WO2016026775A1

WO2016026775A1 - Protective or immobilizing device for a body part

Info

Publication number: WO2016026775A1
Application number: PCT/EP2015/068740
Authority: WO
Inventors: Marc Klein
Original assignee: Sàrl Du Ried
Priority date: 2014-08-18
Filing date: 2015-08-14
Publication date: 2016-02-25
Also published as: LU92522B1

Abstract

A protective or immobilizing device (100) for a body part comprises a thermoformable shell (10), made of a thermoset polymer, the shell being three-dimensionally preformed (e.g. by injection-moulding) to approximately match the shape of the body part to be protected or immobilized.

Description

PROTECTIVE OR IMMOBILIZING DEVICE FOR A BODY PART

Field of the Invention

[0001 ] The invention generally relates to a protective or immobilizing device for a body part. Protective devices for body parts include, for instance, protective gear (such as, e.g. shin or wrist guards) for athletes, workers or animals or any other users. Immobilizing devices include, e.g., orthoses and splints and can be used e.g. in physical rehabilitation.

Background of the Invention

[0002] As taught in US 2013/0072839 A1 , applications such as orthotics, prosthetics, radiation oncology, diagnostic imaging and, in particular, physical rehabilitation, require that the immobilization device is mouldable at an activation temperature directly on the patient, the immobilization device shows good mechanical properties and surface finishing and is light and comfortable to the patient. The document discloses an immobilization device for immobilizing a body part, the immobilization device comprising one or plural sheets of a thermoplastic material shaped to conform to the body part to be immobilized. The thermoplastic material contains at least one exfoliated nano filler material, which allegedly reduces the degree of shrinking of the immobilization device upon cooling from the molten state. In order to produce the immobilization device, a sheet of the thermoplastic material is heated to a temperature corresponding to the melting temperature of the thermoplastic material, positioned on the body part to be immobilised or on a positive mould, moulded and left to cool.

[0003] FR 2 665 075 relates to a thermoformable orthosis for the metacarpophalangeal joint of the thumb. The orthosis is made of trans-polyisoprene originally in the shape of a parallelepiped strip with a length of 15 cm, a width of 4 cm and a thickness of 1 .6 to 1 .8 cm. The strip is wrapped around the metacarpophalangeal joint when heated; thereafter, the hand is held in cold water to solidify the orthosis.

[0004] US 6,261 ,252 discloses a thumb spica splint for being custom-fitted to the thumb portion of the hand for immobilizing the thumb. The splint includes a layer formed of a fabric impregnated or coated with a moisture-curable resin which hardens upon curing to form a rigid structure. The splint is applied to the thumb and the forearm after wetting with water and hardens within a few minutes. Technical Problem

[0005] With regard to existing protective or immobilizing devices, there is a need for still more customer-friendly solutions. It is an object of an aspect of the present invention to provide such a solution. General Description

[0006] According to the invention, a protective or immobilizing device for a body part comprises an in-situ thermoformable shell, which is preferably three-dimensionally preformed by injection-moulding to approximately match the shape of the body part to be protected or immobilized. As used herein, "in-situ thermoformable" designates an item that can be thermoformed in its intended position on the body part to be protected or immobilized without causing harm thereto. That implies that the item is malleable at moderate temperatures (e.g. < 55°C, more preferably < 50°C) that the body part can be exposed to without risk of burning during the time it takes for the item to cool and solidify. As will be appreciated, the fact that a preform shell is used greatly facilitates the correct placement of the device on the body part and reduces the necessary deformations to a minimum. It follows, on the one hand, that a better fitting to the body part can be achieved, which results in better comfort for the wearer. On the other hand, since the deformations that the preform shell undergoes as it is fitted to the body part are minimal, design problems are reduced for the manufacturer. The manufacturer thus benefits from greater design freedom, resulting in more appealing products, more easily acceptable by aesthetically minded customers. It also becomes possible for the manufacturer to more prominently place their logo on the preform shell (e.g. by tampography or any other suitable process), without the risk that the logo or the design becomes substantially alienated or even unrecognizable during thermoforming. [0007] According to a first preferred aspect of the invention, the preform shell is made of a covalently crosslinked polymer (thermoset polymer). Such crosslinked polymer may be obtained from at least one hydroxyl-terminated polyol having a molecular weight of at least 2000 g/mol and at least one crosslinking reagent comprising two or more functional groups reactive with the terminal hydroxyl groups so as to create covalent bonds, the at least one cross-linking reagent being present in an amount such that the functional groups are in excess of the hydroxyl groups. In the context of the present document, the term "crosslinked polymer" designates a polymer, the degree of covalent crosslinking of which is such that the polymer is infusible by heating and insoluble in a solvent. In that sense, a crosslinked polymer is a thermoset polymer (see also: Compendium of Chemical Terminology, Gold Book, Version 2.3.3, 24 February 2014, of the International Union of Pure and Applied Chemistry, p. 1533), where it has to be noted, however, that a crosslinked polymer in accordance with the requirements of the invention is thermoformable, i.e. becomes malleable through the application of heat. Advantageously, the hydroxyl-terminated polyol has a molecular weight of at least 4000 g/mol, preferably of more than 8000 g/mol. The at least one polyol is advantageously a thermoplastic polyol (e.g. a thermoplastic polyester, a thermoplastic polyether or a thermoplastic polyester urethane), with a melting point or a glass transition temperature in the range from 40°C to 100°C, preferably in the range from 50°C to 80°C. As will be appreciated, the melting point or the glass transition temperature of the used polyol will correspond approximately to the temperature around which the crosslinked polymer becomes malleable when heated. An interesting advantage of the crosslinked polymer is that it can be heated well above the melting point or the glass transition temperature of the used polyol without losing its coherence. In other words, heating the crosslinked polymer in order to make it thermoformable is not a temperature-critical process and thus be carried out without precise temperature control. [0008] Particularly preferred polyols are high-molecular weight (> 2000 g/mol, preferably: > 4000 g/mol, and still more preferably > 8000 g/mol) polyether-, polyester- and/or polycaprolactone polyols. The molecular mass of the polyol is preferably not more than 100000 g/mol. Preferably, the at least one hydroxyl-terminated polyol is a semi-crystalline polyol. [0009] Preferably, the polyol is an unbranched (linear) polyol.

[0010] The polyol comprises preferably not more than three, more preferably not more than two, and most preferably not more than one, hydroxyl group per 1000 g/mol of molecular mass of the polyol. Due to the fact that the polyol has a high molecular weight, the polymer obtained after curing comprises relatively long chains of the polyol interconnected and (covalently) crosslinked by the crosslinker. The overall structure is thus relatively sparsely crosslinked in comparison to conventional thermoset polymers. When heated, the sparsely crosslinked polymer becomes malleable approximately at the melting temperature of the polyol. Due to the crosslinking, however, the macromolecules do not melt (but are destroyed if the temperature is increased further). The property of the polymer becoming malleable while preserving cohesion greatly facilitates the fitting of the preform shell to the body part.

[001 1 ] According to a preferred embodiment of the invention, the at least one cross- linking reagent comprises isocyanate with an average functionality of at least 2, preferably of at least 2.2 and even more preferably of at least 2.5. The average functionality of the isocyanate is preferably at most 4, more preferably at most 3. Crosslinking is with isocyanates is achieved through the formation of urethane links and/or urea links and/or allophanate links. [0012] The ratio NNCO/NOH of the isocyanate (-N=C=O) groups of the isocyanate to the hydroxyl groups of the polyol preferably satisfies the following condition:

¾ > max{l; 16 - 6<F_WC0>},

"OH

where max {x; y} is the maximum function that returns the greater of x and y, (F_NC0 ) is the average functionality of the isocyanate and NNCO and NOH are expressed in mol. [0013] According to a second preferred aspect of the invention, a protective or immobilizing device for a body part comprises a thermoformable, injection-moulded preform shell. The preform shell is obtained by injection-molding in such a way as to approximately match the shape of the body part to be protected or immobilized. To the best knowledge of the inventor, such protective or immobilizing device based upon injection-moulded preform shells have never been presented. As such preform shells could be obtained by injection-moulding from various materials departing from the scope of the first aspect of the invention, the applicant herewith reserves the right to claim protection, e.g. by way of a divisional or continuation application, for a protective or immobilizing device for a body part that comprises a thermoformable, injection- moulded polymer preform shell without limitation to the specific composition described hereinbefore. Injection-mouldable materials that could be used according to the second aspect of the invention include, for instance: PE (polyethylene), PP (polypropylene), PS (polystyrene), PET (polyethylene terephthalate), PU (polyurethane), PVC (polyvinyl chloride), PA (polyamide), PCL (polycaprolactone), polyisoprene, PC (polycarbonate), polyacrylate etc., in basic or crosslinked state, and copolymers thereof in basic or crosslinked state. According to the second aspect of the invention, the preform shell is preferably in-situ thermoformable. If the preform shell is not in-situ thermoformable, which is also possible, although somewhat less preferred, the thermoforming of the preform shell could be carried out on an original-size three- dimensional model of the body part capable of withstanding the temperatures necessary for the thermoforming. [0014] According to a preferred embodiment of the first and/or the second aspect of the invention, the protective or immobilizing device is a splint, e.g. a spica splint for the protection and/or immobilization of the carpometacarpal (CMC) joint of the thumb and/or the metacarpophalangeal (MCP) joint of the thumb. In this case, the preform shell preferably comprises a first side lobe and a second side lobe joined to each other by a ridge portion and by a saddle portion, the ridge portion and the saddle portion being joined so as to form a tubular portion for receiving the proximal phalanx member of the wearer's thumb. For the wearer's comfort, the first and/or second side lobe and/or the ridge portion comprises vent holes.

[0015] Advantageously, the tubular portion terminates in an annular edge that comprises an indentation, preferably a V- or U-shaped indentation. The indentation allows the tubular portion to adapt itself to different thumb diameters without creating a sharp fold during thermoforming. Preferably, the depth of the indentation amounts to between 0.5 cm and 2 cm and the width of the indentation amounts to between 0.5 cm and 1 .5 cm. [0016] In a possible variant of the spica splint, the ridge portion and the first and second side lobes extend into a trough-shaped extension configured for being applied against the wearer's wrist and forearm.

[0017] Preferably, the first and second side lobes comprise elongate openings for one or more fixation straps. [0018] The thickness of the preform shell preferably amounts to between 1 mm and 4 mm, more preferably between 1 .2 mm and 2 mm, still more preferably between 1 .4 mm and 1 .8 mm, most preferably to 1 .6 mm.

[0019] The protective or immobilizing device may comprise a label or decorative layer attached to the preform shall. The label may e.g. carry the manufacturer's or seller's logo, an advertising, a drawing or another decorative element. The label or decorative label preferably comprises a PVC or vinyl film carrying an adhesive (e.g. acrylate adhesive) on one of its surfaces. The adhesive-coated PVC or vinyl film preferably has a thickness of 50 μΓη to 120 μΓη . It may be attached on the preform shell after formation thereof in an automated process or by hand. As an alternative to applying a label or decorative layer by gluing, it is also possible to decorate the preform shell by printing with flexible ink, in particular by tampography (pad printing). [0020] Advantageously, the preform shell is ambidextrous, i.e. has a symmetrical shape such that it can be adapted by thermoforming to both a left and a right body part. Ambidextrous preform shells are preferred because of reduced production costs. It should be noted that a preform shell can lose its ambidexterity during thermoforming - in other words, it can be fitted specifically to either a left or a right body part. Accordingly, the ambidextrous character of the preform shell does not lead to any reduction of the wearer's comfort.

[0021 ] A particularly preferred embodiment of the invention relates to a spica splint that comprises a preform shell with a first side lobe and a second side lobe joined to each other by a ridge portion and by a saddle portion, the ridge portion and the saddle portion being joined so as to form a tubular portion for receiving the proximal phalanx member of the wearer's thumb, the preform shell being made of a thermoset polymer obtained from at least one hydroxyl-terminated polyol having a molecular weight of at least 2000 g/mol (preferably: > 4000 g/mol, and still more preferably > 8000 g/mol) and isocyanate with an average functionality of at least 2 as a crosslinking reagent, the amount of isocyanate being such that the isocyanate functional groups are in excess of the terminal hydroxyl groups.

[0022] Yet a further aspect of the present invention relates to a method of conforming a protective or immobilizing device as described hereinbefore to a body part. The method comprises heating the preform shell until it becomes malleable and deforming the heated preform shell by applying it against the body part while the body part is kept substantially immobile until the deformed preform shell solidifies. Optionally, after heating, the preform shell is let cool down such that the temperature on its surface exceeds the wearer's body temperature by not more than 15°C, preferably by not more than 10°C. The therapeutic application of the protective or immobilizing device on the human or animal body is not part of the conforming step. However, the conforming of the preform shell may precede the therapeutic treatment. As a precautionary measure, and with effect for the jurisdictions having an exception from patentability for methods of treatment of the human or animal body, the therapeutic treatment following the conforming step is herewith declared not forming part of the invention.

Brief Description of the Drawings

[0023] By way of example, preferred, non-limiting embodiments of the invention will now be described in detail with reference to the accompanying drawings, in which:

Fig. 1 : is a perspective view of a preform shell for a spica splint according to a first preferred embodiment of the invention;

Fig. 2: is a perspective view of a spica splint using the preform shell of Fig. 1 when applied to a wearer's thumb. Fig. 3: is a perspective view of a preform shell for a splint according to a second preferred embodiment of the invention;

Fig. 4: is a perspective view of a splint using the preform shell of Fig. 3 when applied to a wearer's wrist and thumb.

Detailed Description of Preferred Embodiments of the Invention [0024] Fig. 1 shows a preform shell 10 for a spica splint 100, as indicated, e.g., in the treatment of ligament damage in the metacarpophalangeal joint (e.g. skier's or gamekeeper's thumb). The preform shell 10 consists of an integrally formed, injection- moulded crosslinked polymer, which becomes malleable in the temperature range from 45°C to 120°C and which can be fitted to the wearer's hand as illustrated in Fig. 2. For practical reasons and for accelerating the softening of the crosslinked polymer, it is advantageously heated to a temperature in the range of 65°C to 120°C and let cool down before it is placed on the wearer's hand. The preform shell 10 typically remains malleable for a several minutes (e.g. 1 to 10 minutes) at room temperature.

[0025] The preform shell 10 comprises a first 12 and a second 14 side lobe joining each other in a rounded ridge portion 16 and a saddle portion 18. Where the ridge portion 16 and a saddle portion 18 are adjacent each other, they form a tubular portion 20, which is sized to receive the proximal phalanx member of the wearer's thumb (see Fig. 2). The annular edge 22 of the tubular portion 20 features a substantially V-shaped indentation 24 having a depth of about 1 cm and an opening with a width of roughly 1 cm. Thanks to the indentation, the tubular portion 20 can be tightly fitted to thumbs of different diameters (within a certain range) without buckling of the preform shell 10.

[0026] As best shown in Fig. 2, the saddle portion 18 comes to lie into the region of the adductor pollicis muscle and serves as a spacer between the thumb and the forefinger when the spica splint 100 is in place. The spacing distance can be adjusted during the fitting of the heated preform shell. During the fitting, the wearer is asked to touch the tip of the thumb with his forefinger as if he would carry out a precision grasp. If the thumb is immobilized in that position, the wearer preserves the ability to grasp small items between the thumb and the other fingers and to hold a writing instrument such as, e.g., a pencil.

[0027] The side lobes 12, 14 as well as the rounded ridge portion comprise several vent holes 24, which allows the underlying skin to breathe and moisture to be evacuated. Where the vent holes 24 are closely spaced, they contribute, to some extent, to the formability of the preform shell 10. [0028] Each side lobe 12, 14 further comprises an elongate opening 26, arranged substantially opposite the rounded ridge 16, which serves to receive a fixation strap 28 (see Fig. 2.) The fixation strap 28 preferably comprises hook-and-loop or mushroom- and-velour fasteners. For the wearer's comfort, the hooks and the loops or the mushrooms and the velour should be arranged such that only the side of the strap with the loops / the velour comes into contact with the skin.

[0029] Figs. 3 shows a variant of the preform shell 10 of Fig. 1 . Fig. 4 illustrates a splint 100' based upon the preform shell 10' of Fig. 3. The use of the splint 100' of Fig. 4 may be indicated when the wearer's wrist and thumb need be immobilized, e.g. during the treatment of an injury to the scaphoid bone. The structure of the preform shell 10' differs from that of Fig. 1 essentially in that the first and second side lobes 12, 14 as well as the rounded ridge portion 16 seamlessly extend into a trough-shaped extension 30. Further elongate openings 32 are arranged along the longitudinal edges of the extension 30, allowing the extension 30 to be fixed to the wearer's forearm using further fixation straps 34. In all other aspects, the structure of the variant 100' is the same as that of the preform shell 10 of Fig. 1 . For further details, the reader is thus referred to the corresponding description hereinabove. [0030] The composition and the manufacture of the preform shell will now be detailed in several examples.

Example 1

[0031 ] About 200 medium-sized preforms of the type illustrated in Fig. 1 were produced using the following composition (all component quantities being indicated in parts per hundred of the polyol, "phr"):

2000 g of polycaprolactone granules were introduced into a mixer together with the pigment and the demoulding agent. The isocyanate was added in liquid form and the composition was mixed until a homogenous sticky mixture was obtained. The anticaking agent was then added and the mixing was continued until granules sufficiently separate from introducing them into the hopper of the injection moulding machine were obtained. The granules were allowed to rest for about 24 hours at ambient temperature (about 20°C.)

[0032] Injection moulding was carried out on a BOY™ 25E injection moulding machine. Due to the complex shape of the preforms, the mould comprised several parts. The granules were mixed in the barrel of the injection moulding machine to about 75°C. The temperature of the hot runner was 100°C. The mould and the feeder were cooled to about 14°C. Each injection cycle lasted about 30 s.

[0033] After demoulding, the preforms were kept in a vented place at ambient temperature and humidity for 15 days in order to allow the polymer to set completely.

[0034] The so-formed preforms can be heated using an oven, a hairdryer, a microwave oven, hot water, an airgun, hot plates etc. to make them malleable. Thermoforming on the wearer's hand can be carried out while the preforms are cooling down, preferably at between 40°C and 45°C in order to avoid injuries. Example 2

[0035] Preform shells were produced using the following composition:

The production of the preforms based on that composition was then carried out with the same parameters as in example 1 . [0036] Further compositions have been tested. In those tests, the polyol and the isocyanate (as well as any additives, such as, e.g. pigments and fillers, etc.) were mixed in a recipient at a temperature of about 120°C during about 5 to 15 minutes. The mixture was then injection-moulded or hot-pressed (extrusion would also be possible) and let rest for two days at least at ambient temperature and humidity. As the polyol, partially crystalline and saturated copolyester (e.g. Dynacoll™ 7361 from Evonik), aliphatic polyester (e.g. Stepanpol™ PC-020-01 ), butanediol adipate with an average molecular weight of 4000 g/mol (e.g. Hoopol™ F-531 ) and hexanediol adipate with an average molecular weight of 8500 g/mol (e.g. Hoopol™ F-91 1 ) were successfully tested. Mixtures of the polyols can be used in any proportion. The amount of isocyanate was varied between 2 and 8 phr, depending on the average functionality, the desired stickiness of the mixture, the duration of solidification and the desired malleability.

[0037] The polymer may contain additives such as pigments, rheology agents, slip additives, demoulding agents, fillers, etc. Preferably, the total amount of additives is below 20 phr. [0038] While specific embodiments have been described herein in detail, those skilled in the art will appreciate that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof. [0039] For instance, while the invention has been illustrated with immobilization devices, it will be appreciated that protection devices for humans or animals (e.g. shin or wrist guards) can also be manufactured in accordance with the present invention.

Claims

1 . A protective or immobilizing device for a body part, comprising an in-situ thermoformable shell, made of a thermoset polymer, which shell is three- dimensionally preformed so as to approximately match a shape of said body part.

2. The protective or immobilizing device as claimed in claim 1 , wherein said preform shell is made of a crosslinked polymer obtained from at least one hydroxyl- terminated polyol having a molecular weight of at least 2000 g/mol and at least one crosslinking reagent comprising two or more functional groups reactive with the terminal hydroxyl groups, said at least one cross-linking reagent being present in an amount such that said functional groups are in excess of said terminal hydroxyl groups.

3. The protective or immobilizing device as claimed in claim 1 or 2, wherein said preform shell is injection-moulded.

4. The protective or immobilizing device as claimed in claim 2 or 3, wherein said hydroxyl-terminated polyol has a molecular weight of at least 4000 g/mol, preferably of more than 8000 g/mol.

5. The protective or immobilizing device as claimed in claim 2, 3 or 4, wherein said at least one cross-linking reagent comprises isocyanate with an average functionality of at least 2, preferably of at least 2.2, more preferably of at least 2.5.

6. The protective or immobilizing device as claimed in any one of claims 2 to 5, wherein said at least one polyol is a thermoplastic polyol with a melting point or a glass transition temperature in the range from 40°C to 100°C, preferably in the range from 50°C to 80°C.

7. The protective or immobilizing device as claimed in any one of claims 2 to 6, wherein said at least one polyol is a thermoplastic polyester, a thermoplastic polyether or a thermoplastic polyester urethane.

8. The protective or immobilizing device as claimed in any one of claims 1 to 7, wherein said protective or immobilizing device is a splint, preferably a spica splint.

9. The protective or immobilizing device as claimed in claim 8, wherein said preform shell comprises a first side lobe and a second side lobe joined to each other by a ridge portion and by a saddle portion, said ridge portion and said saddle portion being joined so as to form a tubular portion for receiving the proximal phalanx member of the wearer's thumb.

10. The protective or immobilizing device as claimed in claim 9, wherein said first and/or second side lobe and/or said ridge portion comprises vent holes.

1 1 . The protective or immobilizing device as claimed in claim 9 or 10, wherein said tubular portion terminates in an annular edge, said annular edge comprising an indentation, preferably a V- or U-shaped indentation.

12. The protective or immobilizing device as claimed in any one of claims 9 to 1 1 , wherein said ridge portion and said first and second side lobes extend into a trough-shaped extension configured for being applied against the wearer's wrist and forearm.

13. The protective or immobilizing device as claimed in claim 8 to 12, wherein said preform shell is ambidextrous.

14. The protective or immobilizing device according to the combination of claims 2, 3, 5, 6, and 9.

15. A method of conforming a protective or immobilizing device as claimed in any one of claims 1 to 14 to a body part, said method comprising:

heating said preform shell until it becomes malleable;

optionally: letting said preform shell cool down to a temperature not exceeding a body temperature by more than 15°C;

deforming said heated preform shell by applying it against said body part while said body part is kept substantially immobile until said deformed preform shell solidifies.