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.

Claims

1. A composite material, comprising: a first layer of thermoformable material having a thickness of 0.03 to 0.075 inches, the first layer of thermoformable material being heat formable such that it is at least partially shapeable once heated to within a target temperature range; a second layer of thermoformable material having a thickness of 0.03 to 0.075 inches, the second layer of thermoformable material being heat formable such that it is at least partially shapeable once heated to within a target temperature range; and a foam layer disposed between the first layer of thermoformable material and the second layer of thermoformable material, the foam layer bonded to the first thermoformable layer and second layer of thermoformable material.

2. The composite material of claim 1, wherein the target temperature range is 160-240 degrees Fahrenheit.

3. The composite material of claim 1, wherein a minimum heat formable temperature is 150 degrees Fahrenheit.

4. The composite material of claim 1, wherein a minimum heat formable temperature is 140 degrees Fahrenheit.

5. The composite material of claim 1, wherein the first and second layers of thermoformable material have a dwell time of three to ten minutes.

6. The composite material of claim 1, and wherein the foam layer has a thickness of 0.04 to 0.12 inches.

7. The composite material of claim 1, wherein the target temperature range is 190-225 degrees Fahrenheit.

8. The composite material of claim 1, wherein the first and second layers of thermoformable material have a density which is three to five times greater than a density of the foam layer.

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

10. The composite material of claim 1, wherein the first thermoformable layer comprises glass strand.

11. The composite material of claim 1, wherein the foam layer is double the thickness of one of the first and second layers of thermoformable material.

12. The composite material of claim 1, further comprising a first finishing layer disposed adjacent to the first layer of thermoformable material opposite the foam layer such that the first layer of thermoformable material is between the first finishing layer and the foam layer.

13. The composite material of claim 12, further comprising a second finishing layer disposed adjacent to the second thermoformable layer opposite the foam layer such that the second thermoformable layer is between the second finishing layer and the foam layer.

14. The composite material of claim 1, wherein the first layer of thermoformable material, the foam layer, and the second layer of thermoformable material are laminated together.

15. The composite material of claim 1, wherein the thickness of the first layer of thermoformable material is different than the thickness of the second layer of thermoformable material.

16. The composite material of claim 1, wherein the foam layer has a lower heat density that the first and second layers of thermoformable material.

17. A composite material, comprising: a first layer of thermoformable material having a thickness of 0.03 to 0.075 inches, the first layer of thermoformable material being heat formable such that it is at least partially shapeable once heated to within a target temperature range; a second layer of thermoformable material being heat formable such that it is at least partially shapeable once heated to within a target temperature range; and a foam layer disposed between the first layer of thermoformable material and the second layer of thermoformable material, the foam layer having a lower density that the first layer of thermoformable material and a lower density that the second layer of thermoformable material.

18. The composite material of claim 17, wherein the target temperature range is in the range of 160-240 degrees Fahrenheit, and wherein the first and second layers of thermoformable material have a dwell time of three to ten minutes.

19. The composite material of claim 18, wherein the first and second layers of thermoformable material have a density which is three to five times greater than a density of the foam layer.

20. The composite material of claim 17, and wherein the foam layer has a thickness of 0.04 to 0.12 inches.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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:

(2) FIG. 1 is a schematic cross-section of the composite material according to an embodiment of the present invention.

(3) 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.

(4) 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.

(5) 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

(6) 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.

(7) 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.

(8) 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.

(9) 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.

(10) 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.

(11) 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.

(12) 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{circumflex over ( )}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.

(13) 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.

(14) 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.

(15) 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.

(16) 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.

(17) 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.

(18) 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.

(19) 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 thermoformable 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.

(20) 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.

(21) 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.

(22) 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.

(23) 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.

(24) 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.

(25) 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.

(26) 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.