Abstract:
A gastrocnemius knife and retractor system and kit includes a surgical knife and a soft tissue retractor. The soft tissue retractor is configurable to move from a collapsed mode to an expanded mode and back again, and can be inserted through a small incision when in the collapsed mode. Once inside the incision, the soft tissue retractor is expanded to permit visualization and accessibility of the surgery site. The surgical knife is then introduced and guided along a path in the frame of the soft tissue retractor, thereby incising the desired tissue. Once the tissue is incised, the surgical knife is withdrawn, followed by the soft tissue retractor after it is collapsed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application perfects and claims the benefit of U.S. Provisional Patent Application No. 62/315,725, filed on Mar. 31, 2016, and entitled Gastrocnemius Knife and Retractor System, which is hereby expressively incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    The present disclosure relates to surgical instruments, and, more particularly, to a surgical knife and soft tissue retraction system to incise soft tissues. 
         [0003]    In the field of surgery, there are medical conditions which necessitate operative intervention. One such condition is the inability to fully flex, or bend upwards a patient&#39;s foot. A surgical procedure used to address such a condition is the complete or partial release of the gastrocnemius tendon. This procedure is known as a Strayer Procedure, gastroc release, gastroc slide, tenotomy, or other terms. The cut tendon then heals in an elongated position, which allows more flexibility in the foot. 
         [0004]    In a normal anatomy, the gastrocnemius and soleus muscles abut one another. It is necessary, then, to perform the incision on the gastrocnemius muscle without damaging the soleus muscle. In addition, visibility is limited as to the incision site and accordingly with regard to the target soft tissues that the user wants to avoid. 
         [0005]    Although partial or complete release of the gastrocnemius tendon is discussed herein as an example, the inventions may also be used for other medical conditions such as plantar fasciitis or carpal tunnel syndrome. 
         [0006]    Previous ways to alleviate these problems have been addressed in various ways. For example, surgical instruments attached to endoscopes can be inserted in and among the soft tissues in order to separate them and incise them. Alternatively, handheld retractors can be used by the surgeon and/or assistant in order to retract soft tissues to provide visualization of the incision site. 
         [0007]    Another way to address the problem is a “low technology” solution: the surgeon simply creates an incision in the patient, digitally (with fingers) palpates and separates the soft tissues, and introduces a scalpel into the wound to incise the tendon. 
         [0008]    What is needed in the art is a combination of a soft tissue retractor and a surgical knife which, through a minimally-invasive incision, allows a surgeon to visualize and reproducibly incise the target soft tissues in a safe and controlled manner. 
       SUMMARY 
       [0009]    The present disclosure is directed to an improved surgical knife that has a controlled cutting depth and can provide illumination to the surgical site. 
         [0010]    The present disclosure also provides an improved soft tissue retractor that is of a low profile when collapsed for introduction through a minimally-invasive incision, and expands to both retract soft tissues as well as provide a defined cutting path. 
         [0011]    The present disclosure also provides a method of using the inventive surgical knife and inventive soft tissue retractor in a manner which provides the safe and reproducible incision of soft tissues in a procedure that is not “blind” to the surgeon. 
         [0012]    An advantage of the present disclosure is that the operative area is directly illuminated by the surgical knife and/or soft tissue retractor, thereby eliminating the need for an external lighting source. 
         [0013]    Another advantage of the present disclosure is that, as a result of the design of the surgical knife blade with relationship to the soft tissues retractor, the depth of the incision is controlled and limited to a predetermined depth. 
         [0014]    Yet another advantage of the present disclosure is that the instruments may be disposable, thereby saving the cost and other detrimental aspects of sterilization and re-use. 
         [0015]    Still another advantage of the present disclosure is the small profile of the soft tissue retractor allows it to be used in a minimally-invasive procedure. 
         [0016]    Yet another advantage of the present disclosure is the surgical knife and soft tissue retractor can be made available in a sterilized, pre-packaged kit. 
         [0017]    In one aspect, the present disclosure provides a surgical knife including a handle portion, a beam portion extending from the handle portion, and a nose portion defining a free end. The nose portion includes at least one blade support portion and a cutting blade coupled to the blade support portion. The cutting blade includes a working depth determined by the depth of a portion of the blade that protrudes past a bottom surface of the blade support in a cutting state. 
         [0018]    In some embodiments, the working depth of the blade is adjustable. In some such embodiments, the working depth of the blade is adjustable within the range of 2 mm to 4 mm. In some embodiments, the knife further includes an adjustment knob configured to vary the depth of the portion of the blade that protrudes past the bottom surface of the blade support. In some embodiments, the cutting blade is retractable into a retracted state such that the blade does not protrude past the bottom surface of the blade support. 
         [0019]    In some embodiments, the cutting blade includes a convex cutting edge. In some embodiments, the blade support portion includes at least one blade support extension that defines the bottom surface. In some such embodiments, the at least one blade support extension defines a planar outer surface. In some other such embodiments, the blade support portion includes a pair of blade support extensions that define a cavity therebetween, and wherein a portion of the blade is positioned within the cavity. In some such embodiments, the cutting blade includes a cutting edge, and at least a distal end of the cutting edge is positioned within the cavity. 
         [0020]    In some embodiments, the knife further includes an illumination mechanism that provides illumination. In some embodiments, a handle portion defines an outer dimension that is larger than an outer dimension defined by the beam portion, and the knife further includes a transition portion extending between the handle portion and the beam portion. 
         [0021]    In another aspect, the present disclosure provides a soft tissue retractor including a handle portion, a pivoting mechanism including a pivot bar attached to the handle, and a frame with first and second retractor plates. The at least one of the first and second retractor plates includes a knife slot. The first retractor plate is pivotably coupled to a first portion of the pivot bar and the second retractor plate is pivotably coupled to a second portion of the pivot bar such that rotation of the handle in a first direction translates the first and second retractor plates toward each other and rotation of the handle in a second direction that opposes the first direction translates the first and second retractor plates away from each other. 
         [0022]    In some embodiments, the first and second retractor plates are translatable between a collapsed state with the first and second retractor plates abutting, and an expanded state with the first and second retractor plates spaced apart at a pre-defined distance. In some embodiments, the pivot bar is attached to the handle at a pivot point, the first retractor plate is pivotably coupled to the pivot bar at or on a first side of the pivot point, and the second retractor plate is pivotably coupled to the pivot bar on a second side of the pivot point. 
         [0023]    In some embodiments, the retractor further includes at least one hinge member extending between and pivotably coupled to the first and second retractor plates. In some embodiments, the retractor further includes an end plate member extending between and pivotably coupled to the first and second retractor plates. In some embodiments, the first retractor plate is pivotably coupled to the first portion of the pivot bar via a first frame post, the second retractor plate is pivotably coupled to the second first portion of the pivot bar via a second first frame post, and an inner surface of at least one of the first and second pivot bars includes a convex engagement surface aligned with a knife slot thereof. 
         [0024]    In another aspect, the present disclosure provides method including providing a kit including a surgical knife and a soft tissue retractor. The surgical knife includes a handle portion, a beam portion extending from the handle portion, and a nose portion defining a free end and including at least one blade support portion and a cutting blade coupled to the blade support portion. The cutting blade has a working depth determined by the depth of a portion of the blade that protrudes past a bottom surface of the blade support in a cutting state. The soft tissue retractor includes a frame with first and second retractor plates. At least one of the first and second retractor plates includes a knife slot. The first and second retractor plates are pivotably coupled to each other such that they are translatable toward each other into a collapsed state and translatable away from each other into an expanded state. 
         [0025]    In some embodiments, the method further includes creating an incision in the skin to access a desired soft tissue structure, inserting the frame of the soft tissue retractor into the incision while in a collapsed state, expanding the frame of the soft tissue retractor into an expanded state, introducing the nose of the surgical knife into the knife slot of one of the first and second retractor plates such that the cutting blade extends past an outer surface of the respective first and/or second retractor plate, and advancing the surgical knife along the knife slot to cut the desired soft tissue structure at the outer surface of the respective first and or second retractor plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The above-mentioned and other features and advantages of this disclosure will become more apparent and the disclosure will be better understood by reference to the following descriptions of embodiments of the disclosure taken in conjunction with the accompanying drawings, wherein: 
           [0027]      FIG. 1  is a perspective view of a surgical knife of the present disclosure; 
           [0028]      FIG. 2  is a perspective enlarged view of the distal end of the surgical knife of  FIG. 1 ; 
           [0029]      FIG. 3  is a top view of the surgical knife of  FIG. 1 ; 
           [0030]      FIG. 4  is a bottom view of the surgical knife of  FIG. 1 ; 
           [0031]      FIG. 5  is a top view of a soft tissue retractor of the present disclosure; 
           [0032]      FIG. 6  is a perspective view of the frame and pivoting mechanism of the soft tissue retractor of  FIG. 5 ; 
           [0033]      FIG. 7  is a side view of the soft tissue retractor of  FIG. 5  in a collapsed mode; 
           [0034]      FIG. 8  is a side view of the soft tissue retractor of  FIG. 5  in an expanded mode; 
           [0035]      FIG. 9  is a perspective view of the surgical knife of  FIG. 1  and the soft tissue retractor of  FIG. 5  in an assembly of the present disclosure; 
           [0036]      FIG. 10  is an enlarged perspective view of a portion of the assembly of  FIG. 9 ; 
           [0037]      FIG. 11A  is a side view of an expansion mechanism configured to expand the soft tissue retractor of  FIG. 5 ; 
           [0038]      FIG. 11B  is a top view of the expansion mechanism of  FIG. 11A ; and 
           [0039]      FIG. 11C  is a perspective view of the expansion mechanism of  FIG. 11A . 
       
    
    
       [0040]    Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates embodiments of the disclosure, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner. 
       DETAILED DESCRIPTION 
       [0041]    When introducing elements of various embodiments of the present invention, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Any examples of parameters are not exclusive of other parameters of the disclosed embodiments. Components, aspects, features, configurations, arrangements, uses and the like described, illustrated or otherwise disclosed herein with respect to any particular embodiment may similarly be applied to any other embodiment disclosed herein. 
         [0042]    The terms “proximal” and “distal” are used principally throughout this specification for convenience; but it is to be understood that these terms are not intended to be limiting. Thus “proximal” in this specification refers to the feature of the apparatus closest to the operator during use, and “distal” refers to the end of the apparatus farthest from the operator during use. 
         [0043]    Referring now to  FIGS. 1-4 , there is shown an embodiment of a knife  10  according to the present disclosure. In some embodiments, the knife  10  may be a surgical knife that is particularly advantageous for cutting tissue or other anatomy. In some embodiments, the knife  10  may be configured to be particularly advantageous as a surgical knife for cutting at least a portion of a gastrocnemius tendon, for example, such as for a gastroc release surgery. 
         [0044]    In some embodiments, the knife  10  includes a handle  12 , a beam  20 , and a blade  32 . The handle  12  of the knife  10  may include a proximal end  14  and a distal end  16 , as shown in  FIG. 1 . In some embodiments, the handle  12  may include a cylindrical or substantially cylindrical cross-section. Alternatively, other cross-sectional geometries are possible, including any geometry that is functional and/or provides an ergonomic grip. The handle  12  may have a surface texture that provides a secure grip for the operator. In some embodiments, the handle  12  may also include batteries or other components, as discussed further below. 
         [0045]    The beam  20  of the knife  10  may include a proximal end  22  and a distal end  24 , as shown in  FIG. 1 . In some embodiments, the beam  20  may include, for example a cylindrical cross-section, as shown in  FIG. 1 . Alternatively, any other cross-sectional geometries may be utilized. The beam  20  may include batteries or other components, as further discussed below. 
         [0046]    As shown in  FIG. 1 , the knife  10  may include a transition portion  18  disposed between the handle  12  and the beam  20 . The transition portion  18  may be attached to the distal end  16  of the handle  12 , and the proximal end  22  of beam  20 . The attachment between the transition portion  18  and the other portions of the knife  10  may be permanent or modular; that is, the handle  12 , the transition portion  18  and the beam  20  may be of one-piece construction or monolithic, or alternatively, the handle  12 , the transition portion  18  and the beam  20  may be separate and distinct, or discrete, components that are attached to another component. The cross-sectional geometry of transition portion  18  may be any geometry that provides for a transition from the handle  12  to the beam  20 . In some embodiments, the transition portion  18  may also include an adjustment knob  38  (discussed below) or other mechanical and/or electrical components. 
         [0047]    The handle  12 , the transition portion  18 , and/or the beam  20  may be constructed from metal, plastic, polymer, or any other materials suitable for use in a surgical instrument. They may all be constructed from the same material, or they may be constructed from different materials. 
         [0048]    The distal end  24  of the beam  20  may include a nose  26 , as shown in  FIGS. 1 and 2 . The nose  26  may include at least one blade support  28 , which itself may include at least one blade support portion or extension  36  defining a blade support bottom  34 , as shown in  FIGS. 1 and 2 . The nose  26  and its accompanying components may be of a geometry that allows it to function with a soft tissue retractor, as shown in  FIGS. 5-10  and described below, and may include dovetails or other features to accomplish that function. 
         [0049]    The knife  10  may further include at least one blade  32 , as shown in  FIGS. 1, 2 and 4 . In some embodiments, the blade  32  may be located or positioned in the nose  26  of the beam  20 . The blade  32  may be of a half-circle geometry with a convex cutting edge to be used in a bi-directional manner. However, the blade  32  may be of any other geometry including circular, flat, pointed, or any other configuration that provides a cutting edge. 
         [0050]    As shown in  FIGS. 1, 2 and 4 , the blade  32  may be held in place by a connection to or through the nose  26 . For example, the blade  32  may be held by at least one blade support  28  as shown in  FIGS. 1, 2 and 4  or through any other mechanism which is coupled to or extends from the beam  20 , the transition portion  18 , and/or the handle  12 . 
         [0051]    The blade  32  may protrude or be exposed at a predetermined depth. In some embodiments, the amount or depth of the exposed portion of the blade  32  may be determined by its protrusion or extension past the blade support bottom or edge  34  of the blade support  28 , as shown in  FIGS. 1, 2 and 4 . In this way, the depth of an incision may be determined by the blade  32  cannot go deeper than the amount of the exposed portion, such as the portion of the blade  32  that extends or protrudes beyond the blade support bottom  34 . In some embodiments, the knife  10  may include a manually engageable adjustment knob  38  (e.g., positioned on or in the handle  12 ) that is configured to selectively set the depth of the blade  32 , as shown in  FIGS. 1 and 3 . For example, the adjustment knob  38  may be configured to selectively adjust the amount or depth of the blade  32  that is exposed and/or to retract the blade  32  completely hidden, such that no portion of the blade  32  is exposed (e.g., position the blade  32  completely above the blade support bottom  34 ). The adjustment knob  38  may be configured to effectuate movement of the blade  32  with respect to the blade support bottom  34  and/or movement of the blade support  28  with respect to the blade  32 . 
         [0052]    When fully retracted (i.e., no portion of the blade  32  is exposed), inadvertent cutting may be prevented or avoided. In some embodiments, the blade  32  may be capable of being exposed (e.g., via the adjustment knob  38 ) to a depth or length of within the range of 2 mm to 4 mm for a cutting operation. In some embodiments, the blade  32  may exposed (e.g., via the adjustment knob  38 ) to a depth or length of 2 mm for a cutting operation. As shown in  FIG. 2 , in some embodiments the blade  32  may not extend past the free end of the distal end  24  of the beam  20 , and/or may only be exposed below the bottom surface  34  of the blade support  28  (e.g., the bottom surface  34  of the at least one blade support extension  36 ). The blade support extension  36  may define an outer surface. 
         [0053]    In some embodiments, the knife  10  may be configured to provide illumination and/or visualization of the surgical site, such as via at least one of a camera, CMOS, LED, bulb. In some embodiments, such an illumination and/or visualization mechanism may be positioned within the nose  26  of the knife  10 . In some embodiments, to disperse light and/or ensure light reaches a surgical or cutting site, at least a portion of the knife  10  may be made of transparent materials. The illumination and/or visualization mechanism may be powered by one or more batteries or other electrical-power providing mechanism contained within the knife, such as within the handle  12  or any other portion of the knife  10 . In this way, an external power source to power the illumination and/or visualization mechanism may be avoided or not needed. The at least one electrical-power providing mechanism may be pre-installed within the knife  10  such that it already installed when the knife  10  is supplied, or the electrical-power providing mechanism may be attached to the knife after it has been supplied. Alternatively, in some embodiments the knife  10  may be configured to operate (e.g., the illumination and/or visualization mechanism may be configured to operate) via at least one external power source that can be electrically coupled to the knife  10  prior to use. In some such embodiments, the knife  10  may include the external power source. 
         [0054]    In some embodiments, the knife  10  may be configured to be disposed of after use (e.g., a cutting process). In some other embodiments, the knife  10  may be configured to be cleaned and/or sanitized and reused (e.g., in a subsequent cutting process). 
         [0055]    Referring now to  FIGS. 5-8 , in some embodiments the knife  10  of the present disclosure (or another knife) may be configured to cooperate with a retractor  50 . In some embodiments, the retractor  50  may be configured as a tissue retractor, such as a soft tissue retractor. The retractor  50  may include a handle  52 , a frame  54 , and a pivoting mechanism  56 , as shown in  FIGS. 5-8 . The retractor  50  may be manufactured from metal, plastic, polymer, or any other materials suitable for use as a surgical instrument and capable of separating tissue. All components or portions of the retractor  50  may be constructed from the same material, or they may be constructed from different materials. The retractor  50  may be disposable after a single use, or may be configured to be cleanable (e.g., sterilizable), and thus reusable. 
         [0056]    In some embodiments, the handle  52  of the retractor  50  may include a grip  58  and a shaft  60 , as shown in  FIG. 5 . The handle  52  may be made of any material and any geometry which is ergonomic and capable of being held and manipulated by a user, such as a surgeon. The shaft  60  of the handle  52  may be fixedly attached to the grip  58 , or may be removably attached to the grip  58  (e.g., via threads or any other mechanism). The location/position and/or orientation of the handle  52  in relation to other parts of the retractor  50  may be varied depending on the clinical situation and surgical exposure. 
         [0057]    With reference to  FIG. 6 , the frame  54  of the retractor  50  may include a proximal end  82  and a distal end  84 . The retractor  50  may include frame posts  66 ,  68  at the proximal end  82  of the frame  54 . The frame posts  66 ,  68  may each include an inner concave and/or radiused engagement surface  94  which facilitates the tracking and movement of the knife  10 . The frame  54  of the retractor  50  may include an end plate  74  at the distal end  84  of the frame  54 . 
         [0058]    In further reference to  FIG. 6 , the frame  54  of the retractor  50  may include retractor plates  70 ,  72  extending at least partially between the frame posts  66 ,  68  and the end plate  74 . The end plate  74  may be movably coupled (e.g., rotatably coupled about axes) to the retractor plates  70 ,  72 . For example, the end plate  74  may be rotatably coupled to the retractor plates  70 ,  72  at pivot points or axes  88 . In some such embodiments, the pivot points or axes  88  of the end plate  74  and the retractor plates  70 ,  72  may be pins or similar structures. 
         [0059]    In some embodiments, at least one of the retractor plates  70 ,  72  may include or form at least one knife rail or slot  92  that extends at least partially along a direction extending between the frame posts  66 ,  68  and the end plate  74 . In some embodiments, the at least one knife rail or slot  92  of the retractor plates  70 ,  72  may be elongated along a direction extending between the frame posts  66 ,  68  and the end plate  74 . The one knife rail or slot  92  may be aligned with the engagement surface  94  of the frame posts  66 ,  68 . 
         [0060]    In some embodiments, at least one hinge member  86  may extend between and be movably coupled (e.g., rotatably coupled about axes) to the retractor plates  70 ,  72 . For example, the at least one hinge  86  may be rotatably coupled to the retractor plates  70 ,  72  at pivot points or axes  88 . In some such embodiments, the pivot points or axes  88  of the at least one hinge  86  and the retractor plates  70 ,  72  may be pins or similar structures. At least one of the retractor plates  70 ,  72  may include at least one relief or groove  90  corresponding to the at least one hinge  86  so that the hinge  86  can freely rotate with at least one of the retractor plates  70 ,  72  and extend therein to allow the retractor plates  70 ,  72  to move closer to each other into a collapsed state of the frame  54 , as shown in  FIG. 7 . 
         [0061]    In one exemplary embodiment, the hinge  86  may be positioned about midway along the length of retractor plates  70 ,  72 . The hinge  86  may be configured to aid in stability of the frame  54  construct and/or prevent the knife  10  from skiving (as explained further below). 
         [0062]    As shown in  FIG. 6 , the pivoting mechanism  56  of the frame  54  may be attached to the shaft  60  at pivot point  62 , and include a pivot bar  64  which extends between the pivot posts  66 ,  68  (and thereby the ends of the retractor plates  70 ,  72 ). The pivot bar  64  may include pivot posts  76 ,  78  extending therefrom that are rotatably coupled with the posts  66 ,  68 . 
         [0063]    In use, the retractor  50  may initially be utilized in a fully or partially collapsed state of the frame  54  with the retractor plates  70 ,  72  being positioned substantially proximate to, or in abutment with, each other (i.e., minimal or no space between the retractor plates  70 ,  72 ), as shown in  FIG. 7 . The retractor  50 , in the collapsed state (i.e., partially or fully collapsed), may be inserted through a skin incision and between two anatomical structures of interest (e.g., soft tissue of interest). After being positioned or insertion in a desired location between two anatomical structures of interest, the frame  54  of the retractor may be transitioned or activated into an expanded state such that the retractor plates  70 ,  72  are moved away from each other (i.e., space between the retractor plates  70 ,  72  is expanded), as shown in  FIG. 8 . The degree of spacing between the retractor plates  70 ,  72  in the expanded state may vary depending upon the particular anatomical structures of interest, for example. 
         [0064]    Expansion of frame  54  from the collapsed state (see  FIG. 7 ) to the expanded state (see  FIG. 8 ) to may be accomplished by the twisting or rotating (e.g., manually) of the handle  58  (e.g., counterclockwise or clockwise) while the frame  54  is positioned between the tissues of interest. Rotation of the handle  58  may cause pivot bar  64 , and thereby the attached (e.g., pivotally-attached) pivot posts  76 ,  78  to rotate about the axis of the shaft  60  and/or pivot point  62 . In some embodiments, a first pivot post  78  may rotate coincidentally with the shaft  60 , pivot point  62  and/or a first retractor plate  70 , while a second pivot post  76  may rotate around the longitudinal axis of shaft  60  and/or pivot point  62 , and thereby move in relation to the first pivot post  78 . 
         [0065]    The retractor plates  70 ,  72 , by virtue of their pivotal or rotatable connection to the pivot posts  76 ,  78  by the frame posts  66 ,  68 , are thereby forced apart or away from one another via the pivot bar  64  during rotation of the handle  58  in a rotational direction (and moved toward each other during rotation in an opposing direction), as shown in  FIGS. 7 and 8 . Movement of the retractor plates  70 ,  72  away from each other may also displace the anatomical structures of interest that the frame  54  is positioned between, away from each other. 
         [0066]    As the end plate  74  and the at least one hinge  86  are pivotally or rotatably attached to the retractor plates  70 ,  72  via the pivot points  88 , they are rotated or angled with respect to the retractor plates  70 ,  72  to an expansion position or orientation (see  FIG. 8 ) from their previously collapsed position or orientation (see  FIG. 7 ). The at least one relief  90  in the retractor plates  70 ,  72  associated with the at least one hinge  86  allows the at least one hinge  86  to fit therein so that the frame  54  can be completely collapsed such that the retractor plates  70 ,  72  abut to each other. 
         [0067]    The frame  54  may be configured to stop rotation of the at least one hinge  86 , end plate  74  and/or pivot bar  64  with respect to the retractor plates  70 ,  72  from their collapsed orientation, and thereby movement of the retractor plates  70 ,  72  away from each other, at a particular point, such as when the retractor plates  70 ,  72  are spaced the maximum distance apart afforded by the at least one hinge  86 , end plate  74  and/or pivot bar  64 . For example, as shown in  FIG. 6 , rotation of the retractor plates  70 ,  72  may be stopped via at least one boss  80  (e.g., positioned on the end plate  74  or elsewhere) engaging with at least one of the retractor plates  70 ,  72  (such as at full expansion of the framed  54 ). When frame  54  is fully collapsed, the at least one boss  80  may be configured to fit within at least one knife rail or slot  92  or within a relief or other opening, for example. 
         [0068]    In some embodiments, in a collapsed state, such as in the fully collapsed state with the retractor plates  70 ,  72  in abutment, the frame  54  may define a thickness T 1  with a range of 2 mm to 3 mm, as shown in  FIG. 7 . In some embodiments, in an expanded state, such as in the fully expanded state with the retractor plates  70 ,  72  positioned furthest from each other as provided for by the frame  54 , the frame  54  may define a thickness T 2  with a range of 10 mm to 30 mm, such as about 20 mm, as shown in  FIG. 8 . The length L of the frame  54 , such as the length L of the retractor plates  70 ,  72  and/or the between the end plate  74  and the frame posts  66 ,  68 , may be within the range of 75 mm and 225 mm, as shown in  FIG. 7 . In one exemplary embodiment, a length L of the frame  54  may be 150 mm. The length of an incision in a patient adequate to allow the frame  54  to be positioned between two anatomical structures of interest, may be within the range of 15 mm to 50 mm, such as about 20 mm. However, in some other embodiments the retractor  50  may define other dimensions of the thickness in a collapsed state T 1 , the thickness in an expanded state T 2  and/or the length L of the frame  54  outside of these ranges. 
         [0069]    As noted above an illumination and/or visualization mechanism may be incorporated into retractor  50 , such as into the frame  54 , to assist in visualization during insertion, expansion and/or cutting via the knife  10 . For example, a light may be emitted toward the surgical site upon opening the frame  54  to an expanded position. 
         [0070]    Once the frame  54  has been inserted in vivo and moved into an opened state (i.e., the retractor plates  70 ,  72  are moved away from each other from the collapsed state or relative position), the surgical knife  10  may be introduced into frame  54 , as shown in  FIGS. 9 and 10 . The knife  10  may be introduced into frame  54  by placing the blade  32  and a portion of the nose  26  (e.g., the at least one blade support  28  and/or at least one blade support extension side  36 ) of the knife  10  into at least one of the at least one knife rails or slots  92  of the retractor plate  70 ,  72 . The blade  32  may extend past the bottom surface of the respective retractor plate  70 ,  72  of the knife rail or slot  92  that the blade  32  is positioned within, as shown in  FIGS. 9 and 10 . In this way, at least a portion of the exposed portion of the blade  32  of the knife  10  may extend beneath the frame  54 . The knife  10  may also be introduced into frame  54  such that the engagement surfaces  94  contact and support the beam  20  of the knife  10 , as shown in  FIG. 9 . 
         [0071]    In some embodiments (not shown), the nose  26  of the knife  10  and/or at least one of the retractor plates  70 ,  72  may be configured to be integrated in some manner, rather than have the nose  26  of the knife  10  rest in the knife rail or slot  92  as described above. For example, the nose  26  and at least one of the retractor plates  70 ,  72  may include mating features that slidably or translatably couple these two structures together. The mating features may physically guide the nose  26  portion of the knife  10  tool along at least one of the retractor plates  70 ,  72  as the nose  26  portion moves along the respective knife rail or slot  92 . For example, the retractor plates  70 ,  72  and/or the nose  26  portion may include a groove (e.g., a dovetail) and a projection that engages or is captured in the groove to physically guide the knife  10  as it translates along the respective knife rail or slot  92 . As another example, the retractor plates  70 ,  72  and/or the nose  26  portion may include a captured sleeve to physically guide the knife  10  as it moves along the respective knife rail or slot  92 . 
         [0072]    Once the blade  32  and a portion of the nose  26  are positioned into at least one of the knife rails or slots  92  of the retractor plates  70 ,  72 , the knife  10  may be manually advanced along the length of the at least one knife rail or slot  92  to simultaneously cut the desired tissue positioned at or against the bottom surface of the respective retractor plate  70 ,  72  of the knife rail or slot  92  that the blade  32  is positioned within. In some embodiments, the knife  10  may be used in the knife rail or slot  92  of only one of the retractor plates  70  or  72 , and then removed and reintroduced along the knife rail or slot  92  of the other retractor plate  70 ,  72 . Therefore, two incisions can be made while leaving the soft tissue retractor  50  in place within the patient. 
         [0073]    The nose  26  and the blade  32  of the knife  10 , and the at least one knife rail or slot  92  of the retractor  50 , may be configured to complement each other such a portion of the knife  10  is captured by and continuously rides along the respective knife rails or slots  92  as is translated therethrough. 
         [0074]    As described above, the protrusion of the knife blade  32  under the nose  26 , as well as the thickness of the retractor plates  70 ,  72 , allows the blade  32  to extend past the bottom or outer surface of the retractor plates  70 ,  72  and create an incision in the tissue of a predetermined depth (see  FIGS. 9 and 10 ). In some embodiments, the at least one hinge  86  may prevent the knife  10  from skiving during a cutting procedure, and the engagement surface  94  of one or both of the retractor plates  70 ,  72  may support and guide the beam  20  of the knife  10  to ensure a continuous and stable operation as shown in  FIG. 9 . In some embodiments, the frame  54  may be configured such that in the opened state, such as the fully opened state, both the engagement surfaces  94  of the retractor plates  70 ,  72  support and guide the beam  20  of the knife  10  to ensure a continuous and stable operation as shown in  FIG. 9 . 
         [0075]    After one or more incisions have been made in one or more soft tissue structures via the blade  32  of the knife  10 , knife  10  may be withdrawn from the frame  54 . The soft tissue retractor  50  may then be moved to a collapsed state, such as the fully collapse state, and withdrawn from the surgical site of the patient. 
         [0076]    In some embodiments, that at least one knife  10  and at least one retractor  50  may be supplied as, or otherwise, form, a kit. In some embodiments, the at least one knife  10  and at least one retractor  50  may be supplied or provided in a sterilized state, either alone or within a case. 
         [0077]      FIGS. 11A-11C  illustrate an expansion mechanism  110  configured to manually expand the frame  54  of the retractor  50  from a collapsed state to an expanded state, as described above. Rather than including and/or utilizing the handle portion  52  and/or the pivoting mechanism  56  of the retractor  50 , the expansion mechanism  110  may be utilized to move the retractor plates  70 ,  72  away from each other and into an expanded state. As shown in  FIGS. 11A-11C , the expansion mechanism  110  may include a handle portion  112  and an expansion portion  114  extending from the handle portion  112 . The expansion portion  114  of the expansion mechanism  110  may include at least tine  120  that defines a free end. As shown in  FIGS. 11A-11C , in some embodiments, the expansion portion  114  of the expansion mechanism  110  may include a pair of tines  120  to that correspond to the retractor plates  70 ,  72 . 
         [0078]    As shown in  FIGS. 11A-11C , the at least one tine  120  may include a lower engagement member  118  and an upper engagement member  116 . The upper engagement member  116  may extend away from the lower engagement member  118 , as shown in  FIGS. 11A-11C . For example, the lower engagement member  118  may be substantially linear or flat, and the upper engagement member  116  may be angled, arcuate or otherwise shaped such that a portion of the upper engagement member  116  that is distal to the free end thereof is positioned further away from the lower engagement member  118  than at or proximate to the free end. 
         [0079]    In use, the free end of the at least one tine  120  of the expansion portion  114  of the expansion mechanism  110  may be inserted into the frame  54  between the retractor plates  70 ,  72  of the retractor  50  when the retractor  50  is positioned between anatomical structures in a collapsed state, such as between soft tissue structures. The at least one tine  120  may be inserted such that the upper engagement member  116  engages an upper retractor plate  70  (or another portion of the retractor  50  coupled to the upper retractor plate  70  of the retractor  50 ) and the lower engagement member  118  engages a lower retractor plate  72  of the retractor  50  (or another portion of the retractor  50  coupled to the lower retractor plate  70 ). The at least one tine  120  may be inserted further inserted into the frame  54  of the retractor  50  such that the upper and lower engagement members  116 ,  118  moves or translates the upper and lower retractor plates  70 ,  72  away from each other and into an extended state, such as the fully extended state. The expansion mechanism  110  may then be removed from within the frame  54  of the retractor  50 , or remain within the frame  54 , when the knife  10  is inserted into the frame  54  to cut the tissue. 
         [0080]    In some embodiments, the expansion mechanism  110  may be a separate and distinct component from the knife  10  and/or the retractor  50  assembly, and may or may not be supplied separately. In other embodiments, the expansion mechanism  110  may be movable coupled to the knife  10  and/or the retractor  50 , and potentially supplied with the knife  10  and/or the retractor  50 . 
         [0081]    While knives and retractors and related methods have been described with respect to exemplary embodiments, the knives, retractors and related methods can be modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the knives, retractors and related methods using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims. For example, it is to be understood that the above description is intended to be illustrative, and not restrictive. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a situation or material to the teachings of the various embodiments without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, they are by no means limiting and are merely exemplary. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. 
         [0082]    The scope of the various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Also, the term “operably connected” is used herein to refer to both connections resulting from separate, distinct components being directly or indirectly coupled and components being integrally formed (i.e., monolithic). Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. It is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein. 
         [0083]    While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the disclosure may include only some of the described embodiments. Accordingly, the inventions are not limited by the foregoing description, but is only limited by the scope of the appended claims. 
         [0084]    This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.