Patent Publication Number: US-2021169629-A1

Title: Soft tissue repair prosthesis and expandable device

Description:
FIELD OF INVENTION 
     The present invention is directed to a soft tissue repair prosthesis, an expandable device, and to attachment components for removably securing the prosthesis with the expandable device. 
     BACKGROUND OF INVENTION 
     One technique for repairing a soft tissue defect, such as an abdominal wall hernia, involves inserting a soft tissue repair prosthesis, such as a mesh patch or plug, into an intra-abdominal space, positioning the prosthesis relative to the wall defect, and then, if desired, securing the prosthesis with tacks, sutures, and/or adhesives. 
     To deliver the prosthesis intra-abdominally, the prosthesis may be rolled up, folded or otherwise collapsed into a reduced configuration and then inserted through a small incision or a trocar and into the intra-abdominal space. The prosthesis is then unfurled and positioned relative to the defect. 
     SUMMARY OF INVENTION 
     In one illustrative embodiment, a hernia repair device is provided which includes an expandable device configured to be removably connected with a soft tissue repair prosthesis, the expandable device having a first axis and a second axis, the first axis being substantially perpendicular to the second axis, and where the second axis defines a maximum width of the expandable device. The expandable device is configured to be manipulated about the first axis into a reduced configuration for insertion into a body. The hernia repair device further includes a plurality of attachment components associated with the expandable device to removably connect the prosthesis with the expandable device and the plurality of attachment components are offset from the second axis. 
     In another illustrative embodiment, a hernia repair device is provided which includes an expandable device configured to be removably connected with a soft tissue repair prosthesis, the expandable device having a first axis and a second axis, the first axis being substantially perpendicular to the second axis, and the first axis intersecting the second axis at approximately the center of the expandable device. The expandable device is configured to be manipulated about the first axis into a reduced configuration for insertion into a body. The expandable device includes an expandable forward portion spaced apart from an expandable rear portion by a single intermediate portion which connects the forward portion to the rear portion. The forward portion and the rear portion each include sections that extend outwardly from the first axis. A maximum dimension of the intermediate portion in the reduced configuration along a plane defined by the second axis is less than a maximum dimension of the expandable device at either the forward portion and the rear portion in the reduced configuration defined along a plane substantially parallel to the second axis. 
     In yet another illustrative embodiment, a hernia repair device is provided which includes an expandable device configured to be removably connected with a soft tissue repair prosthesis, the expandable device having a first axis, where the expandable device is configured to be manipulated about the first axis into a reduced configuration for insertion into a body. The hernia repair device further includes a plurality of attachment components coupled to the expandable device to removably connect the prosthesis with the expandable device. At least one of the plurality of attachment components has a maximum dimension which defines a longitudinal axis of the attachment component, and to minimize the size of the hernia repair device in its reduced configuration, the at least one of the plurality of attachment components is arranged on the expandable device such that its longitudinal axis is substantially parallel to the first axis. 
     In yet a further illustrative embodiment, a hernia repair device is provided which includes an expandable device configured to be removably connected with a soft tissue repair prosthesis and a plurality of attachment components coupled to the expandable device to removably connect the prosthesis with the expandable device. The plurality of attachment components are positioned to extend entirely within the perimeter of the expandable device. 
     In another illustrative embodiment, a hernia repair device is provided which includes a soft tissue repair prosthesis, and an expandable device removably connected with the soft tissue repair prosthesis, the expandable device having a first axis and a second axis, the first axis being substantially perpendicular to the second axis, where the second axis defines a maximum width of the expandable device. The expandable device is configured to be manipulated about the first axis into a reduced configuration for insertion into a body. The soft tissue repair prosthesis has a maximum width defined in a direction substantially parallel to the second axis, and to minimize the size of the hernia repair device in its reduced configuration, the maximum width of the expandable device is spaced apart from the maximum width of the soft tissue repair prosthesis. 
     In yet a further illustrative embodiment, a hernia repair device is provided which includes an inflatable device configured to be removably connected with a soft tissue repair prosthesis, the inflatable device having a first axis where, when deflated, the inflatable device is configured to be manipulated about the first axis into a reduced configuration for insertion into a body. The inflatable device includes a plurality of reliefs spaced around the perimeter of the inflatable device configured to minimize bending of the inflatable device when inflated. 
     In another illustrative embodiment, a method of assembling a hernia repair device is provided. The method includes the acts of arranging a soft tissue repair prosthesis on an expandable device with at least one attachment component, where the prosthesis, expandable device and attachment component form a hernia repair device. The method further includes manipulating the hernia repair device about a first axis into a reduced configuration, where the soft tissue repair prosthesis is arranged on the expansion device such that a maximum dimension of the hernia repair device in the reduced configuration is minimized. 
     Various embodiments of the present invention provide certain advantages. Not all embodiments of the invention share the same advantages and those that do may not share them under all circumstances. 
     Further features and advantages of the present invention, as well as the structure of various embodiments that incorporate aspects of the invention are described in detail below with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The foregoing and other objects and advantages of the invention will be appreciated more fully from the following drawings, wherein like reference characters designate like features, in which: 
         FIG. 1A  is a top view of an expandable device and soft tissue repair prosthesis according to one embodiment of the present invention; 
         FIGS. 1B, 1C and 1D  are perspective views illustrating a hernia repair device being manipulated into a reduced configuration; 
         FIG. 2  illustrates an attachment component according to one embodiment of the present invention; 
         FIG. 2A  illustrates the attachment component shown in  FIG. 2  coupled to a soft tissue repair prosthesis; 
         FIG. 3-7  illustrate attachment components according to various embodiments of the present invention; and 
         FIGS. 8-28  illustrate expandable devices according to various embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Aspects of the present invention are directed to a soft tissue repair prosthesis, such as a patch, plug, or patch and plug combination, for augmenting, reconstructing or otherwise repairing a muscle or tissue wall, such as a chest wall or abdominal wall, and that has particular application for repairing a hernia defect to reconstruct the chest wall. 
     An expandable device may be provided for delivering, locating, or otherwise positioning the soft tissue repair prosthesis at the surgical site. The soft tissue repair prosthesis may be carried by or otherwise connected with the expandable device, such that manipulation of the expandable device will effect the shape and/or position of the soft tissue repair prosthesis. The expandable device may have a reduced configuration suitable for introduction to the surgical site and an expanded configuration for deploying, locating, or otherwise positioning the soft tissue repair prosthesis. Expansion of the expandable device, when connected with the soft tissue repair prosthesis, may cause the soft tissue repair prosthesis to transform from a reduced delivery profile to an enlarged configuration suitable for the desired procedure, such as extending over, under, or a hernia defect. The term “hernia repair device” is used throughout the application and may be used to reference the expandable device, the soft tissue repair prosthesis, and/or the combination of the expandable device and soft tissue repair prosthesis, as the invention is not limited in this respect. 
     As set forth below, the expandable device may be in the form of a balloon or other inflatable bladder, or other construction suitable for delivery in a reduced configuration and expansion to a larger size. The soft tissue repair prosthesis may be mounted to, or otherwise connected with, the expandable device, and then the combined components may be reduced in size, such as by rolling, folding, collapsing, or otherwise manipulating, and then inserted through a trocar or small incision into the abdominal cavity or other surgical site. Expansion of the expandable device, such as by inflation where the expandable device is in the form of a balloon, will in turn cause the soft tissue repair prosthesis to move into an expanded configuration suitable for the intended procedure. For example, where the soft tissue repair prosthesis is a mesh sheet and has been rolled up with an associated balloon, inflation of the balloon will cause the mesh sheet to unroll or otherwise expand into an enlarged configuration which can then be positioned relative to the defect. 
     Aspects of the present invention are directed to arrangements for connecting an expandable device with a soft tissue repair prosthesis. In one embodiment, the expandable device and soft tissue repair prosthesis are detachably connected. For example, and without limitation, one or more attachment components may releasably connect the expandable device and soft tissue repair prosthesis. The attachment components may loosely connect the prosthesis and the expandable device together in the reduced profile. As set forth in greater detail below, the attachment components may be configured and arranged to minimize the size of the hernia repair device in its reduced configuration. 
     Other aspects of the present invention are directed to various configurations for the expandable device to minimize the size of the hernia repair device when in its reduced configuration. 
     Turning to  FIG. 1A , one embodiment of a hernia repair device is illustrated. The hernia repair device includes an expandable device  100  that is configured to be removably connected with a soft tissue repair prosthesis  200 . A plurality of attachment components  300   a ,  300   b ,  300   c ,  300   d  are provided to removably connect the prosthesis  200  with the expandable device  100 . In this particular embodiment, the attachment components  300   a - d  are configured as substantially helical shaped coils that may be oriented to extend into/out of the page. As discussed below, in other embodiments, other types of attachment components are also contemplated as the invention is not so limited. 
     Applicant recognized the importance of minimizing the size of the hernia repair device when in its reduced configuration for insertion into a body. The hernia repair device is typically inserted through a small incision or a trocar and into the intra-abdominal space. It may be desirable to minimize the size of the incision or trocar. For example. In one particular embodiment, it may be desirable to use a trocar that is 12 mm or less, which would require that the outer diameter, or other maximum dimension, of the hernia repair device in its reduced configuration is 12 mm or less. In another embodiment, it may be desirable to use a trocar that is 20 mm or less, which would require that the outer diameter, or other maximum dimension, of the hernia repair device in its reduced configuration is 20 mm or less, It should be appreciated that when the hernia repair device is rolled into a cylindrical configuration, it may have a diameter, but that in embodiments where the hernia repair device is folded or otherwise manipulated into its reduced configuration, the device may have a non-circular cross-section and will still have a maximum dimension. The term “maximum dimension” is used throughout the application and may be used to reference this outer dimension of the hernia repair device, or components of the hernia repair device, when in the reduced configuration. 
     As set forth below, Applicant recognized that the particular placement of the attachment components relative to the expandable device and/or prosthesis may be optimized to minimize the maximum dimension of the hernia repair device in its reduced configuration. Applicant recognized that the attachment components may be thicker than the prosthesis and/or the expandable device, and thus, strategic placement of the attachment components may help to minimize the maximum dimension of the hernia repair device when in its reduced configuration. This may help to minimize the size of the incision or trocar needed to delivery the hernia repair device into the body. For example, as discussed in greater detail below, in one embodiment, the attachment components may be offset from the maximum width portion of the expandable device and/or prosthesis. As set forth below, in another embodiment, the attachment components may be positioned relative to the expandable device such that two attachment components are not stacked onto each other when the hernia repair device is manipulated into its reduced configuration. 
     As illustrated in  FIG. 1A , the expandable device  100  has a first axis  110  and the expandable device  100  is configured to be furled, or otherwise manipulated, about the first axis  110  into a reduced configuration for insertion into a body. Thus, the first axis  110  may also be referred to as the furling axis, rolling axis, or manipulation axis. The expandable device also has a second axis  120  which is substantially perpendicular to the first axis. As shown, the second axis  120  defines a maximum width of the expandable device  100  in a plane substantially perpendicular to the first axis  110 . In this particular illustrative embodiment, the first axis  110  intersects the second axis  120  at approximately the center of the expandable device. However, it should be appreciated that in another embodiment where the expandable device is shaped differently, the first axis  110  may intersect the second axis  120  at a location spaced apart from the center of the expandable device. 
     As illustrated in  FIG. 1A , a plurality of attachment components  300   a ,  300   b ,  300   c ,  300   d  are associated with the expandable device  100  to removably connect the prosthesis  200  with the expandable device  100 . In this particular embodiment, the attachment components  300   a - d  are mechanical fasteners coupled to the expandable device  100 . More specifically, as illustrated, the attachment components  300   a - d  are configured as substantially helical shaped coils, where a portion of the coil, such as one end of the coil, is secured to the expandable device, and may, for example pierce through a portion of the expandable device  100 . As set forth in more detail below, in other embodiments, the attachment components may be configured differently as the invention is not limited in this respect. 
     Regardless of the specific type of attachment component, in this embodiment, the attachment components  300   a - d  are offset from the second axis  120 . As mentioned above, the second axis  120  defines a maximum width of the expandable device  100 . Thus, by offsetting the attachment components from the second axis  120 , the attachment components are offset from the maximum width of the expandable device  100 . 
     As shown in  FIG. 1A , in one embodiment, the prosthesis is substantially elliptical shaped, such that the maximum width of the prosthesis  200  is also along, the second axis  120 . Thus, in this particular embodiment, the attachment components  300   a - d  are also offset from the portion of the prosthesis  200  having a maximum width. Applicant recognized that offsetting the attachment components  300   a - d  from the maximum width of the expandable device  100  and/or the maximum width of the prosthesis  200  may minimize the maximum dimension of the hernia repair device when the device is rolled or otherwise manipulated into in its reduced configuration. 
     In one embodiment, the maximum dimension of the expandable device  100  in its reduced configuration is greater along the second axis  120  (i.e. at its location of maximum width). In the particular embodiment illustrated in  FIG. 1 , the maximum dimension of the prosthesis  200  in its reduced configuration will also be greatest along the second axis. Tt is recognized that the attachment components  300   a - d  may also contribute to the maximum dimension of the hernia repair device. As illustrated, in one embodiment, the attachment components  300   a - d  are spaced apart, such that the thickness of the attachment components  300   a - d  may vary across the length of the prosthesis and the expandable device. By spacing the attachment components away from the maximum width of the expandable device and/or prosthesis when in an expanded flat configuration, the attachment components may minimally contribute to the maximum dimension of the hernia repair device, such that the maximum dimension of the hernia repair device in its reduced configuration is minimized. 
     In one embodiment, an attachment component  300   a  is positioned near the second axis  120  along a plane  130  defined as being substantially perpendicular to the first axis  110  (i.e. manipulation axis). Applicant recognized that if multiple attachment components are positioned along plane  130 , then the attachment components will stack on top of each other when the hernia repair device is manipulated into its reduced configuration. Thus, the multiple attachment components along that plane will cause the maximum dimension of the device in its reduced configuration to be greater than if only one attachment component is positioned along the plane  130 . In one embodiment, to minimize the maximum dimension of the hernia repair device in its reduced configuration, no other attachment component is arranged on that same plane  130 . In this respect, as the expandable device  100  is folded, rolled, or otherwise manipulated its reduced configuration, one attachment component  300   a  is not stacked onto another attachment component  300   b . By offsetting the attachment components  300   a - d  across the the hernia repair device, the maximum dimension of the hernia repair device may be minimized when in its reduced configuration. 
     In this embodiment, each attachment component  300   a - d  is positioned along a that defined as being substantially perpendicular to the first axis (i.e. manipulation axis) and no other attachment component is also arranged on that same plane. For example, as illustrated, attachment component  300   a  is positioned on plane  130 , attachment component  300   b  is positioned on plane  132 , attachment component  300   c  is positioned on plane  134 , and attachment component  300   d  is positioned on plane  136 . As illustrated, because all of these planes are substantially perpendicular to the first axis  110  (i.e. manipulation axis), these planes are also substantially parallel to each other. 
     In the particular embodiment illustrated in  FIG. 1A , the length of the expandable device  100  along the first axis  110  is greater than the width of the expandable device  100  along the second axis  120 . In certain embodiments, this may be preferred so that when the expandable device  100  is manipulated into its reduced configuration for insertion into the body, the device is furled, or otherwise manipulated, about its larger dimension so that it has a more slender reduced configuration. It should be appreciated that in other embodiments, the length of the expandable device  100  along the first axis  110  may be substantially equal to the width of the expandable device  100  along the second axis  120 , and in yet other embodiments, the length of the device  100  may be less than the width, as the invention is not so limited. 
     The hernia repair device illustrated in  FIG. 1A  is shown with the expandable device  100  and the prosthesis  200  both having a substantially planar configuration. As discussed above, and as illustrated in  FIGS. 1B-1D , the hernia repair device may be manipulated into a reduced configuration for insertion into the body. As illustrated, a device  20  may be used to manipulate the hernia repair device into its reduced configuration. For simplification of the drawings, in  FIGS. 1B-1C , only the prosthesis  200  is illustrated and the expandable device  100  is not shown. As mentioned above, the hernia repair device may be furled, rolled, or otherwise manipulated about the first axis  110  into its reduced configuration. As shown in  FIG. 1C , in which the prosthesis  200  is partially rolled up, the first axis  110  (which may be considered the manipulation axis) aligns with the longitudinal axis of the device  20  used to manipulate the hernia repair device into its reduced configuration. It should also be appreciated that the hernia repair device may be folded, crumpled, collapsed or otherwise manipulated about the first axis  110  into its reduced configuration. 
     In one embodiment, the expandable device  100  is inflatable (either filled with a gas or a liquid). As shown in  FIG. 1A , an inflation tube  140  may be coupled to the expandable device  100  for selectively inflating the device. In this particular embodiment, the inflation tube is coupled to the center portion of the expandable device, but it should be appreciated that the inflation tube may be coupled to the expandable device in a different location. It should be recognized that before the hernia repair device is inserted into the body that the expandable device  100  may be in a deflated state. The expandable device  100  may not be inflated until after it is within the body. In one particular embodiment, the expandable device  100  is inflatable with air. 
     The expandable device  100  may be removably connected with the soft tissue repair prosthesis  200  by one or more attachment components  300 , including, but not limited to sutures, adhesives, or mechanical fasteners including hook and loop fasteners, rivets, coils, and the like. As discussed above, in one embodiment, the attachment components  300   a - d  are configured as substantially helical shaped coils that extend into/out of the page, where a portion of the coil is secured to the expandable device, and may, for example pierce through a portion of the expandable device  100 . 
     Applicant recognized that the shape and orientation of the attachment components relative to the expandable device and/or the prosthesis may affect the maximum dimension of the hernia repair device when in its reduced configuration. In particular, applicant determined that by orienting the attachment component such that the maximum dimension of the attachment component is aligned with the first axis  110  (i.e. manipulation axis), the maximum dimension of the hernia repair device in its reduced configuration may be minimized. As mentioned above, it may be desirable to minimize the maximum dimension of the hernia repair device in its reduced configuration so that a smaller incision or trocar can be used to delivery the hernia repair device into the body. This concept will be discussed in greater detail with respect to  FIGS. 2-7 , which disclose some various embodiments of attachment components in accordance with aspects of the present invention. 
     The attachment component  310  shown in  FIG. 2  has a substantially linear center  312  with two curved portions  314 ,  316  positioned on each side of the linear portion  312 . Two additional curved portions  318 ,  320  are positioned on each side of the curved portions  314 ,  316 , and they are curved in the opposite direction as the curved portions,  314 ,  316 , such that the two adjacent portions form a substantially S-shaped curve. A portion of the attachment component, such as the center portion  312  may be coupled to the expandable device  100 . For example, in one embodiment, the center portion  312  may be welded, or otherwise secured to the expandable device  100 . As shown in  FIG. 2A , one or both of the S-shaped ends of the attachment component  310  may be used to hook or otherwise couple the prosthesis  200  to the attachment component  310  and the expandable device  100 . These curved ends of the attachment component  310  may assist to retain the prosthesis  200  to the expandable device  100 . 
     The attachment component  310  has a length L which defines its maximum dimension and defines its longitudinal axis. As shown in  FIG. 2A , to minimize the maximum dimension of the hernia repair device in its reduced configuration, the attachment component  310  may be arranged on the hernia repair device such that its longitudinal axis is substantially parallel to the first axis  110 . For simplification, in  FIG. 2A , the prosthesis  200  is illustrated, but the expandable device  100  is not shown. In this respect, as the hernia repair device is furled, rolled, or otherwise manipulated about the first axis  110  into its reduced configuration, the attachment component  310  is oriented to minimally contribute to the maximum dimension of the hernia repair device when the device is manipulated into its reduced configuration. It should be appreciated that if the attachment component  310  is made of a substantially rigid material and is oriented such that its longitudinal axis was, for example, substantially perpendicular to the first axis  110  (i.e. substantially parallel to the second axis  120 ), then the maximum dimension of the hernia repair device in its reduced configuration may be at least as big as the length L of the attachment component  310 , which may be undesirably too large. 
       FIG. 3  illustrates another embodiment of an attachment component  330  which includes two substantially linear center portion  332 ,  334  with two curved portions  336 ,  338  positioned on each side of the linear portions  332 ,  334 . As shown, the two center portions  332 ,  334  may form a substantially V-shape at the center of the attachment component  330 . A portion of the attachment component  330 , such as one or both of the center portions  332 ,  334  may be coupled to the expandable device  100 . One or both of the curved end portions  336 ,  338  of the attachment component  330  may be used to hook or otherwise couple the prosthesis  200  to the attachment component  330  and the expandable device  100 . The attachment component  330  has a length L which defines its maximum dimension and defines its longitudinal axis. As discussed above with respect to attachment component  310 , the attachment component  330  may be arranged on the expandable device such that its longitudinal axis is substantially parallel to the first axis  110  (see  FIG. 2A .) In this respect, as the hernia repair device is furled, rolled, or otherwise manipulated about the first axis  110  into its reduced configuration, the attachment component  330  is oriented to minimally contribute to the maximum dimension of the hernia repair device in its reduced configuration. 
       FIGS. 4-7  illustrate additional attachment components in accordance with aspects of the present invention. In particular,  FIG. 4  illustrates an attachment component  340  that has a V-shaped center portion  342 , with a substantially S-shaped portion  344 ,  346  on each end of the attachment component  340 .  FIG. 5  illustrates an attachment component  350  that has a substantially linear center portion  352 , with a substantially C-shaped portion  354 ,  356  on each end of the attachment component  350 .  FIG. 6  illustrates an attachment component  360  with a plurality of substantially linear center portions  362 ,  364 ,  366  with a substantially S-shaped portion  368 ,  370  on each end of the attachment component  360 . Finally,  FIG. 7  illustrates yet another embodiment of an attachment component  380 . In this particular embodiment, the attachment component  380  is substantially helical shaped. As illustrated, each of these attachment component  340 ,  350 ,  360 ,  380  has a length L which defines its maximum dimension and defines its longitudinal axis. As discussed above with respect to attachment components  310 ,  330 , the attachment components  340 ,  350 ,  360 ,  380  may be arranged on the expandable device such that its longitudinal axis is substantially parallel to the first axis  110  (see  FIG. 2A .) In this respect, as the hernia repair device is furled, rolled, or otherwise manipulated about the first axis  110  into its reduced configuration, the attachment component  340 ,  350 ,  360 ,  380  is oriented to minimally contribute to the maximum dimension of the hernia repair device in its reduced configuration. 
     The attachment components may be formed from a variety of types of materials, as the invention is not so limited. In one embodiment, the attachment components are made from a plastic or a metal material such as, but not limited to a shape memory metal, polyurethane, or nylon heat sealed into its specific configuration. In one embodiment the attachment components are made of a substantially rigid material such that the attachment component substantially maintains its shape and configuration. 
     In one embodiment, the attachment component is made of an elastic or spring-like material which enables the attachment component to be capable of stretching out and lengthening along its longitudinal axis when subjected to a tensile load. In this respect, the attachment component may be stretched or otherwise elongated to either couple or decouple the prosthesis  200  with the attachment component. In particular, when the attachment component is in a stretched or otherwise elongated position (i.e. when one or both ends of the attachment component are pulled), the prosthesis  200  nay more easily slide onto or off from the ends of the attachment component. As mentioned above, the curved ends of the attachment component may be configured to assist in retaining the prosthesis on the attachment component. By applying tension to the attachment component, the curved ends may straighten out which may make it easier to either couple or decouple the prosthesis to the attachment component. Once the prosthesis is in its desired position on the attachment component, the tension may be removed which may cause the curved ends of the attachment component to spring back into a more curved or coiled state to prevent the prosthesis from undesirably decoupling from the attachment component. When the attachment component is in its normal non-stretched position (such as in the configurations illustrated in  FIGS. 2-7 ) the C-shaped, S-shaped, and/or otherwise loop or curved shaped ends of the attachment components may assist in coupling and/or retaining the prosthesis  200  with the attachment component. 
     Although  FIGS. 2-7  illustrate various embodiments of attachment components according to aspects of the present invention, it should also be recognized that the invention is not limited to these specific configurations. 
     Turning now to  FIGS. 8-26 , various embodiments of the expandable device will now be discussed in greater detail. It should also be recognized that the expandable device  100  may be formed from a variety of materials, as the invention is not limited in this respect. In one embodiment, the expandable device is formed of polyurethane, and may, for example, be formed of nylon coated polyurethane. In one embodiment, a coating such as a thermoplastic polyurethane (TPU) coating is employed. In an embodiment where the expandable device  100  is inflatable, the expandable device may be formed of two layers of nylon coated polyurethane that together form a chamber for the introduction of air. 
     Applicant recognized that the expandable device may be shaped and configured in a variety of different ways. Applicant also recognized that it may be desirable for the expandable device to be configured such that the maximum dimension of hernia repair device is minimized in reduced configuration. As discussed below, certain aspects of the present invention are directed to an expandable device configured such that the width of the expandable device is minimized in the region where the width of the prosthesis is the greatest. As mentioned above, the portions of the prosthesis and/or expandable device which have the maximum width may correspond to the portions of the hernia repair device which have the maximum dimension when the device is manipulated into its reduced configuration. Thus, offsetting the maximum width portions of the expandable device from the maximum width portions of the prosthesis may help to minimize the maximum dimension of the device in its reduced configuration. For example, as mentioned above, and as illustrated in  FIG. 1A , in one embodiment, the prosthesis is substantially elliptical shaped. In this embodiment, the width of the prosthesis is greatest in the center, along axis  120 . Thus, in embodiment of the present invention, the width of the center portion of the expandable device is less than the width of an end portion of the expandable device. In this respect, the widest portion of the expandable device is not located near the widest portion of the prosthesis. When the hernia repair device is manipulated into a reduced configuration about the first axis  110 , the widest portions of the expandable device  100  are then offset from the widest portions of the prosthesis  200 . This helps to minimize the maximum dimension of the hernia repair device in its reduced configuration. 
     Although many of the below-described expandable devices are configured for with a substantially elliptical-shaped prosthesis, the invention is not limited in this respect. The invention also is directed to expandable devices which are designed for use with a prosthesis having a different shape, where the widest portion of the expandable device is offset from the widest portion of the prosthesis. 
     As shown in  FIG. 8 , in one embodiment the expandable device  400  includes an expandable first or forward portion  402  spaced apart from an expandable second or rear portion  406  with a single intermediate portion  404  positioned there between connecting the forward portion  402  to the rear portion  406 . In one embodiment, the single intermediate portion  404  is expandable. However, it is also contemplated that the single intermediate portion  404  may be non-expandable. As discussed above, the expandable device  400  has a first axis  110  and the expandable device  400  is configured to be furled, rolled or otherwise manipulated about its first axis  110  into a reduced configuration for insertion into a body. The expandable device may also have a second axis  112  which is substantially perpendicular to the first axis  110 . In this illustrative embodiment, the second axis  112  may define a maximum width of the prosthesis  200 , and in one particular embodiment, such as when the prosthesis is elliptical shaped, the first axis may intersect the second axis substantially at the center of the expandable device  400 . 
     As illustrated, the expandable forward and rear portions  402 ,  406  of the expandable device  400  each include sections that extend outwardly from the first axis  110 . These sections help to unfurl and retain the prosthesis in a planar configuration once the hernia repair device is inserted into the body. In one embodiment, the expandable forward and rear portions  402 ,  406  may be shaped to extend along the perimeter of the prosthesis. The single intermediate portion  404  of the expandable device is configured to align with the widest portion of the prosthesis. Applicant recognized that by strategically placing only a single intermediate connector  404  in the portion of the expandable device that corresponds to the maximum width portion of the prosthesis that the maximum dimension of the hernia repair device in its manipulated reduced configuration can be desirably decreased. 
     To minimize the maximum dimension of the hernia repair device in its reduced configuration, the maximum dimension of the single intermediate portion  404  in a reduced configuration is less than the maximum dimension of the expandable device  400  at either the expandable forward or rear portion  402 ,  406  in a reduced configuration. In particular, the maximum dimension of the intermediate portion  404  in a reduced configuration along a plane P c  defined by the second axis  112  is less than the maximum dimension of either the forward or rear portion  402 ,  406  in a reduced configuration defined along a plane P f , P r  that is substantially parallel to the second axis. Such a configuration may be desirable for use with prosthesis as discussed above, which has a widest portion aligned with the second axis  112 . 
     In the embodiment illustrated in  FIG. 8 , the single intermediate portion  404  extends across approximately a center third of the expandable device  400 . It should be appreciated that in another embodiment, the intermediate portion  404  may extend over more or less of the expandable device. For example, in another embodiment (shown in  FIG. 10  and discussed below), the intermediate portion of the expandable device extends across approximately a center half of the expandable device. 
     As also illustrated in  FIG. 8 , in one embodiment, the single intermediate portion  404  extends substantially along the first axis  110  about which the expandable device is configured to be furled, rolled or otherwise manipulated. And as shown in  FIG. 8 , in one embodiment, the intermediate portion  404  is substantially linear. 
       FIG. 9  illustrates another embodiment of an expandable device  410  which includes an expandable forward portion  412  spaced apart from an expandable rear portion  416  with a single intermediate portion  414  positioned there between connecting the forward portion  412  to the rear portion  416 . In this embodiment, the single intermediate portion  414  is expandable. As shown, both the forward and rear portions  412 ,  416  have hook-shaped ends that extend. outwardly away from the first axis  110  and then curve inwardly back toward the first axis  110 . These hook-shaped ends may be shaped to extend along the perimeter of the prosthesis, Although both the forward and rear portions  412 ,  416  are each illustrated with two hook-shaped ends, it should be appreciated that in another embodiment only one of the forward and rear portions  412 ,  416  may include a hook-shaped end, as the invention is not so limited. Furthermore, although the forward and rear portions  412 ,  416  have a similar shape and configuration, it is also recognized that the forward portion  412  may be shaped and configured differently from the rear portion  416 . 
       FIG. 10  illustrates yet another embodiment of an expandable device  420  which includes an expandable forward portion  422  spaced apart from an expandable rear portion  426  with a single intermediate portion  424  positioned there between connecting the forward portion  422  to the rear portion  426 . As shown, both the forward and rear portions  422 ,  426  have substantially C-shaped ends that extend outwardly away from the first axis  110  that may be shaped to extend along the perimeter of the prosthesis. Although both the forward and rear portions  422 ,  426  are each illustrated with two substantially C-shaped ends, it should be appreciated that in another embodiment only one of the forward and rear portions  422 ,  426  may include a C-shaped end, as the invention is not so limited. In this particular embodiment, the single intermediate portion  424  extends in a substantially linear direction along the first axis  110  and extends across approximately a center half of the expandable device  420 . In this embodiment, the forward portion  422  extends across approximately only one quarter of the expandable device, and similarly, the rear portion  426  also only extends across approximately one quarter of the expandable device  420 . 
       FIG. 11  similarly illustrates yet another embodiment of an expandable device  430  which includes an expandable forward portion  432  spaced apart from an expandable rear portion  436  with a single intermediate portion  434  positioned there between. In this particular embodiment, both the forward and rear portions  432 ,  436  include a substantially linear portion and the intermediate portion  434  is also substantially linear. As shown, the substantially linear portions of the forward and rear portions  432 ,  436  are angled with respect to the linear intermediate portion  434 . Although both the forward and rear portions  432 ,  436  are each illustrated with substantially linear ends, it should be appreciated that in another embodiment only one of the forward and rear portions  432 ,  436  may include a linear end, as the invention is not so limited. 
     The expandable device  440  illustrated in  FIG. 12  also has expandable forward and rear portions  442 ,  446  which include substantially linear portions and a single substantially linear intermediate portion  444 . 
     Furthermore, like the embodiment shown in  FIG. 9 , the expandable device  450  illustrated in  FIG. 13  also has expandable forward and rear portions  452 ,  456  that are connected via a single intermediate portion  454 . The forward and rear portions  452 ,  456  each have hook-shaped ends that extend outwardly away from the first axis  110  and then curve inwardly back toward the first axis  110 . 
       FIG. 14  illustrates yet another embodiment of an expandable device  460  which is similar to the embodiment illustrated in  FIG. 10  in that it includes an expandable forward portion  462  spaced apart from an expandable rear portion  466  with a single intermediate portion  464  positioned there between with both the forward and rear portions  462 ,  466  having substantially C-shaped ends that extend outwardly away from the first axis  110 . 
     The embodiment illustrated in  FIG. 15  includes an expandable device  470  which includes a more angular shaped expandable forward portion  472  and expandable rear portion  476 , each made up of a plurality of substantially linear segments, with a single intermediate portion  474 . 
       FIG. 16  illustrates another embodiment of an expandable device  480  which also includes an expandable forward portion  482 , an expandable rear portion  486  and a single intermediate portion  484  positioned there between connecting the forward portion  482  to the rear portion  486 . In one particular embodiment, the expandable forward portion  482 , expandable rear portion  486  and single intermediate portion  484  are inflatable. The overall shape of the inflatable portion of this expandable device  480  is similar to the overall shape of the expandable device  420  illustrated in  FIG. 10 . In addition, the expandable device  480  may also includes non-expandable portions  488 ,  490  which extend between and connect the forward and rear portions  482 ,  486 . As mentioned above, in an embodiment where the expandable device  100  is inflatable, the expandable device may be formed of two layers of nylon coated polyurethane that together form a chamber for the introduction of air. In such a configuration, the non-expandable portions  488 ,  490  may be funned of only one layer of material, such as one layer of nylon coated polyurethane. These non-expandable portions  488 ,  490  are non-inflatable, but may still assist in retaining the overall shape of the expandable device  480 . Furthermore, in this embodiment, because the non-expandable portions  488 ,  490  are formed of only one layer of the nylon material, in comparison to the two layers of the same nylon material used to form the other portions of the expandable device  480 , the maximum dimension of the center portion of the expandable device in a reduced configuration (which includes the single intermediate portion  484  and the non-expandable portions  488 ,  490 ) may be less than the maximum dimension of the expandable device  480  in a reduced configuration at either the forward or rear portion  482 ,  486 . 
       FIG. 17  illustrates another embodiment of an expandable device  500  which in some respects is similar to the expandable device  420  disclosed in  FIG. 10 , including an expandable forward portion  502 , an expandable rear portion  506  and a single intermediate portion  504  positioned there between connecting the forward portion  502  to the rear portion  506 . However, in the embodiment illustrated in  FIG. 17 , the single expandable intermediate portion  504  is offset from the first axis  110 . 
     The embodiment of the expandable device  510  illustrated in  FIG. 18  is similar some respects to the expandable device  500  shown in  FIG. 17  in that it includes an expandable forward portion  512 , an expandable rear portion  516  and a single intermediate portion  514  positioned there between connecting the forward portion  512  to the rear portion  516 , with the intermediate portion  514  is offset from the first axis  110 . However, in the embodiment illustrated in  FIG. 18 , the intermediate portion  514  is nonlinear and is substantially W-shaped. 
     The embodiment of the expandable device  520  illustrated in  FIG. 19  is also similar to  FIG. 18 , having an expandable forward portion  522 , an expandable rear portion  526  and a single intermediate portion  524  positioned there between connecting the forward portion  522  to the rear portion  526 , with the intermediate portion  524  offset from the first axis  110 . However, in the embodiment illustrated in  FIG. 19 , the intermediate portion  524  is substantially linear. In this particular embodiment, the forward portion  522 , the rear portion  526  and the intermediate portion  524  together are substantially U-shaped. 
       FIG. 20  illustrates yet another embodiment of an expandable device  530  that in some respects is similar to the expandable device  480  shown in  FIG. 16  in that it includes an inflatable portion which includes an expandable forward portion  532 , an expandable rear portion  536  and a single intermediate portion  534  which extends along the first axis  110 . In addition, the expandable device  530  also includes non-expandable portions  538 ,  539  which extend between and connect the forward and rear portions  532 ,  536 . These non-expandable portions  538 ,  540  are non-inflatable, but may assist in retaining the overall shape of the expandable device  530 . Furthermore, in this particular embodiment, these non-expandable portions  538 ,  539  are formed of a thin layer of a material, such as a suture material, so that the maximum dimension of the center portion of the expandable device in a reduced configuration (which includes the single expandable intermediate portion  534  as well as the non-expandable portions  538 ,  539 ) is less than the maximum dimension of either the forward or rear portion  532 ,  536  in the reduced configuration. 
     The embodiment of the expandable device  540  illustrated in  FIG. 21  is similar to the expandable device  530  illustrated in  FIG. 20  except that the shape of the expandable forward and rear portions  542 ,  546  is configured differently. The expandable device  540  also includes a single intermediate portion  544  which extends substantially along the first axis  110  of the device  540 . The device  540  also includes non-expandable portions  548 ,  549 , which may be made of suture material, extending between and connect the forward and rear portions  542 ,  546 . The non-expandable portions  548 ,  549  may be configured to retain the shape of the expandable device when in an expanded or planar configuration. 
       FIG. 22  illustrates another embodiment of an expandable device  550  which includes an expandable forward portion  552 , an expandable rear portion  556  and a single intermediate portion  554 . The intermediate portion  554  includes a substantially linear inflatable segment connecting the forward and rear portions  552 ,  556  along the first axis  110  of the expandable device  550 . The device  550  also includes a substantially linear non-inflatable portion  558  which is offset from the first axis  110 . As discussed above, the non-inflatable portion  558  may be formed of a thin layer of material, so that the maximum dimension of the center portion of the device  550  in the reduced configuration is less than the maximum dimension of either the forward or rear portion  552 ,  556  in the reduced configuration. These non-inflatable portions  558  may be configured to hold the shape of the expandable device when in a planar configuration. 
       FIGS. 23 and 24  illustrate additional embodiments of the expandable device  560 ,  570 , both of which have a substantially S-shaped configuration. Each device  560 ,  570  includes an expandable forward portion  562 , an expandable rear portion  566  and a single intermediate portion  564  extending between and connecting the forward portion  562  and the rear portion  566 . In both of these embodiments, the intermediate portion  564  extends substantially along a diagonal relative to the first axis  110 . 
       FIG. 25  also illustrates an additional embodiment of the expandable device  580  which has a single intermediate portion  584  that extends substantially along a diagonal relative to the first axis  110 . The expandable device  580  shown in  FIG. 25  has an expandable forward portion  582  and an expandable rear portion  586  which form approximately an N-shaped expandable device  580  with the intermediate portion  584 , and the maximum dimension of the intermediate portion  584  in the reduced configuration is less than the maximum dimension of either the forward or rear portion  582 ,  586  in the reduced configuration. 
       FIG. 26  illustrates a further embodiment of an expandable device  590  according to the present invention, in some respects, this expandable device is configured similar to the expandable device  100  shown in  FIG. 1A . In contrast, the expandable device  590  includes indicia  592 ,  594  on each end of the expandable device  590  which indicate the superior and inferior ends of the device. Such indicia  592 ,  594  may assist the user in positioning the expandable device  590  and the prosthesis  200  within the body. In this particular embodiment, the indicia  592 ,  594  are configured as arrow head and an arrow end, but it should be appreciated that other types of indicia, such as numbers, letters, arrows, or other various markings, may be used as the invention is not so limited. 
     With the soft tissue repair prosthesis deployed and expanded in the intra-abdominal space, a suture-grasping device (not shown) may be provided to grasp and hoist the prosthesis  200  towards the defect and/or to position the soft tissue repair prosthesis against the abdominal wall. Once the soft tissue repair prosthesis  200  is positioned relative to the defect, sutures, fasteners, adhesives or the like may be applied to fixate the prosthesis  200  in place. 
     After placement of the prosthesis  200 , the attachment components may be left in place or, instead, removed. As an example, and without limitation, an instrument may be employed to remove the attachment components. In one embodiment, the attachment components are resorbable. 
     A method of repairing a hernia defect in accordance with the present invention includes one or more of the acts of: detachably securing an expandable device to a prosthesis, rolling, folding or otherwise manipulating the prosthesis and detachably secured expandable device into a slender configuration, inserting the prosthesis and expandable device into the intra-intra-abdominal space, inflating or otherwise expanding the expandable device to unfurl the mesh, hoisting the prosthesis up against the abdominal wall, fixating the prosthesis against the abdominal wall, detaching the expandable device from the prosthesis, and removing the attachment components and the expandable device from the intra-intra-abdominal space. 
     A method of assembling a hernia repair device in accordance with the present invention includes one or more of the acts of: arranging a soft tissue repair prosthesis on an expandable device with at least one attachment component, where the prosthesis, expandable device and attachment component form a hernia repair device, and manipulating the hernia repair device about a first axis into a reduced configuration, where the soft tissue repair prosthesis is arranged on the expansion device such that a maximum dimension of the hernia repair device in the reduced configuration is minimized. 
     Turning back to  FIG. 1A , in one embodiment, the attachment components  300   a - d  are positioned to extend entirely within the perimeter (i.e. the outer boundary) of the expandable device  100 . In other words, portions of the attachment components  3000   a - d  do not extend beyond the perimeter of the expandable device  100 . Applicant recognized that when suturing the prosthesis to the abdominal wall, the user may inadvertently pass the suture through the attachment component. Applicant further recognized that it may be desirable to position the attachment components to extend entirely within the perimeter of the expandable device to minimize the risk of inadvertently fixing the attachment components to the prosthesis when the prosthesis is, for example, being fastened to the abdominal wall. 
     Once the prosthesis  100  is positioned against the abdominal wall, it may be difficult for a user to visually detect the location of all of the attachment components. For example, the prosthesis may be opaque and thus the user may not see portions of the attachment component that extend behind the prosthesis. Applicant recognized that the user will be able to visually detect the location of the expandable device. Thus, the user may be able to more easily avoid inadvertently fixing the prosthesis to the expandable device when the prosthesis is being fastened to the abdominal wall. By placing the attachment components entirely within the perimeter of the expandable device  100 , then when the user avoids the expandable device when securing the prosthesis to the wall, the user will also then avoid securing the attachment components to the prosthesis. 
     As shown in  FIG. 1A , in one embodiment, the expandable device  100  may include both an expandable portion  150  and a non-expandable portion  152 . In this particular embodiment, the non-expandable portion  152  is formed around the perimeter of the expandable portion  150  and substantially follows the shape of the expandable portion  150 . 
     Applicant recognized that in some embodiments, it may be desirable to arrange the attachment components to extend within the non-expandable portion  152 . For example, it may be desirable to arrange the attachment components within the non-expandable portion  152  in an embodiment where the expandable device is inflatable. By placing the attachment components, which may include a sharp end, away from the inflatable expandable portion  150 , a user may be less likely to puncture or otherwise damage the expandable device. As shown in  FIG. 1A , the expandable device may include a non-expandable portion  152  with substantially circular shaped portions at locations spaced around the outer portion of the expandable device configured for the placement of the attachment components  300   a - d.    
     As shown in  FIGS. 8, 10, 12, 16, 18, 19 and 25 , the expandable device may include a non-expandable portion  152  positioned on the ends of the expandable device, and as illustrated, such non-expandable portions  152  may be arranged on the first axis  110  (furling axis) to provide a tab for the user to grasp the expandable device  100  while minimizing the risk of damaging the expandable portions. 
       FIGS. 27 and 28  illustrate further embodiments of an expandable device  600 ,  620  according to aspects of the present invention. In one embodiment, these expandable devices  600 ,  620  are inflatable, and as discussed above, these devices  600 ,  620  are configured to be removably connected with a soft tissue repair prosthesis and when deflated, are configured to be manipulated about a first axis  110  into a reduced configuration for insertion into a body. 
     Applicant recognized that when the expandable device is inflated and transformed from a substantially two-dimensional configuration to a three-dimensional configuration that the device may bend, bow or twist such that the three-dimensional inflated configuration may not be a substantially planar configuration. Applicant determined that this bending may be more prominent at the perimeter of the expandable device. 
     In some circumstances, it may be desirable for the three-dimensional inflated configuration to have a substantially planar configuration. In other circumstances, it may be desirable for the three-dimensional inflated configuration to have a substantially curved configuration, but it may be desirable for the device to only curve or bend to a certain degree. For example, when the inflatable device is used to position a prosthesis adjacent a hernia defect in an abdominal wall, it may be desirable for the curvature of the device to follow the contour of the abdominal wall. 
     Thus, Applicant developed an approach to minimize the bending of the inflatable device when inflated. In particular, as illustrated in  FIGS. 27 and 28 , in one embodiment, the inflatable devices include a plurality of reliefs  602 ,  604  spaced around the perimeter of the inflatable device  600 ,  620  which are configured to minimize bending of the inflatable device when inflated. Applicant recognized that the undesirable bending of the inflatable device may occur in regions of the device where the cross-section or diameter of the device is not constant (such as at a joint where multiple inflatable portions intersect). Thus, as shown, the reliefs  602 ,  604  may be positioned in these areas where the cross section of the device is not constant. The reliefs  602 ,  604  may act to minimize variation in the cross-section or diameter of the device such that the device is inflated more evenly and with less twisting. 
     In one illustrative embodiment, a relief  602 ,  604  is configured as a notch, whereas in another embodiment, a relief  602  may be configured as a slit. In the illustrative embodiment, a plurality of substantially V-shaped notches  602  are positioned around the perimeter of the device and are outwardly facing to allow the device to open outwardly as it is inflated. As shown, the device  600 ,  620  may also include reliefs  604  that are substantially U-shaped that are positioned around the perimeter of the device and are inwardly facing to allow the device to open inwardly as it is inflated. In some respects, these reliefs  602 ,  604  help to control where and/or to what degree the device  600 ,  620  bends as it is inflated. 
     In one embodiment, the reliefs  602 ,  604  are configured such that the inflatable device  600 ,  620  is substantially planar when inflated into its three dimensional configuration. In another embodiment, the reliefs  602 ,  604  are configured such that the inflatable device has a substantially curved configuration when inflated into its three-dimensional configuration. The reliefs  602 ,  604  may be configured to minimize the amount of bending which occurs such that a predetermined desired curved configuration is achieved, for example, to follow the contour of the abdominal wall. 
     The embodiment illustrated in  FIG. 28  is similar to the one disclosed in  FIG. 27 , except that the inflatable device  620  in  FIG. 28  includes a plurality of seams  610  which separate portions of the inflatable device. These seams  610  may assist to make inflation of the device  620  more uniform. In one embodiment, the seams  610  may be welded. The inflatable device  600 ,  620  may be inflated with an inflation tube (not shown) that may connect to the device  600 ,  620  at an inflation port  612  positioned approximately at the center of the device. Furthermore, the device  600 ,  620  may include a plurality of non-expandable portions  152 , and as mentioned above, it may be desirable to arrange the attachment components within the non-expandable portions  152  in an embodiment where expandable device is inflatable. 
     The prosthesis  200  may be formed of a porous material, such as a knit, woven or non-woven fabric, or may be composed of a solid, substantially non-porous, or micro-porous material. The prosthesis may be formed of one or more layers of the same or dissimilar material. The prosthesis may be formed with portions that are tissue infiltratable and other portions that are non-tissue infiltratable, providing selected areas of the repair device with different, tissue ingrowth and adhesion resistant properties. The prosthesis may be formed of permanent material, resorbable material, or a combination of permanent and resorbable, materials, It should be appreciated that the prosthesis may be formed of any biologically compatible material, synthetic, or natural, suitable for repairing a tissue or muscle wall defect as would be apparent to one of skill in the art. The prosthesis may be formed into a patch, plug or combination patch and plug. 
     In one embodiment, the prosthesis  200  is formed from a mesh fabric, such as a sheet of knitted polypropylene monofilament mesh fabric. The sheet may have a thickness of approximately 0.014 inches and may be knitted from polypropylene monofilament having a diameter of approximately 0.0042 inches. When implanted, the polypropylene mesh promotes rapid tissue or muscle ingrowth into and around the mesh structure. Alternatively, other surgical materials which are suitable for tissue or muscle reinforcement and defect correction may be utilized including BARD MESH (available from C.R. Bard, Inc.), SOFT TISSUE PATCH (microporous ePTFE—available from W.L. Gore. &amp; Associates, Inc.); SURGIPRO (available from US Surgical, Inc.); TRELEX (available from Meadox Medical); PROLENE and MERSILENE (available from Ethicon, Inc.); and other mesh materials (e.g., available from Atrium Medical Corporation). Biologic materials, including XENMATRLX, COLLAMEND, and ALLOMAX (all available from C.R. Bard, Inc.) or COOK SURGISIS (available from Cook Biomedical, Inc.) may also be used. Resorbable materials, including polyglactin (VICRYL—available from Ethicon, Inc.) and polyglycolic acid (DEXON—available from US Surgical, Inc.), may be suitable for applications involving temporary correction of tissue or muscle defects. The fabric may be formed from multifilament yarns and that any suitable method, such as knitting, weaving, braiding, molding and the like, may be employed to form the mesh material. It should be appreciated that when the soft repair prosthesis is in the form of a sheet, it may be configured in many shapes, including, but not limited to flat, concave, and convex, and may, for example, be in the form of a square, rectangle, circle, or ellipse. 
     The present invention also contemplates other systems for expanding and/or unfurling the prosthesis. Although inflatable expandable devices (either filled with a gas or a liquid) are primarily discussed above, other expandable devices that do not rely on inflation are contemplated. For example, and without limitation, also contemplated are an expandable device that includes telescoping, portions and/or umbrella-like spokes, an expandable device including shape memory material, and an expandable device that resiliently expands into an enlarged configuration. 
     It should be appreciated that various embodiments of the present invention may be formed with one or more of the above-described features. The above aspects and features of the invention may be employed in any suitable combination as the present invention is not limited in this respect. It should also be appreciated that the drawings illustrate various components and features which may be incorporated into various embodiments of the present invention. For simplification, some of the drawings may illustrate more than one optional feature or component. However, the present invention is not limited to the specific embodiments disclosed in the drawings. It should be recognized that the present invention encompasses embodiments which may include only a portion of the components illustrated in any one drawing figure, and/or may also encompass embodiments combining components illustrated in multiple different drawing figures. 
     It should be understood that the foregoing description of various embodiments of the invention are intended merely to be illustrative thereof and that other embodiments, modifications, and equivalents of the invention are within the scope of the invention recited in the claims appended hereto.