Patent Publication Number: US-11020303-B2

Title: Method and apparatus for securing a patient&#39;s limb

Description:
RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 16/249,813, filed on Jan. 16, 2019, which claims priority to and benefit of U.S. Provisional Application No. 62/709,380, filed on Jan. 16, 2018. The teachings of these earlier applications are incorporated by reference herein in their entirety. 
    
    
     FIELD 
     The present disclosure generally relates to limb holders, such as limb holders used before, during, and after surgical procedures for supporting patient&#39;s limbs, and related methods for making same. 
     BACKGROUND 
     During most surgical operations, nurses and surgical and support staff are often responsible for tending to the general health and safety of a patient. For example, nurses and surgical staff often tend to patients while they are under anesthesia and/or while they are recovering after a surgical procedure. In doing so, nurses and surgical staff often consider a variety of factors to ensure a patient&#39;s safety. For example, in addition to considering factors for mitigating possible risks associated with the surgical procedure at hand, nurses and hospital staff must also ensure that the patient&#39;s possibly unconscious body is also protected from possible physical injuries that may be caused by unwanted movement of the patient&#39;s body (e.g., unconscious movements and repositioning of the patient while under anesthesia or sleeping). 
     To date, various approaches have been developed to standardize the measures used to protect patients, including usage of padding on the surfaces that come in contact with the patient. Since a patient&#39;s natural defenses can be inhibited due to anesthesia, normal responses to discomfort or pressure points, which would normally occur if the patient were merely asleep, cannot be relied upon to prevent injury. As such, padding of the surfaces with which the patient&#39;s body may come in contact is often used to reduce and mitigate injury to the patient. 
     For example, the operating table surface in some operating rooms can include a thick pad cover that has been secured to the operating table in order to protect the patient from surface pressure. Supportive devices such as lithotomy stirrups (e.g., used to hold the legs up and apart during surgeries in which the patient is on his/her back or a supine position) can also be padded to mitigate unwanted pressure. Such lithotomy stirrup pads are often held in place using “hook and loop” fastening systems, such as VELCRO® brand fasteners. 
     Operating rooms can also contain surface and/or airborne contaminates (e.g., bacteria or viruses), which can put patients at the risk of contracting an infection. In fact, infections due to surface or airborne contaminants, such as bacteria or viruses, are among other risks that patients in hospitals and operating rooms can face. For this reason, operating rooms are often cleaned between each procedure, including the padding and other patient contact surfaces. Generally, any impediment to proper cleaning can put the patients&#39; health and desired recovery at risk. 
     Although operating rooms, paddings, and other patient surfaces are usually cleaned and disinfected between surgical procedures, any impediment to proper cleaning can put the patients&#39; health and desired recovery at risk. For example, many fastening systems (e.g., traditional hook and loop style fastening systems) used in common lithotomy stirrups are often very difficult to clean. Specifically, traditional hook and loop fasteners can have many cervices, which can in turn render surface cleaning impossible. The loop portion of these fasteners can also be very difficult to surface clean due to its tendency for retaining fluids. 
     SUMMARY 
     The present disclosure relates to methods, apparatus, and corresponding systems for securing a patient&#39;s limb, for example during a surgical procedure. Embodiments disclosed herein reduce the number of attachments used in traditional limb holders and eliminate parts that are traditionally difficult to sterilize and/or clean. 
     In one aspects, apparatus and corresponding methods for attaching one or more paddings to a limb support shell is disclosed. The apparatus and corresponding method utilize discrete mating features between the padding(s) and the shell to create a padded support system. The disclosed embodiments can remove the necessity for traditional “hook and loop” fastener systems, thereby improving the ability to clean the devices and decreasing the tendency for the fastening system to entrap microscopic and macroscopic debris and/or organisms. 
     In another aspect, apparatus and corresponding methods that employ discrete structures attached to a surface of one or more padding(s) and mating features, which are built into a limb support shell, are disclosed. The mating features can be mounting openings that are configured to accept these discrete structures and remain engaged to the discrete structures through a mechanical interference. The mating features can be manually engaged, holding the padding and the shell together as a combined system until manually disengaged by the user. While in use as a padded support system, the mechanical interference can provide sufficient resistance to prevent the pad from inadvertently disengaging from the shell during use. 
     In some aspects, a support structure for holding a patient&#39;s limb is disclosed. The support structure can comprise a shell configured to at least partially receive and support the patient&#39;s limb. The shell can comprise at least one mounting opening. The support structure can also comprise a padding coupled to the shell and configured to provide a protective surface for the patient&#39;s limb. The padding can comprise at least one mounting structure configured to be coupled to the mounting opening and coupling of the at least one mounting structure to the at least one mounting opening can be configured to provide an interference fit that secures the padding to the shell. 
     In another aspect, a method for providing a support structure for holding a patient&#39;s limb is disclosed. The method can include coupling at least one mating opening disposed on a surface of a shell configured for at least partially receiving the patient&#39;s limb with at least one mating structure of a protective padding via an interference fit and receiving the patient&#39;s limb on the protective padding. 
     In other examples, the aspects above, or any system, method, apparatus described herein can include one or more of the following features. 
     The shell can comprise at least one of a thermoplastic material, polyethylene, polypropylene, Acrylonitrile Butadiene Styrene (ABS), structural foam, and formed sheet metal. 
     The at least one mounting structure can comprise a base configured to be coupled with/connect to an outer surface of the padding and a neck extending substantially orthogonally from the base. The neck can comprise at least one interference ring. Further, the neck can be hollow and an insert can be configured for positioning in the hollow neck. Furthermore, the mounting structure can comprise at least one of a liquid injection molded silicone, thermoplastic elastomer, thermoplastic urethane, a rubber-like material, and a soft plastic. 
     Additionally, or alternatively, the at least one mounting structure can be disposed within at a predetermined distance from an edge of the padding. The predetermined distance can be any suitable distance. For example, in some embodiments, the predetermined distance can be less than or including three inches and/or less than or including five inches. 
     Further, in some embodiments, the mounting openings can be disposed at a predetermined distance from an edge of the shell. The predetermined distance can be any suitable distance. For example, the predetermined distance can be less than about five inches 5″ from the edge of the shell. 
     Further, the at least one mounting opening can be configured to extend through a thickness of the shell. Additionally, or alternatively, the mounting structure can be configured to extend through an entire length of the at least one mounting opening. Further, the at least a portion of the shell can comprise an inner wall and an outer wall and the mounting opening can be disposed on the outer wall of the shell. 
     In some embodiments, the mounting structure can be configured to expand on an inner surface of the outer wall of the shell to secure the padding to the shell. Further, the at least one mounting structure can comprise at least one interference ring configured to provide the interference fit that secures the padding to the shell. Additionally, or alternatively, the at least one portion of the interference ring can be configured to be larger in diameter than a diameter of the at least one mounting opening in which the at least one mounting structure is received. 
     In some embodiments, the interference fit between an inner diameter of the mounting opening and an outer diameter of the mounting structure can be in a range varying from about 0.020 inches to 0.040 inches. 
     Additionally, or alternatively, the at least one portion of the mounting structure can comprise at least one of a generally square-shaped, a generally rounded, and generally triangular-shaped cross section. Further, in some embodiments, the at least one mounting structure comprises at least one extension configured to at least partially extend over an edge of the shell to couple the padding to an outer surface of the shell. 
     In some embodiments, the at least one extension can comprise a notch configured to engage a corresponding recess in the outer surface of the shell. Further, the notch and the corresponding recess can be compatibly shaped so as to mate with one another. 
     Other aspects and advantages of the invention can become apparent from the following drawings and description, all of which illustrate the various aspects of the invention, by way of example only. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  schematically illustrates a limb holder according to some aspects disclosed herein. 
         FIG. 2  schematically illustrates a limb holder according to some embodiments disclosed herein. 
         FIG. 3  schematically illustrates an exploded view of a support element. 
         FIG. 4A  schematically illustrates a front view of a support element padding according to some embodiments disclosed herein. 
         FIG. 4B  schematically illustrates a rear view of a support element padding according to some embodiments disclosed herein. 
         FIG. 5  schematically illustrates a shell according to some embodiments disclosed herein. 
         FIG. 6  schematically illustrates a limb holder according to some embodiments disclosed herein. 
         FIG. 7A  schematically illustrates a cross-section of a mounting structure secured in a mounting opening via an interface fit according to embodiments disclosed herein. 
         FIG. 7B-7G  schematically illustrate several examples of mounting structures according to some embodiments disclosed herein. 
         FIGS. 8A-8H  schematically illustrate several examples of mounting structures according to some embodiments disclosed herein. 
         FIGS. 9A-9E  schematically illustrate examples of mounting structures according to some embodiments disclosed herein. 
         FIGS. 10A-10B  schematically illustrate examples of a shell and a corresponding padding according to some embodiments disclosed herein. 
     
    
    
     DETAILED DESCRIPTION 
     Patient limb support devices are often configured to hold and/or support relevant portion(s) of a patient&#39;s body using a substantially rigid frame that has been padded to protect the patient&#39;s body/limb from the rigid frame. Such supporting devices are commonly used during surgical procedures (or during recovery or treatment), in which the patient&#39;s limb needs to be elevated or safely held in place. The padding covering the rigid surface is often held in place through attachment to the rigid support frame. 
       FIG. 1  schematically illustrates a patient  101  in a lithotomy position. The term “lithotomy position,” as used herein is intended to refer to a position (e.g., for surgical procedures or medical examinations), in which at least a portion of the patient&#39;s body  101  is maintained above or at the same level as the patient&#39;s hip. However, although described in terms of the lithotomy position and shown as supporting the patient&#39;s lower body, the embodiments disclosed herein can be used in conjunction with any support device, apparatus, system, or mechanism used to support, maintain in place, and/or hold any part or portion of the anatomical structure of a patient. The term patient, as disclosed herein, can refer to a human or an animal patient. Further, although described as being used during surgical procedures, the embodiments disclosed herein can be used to support a part of a patient&#39;s body at any point or time during examination, treatment, surgical procedures, and/or recovery. 
     Referring back to  FIG. 1 , a limb holder  100  according to some aspects herein is illustrated. The limb holder  100  can be used to support any portion of the patient&#39;s  101  anatomy (e.g., the patient&#39;s leg  110 ). For example, the limb holder  110  can be a lithotomy stirrup used to hold or elevate the patient&#39;s  101  leg  110 . Although not shown in  FIG. 1 , it should be noted that depending on the application at hand, one or more limb holders  100  can be used (e.g., in a gynecological exam, a pair of limb holders  100  can be used). The limb holder  100  can be used to hold the patient&#39;s limb in space, relative to at least one surface  112  on which the remaining portions of the body of the patient  101  are disposed. Although the term bed  112  is used hereinafter to refer to the at least one surface, the surface  112  can be the surface of a bed, an operating table, an examination table, etc. 
     The limb holder  100  can comprise one or more support elements  116  that are used to support at least one part of the limb. For example, as shown in  FIG. 1 , the limb holder  100  can comprise a support element  116  (formed to resemble the rear portion of a boot in the example shown in  FIG. 1 ) configured to support the lower portion  114  of the patient&#39;s leg  110 . In some implementation, the support element  116  can be configured to support the at least one portion  114  of the limb by wrapping around and/or cradling the portion  114  of the limb. The support element  116  can be padded to prevent injury to the patient. 
     The limb holder  100  can further comprise a support structure  118  that is configured to be coupled to the bed  112  via a mounting rail  120 . Generally, any suitable means available in the art can be used to connect and mount the support structure  118  to the mounting rail  120 . For example, one or more clamps  121  can be used to connect the support structure  118  to the mounting rail  120 . Generally, any suitable clamp or connecting mechanism can be used. However, the type of clamp or connecting mechanism used can depend on the required mating geometry (e.g., the type or shape of the corresponding mating/mounting features on the mounting rail  120  and/or the support structure  118 ) and/or the desired range of motion (the range of motion of the device  100 ). 
       FIG. 2  illustrates a limb holder  200  according to some embodiments disclosed herein. As noted previously, although shown as supporting a leg of the patient, the limb holder  200  can be used to support any limb and/or body part of the patient. Further, the limb holder  200  can comprise any shape or size. For example, as shown in  FIG. 2 , the limb holder  200  can comprise a semi boot-shaped support element  116  that is configured to support a portion  114  of the patient&#39;s limb (e.g., leg). The support element  116  can be padded and configured to cradle the patient&#39;s limb. 
     Specifically, the support element  116  can comprise a shell  212 . The shell  212  can be coupled to the support structure  118  via any suitable means available in the art. The shell  212  can also be configured to support one or more padding(s)  210 . The padding  210  can comprise any suitable padding or cushioning material. The padding  210  can be configured such that it is removable and/or replaceable. Specifically, as described with respect to  FIG. 3 , the padding  210  can be configured such that it can be separated from the shell  212 . 
     The support element  116  can further comprise a cover  214 . The cover  214  can be removably and replaceably or permanently coupled to the support element  116 . Alternatively, or additionally, the cover  214  can be configured to be movable with respect to the support element  116 . Generally, any suitable available mechanism can be used to couple the cover  214  to the support element  116  and/or provide the cover with the required movement with respect to the support element  116 . 
     The cover  214  can be configured such that it covers at least one portion of the patient&#39;s limb that is not covered and/or cradled by the support element  116 . For example, as shown in  FIG. 2 , the support element can comprise a half-boot structure that leaves the top portion T of the patient&#39;s limb exposed/uncovered. The cover  214  can be configured, as shown in  FIG. 2 , to cover at least one part of the portion T that is not covered by the support element  116 . The cover  214  can function to protect the patient&#39;s limb (body) from possible and/or inadvertent, unwanted impact that may occur during care, operation, treatment and/or recovery. 
     As noted, the cover  214  can be an integral part of the support element  116  and permanently coupled to the support element  116 . Alternatively, the cover  214  can be a removable, replaceable, and independent component that is coupled via suitable mechanical means to the support element  116 . Further, although shown as being coupled to the side of the support element, the cover  214  can be coupled to any suitable part of the support element  116 . 
     The shell  212  can comprise any suitable available material. For example, the shell  212  can comprise at least one of a thermoplastic material (e.g., polyethylene, polypropylene, or Acrylonitrile Butadiene Styrene (ABS)), structural foam, or formed sheet metal. Generally, the shell  212  can be manufactured via any suitable manufacturing process such as injection molding, rotational molding, thermoforming, or vacuum forming. 
       FIG. 3  schematically illustrates how a shell  212  of a support element  116 , such as the support element shown in  FIG. 2 , can secure a padding  210 . In the example shown in  FIG. 3 , the shell  212  is shown separately from the padding  210 . Generally, any suitable means available in the art can be used to connect and secure the padding  210  to the shell  212 . For example, traditionally, one or more fasteners (e.g., Velcro® brand fasteners or hook and loop fasteners) are used to secure the padding  210  to the shell  212 . 
     In the example shown in  FIG. 3 , a hook  310  is attached to an inside surface  312  of the shell  212 . Generally, any suitable means can be used to connect the hook  310  to the shell. For example, an adhesive, one or more staples, one or more screws, or a combination thereof can be used to secure the hook  310  to the surface  312 . Similarly, a loop  314  can be attached to underside surface  313  of the padding  210  in an area corresponding to the area of the shell  212 , to which the hook  310  is attached. The loop  314  can be attached to the padding using any suitable means available in the art. For example, the loop  314  can be sewn and/or adhered to the padding  210 . Further, the lateral and medial sides of the padding  210  can be secured using loop flaps  316  to corresponding hook patches  318  on an outer surface  320  of the shell  212 . 
       FIG. 4A-4B  illustrate a padding  400  according to some embodiments disclosed herein. Although described as having a single padding  400 , one or more paddings  400  can be used with embodiments disclosed herein. As shown in  FIG. 4A , which illustrates a front view of the padding  400 , the padding  400  can comprise one or more mounting structures  410  secured to an outer surface  412  of the padding  400 . Generally, any suitable number of mounting structures  410  can be used and the mounting structures  410  can disposed at any suitable location on the outer surface  412  of the padding  400 . For example, as shown in  FIG. 4A , at least mounting structure  410  can be disposed within a predetermined distance d 1  from at least one portion of an edge  444  of the padding  400 . For example, in some implementations, the distance d 1  is configured such that it is less than or including three inches (d 1 &lt;3″) and/or less than or including five inches (d 1 &lt;5″). Limiting the distance d 1  to &lt;5 can provide certain advantages. For example, limiting the distance can reduce possible dislodgment of the padding  400  from the shell  500  (shown in  FIG. 5 ) due to axial forces exerted on the padding  400  as the patient&#39;s limb is secured by the limb holder. 
     The mounting structures  410  can be in the form of protruding pins that can be inserted into respective mounting openings  510  (shown later in  FIG. 5 ) to secure the padding  400  to a shell  500  (later shown in  FIG. 5 ). For example, in the embodiment shown in  FIG. 4A , the mounting structures  410  are disposed on the outside of the lateral wing  414  and near the lateral ankle section  416  of the padding  400 . Additional mounting structures  410  can also be utilized. For example, as shown in  FIG. 4B , the padding  400  can include any number of mounting structures  410  (for example, three structures as shown in  FIG. 4B ) on an outside surface of the medial wing  418 , on a medial ankle section  420 , and on an outer surface of the upper toe section  422 . Generally, any number of mounting structures  410  can be used. The number of mounting structures  410  can depend on the level of mounting security that the padding  400  is desired to have, once mounted and secured by the shell  500  (shown in  FIG. 5 ). 
     The mounting structures  410  can be secured to the surface of the padding  400  using any suitable means available in the art, such as but not limited to adhesives, sewing, and/or other physical and/or chemical means. Alternatively or additionally, the mounting structures  410  can be molded into the padding  400 , passed through hole(s) disposed in the padding (not shown), or upholstered in the padding  400 . 
     The mounting structures  410  can be configured such that they are only exposed on the outer surface  412  of the padding  400 . The exposed surfaces  411  of the mounting structures  410  are, therefore, the only surfaces that need to be cleaned, disinfected, and/or kept sterile. Further, since the external surfaces  411  of the mounting structures  410  are configured such that they protrude/project out of the padding, these surfaces can be easily cleaned using common methods for disinfecting surfaces in hospitals and/or operating rooms. Accordingly, by utilizing mounting structures  410  as disclosed herein, embodiments of the present disclosure reduce and minimize potential entrapment of debris or organisms in the padding, thereby providing superior means for securing the padding  400  to the shell  500  over commonly used hook and loop fastening systems with regard to infection control. 
     The mounting structures  410  can be configured for mating with corresponding mounting openings of a shell.  FIG. 5  schematically illustrates a shell  500  according to some embodiments disclosed herein. As shown in  FIG. 5 , the shell  500  can comprise a plurality of mounting openings  510  each configured to receive a corresponding mounting structure  410  of the padding  400 . As explained with reference to the mounting structures  410 , generally any number of mounting openings  510  can be used and the mounting openings  510  can be disposed at any suitable location on the shell  500 . Further, the number of mounting openings  510  and the mounting structures  410  need not be the same. For example, in some embodiments, the shell  500  can have more mounting openings  510  than the mounting structures  410  provided in the padding  400 . Generally, the number of mounting openings  510  utilized can depend on the level of mounting security that the padding  400  is desired to have, once mounted and secured by the shell  500 . By way of example, the number of mounting structures  410  and the mounting openings  510  can be in a range of about two to about ten, although other numbers of mounting structures  410  and mounting openings  510  can be used. 
     The mounting openings  510  can comprise any suitable shape and size. The openings  510  can further be configured such that they can accommodate the size and shape of the mounting structures  410 . Generally, the location of the mounting openings  510  on the shell  500  can be configured to ensure that they correspond to and/or match the locations of the mounting structures  410  on the padding  400 . 
     Further, the mounting openings  510  can be configured to be through holes. Specifically, the mounting openings  510  can be configured such that they pass through from the inner surface  512  to the outer surface  514  of the boot shell  500 . The mounting openings  510  can further be configured to provide a mechanical interference fit with the mounting structures  410  on the padding  400 . 
     For example, as shown in  FIG. 5 , at least mounting opening  510  can be disposed within a predetermined distance x 1  from at least one portion of an edge  555  of the padding  500 . The distance x 1  can be any suitable distance. For example, in some implementations, the distance x 1  is configured such that it is less than or including three inches (x 1 &lt;3″) and/or less than or including five inches (x 1 &lt;5″). 
       FIG. 6  schematically illustrates a limb support  600  according to some embodiments disclosed herein. As shown, the limb support  600  comprises a padding  400  that is secured to an inner surface of a shell  500  via an interface fit between the mounting structures  410  of the padding  400  and mounting openings  510  of the shell  500 . The interface fit is formed via engagement between a given mounting structure  410  and a corresponding mounting opening  510 . 
       FIG. 7A  schematically illustrates a cross-sectional view of interface fit established via engagement of a mounting structure  410  and a mounting opening  510 . As shown, a mounting structure  410  can comprise a base  710  disposed and attached to an outer surface  412  of the padding  400 . The mounting structure  410  can further comprise a neck section  712  configured to protrude substantially perpendicularly out of the base  710  of the mounting structure  410 . 
     In some embodiments, the neck section  712  can be hollow and configured to receive an insert. Specifically, as shown in  FIG. 7B , the neck section  712  can be hollow and configured to receive an insert  777  to allow the mounting structure  410  to flex to accommodate any variation between the location of the attachment of the mounting structure  410 , on the outer surface  412  of the padding  400 , and the location of the mounting opening  510  on boot shell  500 . More particularly, the mounting structure  410  can be a hollow and/or flexible structure that can be flexed and/or slightly moved and inserted into a corresponding mounting opening  510 . This allows for the mounting structure  410  to be capable of passing through a corresponding mounting opening  510  even if the mounting structure  410  and the mounting opening  510  are not perfectly aligned. Once inserted into the mounting opening  510 , an insert  777  can be inserted into the hollow mounting structure  410  to reinforce the structure and secure the padding against the shell. The insert can comprise any suitable material known in the art. Further, in some embodiments, the insert can be disposable. In some embodiments, the insert  777  can be more rigid than the hollow mounting structure  410 . Further, the insert  777  can comprise any suitable material, for example, a polymeric material. 
     Alternatively, the neck section  712  can be solid and configured to allow the mounting structure  410  to be easily passed through mounting opening  510 . 
     The mounting structure can further comprise an interface ring  714  that is slightly larger in diameter R 1  than the diameter R 2  of the mounting opening  510  that is receiving the mounting structure  410 . In some implementations, the interface ring  714  can be configured to have a diameter R 1  that is slightly larger than the diameter R 2  of the mounting opening  510 . For example, in some embodiments, the diameter R 1  can be about 0.02 inches to about 0.04 inches larger than the diameter R 2 . In other implementations, the diameter R 1  can be about 0.02 inches to about 0.09 inches larger than the diameter R 2 . 
     The interface ring  714  can be disposed at any suitable location on the mounting structure  410  and configured such that it is exposed on the surface of the shell  500  and engages the outer surface  514  of the shell  500 . In some implementations, the interface ring  714  can be exposed near a tip  711  of the mounting structure  410 , for example in a location disposed at a distance about between 0.11 inches to 0.33 inches from the tip  711 . In some implementations, the mounting structure  410  can be configured such that it protrudes between 0.5 inches to 3.5 inches from the outer surface  412  of the padding  400  in order to secure the padding  412  to the shell  500 . 
     As noted, the mounting openings  510  of the shell  500  can comprise any suitable shape. For example, the mounting openings  510  can be circular, elliptical, triangular, and/or trapezoidal. Further, the mounting openings  510  can be implemented in the shell using any suitable technique available in the art. For example, the mounting openings  510  can be bored, cut, or molded into the shell  500 . The circumference  720  of at least one mount opening  510  can be configured to allow the interference ring  714  to compress inward while passing through the mounting opening  510 . The interference ring  714  can be configured such that, once passed through the mounting opening  510  and the circumference  720  of the mount opening  510 , the interference ring  714  expands outwardly to secure the padding  400  against the outer surface  514  of the shell  500 . 
     The engagement of the interference ring  714  and the mounting opening  510  forms a mechanical interference fit configured to resist an incidental axial force  716  caused, for example, as a result of inserting a patient&#39;s limb into the shell  500 . The incidental axial force  716  can, alternatively or additionally, be caused from inadvertent pressure resulting from users leaning or pushing against the mounting structure  410  or force exerted by other equipment used in conjunction with the limb holder and/or pushing against the mounting structure  410 . 
     The mechanical interference fit between the neck section  712  and the inner surface of the mounting opening  510  thereby provides a resistive counter force  717  configured to restrict relative lateral movement  718  of the outer surface  412  of the padding  400  and the inner surface  512  of the shell  400 , such as lateral force caused by movement of the patient&#39;s limb(s) against the padding  400 , or adjustment of the padding  400 . 
     Generally, the mounting structure  410  can comprise any suitable material. For example, the mounting structure  410  can comprise a molded flexible material including but not limited to liquid injection molded silicone, thermoplastic elastomer, thermoplastic urethane, or other rubber-like materials. Flexible, rubber-like materials can allow for repeated compression and expansion of the mounting structure  410  without permanent deformation, allowing the engagement to be established and released repeatedly. 
     Generally, the interference fit between the inner diameter R 2  of the mounting opening  510  and the outer diameter R 1  of the mounting structure  410  can be any suitable size. The size of the interference fit can depend on the material selected to construct the mounting structure  410  and the desired strength of the intimate engagement while resisting axial forces  716 . For example, in some implementations, the interference fit can be between 0.020″ and 0.040″ or between 0.010″ and 0.080″. 
     As noted above, mounting structures and mounting openings disclosed herein can comprise any suitable shape and size and be disposed at any suitable location on the shell and/or the padding. For example, as shown in  FIG. 7C , the mounting opening can be a slot  1012  having a seat  1010  configured to receive the neck portion  712  of a mounting structure  410 . The padding  400  can be secured against the shell  500  by pressing/pushing the neck  712  of the mounting structure  410  in a downward motion  1016  through the slot  1012 , overcoming an interference fit between the outer dimensions of the neck  712  and the inner dimension of the slot  1012  until the neck  712  is seated in the seat  1010 . As shown in  FIG. 7D , once the mounting structure  410  is positioned within the seat  1010 , the dimensional interference retains the neck  712  from moving opposite the direction of the arrow  1016 , while the dimensional interference between interference ring  714  and the seat  1010  resists the incidental axial force  716  thereby securing the mounting structure  410  in the slot  1012 . 
     Further, as shown in  FIGS. 7D-7G , the mounting opening can comprise any suitable shape, including but not limited to a key-hole shaped slot  1018  (shown in  FIG. 7E ) and/or a U-shaped slot  1014  (shown in  FIG. 7G ). 
     Generally, mounting structures  410  can comprise any suitable shape required to accommodate the shape of their corresponding mounting openings. For example, as shown in  FIG. 7F , in implementations that utilize a key-hole shaped slot  1018  ( FIG. 7E ), a mounting structure  1020  having an accommodating shape (e.g., a key-shaped configuration) can be used, which can allow the mounting structure to mate with the respective opening so as to couple the padding to the shell. The key-shaped mounting structure  1020  can be configured such that it can be pushed through the key hole slot  1018 . Further, the key-shaped mounting structure  1020  can be configured to be oversized relative to the key-hole shaped slot  1018 . Specifically, the key-shaped mounting structure  1020  can comprise a flexible material, and be configured to have a similar shape as the key-hole shaped slot  1018  but be slightly oversized relative to the key-hole shaped slot  1018 . The difference in the size between the key-shaped mounting structure  1020  and the key-hole shaped slot  1018  allows the flexible key-shaped mounting structure  1020  to expand once in the key-hole shaped slot  1018 , thereby securing the padding, on which the key-hole shaped slot  1018  is disposed, to the shell, on which the key-hole shaped slot  1018  is disposed. 
     Similarly, as shown in  FIG. 7G , a U-shaped slot  1014  with a corresponding mounting structure  410  having an accommodating shape can be utilized. The U-shaped slot  1014  can be disposed at any suitable position on the shell  500 . For example, as shown in  FIG. 7G , the U-shaped slot  1014  can be positioned at an upper edge of the shell  500  such that mounting structure  410  with the neck  712  and interference ring  714 , attached to padding  400 , can be moved downward, along a direction  1016 , to secure padding to boot shell  500  (not shown). 
       FIGS. 8A-8H  schematically illustrate non-limiting examples of mounting structures  410  that can be used with the embodiments disclosed herein. As shown and noted previously, the mounting structure can comprise any suitable shape and size known and available in the art. The neck section  712  of the mounting structure  410  can also comprise any suitable shape and size known and available in the art. For example, the mounting structure  410  can comprise a neck cross-section having a square  810  ( FIG. 8A ), triangular  812  ( FIG. 8B ), and non-rectilinear  814  ( FIG. 8C ), or circular  816  ( FIG. 8D ) shape. 
     Further, the interface ring  714  can comprise any suitable shape and/or size known and available in the art and be disposed at any suitable position on the mounting structure  410 . For example, as shown in  FIGS. 8E-8F , the interface ring  714  can be positioned at or near the tip  711  of the mounting structure  410 . Alternatively or additionally, as shown in  FIG. 8G , the interference ring  714  can be positioned at any location below the tip  711  of the mounting structure  410 . Further, as shown in  FIG. 8H , the mounting structure  410  can comprise one or more interference rings  714 ,  714 ′,  714 ″. Furthermore, the interference ring  714  can comprise any suitable size and shape available in the art. For example, as shown in  FIGS. 8E-8F , the interference ring  714  can comprise a rounded tip ( FIG. 8E ) or a flat tip ( FIG. 8F ). 
     Additionally, or alternatively, a bent-shaped mounting structure can be used to couple the padding  400  to the shell  500 . For example, as shown in  FIG. 9A , a mounting structure  910  can comprise a rounded (or bent) portion  901  that is configured to clip and extend over an edge  916  of the shell  500 . The rounded portion of the mounting structure that clips and extends over the edge  916  of the shell  500  can comprise a protrusion or a nub  912  that is configured to mate with a corresponding indentation (notch)  914  disposed on the outer surface  514  of the shell  500 . Regardless of whether the mounting structure comprises the nub  912  and/or whether the shell comprises the notch  914 , the mounting structure  910  can be configured such that upon being passed over the edge  916  of the shell, the mounting structure  910  remains flush with the edge  916 . 
     In some implementations, the shell  500  can include one or more through holes  924  configured to receive a bent-shaped mounting structure  910 . Specifically, as shown in  FIG. 9B , the shell  500  can include one or more through holes  924  configured to receive a portion of the mounting structure  910 . The mounting structure  910  can be configured such that it can pass through the through hole  924  and clip over a portion of the outer surface  514  of the shell  500 . The rounded portion of the mounting structure that clips and extends through the through hole  912  can comprise a nub  912  that is configured to mate with a corresponding indentation (notch)  914  disposed on the outer surface  514  of the shell  500 . 
     In embodiments that utilize the nub and notch configuration, the mounting structure  910  can be coupled to the shell by engaging the nub  912  in the notch  914 . Similarly, the mounting structure  910  can be disengaged from the shell by pulling an outer leg  920  of the bent mounting structure  910  to disengage the nub  912  from the compatibly shaped mating notch  914  and lift the bent mating structure off of the shell edge  916 . Generally, the nub and notch can comprise any suitable shape and size and be disposed at any suitable location on the mating structure (nub) or the shell (notch). 
     In some embodiments, the shell  500  can comprise a through hole  922 . Specifically, as shown in  FIG. 9C , the mounting indentation can be a through hole  922  that extends through a width of the shell  500 . The through hole  922  divides the portion of the shell  500  upon which it is disposed to two portions  922 A,  922 B. The through hole  922  can be disposed at any suitable location on the shell  500 , for example at a location near the edge  916  of the shell. In some implementations, the through hole  922  can be disposed at a position within five inches (5″) of the upper edge of shell  500  in order to secure the upper edge of the padding  400  and prevent it from flopping inward. 
     Further, as shown in  FIG. 9D , the through hole  922  can comprise a notch  918  on at least one of its internal surfaces  917 . Although shown as being disposed on one side  922 A of the shell, the notch  918  can be disposed on the surface  917  of one or both  922 A,  922 B portions of the shell  500 . The notch  918  can be configured such that it can receive a mounting structure  910  (shown in  FIG. 9D ). In this embodiment, the mounting structure  910  comprises an extension  977  that clips over the notch  918 , disposed on the internal surface  917  of the shell portion  922 A, and extends over the external/outer surface  514 . Further, as shown in  FIG. 9E , the extension  977  can comprise a mating feature  999  that is configured to mate with the indentation  914  disposed on the external surface  514  of the shell  500 . The coupling of the mating feature  999  with the indentation  914  can further secure the padding to the shell. Specifically, a user can secure the padding  400  against the shell  500  by passing the extension  977  over the notch  918  (which can be a U-shaped notch) such that the extension extends over the surface/wall  514  of the shell. This configuration places the upper part  998  of the mounting structure  910  in the notch  918 , thereby securing the mounting structure  910  against the surface  514  of the shell  500 . The engagement of the mating feature  999  with the notch  914  can be utilized to further secure the padding to the shell. In some embodiments, the extension  977  can be configured such that upon passing of the extension  977  over the notch  918 , the extension  977  is flush with the top edge of the shell. 
     The mounting structure  910  can be attached to the padding  400  using any suitable means available in the art. For example, the mounting structure  910  can be glued to the padding  400  and/or molded in the padding  400 . Further, the mounting structure  998  can comprise any suitable configuration or materials and be formed using any suitable technique, including but not limited to injection molding (for thermos-plastics) or reaction injection molding (such as structural foam). In some implementations, the mounting structure  998  can be cut from any suitable material available in the art. 
       FIG. 10A  schematically illustrates a shell  1110  according to some embodiments disclosed herein. Generally, the shell can comprise any configuration or material and formed using any suitable manufacturing techniques, such as injection molding, roto-molding (for thermoplastics), or reaction injection molding (for structural foams). For example, the shell can be a double-walled or thick-walled structure  1110  having a thickness  1112  formed by an inner wall  1120 , an outer wall  1116 , and a space  1118  between the inner wall  1120  and the outer wall  1116 . Alternatively, the shell can be a solid single layer or multi-layer structure. 
     The space  1118  can be a void space or a filled space. For example, the space  1118  can be filled with a foamed material. The space  1118  can be filled with material foamed based on the process used to form the shell, during or after manufacture of the shell. Some examples of such foamed material can include, without limitation, polyurethane, polyethylene, or Polyisocyanurate foams. 
     In some embodiments, the thickness of the shell can comprise a mounting feature  1114 , which can be provided within the thickness of the shell and configured to receive and engage a mounting structure  410  of the padding. As shown in  FIG. 10B , the mounting structure  410  can comprise an interference ring  1714  that is configured to expand, once passed through the opening of the mounting feature  1114 , to secure the mounting structure  410  to the mounting feature  1114 . 
     Although this specification discloses advantages in the context of certain illustrative, non-limiting embodiments, various changes, substitutions, permutations, and alterations may be made without departing from the scope of the specification as defined by the appended claims. Further, any feature described in connection with any one embodiment may also be applicable to any other embodiment.