming the biasing force of the lifter spring  132  and causing the lifter spring  132  to deflect out of the way, thereby allowing the distal-most clip  126   d  to be advanced into the jaws  112 ,  114 . In this way, the distal-most clip becomes positioned in the jaws&#39; clip track, like the clip  127  in  FIG. 3 . The floor  130  helps guide the distal-most clip into the clip tracks of the jaws  112 ,  114 . 
     A person skilled in the art will appreciate that, while a trigger is shown and described, the clip appliers disclosed herein need not include a trigger, and can have a variety of other actuation mechanisms. For example, the clip applier can be powered and can include an actuation button for actuating a motor to control firing of the device. In other embodiments, the housing can be configured to couple to a robotic or telemanipulator system, such that actuation of the device is controlled through the robotic system. 
     A variety of different jaw assemblies incorporating various overmolded features can be used with a clip applier, such as the clip applier  100  illustrated in  FIGS. 1-4A . The use of an overmolded housing can allow various features to be incorporated into the jaws that are not otherwise achievable using a typical stamping process for forming metal jaws. 
       FIGS. 5 and 6  illustrate a portion of one embodiment of a jaw assembly  500  that can be used with a clip applier, such as the clip applier  100 , and that can be configured to grasp tissue and form and apply surgical clips, similar to the first and second jaws  112 ,  114  discussed above regarding clip applier  100 . 
     The illustrated jaw assembly  500  includes a frame having a proximal portion  500   p  (only a portion of which is shown) that is configured to extend into the distal end of an elongate shaft of a clip applier, and a distal portion  500   d  with first and second jaws  502 ,  504  forming an approximate Y-shape. The first and second jaws  502 ,  504  can each include a tip portion  506 ,  508  having opposed inward facing surfaces  514 ,  515  from which engagement features, such as protrusions  510 ,  511 , can extend towards one another into a central opening of the Y-shape of the jaws  500 . The protrusions  510 ,  511  can be configured to help retain the overmolded housing on each jaw  502 ,  504 , as will be discussed in more detail below. In certain embodiments, the protrusions  510 ,  511  can also provide support to a clip seated within the jaws during clip formation, such as being configured to provide a rigid surface that can directly contact and compress a clip. In certain exemplary embodiments, the protrusions  510 ,  511  can be configured to contact a bend zone or curve in the clip configured to assist in clip formation and closure, as will also be discussed in more detail below. A shroud  513  similar to the upper shroud  122  can be provided. 
     The engagement features, such as protrusions  510 ,  511 , can have a variety of shapes and sizes, and can be positioned at various locations. In the illustrate embodiment, the protrusions  510 ,  511  are generally rectangular in shape, and the protrusions  510 ,  511  extend across at least part of a height of the surface  514  or entirely across the height of the surface  541 , and along a portion of the length of each tip portion  506 ,  508 , in the proximal/distal direction. There can be one or more protrusions on each tip portion  506 ,  508 . 
     The jaw frame can be formed from various materials, but in an exemplary embodiment the jaw frame is formed from a stamped, machined, Electrical Discharge Machining (EDM), or Direct Metal Laser Sintering (DMLS) metal. The metal can vary in hardness (or a material&#39;s resistance to indentation as measured by the modulus of elasticity scale), depending on desired properties of the material. The jaw frame should be sufficiently flexible to allow the jaws to move between opened and closed positions, while having sufficient stiffness to prevent deformation of the jaws when forces are applied thereto. Since the metal frame need not include clip tracks or other features for retaining a clip therein, the process for manufacturing the frame can be significantly simplified. 
     As indicated above, features can be formed around the tip portion  506 ,  508  of the first and second jaws  502 ,  504 . For example, features can be overmolded onto the tip portion or can be molded separately and attached to the tip portion by a variety of means, such as adhesives, laser weld, snap features, interference fit, etc. As illustrated in  FIG. 5 , overmolded housings  520 ,  522  can be formed over the tip portions  506 ,  508 . The overmolded housings  520 ,  522  can partially or fully surround the tip portions  506 ,  508 , and can include opposed inward facing surfaces  530 ,  531  positioning in alignment with the inward facing surfaces  514 ,  515  of the tip portions  506 ,  508 . Each inward facing surface  530 ,  531  can have features that define, for example, a clip track  532 ,  533  extending longitudinally therealong for receiving and guiding legs of a clip  540  into the first and second jaws  502 ,  504 . In certain embodiments, the clip tracks  532 ,  533  can be in the form of a generally rectangular-groove extending from a proximal end to a distal end of each inward facing surface  530 ,  531 . Each clip track  532 ,  533  can be defined by opposed upper and lower rails (only one rail  532   a,    533   a  on each clip track  532 ,  533  is shown) extending longitudinally along upper and lower edges of the inward facing surface  530 ,  531  of each housing  520 ,  522 . The opposed legs of the clip  540  can thus extend between the rails such that the legs of the clip  540  are axially aligned with one another. 
     As indicated above, the protrusions  510 ,  511  can help prevent sliding movement of the overmolded housings  520 ,  522 . For example, each protrusion  510 ,  511  can extend at least partially into the housing  520 ,  522  to thereby retain the housing on the jaws. This can be achieved during manufacturing by overmolding the housings  520 ,  522 , e.g., using injection molding or other molding techniques, directly onto the tip portions  506 ,  508  such that the protrusions  510 ,  511  extend into the body of the housings  520 ,  522 , thereby preventing movement of the housings  520 ,  522 . The housings  520 ,  522  can be made with a variety of materials, such as various plastics, liquid crystal polymer (LCP), elastomers, etc., and can vary in hardness (or a material&#39;s resistance to indentation as measured by the modulus of elasticity scale), depending on desired properties of the material. In some embodiments, the modulus of elasticity of the overmolded housings  520 ,  522  can be less than a modulus of elasticity of at least the tip portions  506 ,  508  of the first and second jaws  502 ,  504 . 
     The protrusions  510 ,  511  can also assist in clip formation. In particular, the protrusions  510 ,  511  can be flush, can sit proud, or can be slightly subflush of the outer surface of each clip track  532 ,  533  such that the protrusions  510 ,  511  will contact a clip either directly or indirectly (while still providing structural support and a rigid surface) when the clip is seated in the clip tracks  532 ,  533 . In an exemplary embodiment, the protrusions  510 ,  511  are flush with the outer surface so that the protrusions  510 ,  511  directly contact a clip seating in the clip track. As a result, the protrusions  510 ,  511  can provide a rigid surface for applying a force directly to the clips to aid in clip formation. In an exemplary embodiment, each protrusion  510 ,  511  is positioned to engage a bend zone of the clip, e.g., a region where the clip bends to move from the open configuration to the closed configuration. This is illustrated in  FIG. 8 , which shows protrusions  710 ,  711  located at about a mid-portion along the length of each tip portion and in contact with the bend zone. In other embodiments, the housings  520 ,  522  can be molded separately and attached to the tip portions  506 ,  508  by a variety of means, such as adhesives, laser welding, snap features, interference fit, etc. 
     In use, a clip advancing assembly can advance a clip  540  distally into the jaws  502 ,  504  such that the legs of the clip  540  are received within the clip track  532 ,  533  of each of the jaws  502 ,  504 . The first and second jaws  502 ,  504  can move to the closed position, grasping tissue therebetween. This can be achieved using a former tube, for example, that is advanced around the jaws  502 ,  504 , as previously discussed herein with respect to clip applier  100 . When the jaws are closed, the clip  540  is compressed around tissue grasped therebetween. The protrusions  510 ,  511  act to provide additional structural force for deforming the clip  540  around the tissue. 
     The overmolded housings can have a variety of features and structures formed thereon as injection molding materials onto the jaws can allow for a variety of geometries that are not possible when jaws are only stamped or machined.  FIG. 7  illustrates another embodiment of a jaw assembly  600  with overmolded housings  620 ,  622 , similar to jaw assembly  500  with overmolded housings  520 ,  522 . The illustrated jaw assembly  600  has a frame with a proximal portion  600   p  (only a portion of which is shown) that is configured to extend into the distal end of an elongate shaft of a clip applier, and a distal portion  600   d  with first and second jaws  602 ,  604 . The first and second jaws  602 ,  604  can each include a tip portion  606 ,  608  having opposed inward facing surfaces  614 ,  615  from which engagement features, such as protrusions  610 ,  611 , can extend towards one another. Overmolded features can be formed over the tip portions  606 ,  608 , such as the overmolded housings  620 ,  622  with opposed inward facing surfaces  630 ,  631 . Each inward facing surface  630 ,  631  can have a clip track  632 ,  633  formed therealong for receiving and guiding legs of a clip  640 . Each clip track  632 ,  633  can be defined by opposed upper and lower rails (only one rail  632   a,    633   a  on each clip track  632 ,  633  is shown) extending longitudinally along upper and lower edges of the inward facing surface  630 ,  631  of each housing  620 ,  622 . The opposed legs of the clip  640  can extend between the rails such that the legs of the clip  640  are axially aligned with one another. A shroud  613  similar to the upper shroud  122  can be provided. 
     In this embodiment, the opposed inward facing surfaces  630 ,  631  can also have ridges or protrusions  638 ,  639  formed on the upper and/or lower rails  632   a,    633   a  that extend towards the opposed inward facing surface  630 ,  631  and surround the clip tracks  632 ,  633 . As illustrated in  FIG. 7 , the protrusions  638 ,  639  can be configured to increase a depth of the clip tracks  632 ,  633  and/or to increase clip visibility while a clip is within the clip tracks  632 ,  633 . The protrusions  638 ,  630  can also assist in grasping tissue to be clamped. The protrusions  638 ,  639  can be identical on each opposed jaw or can be complementary to one another for mating with one another when the jaws are closed. The protrusions  638 ,  639  can be made of the same material as the overmolded housings  620 ,  622  or can be made of a different material with a different modulus of elasticity, for example the protrusions  638 ,  639  can have a modulus of elasticity less than a modulus of elasticity of the material of the overmolded housings  620 ,  622 , and thus less than a modulus of elasticity of the metal frame. When the protrusions  638 ,  639  are made of a different material, the overmolded housings  620 ,  622  can have cavities formed therein for receiving material for the protrusions  638 ,  639  during manufacturing. 
     While  FIG. 7  illustrates a plurality of ridges or protrusions  638 ,  639  formed on the upper and lower rails that define the clip track, the overmolded housings  720 ,  722  can have a number of different protrusions or other features formed thereon.  FIG. 8  illustrates another embodiment of a jaw assembly  700  with overmolded housings  720 ,  722 , similar to jaw assembly  500  with overmolded housings  520 ,  522 . The illustrated jaw assembly  700  can have a frame with a proximal portion  700   p  (only a portion of which is shown) that is configured to extend into the distal end of an elongate shaft of a clip applier, and a distal portion  700   d  with first and second jaws  702 ,  704 . The first and second jaws  702 ,  704  can each include a tip portion  706 ,  708  having opposed inward facing surfaces  714 ,  715  from which engagement features, such as protrusions  710 ,  711 , can extend towards one another. Overmolded features can be formed over the tip portions  706 ,  708 , such as overmolded housings  720 ,  722  with opposed inward facing surfaces  730 ,  731 . Each inward facing surface  730 ,  731  can have a clip track  732 ,  733  formed therealong for receiving and guiding legs of a clip  740 . Each clip track  732 ,  733  can be defined by opposed upper and lower rails (only one rail  732   a,    733   a  on each clip track  732 ,  733  is shown) extending longitudinally along upper and lower edges of the inward facing surface  730 ,  731  of each housing  720 ,  722 . The opposed legs of the clip  740  can extend between the rails such that the legs of the clip are axially aligned with one another. A shroud  713  similar to the upper shroud  122  can be provided. 
     The opposed inward facing surfaces  730  can have protrusions  738 ,  739  formed thereon that extend towards the opposed inward facing surface  730 ,  731 , similar to the protrusions  638 ,  639 . However, in this embodiment the protrusions  738 ,  739  can extend from the upper and/or lower rails  632   a,    633   a  around the protrusions  710 ,  711 , and can be configured to increase retention of the clip  740  within the jaw assembly  700  and help prevent clip fallout during formation. In other words, upper and lower protrusions on the upper and lower rails of each clip track can define a gap therebetween that is less than a height of the clip track, such that the upper and lower protrusions will help engage a clip seated therebetween. The protrusions  738 ,  739  can be made of the same material as the overmolded housings  720 ,  722  or can be made of a different material with a different modulus of elasticity, for example having a modulus of elasticity less than the material of the overmolded housings  720 ,  722 . When the protrusions  738 ,  739  are made of a different material, the overmolded housings  720 ,  722  can have cavities formed therein for receiving material for the protrusions  738 ,  739  during manufacturing. 
     In other embodiments, various windows or openings can be formed in overmolded housings along clip tracks to allow users to view a location of a clip therein. As discussed above, the protrusions  638  can be configured to increase clip visibility while a clip is within the clip track  632 , but openings can be formed anywhere along a length of the clip track.  FIG. 9  illustrates a jaw assembly  800  with overmolded housings  820 ,  822 , similar to jaw assembly  500  with overmolded housings  520 ,  522 . The illustrated jaw assembly  800  has a frame with a proximal portion  800   p  (only a portion of which is shown) that is configured to extend into the distal end of an elongate shaft of a clip applier, and a distal portion  800   d  with first and second jaws  802 ,  804 . The first and second jaws  802 ,  804  can each include a tip portion  806 ,  808  having opposed inward facing surfaces  814 ,  815  from which engagement features, such as protrusions  810 ,  811 , can extend towards one another. Overmolded features can be formed over the tip portions  806 ,  808 , such as the overmolded housings  820 ,  822  with opposed inward facing surfaces  830 ,  831 . Each inward facing surface  830 ,  831  can have a clip track  832 ,  833  formed therealong for receiving and guiding legs of a clip  840 . Each clip track  832 ,  833  can be defined by opposed upper and lower rails (only one rail  832   a,    833   a  on each clip track  832 ,  833  is shown) extending longitudinally along upper and lower edges of the inward facing surface  830 ,  831  of each housing  820 ,  822 . The opposed legs of the clip  840  can extend between the rails such that the legs of the clip are axially aligned with one another. A shroud  813  similar to the upper shroud  122  can be provided. 
     In this embodiment, the overmolded housings  820 ,  822  can have openings formed therein, for example openings formed in proximal and/or distal portions of the upper and/or lower rails.  FIG. 9  illustrates openings formed in distal ends of the upper and lower rails  832   a ,  833   a,  however the openings can be formed at any location that allows for visibility of a clip seating in the clip tracks. In the illustrated embodiment, ends  842 ,  843  of the clip  840  can be seen by a user through the distal window to thereby increase visibility of the clip  840  and assist with alignment during placement. 
     The clip track can also have a variety of configurations because of the injection molding process that are not possible with jaws that are stamped or machined.  FIG. 10  illustrates another embodiment of a jaw assembly  900  with overmolded housings (with only one jaw and overmolded housing  920  being illustrated), similar to jaw assembly  500  with overmolded housings  520 ,  522 . While only shown in part, the illustrated jaw assembly  900  has a frame with a proximal portion that is configured to extend into the distal end of an elongate shaft of a clip applier, and a distal portion  900   d  with first and second jaws (with only the first jaw  902  being illustrated, and the second jaw being a mirror image of the first jaw  902 ). The first and second jaws  902  can each include a tip portion  906  having opposed inward facing surfaces  914  from which engagement features, such as protrusions (not illustrated), can extend towards one another. Overmolded features can be formed over the tip portions  906 , such as the overmolded housings  920  with opposed inward facing surfaces  930 . Each inward facing surface  930  can have a clip track  932  formed therealong for receiving and guiding legs of a clip  940 . Each clip track  932  can be defined by opposed upper and lower rails extending longitudinally along upper and lower edges of the inward facing surface  930  of each of the first and second housings  920 . The opposed legs of the clip  940  can extend between the rails such that the legs of the clip are axially aligned with one another. 
     In this embodiment, the clip track  932  is tapered distally with a wider portion of the clip track  932  on a proximal end  932   p  thereof closer to a clip applier and a narrower portion of the clip track  932  on a distal end  932   d  thereof. The taper in the clip track  932  can be configured to allow easy and effective feeding of the clip  940  into the clip track  932  while also reducing clearance between the clip  940  and the clip track  932  as the clip  940  is fully fed into the clip track  932  and approaches the distal end  932   d  thereof. Widths of distal and proximal ends of the tapered clip track  932  can vary, for example a width of the clip track  932  at the proximal end  932   p  can be approximately double a width of the clip track  932  at the distal end  932   d.    
     Protrusions can also extend into the clip track itself.  FIG. 11  illustrates another embodiment of a jaw assembly  1000  with overmolded housings (with only one jaw and overmolded housing  1020  being illustrated), similar to jaw assembly  500  with overmolded housings  520 ,  522 . The illustrated jaw assembly  1000  can have a frame with a proximal portion that is configured to extend into the distal end of an elongate shaft of a clip applier, and a distal portion  1000   d  with first and second jaws (with only the first jaw  1002  being illustrated, and the second jaw being a mirror image of the first jaw  1002 ). The first and second jaws  1002  can each include a tip portion  1006  having opposed inward facing surfaces  1014  from which engagement features, such as protrusions (not illustrated), can extend towards one another. Overmolded features can be formed over the tip portions  1006 , such as the overmolded housings  1020  with opposed inward facing surfaces  1030 . Each inward facing surface  1030  can have a clip track  1032  formed therealong for receiving and guiding legs of a clip  1040 . Each clip track  1032  can be defined by opposed upper and lower rails extending longitudinally along upper and lower edges of the inward facing surface  1030  of each of the first and second housings  1020 . The opposed legs of the clip  1040  can extend between the rails such that the legs of the clip are axially aligned with one another. 
     As shown, protrusions  1038  can be formed at various locations along the clip track  1032 , for example being formed on and extending from each of the rails, and configured to extend into the clip track  1032  and engage the clip  1040  therein. The protrusions  1038  can be configured to assist in holding and aligning the clip  1040  in the clip track  1032  during formation. The protrusions  1038  can take a variety of forms, such as flexible fingers, pegs, fins, pads, wedges, etc., and there can be one or more protrusions  1038  formed in the clip track  1032 . Widths, lengths, and stiffness levels (modulus of elasticity) of the protrusions  1038  can vary depending on desired uses. For example, the protrusions  1038  can have lengths such that a clip entering the clip track  1032  will be engaged by protrusions  1038  on either side of the clip track  1032  and be forced into an aligned, middle position in the clip track  1032 , and the protrusions  1038  can be configured to flex or bend out of the way of a clip as it advances along the clip track  1038 . This can be beneficial with surgical clips that have widths that vary along a length of the clip itself. The protrusions  1038  can be made of the same material as the overmolded housing  1020  or can be made of a different material with a different modulus of elasticity, for example having a modulus of elasticity less than a modulus of elasticity of the material of the overmolded housing  1020  to allow the protrusions  1038  to bend and flex with the clip  1040  while the housing  1020  provides stiffer support. When the protrusions  1038  are made of a different material, the overmolded housing  1020  can have cavities formed therein for receiving material for the protrusions  1038  during manufacturing. 
     Additional features can be added to a clip applier to improve clip retention in a jaw using an overmolded process, for example to keep a clip securely in a clip track with high clip retention forces while still having strong clip forming abilities.  FIG. 12  illustrates another embodiment of a jaw assembly  1100  with overmolded housings (with only a cross-section of one jaw  1102  and overmolded features  1120  being illustrated), similar to jaw assembly  500  with overmolded housings  520 ,  522 . The jaw  1102  of the illustrated jaw assembly  1100  is rigid and has overmolded features  1120  in the form of polymer rails formed thereon. As a clip  1140  is inserted into the jaw  1102 , the polymer rails of the overmolded features  1120  can be configured to deform only slightly and allow for the clip  1140  to snap into place, being configured to keep the clip  1140  retained more securely against the jaw  1102  than many common designs that use only metal jaws. As illustrated in  FIG. 12 , the clip  1140  is configured to sit securely in a clip track  1132  of the jaw  1102 . 
     Another embodiment with a similar structure is illustrated in  FIG. 13 . A jaw assembly  1200  with overmolded housings (with only a cross-section of one jaw  1202  and overmolded features  1220  being illustrated), similar to jaw assembly  500  with overmolded housings  520 ,  522 . The jaw  1202  of the illustrated jaw assembly  1200  is rigid and has overmolded features  1220  in the form of elastomer rails formed thereon. As a clip  1240  is inserted into the jaw  1202 , the elastomer rails of the overmolded features  1220  can be configured to deform and allow for the clip  1240  to deform the overmolded features  1220  and secure itself into place. As illustrated in  FIG. 13 , the clip  1240  is configured to sit securely in a clip track  1232  of the jaw  1202 . The elastomer rails of the overmolded features  1220  can have a lower modulus of elasticity than a modulus of elasticity of the polymer rails of the overmolded features  1120 . The overmolded features  1120  can thus cause the clip  1140  to snap into place in the jaw  1102  while the overmolded features  1220  allow for more deformation of the elastomer rails and an easier release of the clip  1240 . 
       FIG. 14  illustrates another embodiment of a jaw assembly  1300  with overmolded housings (with only a cross-section of one jaw  1302  and overmolded features  1320 ,  1322  being illustrated), similar to jaw assembly  500  with overmolded housings  520 ,  522 . The jaw  1302  of the illustrated jaw assembly  1300  is rigid and has first overmolded features  1320  in the form of polymer sidewall rails formed on either side of the jaw  1302  and second overmolded features  1322  in the form of elastomer inserts formed in a clip track  1332 . As a clip  1340  is inserted into the jaw  1302 , the polymer sidewall rails of the overmolded features  1320  can be configured to guide the clip  1340  along the clip track  1332 , providing a rigid guide. The elastomer inserts can be positioned in the clip track  1332  itself and provide an interference fit between the clip  1340  and the clip track  1332  so that the clip  1340  can sit securely in the clip track  1323  while benefiting from a rigid guide from the overmolded features  1320  because the polymer sidewalls of the overmolded features  1320  can have a higher modulus of elasticity than a modulus of elasticity of the elastomer inserts of the overmolded features  1322 . 
     While various structures are provided above for overmolded features, additional features and structures are possible. For example,  FIG. 15  illustrates another embodiment of a jaw assembly  1400  with overmolded housings (with only a cross-section of one jaw  1402  and overmolded features  1420  being illustrated), similar to jaw assembly  500  with overmolded housings  520 ,  522 . The jaw  1402  of the illustrated jaw assembly  1400  is rigid and has overmolded features  1420  in the form of polymer sidewall rails formed on either side of the jaw  1402  with arms  1422  formed to extend slightly into a clip track  1432  and help secure a clip  1440  therein. 
     Another possible geometry is illustrated in  FIG. 16 , in which another embodiment of a jaw assembly  1500  with overmolded housings (with only a cross-section of one jaw  1502  and overmolded features  1520  being illustrated), similar to jaw assembly  500  with overmolded housings  520 ,  522 . The jaw  1502  of the illustrated jaw assembly  1500  is rigid and has overmolded features  1520  in the form of polymer sidewall rails formed on either side of the jaw  1502  in a dovetail shape such that inner surfaces  1522  of the sidewall rails are thicker than outer surfaces and are thus configured to extend slightly into a clip track  1532  to help secure a clip  1540  therein. While the materials discussed herein are polymers and elastomers, any materials can be used that can have lower values for modulus of elasticity than the rigid jaws. 
     The various clip retaining features disclosed herein can have a variety of other configurations, as disclosed in U.S. Application No. [] (Atty. Docket No. 47364-309F01US, END8262USNP), filed on even date herewith and entitled “Clip Retention for Surgical Clip Applier,” which is hereby incorporated by reference in its entirety. 
     During manufacturing, a rigid frame defining one of the jaws  500 ,  600 ,  700 ,  800 ,  900 ,  1000  discussed above can be stamped from a rigid material, such as metal, including the one or more protrusions extending from distal portions thereof. Housings defining the overmolded housings  520 ,  522 ,  620 ,  622 ,  720 ,  722 ,  820 ,  822 ,  920 ,  1020  can be formed by injection molding a material, such as various plastics, liquid crystal polymer (LCP), elastomer, etc., around each of the corresponding jaws  500 ,  600 ,  700 ,  800 ,  900 ,  1000  to form the housings with the opposed inward facing surfaces defining the clip tracks therein. The protrusions on the metal frame can prevent sliding movement of the overmolded housings relative to the frame. 
     The various protrusions or other features of the overmolded housings  620 ,  622 ,  720 ,  722 ,  820 ,  822 ,  920 ,  1020  discussed above located around and/or within the clip tracks can either be formed of the same material as the overmolded housings  620 ,  622 ,  720 ,  722 ,  820 ,  822 ,  920 ,  1020  and can be injection molded simultaneously with the overmolded housings  620 ,  622 ,  720 ,  722 ,  820 ,  822 ,  920 ,  1020  or can be made from a different material, such as various plastics, liquid crystal polymer (LCP), elastomer, etc., and can be formed after injection molding of the overmolded housings  620 ,  622 ,  720 ,  722 ,  820 ,  822 ,  920 ,  1020  has been completed. In such an embodiment, material for the various protrusions of the overmolded housings  620 ,  622 ,  720 ,  722 ,  820 ,  822 ,  920 ,  1020  can be injection molded into cavities or spacings formed on the overmolded housings  620 ,  622 ,  720 ,  722 ,  820 ,  822 ,  920 ,  1020  and configured to receive material for the protrusions therein. In some embodiments, material used to injection mold the overmolded housings  620 ,  622 ,  720 ,  722 ,  820 ,  822 ,  920 ,  1020  can be varied within a single overmolded housing to create varying material properties within one overmolded housing, for example increasing friction in various molded parts of the molded housings  620 ,  622 ,  720 ,  722 ,  820 ,  822 ,  920 ,  1020 . Injection molding can thus occur in one step or over multiple steps depending on a desired complexity of the overmolded housings and how many materials are to be used in the overmolded housings. 
     In the present disclosure, like-numbered components of the embodiments generally have similar features, and thus within a particular embodiment each feature of each like-numbered component is not necessarily fully elaborated upon. Sizes and shapes of the devices described herein, and the components thereof, can depend at least on the anatomy of the subject in which the devices will be used, the size and shape of components with which the devices will be used, and the methods and procedures in which the devices will be used. The figures provided herein are not necessarily to scale. Although the devices and methods disclosed herein are generally directed to surgical techniques, they can also be used in applications outside of the surgical field. 
     Although the invention has been described by reference to specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but that it have the full scope defined by the language of the following claims.