Patent Publication Number: US-2017367897-A1

Title: Conforming rigid cast and brace comprising a curable polymeric material

Description:
FIELD OF THE DISCLOSURE 
     The present invention relates generally to medical casts and braces, and more specifically, to methods of creating and affixing a protective medical cast or brace that comprises a curable polymeric material. 
     BACKGROUND 
     Bone fractures are a common result of blunt trauma and other types of accidents. A fracture occurs when sufficient force is applied to a bone such that the bone chips, cracks, or breaks. Once a fracture is diagnosed, the pieces or fragments of the broken bone are properly realigned by medical personnel through a process called reduction. The pieces are then held in position by means of a splint, cast, brace, or traction to allow them to properly fuse together during the healing process. In addition to maintaining the bone fragments in proper alignment, a cast, splint or brace may serve to decrease pain, keep surrounding tissue from becoming damaged, reduce the chance of serious bleeding and lost circulation to the injured part, and prevent movement, and perhaps re-injury, of the fractured bone during the healing process. 
     For many years, casts were made of plaster and cloth, or “padding.” Typically, the plaster for such casts comes in strips or rolls which are dipped in water and applied over the padding. The padding itself is usually a layer of cotton or synthetic fiber that covers the injured area. Once watered and positioned, the plaster is allowed to harden or cure. While the plaster cures, the patient must remain still so that the resultant cast can set into its proper shape. This method of treating a broken bone in this manner is both messy for the health care provider and inconvenient for the patient. In addition, a plaster cast is heavy and, as a result, unwieldy through out the healing process, which typically last eight through ten weeks. 
     In some casts, the plaster may be replaced with fiberglass. Fiberglass is lighter, longer wearing, and provides better ventilation than plaster. It is also more transparent to x-rays, thus allowing the medical personnel to easily monitor the healing process. However, fiberglass casts are generally more expensive than plaster casts, are often equally difficult and messy to work with, and still require the use of padding material. As with plaster, fiberglass comes in strips or rolls which are dipped in hot water and applied over the padding that covers the injured area. 
     In addition to casts, other types of protective shells and braces have found use in medical applications. Examples include braces of the type that are commonly used to treat back and knee injuries or conditions. For example, back braces have been developed that are designed to compress and unload weight from the lumbar region of a patient&#39;s back. These braces fall into two general categories, Lumbosacral Orthosis (LSO) braces and Thoracic Lumbosacral Orthosis (TLSO) braces. These braces may include posterior and/or anterior protective shells. Both the anterior and posterior shells are typically constructed light-weight, inexpensive thermoplastics. 
     Currently, braces are either dispensed in a limited number of sizes and shapes, or are custom manufactured using expensive and time-consuming procedures. Braces that are sold in a limited number of sizes (so called “off-the-shelf” braces) suffer from the infirmity that they can not be fitted as precisely as a custom brace, and are thus less comfortable and effective in use. Custom braces overcome this infirmity, but are typically much more expensive and time consuming to fabricate than off-the-shelf braces of the type that can be made using economies of scale. In particular, custom braces may cost thousands of dollars to produce, and may take weeks to fabricate. 
     SUMMARY 
     In accordance with the teachings herein, casts, braces, and related medical devices are provided that can be conveniently and inexpensively customized to the patient, that are not messy to apply, that are light-weight and wear-resistant, and that have good breathability. These devices are suitable for treating bone fractures, for providing support, and for other medical applications. Systems and methods for fabricating these devices are also provided. 
     As the Inventors herein have realized, there is thus a need in the art for casts and braces that can be conveniently and inexpensively customized to the patient, that are not messy to apply, that are light-weight and wear-resistant, and that have good breathability. These and other needs are met by the systems, devices and methodologies disclosed herein. 
     Although the devices, systems and methodologies disclosed herein will frequently be described in the context of treating bone fractures, and in particular, broken arms, these devices and methodologies are equally applicable to any type of situation in which a cast is required. In addition, the methods and devices described herein are not restricted to human applications, but may also be applied in the veterinary arts. 
     Briefly, a method is provided herein in which an encased, curable (preferably photocurable) cast material is wrapped around a body part such as, but not limited to, a broken arm. Once the curable cast material is positioned and shaped, an actinic radiation source, such as, but not limited to, an ultraviolet (UV) light source, is applied to the cast material. The radiation emitted by the actinic radiation source reacts with the cast material, causing it to cure or harden. Unlike plaster or fiberglass cast materials, the radiation curable cast materials described herein can be positioned and shaped for an indefinite period of time because the material does not begin to harden until exposed to the actinic radiation source. In addition, the rate at which the cast material hardens can be controlled by varying the conditions of exposure. including, but not limited to, the intensity and wavelengths of the actinic radiation source. Using a typical UV light source, a cast or brace can be made in accordance with the teachings herein that may cure in as little as five seconds or less. 
     In addition, the systems and methods disclosed herein may be employed to produce custom-fitted medical braces, such as back and knee braces. In contrast to conventional braces, which are very expensive and typically take several weeks to fit and fabricate, customized braces may be made in accordance with the methodologies disclosed herein that are ready for use concurrently with the fitting procedure. This greatly reduces the inconvenience to the patient, and avoids further injury that might otherwise occur while the patient is waiting for the brace to be prepared. 
     This summary is not intended as a comprehensive description of the claimed subject matter but, rather, is intended to provide a brief overview of some of the functionality associated therewith. Other systems, methods, functionality, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be better understood with reference to the following figures. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention. Moreover, in the figures, like reference numerals designate corresponding parts throughout the different views. 
         FIG. 1  is an illustration of an exemplary arm cast system constructed in accordance with the claimed subject matter. 
         FIG. 2  is a cross-sectional view of the arm cast system of  FIG. 1  taken along a LINE  1 A- 1 A. 
         FIG. 3  is a cross-sectional view of the arm cast system of  FIG. 1  taken along a LINE  1 B- 1 B. 
         FIG. 4  is a to view of the arm cast system of  FIG. 1  as applied to a patient&#39;s arm. 
         FIG. 5  is a bottom view of the arm cast system of  FIGS. 1-4  as applied o the patient&#39;s arm. 
         FIG. 6  is an illustration of an embodiment of a back brace made in accordance with the claimed subject matter. 
         FIG. 7  is a cross-sectional view of the back brace of  FIG. 6  taken along a LINE  6 A- 6 A. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     In the ensuing detailed description, the systems, methodologies and devices disclosed herein will frequently be described with reference to particular embodiments, such as back braces, knee braces and casts, and with respect to particular applications, such as the treatment of broken bones in the arms or legs. However, it will be appreciated that the systems, methodologies and devices disclosed herein may be implemented in a variety of embodiments and applications. Moreover, while the systems, methodologies and devices disclosed herein will be described primarily with reference to their use in human medical applications, it will be appreciated that these systems, methodologies and devices will also find use in various other fields, such as the veterinary arts. 
       FIG. 1  illustrates one embodiment of an arm cast system  100  which may be constructed in accordance with the claimed subject matter. A bottom portion or pad  101  is provided which is preferably constructed of a breathable, resilient material, such as GORETEX® neoprene, and which allows air to permeate to the injured area while also protecting the area from other, perhaps harder portions of cast system  100 . Pad  101  also serves, if necessary, to insulate a patient from heat produced by the curing of cast system  100 . A top portion  103  is provided which is constructed of a flexible material such as standard, medical grade silicon. In an alternative embodiment, pad  101  is made of the same material as top portion  103 , and a separate padding material is used beneath cast system  100 . It should be noted that pad  101  may extend from one side of top portion  103  to the other side, i.e., pad  101  includes material beneath top portion  103 . In this view, pad  101  extends out from the edges of top portion  103 . In an alternative embodiment, pad  101  may have the same approximate size and shape as top portion  103  so that pad  101  does not extend past the edge of top portion  103 . 
     The perimeter of top portion  103  of the cast system  109  is equipped with a ridge  105 . The top portion  103  and ridge  105  are preferably fabricated as a single piece of flexible material, though in some embodiments top portion  103  and ridge  105  may be fabricated separately or as distinct components. Thus, for example, ridge  105  may be fabricated as a distinct component similar to a gasket. Top portion  103  and pad  101  are affixed to each other along the length of ridge  105 . This may be accomplished by means of a suitable adhesive, by thermally bonding the materials together, or through other suitable means as are known to the art. One skilled in the art will appreciate that the choice of a suitable adhesive for attaching pad  101 , top portion  103  and ridge  105  may vary, and may depend on such factors as the specific materials employed in the manufacture of pad  101 , top portion  103  and ridge  105 . Ridge  105  is sufficiently raised from top portion  103  such that there is a gap  131  (see  FIGS. 2 and 3 ) between top portion  103  and pad  101 . As explained in greater detail below in conjunction with  FIGS. 2 and 3 , gap  131  is preferably filled with a radiation curable or energy-sensitive material, such as a polyurethane- or polyacrylate-based resin. 
     In this embodiment, top portion  103  has ten (10) holes  107 , each of which is surrounded by a corresponding ridge  109 . Ridges  109  are approximately the same height as a ridge  105  and also are affixed to pad  101 . In this manner, the radiation curable or energy curable resin that fills gap  131  does not leak out through holes  107 . Holes  107  are designed to enable cast system  100  to breath, and thus increase the comfort to a patient employing cast system  100 . The precise arrangement, size and number of holes  107  may vary. In an alternative embodiment, pad  101  is also cut out in areas corresponding to holes  107  such that holes  107  extend through both pad  101  and top portion  103 . 
     Pad  101  and top portion  103  are contoured such that portions are convex and concave in corresponding portions of opposing sides of pad  101  and top portion  103 , e.g. e.g. a convex portion  111  and a concave portion  113 . When cast system  100  is wrapped around a patient&#39;s limb, convex portion  111  fits into concave portion  113 . This positioning is shown in more detail below in conjunction with  FIG. 5 . In alternative embodiments, cast system  100  may have multiple convex and corresponding concave portions, or simply have a straight edge. 
     A portion of pad  101  and top portion  103  also extend outward in a finger-like extension  115 . Extension  115  is configured, in the context of an arm cast such as cast system  100 , to extend between the patient&#39;s thumb and first finger when cast system  100  is positioned on the patient&#39;s arm. Extension  115  helps cast system  100  from moving relative to the patient&#39;s arm once cast system  100  has been positioned on the patient&#39;s arm and hardened. The relative position of extension  115  with respect to cast system  100  and an exemplary patient&#39;s arm are shown in more detail below in conjunction with  FIG. 5 . 
     Cast system  100  also includes one or more radiation access channels  117  and  119 , each of which is constructed of a transparent material through which radiation for curing the energy sensitive material that fills gap  131  can pass. Radiation access channels  117  and  119  are positioned on top of pad  101  and extend through ridge  105 . 
     Also shown in  FIG. 1  are dotted lines  1 A- 1 A and  1 B- 1 B. Lines  1 A- 1 A and  1 B- 1 B are not actually part of cast system  100 , but rather are used to provide points of reference in cast system  100  corresponding to the cross-sectional views illustrated in  FIGS. 2 and 3 , respectively. 
       FIG. 2  is a cross-sectional view  130  of arm cast system  100  ( FIG. 1 ) taken along LINE  1 A- 1 A ( FIG. 1 ). The relationship of pad  101 , top portion  103  and ridge  105  is clearly illustrated. Ridge  105  is raised from pad and attached to  101  top portion  103  such that gap  131  is created in between pad  101  and top portion  103 . As alluded to above in conjunction with  FIG. 1 , gap  131  is filled with a curable polymeric material, such as a radiation curable or energy-sensitive polymeric material or resin. The curable polymeric material or resin is preferably curable through exposure to a source of actinic radiation such as, but not limited to, ultraviolet (UV) light, or through exposure to an electrical current or voltage. The curable polymeric material that fills gap  131  is typically a liquid or gel that solidifies upon curing into a substantially rigid mass. The curable polymeric material may solidify as a result of various chemical reactions, including crosslinking and addition reactions. Within gap  131  is a mesh  137  that serves prevent cast  100  from stretching and thus strengthening cast  100  in much the same way that iron rebar placed within concrete strengths, or reinforces, the concrete. 
     A layer  133  positioned on gap  131  side of top portion  103  is reflective to the radiation that cures the energy-activated polymeric material that fills gap  131 . Layer  133  serves to enable radiation passing through radiation access channels  117  and  119  to be distributed throughout gap  131 , thus enabling all the curable polymeric material to be exposed to the radiation and thereby cured or hardened. A layer  135  on the gap  131  side of pad  101 , like layer  133 , also enables radiation transmitted through radiation access channels  117  and  119  to expose and thereby cure the curable polymeric material that fills gap  131 . 
     In an alternative embodiment, cast system  100  does not include radiation access channels  117  or  119 , or layers  133  or  135  but, rather, top portion  103  allows enough curing radiation from an external exposure unit to pass through the material of which it is constructed to quickly cure the energy-activated polymeric material. 
     In another embodiment, an electric current is introduced to the polymeric material by means of electrodes (not shown) implanted into gap  131  through either top portion  103  or ridge  105 . This electric current causes the polymeric material to undergo a reaction by which it changes from a liquid or gel to a substantially rigid mass. In this manner, cast system  100  may be configured into a desired shape (see  FIGS. 4 and 5 ) and subsequently (as through exposure to a suitable activation energy source to which the polymeric material is sensitive) turned into a hardened shell that functions as a medical cast. 
       FIG. 3  is a cross-sectional view  140  of arm cast system  100  taken along LINE  1 B- 1 B of  FIG. 1 . In view  140 , pad  101 , top portion  103 , holes  107  and their respective ridges  109 , ridge  105 , layers  133  and  135  and radiation access channels are the same as described above in conjunction with  FIG. 2 . As explained above in conjunction with  FIG. 1 , holes  107  may extend through pad  101  rather than only through top portion  103 . As explained shove in conjunction with  FIG. 2 , gap  131  is filled with an energy-activated polymeric material so that, when cast system  100  is exposed to the particular UV or electrical energy to which the polymeric material is sensitive, system  100  turns into a hard shell that functions as a medical cast. Mesh  137  positioned within gap  131  provides extra strength to cast  100  once energy-activated polymeric material is hardened. 
       FIG. 4  is a top view illustrating the application of the arm cast system  100  of  FIG. 1  to a patient&#39;s lower arm  151 .  FIG. 4  shows pad  101 , top portion  103 , holes  107  and radiation access channels  117  and  119 , all of which are introduced above in conjunction with  FIG. 1 . Arm  151  includes a first metacarpal, or “thumb,”  153  and a second metacarpal, or “index finger,”  155 . Cast system  100  is placed against arm  151  such that pad  101  is in contact with the skin of arm  151  and functions both to both cushion arm  151  from the rest of cast  100  and to insulate arm  100  form any heat that may be generated during the curing of the polymeric material encased in gap  131  ( FIGS. 2 and 3 ). Cast system  100  is positioned upon arm  151  such that finger-like extension  115  ( FIG. 1 ) wraps around arm  151  in between thumb  153  and index finger  155 . The positioning of extension  115  between thumb  153  and index finger  155  may also be seen below in  FIG. 5 . 
       FIG. 5  is a bottom view illustrating the application of arm cast system  100  of  FIGS. 1-4  to a patient&#39;s lower arm  151  ( FIG. 4 ). In this perspective, arm  151  is turned over so that the bottom side is up. Pad  101  ( FIGS. 1-4 ) and top portion  103  ( FIGS. 1-4 ) are wrapped around arm  151  such that convex portion  111  ( FIG. 1 ) fits adjacent to corresponding convex portion  113  ( FIG. 1 ). Extension  115  ( FIG. 1 ) is positioned between thumb  153  ( FIG. 4 ) and index finger  155  ( FIG. 4 ). 
     In this embodiment, cast system  100  is positioned against arm  151  as shown in  FIGS. 3 and 4  while the polymeric material that fills gap  131  ( FIGS. 2 and 3 ) is still of a liquid or gel-like consistency. Once positioned against arm  151 , cast system  100  is then exposed to the activating energy source to which it is sensitive, thus causing the polymeric material to harden. Thus, cast system  100  becomes a hard cast with padding material provided by pad  101 , a protective shell provided by the hardened polymeric material that fills gap  131 , and a cushion for the protective shell provided by top portion  103 . 
     In an alternative embodiment, pad  101  is made of the same material as top portion  103  and a separate, more traditional padding is employed between cast system  100  and arm  151 . In this embodiment, the polymeric material is simply encased in a single piece of material of the type used to construct top portion  103  above. The corresponding pad may be attached to the encasing material or applied separately as the cast is positions on the patient&#39;s arm. 
       FIG. 6  illustrates a portion of an exemplary back brace  180  that incorporates the claimed subject matter. In this example, brace  180  is shown installed on the posterior side of a human torso  181 . Typically, a posterior back brace such as brace  180  is employed for either corrective or immobilizing purposes, and may have either a “short” or “long” configuration. Of course, it will be appreciated that the teachings herein may be applied to the construction of a brace having almost any purpose or configuration. 
     Brace  180  includes a posterior shell  183 , adjustable straps  185  and elastic webbing  189 . Adjustable straps  185  and elastic webbings  189  hold shell  183  in place against torso  181 . Both straps  185  and webbings  189  fasten in the anterior, or front, (not shown) of torso  181 . Dotted lines shown in the outline of straps  185  and webbing  189  indicate that those particular potions of straps  185  and webbing  189  are obscured from view by shell  183 . 
     The teachings herein are equally applicable to an anterior shell brace (not shown), whether used on its own or in conjunction with a posterior brace such as brace  180 . One with skill in the medical arts should recognize that there are many configurations suitable for securing a brace such as brace  180  to a torso or other body part. The particular brace configuration or body part application may vary from one implementation to the next. 
     Webbings  189  are attached to shell  183  at attachment points  191  by suitable fasteners, including, but not limited to, hook-and-loop type fasteners and repositionable adhesives. Straps  185  are likewise attached at attachment points  187  by suitable fasteners, which may be of the same or different type as the fasteners used to attach webbings  189  to shell  183 . In one particular embodiment, an actinic radiation source is used to cure the polymeric material, and the fasteners that attach straps  185  and webbings  189  to shell  183  comprise a material that is transparent to the actinic radiation source. One skilled in the art will appreciate that a variety of plastics may be used for this purpose, and that the particular choice of plastic may depend on the actinic radiation source that is to be used to cure the polymeric material. 
     Brace  180  also includes one or more radiation access channels, in this example, radiation access channels  193  and  195 . Radiation access channels  193  and  195  serve the same function with respect to brace  180  as radiation access channels  117  and  119  ( FIGS. 1 and 4 ) serve with respect to cast  100  of  FIGS. 1-5 . Of course, as with cast system  100 , there are alternative methods to ensure that shell  183  is properly cured. 
     In an alternative embodiment, shell  183  is cured without the fasteners, straps  185  and/or webbing  189  attached, and these items are added subsequent to curing. A dashed LINE  6 A- 6 A is not part of brace  180  but rather indicates the position of a cut-away view  200  along a LINE  6 A- 6 A with respect to brace  180 . View  200  is illustrated below in conjunction with  FIG. 7 . 
       FIG. 7  is a cross-sectional view of brace  180  taken along LINE  6 A- 6 A of  FIG. 6  and depicting brace  180  positioned against a surface  203  of torso  181 . The curvature of surface  203  may be equal, greater or less than the actual curvature of a human torso. Surface  203  is used only as an example of part of a human torso&#39;s topology, which may in fact be quite irregular. However, the teachings herein may be used to construct a brace having a shell ( FIG. 7 ) that conforms to whatever shape torso  181  assumes, however irregular. 
     Like cast system  100  ( FIGS. 1-5 ), brace  180  includes a pad  201  and an upper portion  203 . Although view  200  appears to show several pieces to pad  201  and upper portion  203 , preferably, pad  201  and top portion  203  are each of a singular construction and spaces  207  represent fastening points  187  ( FIG. 5 ) through which fasteners (not shown) extend to attach straps  185  ( FIG. 5 ) to shell  183  ( FIG. 5 ), which in this illustration is represented by pad  201 , top portion  203 , holes  207  and so on. At the bottom of holes  207  are notches or recessions  209  that serve as space for heads (not shown) on fasteners  187  ( FIG. 7 ) to fit so that fasteners  187  do not pull out of holes  207 . Each notch  213  may extend entirely around the circumference of corresponding hole  207 , or, in the alternative, may only be partially around hole  207  such that a fastener  187  with a matching head is prevented from rotating. 
     Pad  201  and top portion  203  are attached to each other at ridges  205  formed at the edges of top portion  203  and at ridges  209  formed on top portion  203  around holes  207 . Similar ridges are formed in upper portion  203  around holes (not shown) at attachment points  191  ( FIG. 7 ). Ridges  205  and  209  enable pad  201  and upper portion  203  to be attached to each other while leaving a gap  211  in between the portions of pad  201  and upper portion  203  that are not attached. 
     In an alternative embodiment, either or both ridges  205  and  209  are formed on pad  201  rather than upper portion  203 . Further, pad  201  and upper portion  203  may not include ridges  205  and  209  but rather their function, i.e., attaching and creating gap  211  between pad  201  and upper portion  203 , may be performed by a separate piece of suitable material in the form of one or more gaskets. In another embodiment, pad  201  is constructed of the same material as top portion  101 , both of which are a single piece of material molded to create a gap such as gap  211 . In this embodiment, a separate piece of material, either attached or unattached, is employed as padding. 
     Like gap  131  of cast system  100 , gap  211  is filled with an energy-activated polymeric material. Thus, for example, the polymeric material may be curable through exposure to a particular type of energy such as, but not limited to, UV light or an electrical current. In the example of UV light, the energy-activated polymeric material that fills gap  211  has a liquid or gel-like consistency when placed into gap  211 . When brace shell  180  is exposed to a UV light source, the polymeric material in gap  211  hardens or cures, forming a permanent, custom-fitted shell. Both UV curable and electrically curable polymeric materials can be employed in gap  211  that are curable relatively quickly. 
     Various curable polymeric materials may be used in the devices and methodologies disclosed herein. These include, but are not limited to, radiation curable materials based on acrylates, epoxides, urethanes, urea-acrylates, urethane-acrylates, epoxy-acrylates, polyether acrylates, polyester acrylates, urethane epoxides, silicone acrylates, acrylate-thiol-ene systems, ethylene copolymer elastomer compositions, acrylate rubber compositions, nitrile rubber compositions, fluoroelastomer compositions, chlorinated elastomer compositions, and silicone polymers. When the curable polymeric materials comprise photocurable polymers, they may be employed with appropriate catalysts, photoinitiators or crosslinking agents. Thus, for example, some epoxide-based systems may be cured through crosslinking reactions based on photoinitiated acid formation (using, for example, photo-acid generators based on aromatic diazonium salts, aromatic iodonium salts and triarylsulfonium salts), photoinitiated base formation (using, for example, photo-base generators bearing acyloxyimino groups), or photogenerated amines (using, for example, oxime-urethane derivatives). Photocurable polymeric materials may also be formed from various multifunctional monomers. 
     The curable polymeric materials employed in the devices and methodologies described herein may be cured through a variety of means. Thus, for example, these materials may be cured through irradiation with actinic energy rays, such as UV radiation (both short and long wavelength UV radiation), IR radiation, electron rays, and X-rays. Suitable sources of actinic radiation may include mercury lamps of low, medium, high, or super-high pressure, metal halide lamps, xenon lamps, and carbon arc lamps. These materials may also be cured through exposure to various laser sources, including semiconductor lasers, argon lasers and He—Cd lasers, or through exposure to ionizing radiation, such as alpha-rays, beta-rays, gamma rays, neutron beams, X-rays and accelerated electron rays. In some embodiments, one or more layers of materials that reflect or adsorb the radiation emitted by the radiation source may be disposed between the curable polymeric material and the patient to protect the patient from any harmful effects associated with exposure to the emitted radiation. 
     The curable polymeric materials employed in the devices and methodologies described herein may have various components as are known to the art. These include, in addition to the curable polymers themselves, various crosslinking agents, activators, photoinitiators, fillers, plasticizers, pigments, dyes, solvents, cosolvents, stabilizers, surfactants, metallocene compounds (these may have various aromatic electron system ligands), and the like. 
     While various embodiments of the application have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of this invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.