# Patent

## Title
Foam core sandwich splint

## Abstract

A multi-layered composite material suitable for use in orthopedics includes a foam core layer bonded between two layers of thermoformable polymer material. The thermoformable material is heat formable within a target temperature range allowing for rapid heating and application to a patient such as in the form of a splint. While within the target temperature range, the composite material includes a dwell time sufficiently long to enable proper fitment and adjustment, yet not overly long requiring extended periods of holding the composite material in place. The composite material is very light yet extremely rigid and easily conformable to patients.

## Background
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of U.S. Provisional Application No. 61/677,779, filed Jul. 31, 2012, entitled “Foam Core Sandwich Splint.”


FIELD OF THE INVENTION
The present invention related generally to orthopedic braces. More specifically, the present invention relates to a thermoformable splint having a composite material construction.
BACKGROUND OF THE INVENTION
Orthopedic splints are typically used during the first few days of a serious injury such as a fracture, ligament tear or other injury that needs to be stabilized while swelling subsides. Splints are typically partially circumferential or they may wrap around an elbow or ankle and extend up both sides allowing a space on either side. They allow for swelling to occur and are typically wrapped with an Ace-type bandage or the like, which is elastic and may provide compression, yet stretches to accommodate swelling. A complication, Compartment Syndrome, may occur if an injury is casted too soon or splinted too tightly which causes tissue to rapidly die from pressure buildup. Temporary proper splinting mitigates most complications in this regard. Typically, after 4-10 days, the splint is removed for procedures to reduce fractures, surgery or the like.
Conventional splints may be constructed from uncured plaster-impregnated fabric, or fiberglass impregnated with resin that is water activated. They are initially pliable and soaked in water to activate the curing process. Such conventional splints typically come in rolls or pre sized blanks.
While conventional splints are sufficient for their intended purpose, they do exhibit a number of drawbacks which can be improved upon. For example, some sort of padding must be applied to the limb prior to applying the splint. The splint material must be soaked in water to begin the curing process, and variables such as water temperature and room humidity can alter the cure time for the splint material. Once wetted, the splint material is applied over the padding, which must be kept in proper alignment to be effective. Prior to wetting, the splint material is trimmed to a rough desired shape, but upon wetting and application to a patient, additional trimming of the material is often needed. The process is quite messy, and must be carried out very quickly before the splint material begins to cure. Initial curing can start in 2-5 minutes depending on the product and water temperature used. Once initiated, there is no stopping it and the application process must be completed with precise timing to allow for the body part to be aligned, reduced in fracture or otherwise completed before the splint cures. This process requires considerable training and the practitioner must have the splint in place in time to make the final alignment while the splint is still soft enough. Often, there is a minor complication or the splint is wetted too early or too warm and the curing starts during application so there is not enough time to finish the job properly before curing. In this case, the splint must be discarded and the process started over. This not uncommon occurrence is very wasteful, time consuming and costly, not to mention uncomfortable for the injured patient. Wrapping the padding and splint material can often take two people to support and wrap, and the manipulation is often painful to the patient.
On occasion, for a complicated reduction or alignment of a fracture or other injury, an X-Ray or fluoroscope view is needed during the procedure to see through the body to accomplish the correct procedure. Fiberglass and plaster materials tend to scatter X-rays and are somewhat impenetrable, so the view is typically obscured. These poor images can pose problems and the images must often be made with the patient at odd angles so as to image through the body without imaging through much of the splint. This can require complicated alignment of the machinery and patient which can cause great discomfort and complication.
Additionally, complicated reduction and alignment procedures may require a short period of sedation of the patient as the pain is too great to endure. The patient could react and possibly spoil the procedure. All of this can require a number of qualified people in close proximity doing several procedures at once. Along with the usual practitioners, the group can grow quite large. Everything must be orchestrated precisely and timed with the curing of the splint.
Another concern with conventional splinting materials and techniques is the wet environment created during their use. Because plaster and fiberglass splints will typically remain damp for 12 hours or more as the moisture slowly dissipates from the splint and padding through the Ace-type wrap, the moist environment from the splint combined with the body's heat and moisture provides the ideal place for bacterial reproduction.
This wet insulated environment also can provide a great deal of discomfort to the patient, especially in warm climates. Additionally, both fiberglass and plaster are virtually sealed against moisture passing through them so the splints do not breath or allow moisture to easily escape from inside near the body. Any moisture management must be provided by the thick padding or other wrapping.
In view of the drawbacks of conventional splints, a need exists for an improved splint which is less messy, requires fewer personnel to apply, has less likelihood of wasted material due to improper application, and is more comfortable and hygienic for the patient.
One proposed improvement on conventional splints is described in commonly assigned U.S. Published Patent Application No. 2012/0101417 to Joseph, which describes a splint having a composite laminate construction, consisting of thermoformable middle layer, and outer layers of foam and/or fabric which represents an improvement on conventional splints. Opportunities for improvement on the splints described therein still exist, however.
Additionally, prior splint constructions utilizing one or more polymer layers for rigidity typically include either a thin layer of polymer sheet material which is prone to flexing and twisting, or a thicker layer which can provide sufficient rigidity but is unable to be formed into complex shapes or contours and is unacceptably heavy.
A need exists, therefore, for an improved construction for splints which is lightweight, formable to the contours of a patient's anatomy, and which is sufficiently rigid to support the injury.
SUMMARY OF THE INVENTION
In one embodiment, the present invention comprises a composite material including a first layer of thermoformable material, a second layer of thermoformable material, and a foam layer disposed between, and bonded to, the first and second layers of thermoformable material, wherein the first and second layers of thermoformable material are heat formable within a target temperature range and substantially rigid at temperatures below a minimum formable temperature of about 130 degrees Fahrenheit.
In another embodiment, the present invention comprises a method including causing a composite material to be manufactured and made available to a user, and providing instructions to the user for creating a splint with the composite material. The composite material comprises a first layer of thermoformable material, a second layer of thermoformable material, and a foam layer disposed between, and bonded to, the first and second layers of thermoformable material, wherein the first and second layers of thermoformable material are heat formable within a target temperature range and substantially rigid at temperatures below a minimum formable temperature of about 130 degrees Fahrenheit. The instructions for creating a splint with the composite material include heating the composite material such that the layers of thermoformable material are above the minimum formable temperature, forming the composite material about a body part while the layers of thermoformable material are above the minimum formable temperature, and holding the composite material in place until expiration of the dwell time such that the layers of thermoformable material are below the minimum formable temperature.
In another embodiment, the present invention comprises a method of applying a splint to a patient, comprising providing a composite material including a first layer of thermoformable material, a second layer of thermoformable material, and a foam layer disposed between, and bonded to, the first and second layers of thermoformable material, wherein the first and second layers of thermoformable material are heat formable within a target temperature range and substantially rigid at temperatures below a minimum formable temperature of about 130 degrees Fahrenheit. The method further comprises heating the composite material such that the layers of thermoformable material are above the minimum formable temperature, forming the composite material about a body part while the layers of thermoformable material are above the minimum formable temperature, and holding the composite material in place until expiration of the dwell time such that the layers of thermoformable material are below the minimum formable temperature.



BRIEF DESCRIPTION OF THE DRAWINGS
Embodiments of the present invention may be more completely understood in consideration of the following detailed description of various embodiments of the invention in connection with the accompanying drawings, in which:
FIG. 1 is a schematic cross-section of the composite material according to an embodiment of the present invention.
FIG. 2 is a table depicting suitable material properties of a thermoformable material layer of the composite material according to an embodiment of the present invention.
FIG. 3 is a table depicting suitable material properties of a foam layer of the composite material according to an embodiment of the present invention.



While the various embodiments of the invention are amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will be described in detail. It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the inventions as may be claimed.
DETAILED DESCRIPTION OF THE DRAWINGS
The following detailed description should be read with reference to the drawings in which similar elements in different drawings are numbered the same. The drawings, which are not necessarily to scale, depict illustrative embodiments and are not intended to limit the scope of the inventions as claimed.
Although embodiments of the present invention are described chiefly in context of a splint, it should be appreciated that the materials, construction techniques, and methods described herein are also applicable to other orthopedic products such as braces, or for use as supports in combination with other orthopedic products.
The splints described in U.S. Pat. No. 8,303,527 to Joseph and U.S. Published Patent Application No. 2012/0101417 to Joseph, the disclosures of which are incorporated herein by reference, present a significant improvement over conventional wet lay-up splints but room for further improvement still exists. For example, certain splinting situations may call for a more rigid structure than is possible with the materials and structures described in these publications.
Referring now to FIG. 1, embodiments of the present invention generally comprise a composite sandwich material 20, having two layers of thermoformable material 22, 24, separated by a foam core layer 26, and optionally one or more finishing layers 28, 30.
The thermoformable material 22, 24 may include material properties as depicted in FIG. 2. Thermoformable material 22, 24 is preferably rigid at room temperatures, and more preferably rigid at temperatures below about 130 degrees Fahrenheit. Thermoformable material 22, 24 may be heat formable within a target temperature range of about 160-240 degrees Fahrenheit, and more suitably within a range of 190-225 degrees Fahrenheit. The minimum heat formable temperature may be about 160 degrees Fahrenheit, or about 150 degrees Fahrenheit, or about 140 degrees Fahrenheit. Advantageously, the target temperature range is relatively low, allowing quicker heating times, while the minimum heat formable temperature is high enough to prevent unintended alterations of shape during normal use if accidentally exposed to high temperatures.
Within the target temperature range, thermoformable material 22, 24 is pliable and shapeable to the profile of a patient. Thermoformable material 22, 24 may include a dwell time of about three minutes to ten minutes, or of about five minutes to ten minutes. Dwell time refers to the amount of time that thermoformable material 22, 24, once heated to within its target temperature range, is at least partially shapeable. In one embodiment, after being heated to within the target temperature range, thermoformable material 22, 24 is at least partially rigid after five minutes such that during a fitting process, a healthcare professional may cease applying pressure to the splint after five minutes and allow thermoformable material 22, 24 to fully cure without further intervention for the remainder of the dwell time. As utilized in composite material 20, a suitable thickness range of thermoformable layers 22, 24 is from about 0.030 inch to about 0.075 inch for each layer, with a more suitable range from about 0.035 inch to about 0.045 inch for each layer. In another embodiment, the thermoformable material may include glass strand added to the polymer to further increase modulus.
Foam layer 26 preferably comprises a closed cell foam, and is of a relatively high density. Suitable materials for construction of foam layer 26 in whole or in part may include low density polyethylene (LDPE), medium density polyethylene (MDPE), high density polyethylene (HDPE), polyethylene terephtalate glycol-modified (PETG), polyolefin blends, optionally any of these blended with ethylene-vinyl acetate (EVA), and any of which may or may not be crosslinked. One preferred density of foam layer 26 is from about 150 to 300 kg/m^2 or about 16 to 20 lbs/sq. ft. Suitable thickness of foam layer 26 is from about 1 mm to about 3 mm, with a more suitable range from about 1.5 mm to about 2 mm. In one embodiment, the thickness of foam layer 26 is about double the thickness of one layer of thermoformable material 22, 24. In one embodiment, the foam layer has properties as listed in FIG. 3, and is available under the name Microzote which is a LDPE fine celled closed cell foam blown with an inert gas and lacking reactive agents as are commonly used. Foam layer 26 thus provides a connective layer between thermoformable layers 22, 24 that is somewhat compliant and formable when heated, yet rigid and connected enough to resist compression and shearing thus allowing multi-layered composite material 20 to act as a unitized structure.
The combination of two layers of thermoformable material 22, 24 and foam core 26 results in a very light, thin, and rigid piece of composite material 20 which is extremely rigid when formed into a three dimensional shape.
Finishing layers 28, 30 may be selected from a variety of materials. Typically, one of layers 28, 30 will be positioned against the skin of the patient thereby comprising an inner layer, and therefore suitable materials will be comfortable, breathable, antimicrobial, and/or padded, and may comprise closed cell foam, open cell foam, an insulating fabric, a multilayer or lofted insulating fabric layer, or any other suitable material. While open cell foam is desirable for breathability, a closed cell may be advantageous for waterproof characteristics. Optionally, an additional layer may be included which is configured to be in contact with the skin of the patient, the additional layer comprising a fabric that is comfortable on the skin and wicks moisture into the layer 28, 30 for dissipation.
The other of layers 28, 30 will typically comprise an outer layer, and suitable materials will be durable, such as knit nylon spandex blend, knit polyester spandex blend, nylon fabrics, polyester or other fibers that stretch due to the design of the knit, rubberized materials, or foams such as urethane foam, foam rubber or EVA foam. Additionally, unbroken loop fabric, which is operably coupleable to hook-type fasteners, may be included as part of one of layers 28, 30 so as to provide functionality for hook-and-loop (VELCRO) type fastening arrangements.
Referring now to construction of an embodiment of composite material 20, the multiple layers may be bonded together by means of hot melt, PSA adhesive, or even by heat and pressure alone. In one embodiment, layers 22, 24, 26, 28 and 30 are laminated together at a temperature of 250-300 degrees Fahrenheit, under pressure. Variations on the construction of composite material 20 described herein may be made in order to alter the characteristics of composite material 20. For example, the thickness of the layers of thermoformable material 22, 24 may be varied such that each layer has a unique thickness. The hardness of foam layer 26 may be increased, to increase rigidity. The thickness of foam layer 26 may be varied to vary the dwell time of thermoformable layers 22, 24.
Additional layers of material may also be added as desired, such as spacer fabric, reinforcing material, waterproofing material, and/or additional foam layers for padding. The outer, middle and inner layers may be joined at their edges, such as by sewing, gluing, thermal or chemical bonding, or other suitable methods. Composite material 20 may be perforated with ventilation holes to aid in evaporation and cooling so transport occurs along foam layer 26 and out the vents.
In one embodiment, composite material 20 is provided for splinting, which can be fitted to a patient as follows. Composite material 20 is heated, preferably with a dry heat source such as an oven, microwave, heat gun, radiant lamp heat sources, infrared heaters, a heating bag, pouch, or other heat enclosure, or an exothermic heat source. Wet heat may also be utilized by immersing composite material 20 into a container of hot liquid such as water, or by placing composite material 20 within a liquid-filled bag and placing the bag in a microwave. Composite material 20 is heated for a length of time sufficient to bring the temperature of the layers of thermoformable material 22, 24 within their target temperature range such that composite material is pliable and formable to the patient. In one embodiment, composite material 20 is constructed such that the layers of thermoformable material 22, 24 are within their target temperature range after ten minutes of heating. In another embodiment, composite material 20 is constructed such that the layers of thermoformable material 22, 24 are within their target temperature range after about five minutes of heating.
Once thermoformable material 22, 24 is within its target temperature range, composite material 20 is removed from the heat source and applied to the desired location on the patient. While working in the dwell time of the material, the material is shapeable as desired to the patient, yet will somewhat hold its shape. During heating of the composite material, the thin layers of thermoforable material tend to warm comparatively faster than the foam and fabric layers, reducing the amount of time necessary to heat composite material 20 to its target temperature. Foam layer 26, having a lower density than the thermoformable layers 22, 24, does not retain as much heat as the thermoformable layers 22, 24 so heat dissipates more quickly from thermoformable layers 22, 24 and composite material 20 hardens more rapidly.
An outer bandage wrap may be utilized to retain the material in a desired shape, and/or the physician may hold the material in place with his/her hands while the material cools. In another embodiment, a universal closure system may be provided, such as those described in U.S. Pat. No. 8,303,527 to Joseph and U.S. Published Patent Application No. 2012/0101417 to Joseph. A suitable closure system includes a plurality of attachment members configured to releasably couple to composite material 20 such as by hook-and-loop fasteners, an elongated flexible member configured to be routed through one or more guide elements affixed to the attachment members, and a tensioning mechanism configured to be operable so as to engage the flexible member and tighten the fit of composite material 20.
In another embodiment, the present invention comprises a kit including composite material 20 according to one or more of the embodiments described herein, and a set of instructions recorded on a tangible medium for fitting composite material 20 to a patient as a splint according to the methods described herein. In one embodiment, the instructions may comprise instructions for use (IFU) or directions for use, according to the requirements of one or more regulatory bodies and/or government agencies. The instructions may be intended for a patient, or for a health care professional. Alternatively, the kit may include indications which link a user to electronically accessible instructions.
The composite material 20 described herein may be used in conjunction with other orthopedic products, such as those described in U.S. Pat. No. 8,303,527 to Joseph, U.S. Published Patent Application No. 2012/0101417 to Joseph, and application Ser. No. 13/674,613 to Joseph et al., the disclosures of which are incorporated by reference herein. Composite material 20 may be utilized in place of previously-disclosed rigid supports, or may be used selectively as a supplemental support such as to provide additional support and rigidity in select locations on an orthopedic product.
Various modifications to the embodiments of the inventions may be apparent to one of skill in the art upon reading this disclosure. For example, persons of ordinary skill in the relevant art will recognize that the various features described for the different embodiments of the inventions can be suitably combined, un-combined, and re-combined with other features, alone, or in different combinations, within the spirit of the invention. Likewise, the various features described above should all be regarded as example embodiments, rather than limitations to the scope or spirit of the inventions. Therefore, the above is not contemplated to limit the scope of the present inventions.
Persons of ordinary skill in the relevant arts will recognize that the inventions may comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features of the inventions may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the inventions may comprise a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art.
Any incorporation by reference of documents above is limited such that no subject matter is incorporated that is contrary to the explicit disclosure herein. Any incorporation by reference of documents above is further limited such that no claims included in the documents are incorporated by reference herein. Any incorporation by reference of documents above is yet further limited such that any definitions provided in the documents are not incorporated by reference herein unless expressly included herein.
For purposes of interpreting the claims for the embodiments of the present inventions, it is expressly intended that the provisions of Section 112, sixth paragraph of 35 U.S.C. are not to be invoked unless the specific terms “means for” or “step for” are recited in a claim.

## Claims

1. A composite material, comprising:
a first layer of thermoformable material;
a second layer of thermoformable material; and
a foam layer disposed between, and bonded to, the first and second layers of thermoformable material,
wherein the first and second layers of thermoformable material are heat formable within a target temperature range and substantially rigid at temperatures below a minimum formable temperature of about 130 degrees Fahrenheit, and
wherein the first and second layers of thermoformable material have a density which is about three to five times greater than a density of the foam layer.

2. The composite material of claim 1, wherein the density of the first and second layers of thermoformable material is about 1200 kg/m^3 and the density of the foam layer is about 300 kg/m^3.

3. A composite material, comprising:
a first layer of thermoformable material;
a second layer of thermoformable material; and
a foam layer disposed between, and bonded to, the first and second layers of thermoformable material,
wherein the first and second layers of thermoformable material are heat formable within a target temperature range and substantially rigid at temperatures below a minimum formable temperature of about 130 degrees Fahrenheit, and
wherein the first and second layers of thermoformable material each have a thickness which is about one-half of a thickness of the foam layer.

4. A composite material, comprising:
a first layer of thermoformable material;
a second layer of thermoformable material; and
a foam layer disposed between, and bonded to, the first and second layers of thermoformable material,
wherein the first and second layers of thermoformable material are heat formable within a target temperature range and substantially rigid at temperatures below a minimum formable temperature of about 130 degrees Fahrenheit, and
wherein the first and second layers of thermoformable material each have a thickness of about 0.03 to 0.045 inches, and wherein the foam layer has a thickness of about 0.06 to 0.09 inches.

5. A composite material, comprising:
a first layer of thermoformable material;
a second layer of thermoformable material;
a foam layer disposed between, and bonded to, the first and second layers of thermoformable material, wherein the first and second layers of thermoformable material are heat formable within a target temperature range and substantially rigid at temperatures below a minimum formable temperature of about 130 degrees Fahrenheit;
an inner layer coupled to the first layer of thermoformable material; and
an outer layer coupled to the second layer of thermoformable material.

6. The composite material of claim 5, wherein the inner layer comprises materials suitable for comfortable contact with skin.

7. The composite material of claim 5, wherein the inner layer comprises a fabric that wicks moisture into the inner layer.

8. The composite material of claim 5, wherein the outer layer comprises durable materials.

9. The composite material of claim 5, wherein the outer layer comprises unbroken loop fabric suitable for hook-and-loop fastening arrangements.

10. A composite material, comprising:
a first layer of thermoformable material;
a second layer of thermoformable material; and
a foam layer disposed between, and bonded to, the first and second layers of thermoformable material,
wherein the first and second layers of thermoformable material are heat formable within a target temperature range and substantially rigid at temperatures below a minimum formable temperature of about 130 degrees Fahrenheit, and
wherein the first and second layers of thermoformable material have a hardness within a range of Shore 65D-80D in accordance with ASTM D2240, a tensile strength in the range of 6000-9000 psi in accordance with ASTM D638, an elongation at break of 5% in accordance with ASTM D638, and a flexural modulus of between 270,000-340,000 psi in accordance with ASTM D5023.

11. A method, comprising:
causing a composite material to be manufactured and available to a user, the composite material including:
a first layer of thermoformable material,
a second layer of thermoformable material, and
a foam layer disposed between, and bonded to, the first and second layers of thermoformable material, wherein the first and second layers of thermoformable material are heat formable within a target temperature range and substantially rigid at temperatures below a minimum formable temperature of about 130 degrees Fahrenheit; and

providing instructions to the user for creating a splint with the composite material, the instructions including:
heating the composite material such that the layers of thermoformable material are above the minimum formable temperature,
forming the composite material about a body part while the layers of thermoformable material are above the minimum formable temperature, and
holding the composite material in place until expiration of the dwell time such that the layers of thermoformable material are below the minimum formable temperature.

12. The method of claim 11, wherein the dwell time is between five and ten minutes.

13. The method of claim 11, wherein heating the composite material such that the layers of thermoformable material are above the minimum formable temperature further comprises:
heating the composite material such that the layers of thermoformable material are within the target temperature range, the target temperature range being between 160-240 degrees Fahrenheit.

14. The method of claim 11, wherein heating the composite material such that the layers of thermoformable material are above the minimum formable temperature further comprises:
heating the composite material such that the layers of thermoformable material are within the target temperature range, the target temperature range being between 190-225 degrees Fahrenheit.

15. The method of claim 11, wherein the first and second layers of thermoformable material have a density which is about three to five times greater than a density of the foam layer.

16. The method of claim 11, wherein the instructions further include joining or bonding the layers at their edges.

17. A method of applying a splint to a patient, comprising:
providing a composite material including:
a first layer of thermoformable material;
a second layer of thermoformable material; and
a foam layer disposed between, and bonded to, the first and second layers of thermoformable material, wherein the first and second layers of thermoformable material are heat formable within a target temperature range and substantially rigid at temperatures below a minimum formable temperature of about 130 degrees Fahrenheit; and
heating the composite material such that the layers of thermoformable material are above the minimum formable temperature;
forming the composite material about a body part while the layers of thermoformable material are above the minimum formable temperature; and
holding the composite material in place until expiration of the dwell time such that the layers of thermoformable material are below the minimum formable temperature.