AU2006209185A1

AU2006209185A1 - Synthetic medical bandage product with waterless hardening feature and method of applying cast tape to form cast

Info

Publication number: AU2006209185A1
Application number: AU2006209185A
Authority: AU
Inventors: Shitij Chabba; John Evans; Martin O'hara
Original assignee: BSN Medical Inc
Current assignee: BSN Medical Inc
Priority date: 2005-01-25
Filing date: 2006-01-23
Publication date: 2006-08-03
Anticipated expiration: 2026-01-23
Also published as: JP2008528118A; EP1855627A2; WO2006081164A2; WO2006081164A3; CA2595806A1; MX2007008937A; AU2006209185B2

Description

WO 2006/081164 PCT/US2006/002234 SYNTHETIC MEDICAL BANDAGE PRODUCT WITH WATERLESS HARDENING FEATURE AND METHOD OF APPLYING CAST TAPE TO FORM CAST Technical Field and Background of the Invention [oool] This invention relates to a medical bandage casting system comprising a latent resin/polymer impregnated substrate that can be activated/cured using a suitable activator. The casting system includes a cast tape intended to be placed around an injured limb, over a padding, and hardened in place to form a rigid, orthopedically-effective structure. The invention also relates to a method of applying a cast tape to form a cast. [0002] Conventional casting systems that presently predominate in the market are either a plaster-coated fabric that is wetted and placed on a limb to harden in place, or a moisture cured polyurethane resin system impregnated into or coated onto a fabric tape. The cast tape is applied in a flexible, limp condition to the limb by a technician after wetting but before the tape hardens. The resin system relies on a substantial amount of water to initiate the reaction that hardens the tape into a cast. [00o03] The resin impregnated cast tape is packaged in a moisture impervious package, usually a lamination of plastic film and metal foil. However, once the package is open and the cast tape is brought into contact with the ambient environment, the polyurethane resin activates and hardens over a period of time due to the presence of moisture in the atmosphere. The speed of activation and hardening of the cast tape depends on the amount of moisture available for the tape. If the cast tape is saturated with water, the activation will be faster. [0004] The temperature of the ambient air as well as the temperature of the water also affects the speed of activation. All these factors introduce a wide variability in the performance of current casting tape products and systems. There thus exists a need for a product that remains soft and flexible even during exposure to the ambient environment and thus provides the cast technician sufficient time to mold the cast tape 1 WO 2006/081164 PCT/US2006/002234 onto the fractured limb and set the bone in position without premature hardening of the cast tape. [0005] Another drawback of the conventional polyurethane based casting systems is that water is required for activation. In current clinical practice, the cast tape is dipped into water, squeezed to remove excess water, and then quickly applied to the patient. However, in many emergency situations, such at accident sites, water for activating the cast tape is not readily available. This creates a need for a casting system that can be activated without the need of water. [0006] The invention described here provides a resin chemistry that offers a solution to the problems associated with water activation. Summary of the Invention [0007] Therefore, it is an object of the invention to provide a resin system for a cast tape that can use any suitable chemistry, including but not limited to a two component epoxy and polyurethane system. [0008] It is another object of the invention to provide a medical bandage product that need not be stored in expensive moisture barrier containers. [ooo]0009 It is another object of the invention to provide a medical bandage product that does not require water to harden the bandage into a rigid cast product. [00101 It is another object of the invention to provide a method of applying a cast tape to form a cast that hardens in situ on a limb. [0011] These and objects and advantages of the invention are achieved by providing a latent resin system for a medical bandage, comprising resin for being coated onto or impregnated into a medical bandage, the resin remaining soft and comformable during exposure to ambient moisture. An activator is provided for reacting with the resin for initiating hardening of the resin and thereby the medical bandage. 2 WO 2006/081164 PCT/US2006/002234 [0012] According to another embodiment of the invention, the resin system comprises a polyurethane system and the activator comprises a compound containing active hydrogen sites for curing the polyurethane. [0013] According to yet another embodiment of the invention, the resin system comprises an isocyanate-containing monomer/polymer/prepolymer, and the activator is selected from the group consisting of water, polyol, primary aliphatic amine, secondary aliphatic amine, carboxylic acid, primary aromatic amine, urethane and urea. [0014] According to yet another embodiment of the invention, the prepolymer comprises a blend of cycloaliphatic diisocyanate (IPDI), polycaprolactone and polycarbonate diol. [00151] According to yet another embodiment of the invention, the resin system comprises an epoxy system and an activator containing active hydrogen sites for curing the epoxy. [0016] According to yet another embodiment of the invention, the epoxy system includes epoxide groups for reacting the the active hydrogen sites of the activator. [0017] According to yet another embodiment of the invention, the activator comprises a compound selected from the group consisting of aliphatic amine, aromatic amine and acid anhydride. [00181 According to yet another embodiment of the invention, the activator comprises a viscous liquid for being applied to the medical bandage after application to an injured limb to thereby activate and harden the resin system. [0019] According to yet another embodiment of the invention, a medical bandage product is provided, and comprises a medical bandage and a latent resin system coated onto or impregnated into the medical bandage. A resin activator is provided and is maintained apart from the medical bandage until after the medical bandage has been applied to an injury site. The resin activator comprises a compound for reacting with the resin for initiating hardening of the resin and thereby the medical bandage. 3 WO 2006/081164 PCT/US2006/002234 [0020] According to yet another embodiment of the invention, the medical bandage product includes a package within which the medical bandage is packaged until ready for use in a package that is not impervious to ambient moisture. [0021] According to yet another embodiment of the invention, the resin system comprises a polyurethane system and the activator comprises a compound containing active hydrogen sites for curing the polyurethane. [0022] According to yet another embodiment of the invention, the resin system comprises an isocyanate-containing monomer/polymer/prepolymer, and the activator is selected from the group consisting of water, polyol, primary aliphatic amine, secondary aliphatic amine, carboxylic acid, primary aromatic amine, urethane and urea. [0023] According to yet another embodiment of the invention, the prepolymer comprises a blend of cycloaliphatic diisocyanate (IPDI), polycaprolactone and polycarbonate diol. [0024] According to yet another embodiment of the invention, the resin system comprises an epoxy system and an activator containing active hydrogen sites for curing the epoxy. [0025] According to yet another embodiment of the invention, the epoxy system includes epoxide groups for reacting the the active hydrogen sites of the activator. [00261 According to yet another embodiment of the invention, the activator comprises a compound selected from the group consisting of aliphatic amine, aromatic amine and acid anhydride. [0027] According to yet another embodiment of the invention, the activator comprises a viscous liquid for being applied to the medical bandage after application to an injured limb to thereby activate and harden the resin system. [0028] According to yet another embodiment of the invention, the medical bandage comprises a cast tape. [0029] A method according to the invention comprises the steps of providing a medical bandage, coating or impregnating the medical bandage with a resin system that 4 WO 2006/081164 PCT/US2006/002234 remains soft and comformable during exposure to ambient moisture. The medical bandage is applied to an injury site. A resin activator is provided and is maintained separate from the medical bandage until after application of the medical bandage to the injury site. The resin activator is applied to the medical bandage after application of the medical bandage to the injury site to thereby harden the medical bandage into a rigid cast. [0030] According to yet another embodiment of the invention, the method includes the step of packaging the medical bandage in a package until use that is not impervious to ambient moisture. Brief Description of the Drawings [0031] Some of the objects of the invention have been set forth above. Other objects and advantages of the invention will appear as the invention proceeds when taken in conjunction with the following drawings, in which: [0032] Figure 1 is a medical bandaging product that includes a cast tape according to an embodiment of the invention; [00331] Figure 2 shows the cast tape when removed from its protective pouch; [0034] Figure 3 illustrates application of the cast tape to the lower leg to form a cast when hardened; [00351 Figure 4 illustrated dispensing of the activator preliminary to application to the cast tape to initiate hardening; [0036] Figure 5 shows application of the activator to the cast; [0037] Figure 6 shows the completed cast; and [0oo038] Figure 7 shows a completed forearm cast formed using the cast tape according to an embodiment of the invention. 5 WO 2006/081164 PCT/US2006/002234 Description of the Preferred Embodiment and Best Mode [0o039] Referring now specifically to the drawings, a medical bandaging product according to the present invention is illustrated in Figure 1 and shown generally at reference numeral 10. The medical bandaging product comprises an outer pouch 11 in which is contained a roll of cast tape 12. Unlike moisture-curable cast tapes, cast tape 12 need not be sealed in a moisture impervious package, but merely in a package of a type sufficient to keep the cast tape clean, relatively dry and in its proper shape. [0040] As is shown in Figure 2, the cast tape 12 comprises an elongate textile substrate that can be any suitable knitted, woven or a non-woven fabric constructed using any organic or inorganic yarns or a blend of the same. In the most preferred form, the textile substrate is a warp knitted fabric constructed using polyester and polypropylene yarns. The tape 12 may be wound onto a tube 13 for shipment and storage until use. [0041] Use of the cast tape 12 according to a preferred method according to the invention is carried out by removing the cast tape 12 in roll form from the pouch 11 and applying the cast tape 12 to an injured limb in a conventional manner after placement of a suitable underpadding 14 on the limb. As described below, the cast tape 12 remains in a soft, flexible state until the cast technician is satisfied that the cast has been properly applied and adjusted, and is ready to be transformed into its hardened state. [0042] In accordance with the invention, the chemical system comprises a resin and an activator, and is preferably either a polyurethane system or an epoxy system. The polyurethane system is based on the reaction of an isocyanate containing monomer/polymer/prepolymer with a suitable compound containing active hydrogen. Compounds containing active hydrogen sites that can be used for curing the isocyanate include water, polyol (primary, secondary and tertiary hydroxyl groups), primary and secondary aliphatic amines, amides, carboxylic acids, primary aromatic amines, urethanes and urea. Epoxy-based resin systems are similar to polyurethanes in that 6 WO 2006/081164 PCT/US2006/002234 the epoxide group reacts with an active hydrogen containing compound. The preferred active hydrogen containing compound is an aliphatic or aromatic amine and/or acid anhydride. [0043] In this disclosure of the invention, a preferred resin chemistry comprises a polyurethane-based resin system. The prepolymer is a blend of a cycloaliphatic diisocyanate (IPDI), polycaprolactone and polycarbonate diols. [0044] The prepolymer is applied onto the textile substrate forming the cast tape 12 by either coating or impregnating the substrate with a liquid containing the prepolymer. The prepolymer loading level varies depending on the weight, density, thickness and materials from which the textile substrate is fabricated. The prepolymer impregnated textile will remain latent and thus in its flexible form after opening the package and can be easily applied on the patient's limb without the resin hardening. [0045] Once the limb is set in the correct position and the cast technician is ready to activate the cast tape 12, the activator is applied onto the surface of the cast tape 12 to harden the cast in position. The activator is preferably a secondary diamine such as Clearlink 1000 by Dorf Ketal Chemicals LLC, Texas, USA. As shown in Figure 4, the activator may preferably be in the form of a viscous, creamy liquid 21 and may suitably be stored in a dispenser 20, such as a soap dispenser, conveniently located for ready access by the cast technician. Other containers may be used, such as small single-use pouches or envelopes, tubes or squeeze bottles. The activator liquid is formulated to be essentially dripless and with sufficient lubricity and spread rate to readily and evenly coat the cast tape 12 with a light, rubbing pressure applied by the cast technician. [0046] Typically, protective gloves are worn to prevent contact between the hands and the chemicals in the resin and the activator, as shown in Figures 4 and 5. [0047] As also shown in Figure 5, the cast technician applies the activator evenly onto the outer surface of the cast tape 12, already properly in place on the limb. Contact between the activator and the resin initiates the above-described reaction that quickly hardens the cast tape 12, forming a rigid cast, as shown in Figure 6. The 7 WO 2006/081164 PCT/US2006/002234 hardening is irreversible, i.e., the cast formed from the rigid cast tape 12 will not soften if wetted or heated. The cast may be removed in the usual manner when healing is complete by use of a standard cast removal saw. [0048] The waterless cast system can also be produced using activator components encapsulated in microspheres or microcapsules. The microcapsules, known in fields such as printing ink containment, contain the activator, or both the activator and the catalyst. In this embodiment, the cast tape is coated with a latent polymer system that remains stable and does not activate on exposure to ambient conditions, as described above. The microcapsules are embedded either in the resin system or coated onto the surface of the substrate. In the preferred form, the microcapsules are embedded in the latent resin system itself. The clinician applies the cast tape around the fractured limb as described above. To activate the cast system, the clinician rubs or gently presses around the cast during application, as is the case with application of ordinary casts. [0049] Applying the pressure on the cast will break a sufficient number of the microcapsules to release the components from the microcapsules. Upon releasing the activator or activator/catalyst, they react with and activate the the polymer system. The rubbing and pressing promotes even distribution across the surface area of the cast, however, the microcapsules are themselves relatively evenly distributed so that only a minimal amount of rubbing or pressing, for example only that amount normally provided during cast application, is required. [00oos50] The microencapsulation technique offers advantages, including improved lamination between layers and eliminates the requirement for a separate activator component delivery system. Since the microcapsules are present in the resin system itself, the activator is available between every layer and provides uniform setting time and rigidity level across several layers of the cast. The microcapsule construction is selected with desired material and wall thickness to control the pressure required to rupture the microcapsules, and prevent any premature rupture of microcapsules during the cast tape application. 8 WO 2006/081164 PCT/US2006/002234 [0051] The lower leg cast shown in the preceding drawings are merely illustrative of the many types of casts that can be formed using the cast tape 12. In general, any cast that can be formed using a prior art plaster or synthetic, moisture-curable cast tape can be formed using the cast tape 12 according to the invention described above. See, for example, the forearm cast as shown in Figure 7. [0052] The term resin and polymer are used interchangeably in this application to describe the material applied to the cast tape 12 before being sealed into the pouch 11. The term "latent resin system" as used herein refers to a resin system that will not activate or cure upon exposure to air, moisture or ambient environment, but will only activate once the curing agent is brought in contact with the activator part of the resin system. [0053] A synthetic waterless cast tape is described above. Various details of the invention may be changed without departing from its scope. Furthermore, the foregoing description of the preferred embodiment of the invention and the best mode for practicing the invention are provided for the purpose of illustration only and not for the purpose of limitation--the invention being defined by the claims. 9

Claims

1. A latent resin system for a medical bandage, comprising: (a) a resin for being coated onto or impregnated into a medical bandage, the resin remaining soft and comformable during exposure to ambient moisture; and (b) an activator for reacting with the resin for initiating hardening of the resin and thereby the medical bandage.

2. A latent resin system according to claim 1, wherein the resin system comprises a polyurethane system and the activator comprises a compound containing active hydrogen sites for curing the polyurethane.

3. A latent resin system according to claim 1, wherein the resin system comprises an isocyanate-containing monomer/polymer/prepolymer, and the activator is selected from the group consisting of water, polyol, primary aliphatic amine, secondary aliphatic amine, carboxylic acid, primary aromatic amine, urethane and urea.

4. A latent resin system according to claim 3, wherein the prepolymer comprises a blend of cycloaliphatic diisocyanate (IPDI), polycaprolactone and polycarbonate diol. 10 WO 2006/081164 PCT/US2006/002234

5. A latent resin system according to claim 1, wherein the resin system comprises an epoxy system and an activator containing active hydrogen sites for curing the epoxy.

6. A latent resin system according to claim 5, wherein the epoxy system includes epoxide groups for reacting with the active hydrogen sites of the activator.

7. A latent resin system according to claim 6, wherein the activator comprises a compound selected from the group consisting of aliphatic amine, aromatic amine and acid anhydride.

8. A latent resin system according to claim 1, wherein the activator comprises a viscous liquid for being applied to the medical bandage after application to an injured limb to thereby activate and harden the resin system.

9. A latent resin system according to claim 1, wherein the activator comprises a liquid contained in a multitude of microcapsules dispersed across the surface area of the medical bandage for being ruptured after application to an injured limb to release the activator into contact with the resin system to thereby activate and harden the resin system. 11 WO 2006/081164 PCT/US2006/002234

10. A latent resin system according to claim 1, wherein the activator comprises a liquid contained in a multitude of first microcapsules dispersed on the medical bandage for being ruptured after application to an injured limb to release the activator, and the resin system comprises a liquid contained in a multitude of second microcapsules dispersed on the medical bandage for being ruptured after application to an injured limb to release the resin into contact with the activator released from the ruptured first microcapsules to thereby activate and harden the resin system.

11. A medical bandage product, comprising: (a) a medical bandage; (b) a latent resin system coated onto or impregnated into the medical bandage; and (c) a resin activator maintained apart from the medical bandage until after the medical bandage has been applied to an injury site, the resin activator comprising a compound for reacting with the resin for initiating hardening of the resin and thereby the medical bandage.

12. A medical bandage product according to claim 11, and including a package within which the medical bandage is packaged until ready for use that is not impervious to ambient moisture. 12 WO 2006/081164 PCT/US2006/002234

13. A medical bandage product according to claim 11, wherein the resin system comprises a polyurethane system, and the activator comprises a compound containing active hydrogen sites for curing the polyurethane.

14. A medical bandage product according to claim 11, wherein the resin system comprises an isocyanate-containing monomer/polymer/prepolymer, and the activator is selected from the group consisting of water, polyol, primary aliphatic amine, secondary aliphatic amine, carboxylic acid, primary aromatic amine, urethane and urea.

15. A medical bandage product according to claim 11, wherein the prepolymer comprises a blend of cycloaliphatic diisocyanate (IPDI), polycaprolactone and polycarbonate diol.

16. A medical bandage product according to claim 11, wherein the resin system comprises an epoxy system and an activator containing active hydrogen sites for curing the epoxy.

17. A medical bandage product according to claim 16, wherein the epoxy system includes epoxide groups for reacting the the active hydrogen sites of the activator. 13 WO 2006/081164 PCT/US2006/002234

18. A medical bandage product according to claim 17, wherein the activator comprises a compound selected from the group consisting of aliphatic amine, aromatic amine and acid anhydride.

19. A medical bandage product according to claim 11, wherein the activator comprises a viscous liquid for being applied to the medical bandage after application to an injury site to thereby activate and harden the resin system.

20. A medical bandage product according to claim 11, wherein the medical bandage comprises a cast tape.

21. A medical bandage product according to claim 11, wherein the activator comprises a liquid contained in a multitude of microcapsules dispersed across the surface area of the medical bandage for being ruptured after application to an injured limb to release the activator into contact with the resin system to thereby activate and harden the resin system. 14 WO 2006/081164 PCT/US2006/002234

22. A medical bandage product according to claim 11, wherein the activator comprises a liquid contained in a multitude of first microcapsules dispersed on the medical bandage for being ruptured after application to an injured limb to release the activator, and the resin system comprises a liquid contained in a multitude of second microcapsules dispersed on the medical bandage for being ruptured after application to an injured limb to release the resin into contact with the activator released from the ruptured first microcapsules to thereby activate and harden the resin system.

23. A method of forming a medical bandage product, comprising the steps of: (a) providing a medical bandage; (b) coating or impregnating the medical bandage with a resin system that remains soft and comformable during exposure to ambient moisture; (c) removing the medical bandage from the package and applying the medical bandage to an injury site; (d) providing a resin activator that is maintained separate from the medical bandage until after application of the medical bandage to the injury site; and (e) applying the resin activator to the medical bandage after application of the medical bandage to the injury site to thereby harden the medical bandage into a rigid cast.

24. A method according to claim 23, and including the step of packaging the medical bandage in a package until use that is not impervious to ambient moisture. 15 WO 2006/081164 PCT/US2006/002234

25. A method according to claim 23, and including the step of encapsulating the activator as a liquid in a multitude of microcapsules dispersed across the surface area of the medical bandage for being ruptured after application to an injured limb to release the activator into contact with the resin system to thereby activate and harden the resin system.

26. A method according to claim 23, and including the steps of: (a) encapsulating the activator in a multitude of first microcapsules dispersed on the medical bandage for being ruptured after application to an injured limb to release the activator; and (b) encapsulating the resin system in a multitude of second microcapsules dispersed on the medical bandage for being ruptured after application to an injured limb to release the resin into contact with the activator released from the ruptured first microcapsules to thereby activate and harden the resin system. 16