WO2019076647A1

WO2019076647A1 - Cast

Info

Publication number: WO2019076647A1
Application number: PCT/EP2018/077098
Authority: WO
Inventors: Adam Michael BEST; Stuart John ASHMAN
Original assignee: Onbone Oy
Priority date: 2017-10-20
Filing date: 2018-10-05
Publication date: 2019-04-25
Also published as: GB201717223D0

Abstract

The present invention provides a total contact cast for protecting a wearer's foot, the total contact cast comprising a composite foot support, the composite foot support being formed of a composite material comprising wood particles within a thermoplastic polymer matrix. The composite foot support is moulded to substantially match the contour of a portion of the wearer's foot and leg. The present invention also provides a method of forming and a kit for forming a total contact cast.

Description

CAST

Field of the Invention

The present invention relates to a total contact cast for providing support and protection to an individual's foot whilst they are recovering from a diabetic foot ulceration. The invention further provides a method of applying a total contact cast and a kit for applying a total contact cast.

Background of the Invention

A significant number of individuals with diabetes suffer from diabetic foot ulcers. Metabolic factors arising from their diabetes impede wound healing. It is therefore imperative that the ulcer is protected to take the pressure off the ulcer in order to allow healing to occur. It is known to provide a non-removable total contact cast which reduces the pressure on the wound by taking the weight off the sole of the foot (off-loading). A total contact cast encases the wearer's entire foot (including toes) and redistributes weight to the wearer's lower leg which is also encased by the total contact cast.

After fitting by a medical clinician, the total contact cast is left in place and only removed by the medical clinician in order to replace the wound dressing lying over the ulcer. A new total contact cast is then re-applied.

Known total contact casts typically comprise a number of layers including a wound dressing, a padding layer and a foot support. The foot support may be formed of semi-rigid plastic and may comprise a foot pad and side extensions as described in US9192504B. This foot support does not conform to the wearer's leg, sits over the wearer's ankle and thus may cause discomfort for the wearer.

In other known total contacts casts such as that described in US6974431 B, the foot support comprises a posterior splint formed of un-wetted fibreglass casting tape that is applied to the rear of the leg and sole of the foot and held in place with non-reactive tape. It further comprises a separate plantar splint formed of un-wetted fibreglass tape that is applied to the sole of the foot and up the sides of the foot and held in place with a non-reactive tape. A further portion of fibreglass casting tape is wetted and wrapped around the splints and the patient's leg. Using numerus layers of (environmentally-unfriendly) fibreglass casting table is fiddly and time consuming. The posterior and plantar splints cannot be re-applied after removing the total contact cast.

There is a need for a total contact cast that is environmentally-friendly, comfortable and where certain components can be reused to reduce waste and cost.

Summary of the Invention

In a first aspect, the present invention provides a total contact cast for protecting a wearer's foot, the total contact cast comprising:

a composite foot support, the composite foot support being formed of a composite material comprising wood particles within a thermoplastic polymer matrix, the composite foot support being moulded to substantially match the contour of a portion of the wearer's foot and leg.

The present inventors have found that a composite foot support formed of a composite material comprising a thermoplastic polymer and wood particles can be moulded to substantially match the contour of the wearer's foot/leg portion such that it provides support and protection to a wearer's foot whilst being lightweight and unbulky and thus improving mobility of the wearer. Furthermore, unlike known total contact casts, the composite foot support can be reused each time the total contact cast is changed thus reducing waste and costs. Optional features of the invention will now be set out. These are applicable singly or in any combination with any aspect of the invention.

The term "total contact cast" refers to a cast that is in contact with the foot and lower leg and used to treat diabetic foot ulcers.

The composite material used to form the composite foot support may be as described in WO2010/103186 herein incorporated by reference.

The thermoplastic polymer is preferably a biodegradable polymer (only) but also nonbiodegradable polymers may be utilized.

Examples of polymers include polyolefins, e.g. polyethylene (HD or LD), polypropylene, and polyesters, e.g. poly(ethylene terephthalate) and poly(butylenes terephthalate), polystyrene homopolymer and copolymers including acrylonitrile-butadiene-styrene (ABS), polycarbonates, polyethers, polyetheresters, polyamides e.g. nylon, lactic or butyric acid derivativesm polybenzimidazole (PBI), polyethersulfones (PES), polyvinyl alcohols (PVA), ethyl vinyl acetates (EVA), polyether ether ketones (PEEK), polyetherimides (PEI), polyphenylene oxide (PPO), polyphenylene sulphide (PPS), polyvinyl chloride (PVC) and acrylic polymers. Copolymers, blends and mixtures of polymers may also be used.

The thermoplastic polymer may also be any cross-linked polymers manufactured prior to processing or in situ during the compounding process for example by means of ionizing radiation or chemical free- radical generators. Examples of such polymers are cross-linked polyesters, such as polycaprolactone (PCL).

Generally, the weight ratio of biodegradable polymer to any non-biodegradable polymer is 100:1 to 1 :100, preferably 50:50 to 100:1 and in particular 75:25 to 100:1.

The thermoplastic polymer may comprise a biodegradable polymer i.e. a polymer which can degrade into natural by-products such as carbon dioxide, nitrogen, water, biomass and inorganic salts. By using a biodegradable polymer in combination with the wood particles for the composite foot support, the total contact cast can be made substantially biodegradable offering environmental advantages after disposal.

For example, the thermoplastic polymer may be a thermoplastic polyester e.g. a biodegradable thermoplastic polyester. Suitable examples for the thermoplastic polymer are polylactide, polyglycolide, polycaprolactone (PCL), mixtures/blends thereof and copolymers thereof.

The thermoplastic polymer may comprise a mixture/blend of 5-99 wt%, in particular 40 to 99 wt%, of a caprolactone homopolymer and 1-95 wt%, in particular 1 to 60 wt%, of another thermoplastic polymer e.g. another biodegradable or non-biodegradable thermoplastic polymer.

Copolymers of caprolactone include copolymers formed with caprolactone, lactic acid and/or glycolic acid monomers. The copolymer may contain at least 80 % by volume of (epsilon) caprolactone monomer, in particular at least 90 % by volume and in particular about 95 to 100 % epsilon caprolactone monomer. The copolymer may contain 5 to 99 wt% and especially 40 to 99 wt% of repeating units derived from (epsilon) caprolactone monomer with 1 to 95 wt% and especially 1 to 60 wt% of repeating units derived from another polymerisable monomer. The thermoplastic polymer (e.g. the polycaprolactone polymer) may have a molecular weight of between 60,000 g/mol and 500,000 g/mol. For example, the thermoplastic polymer may have a molecular weight between 65,000 - 300,000 g/mol, preferably above 70,000 g/mol such as between 75.000 g/mol and 100.000 or 200,000 g/mol. This has been found to be advantageous both in terms of resultant properties and cost.

The thermoplastic polymer is preferably selected such that it softens when it is heated to a temperature of approximately 50 to 70 °C.

The molding properties of the composite foot support can be determined by the average molecular weight (Mn) of the polymer, such as epsilon caprolactone homo- or copolymer. A particularly preferred molecular weight range for the Mn value of the thermoplastic polymer (e.g. PCL) is from about 75.000 to about 100,000 g/mol, e.g. around 80,000 g/mol.

The number average molar mass (Mn) and the weight average molar mass (Mw) as well as the polydispersity (PDI) were measured by gel permeation chromatography. Samples for GPC measurements were taken directly from the polymerization reactor and dissolved in tetrahydrofuran (THF). The GPC was equipped with a Waters column set styragel HR(1 , 2 and 4) and a Waters 2410 Refractive Index Detector. THF was used as eluent with a flow rate of 0.80 ml/min at a column temperature of 35 C. A conventional polystyrene calibration was used. In determination of the water content of the monomer at different temperatures a Metroohm 756 KF Coulo meter was used. The properties of moldability of the composite foot support can also be determined by the viscosity value of the polymer. When the inherent viscosity (IV) -value (e.g. of PCL) is less than 1 dl/g the composite is sticky, flows while formed and forms undesired wrinkles while cooling. When the IV-value (e.g. of PCL) is closer to 2 dl/g, the composite foot support maintains its geometry during molding on the wearer and it may be handled without adhesive properties. Thus, IV values in excess of 1 dl/g are preferred, values in excess to 1.2 dl/g are preferred and values in excess of 1 .3 dl/g are particularly suitable. Advantageously the values are in the range of about 1.5 to 2.5 dl/g, for example 1.6 to 2.1 dl/g. Inherent Viscosity values were determined by LAUDA PVS 2.55d rheometer at 25 °C. The samples were prepared by solvating 1 mg of PCL in 1 ml chloroform (CH3CI). The viscosity of the thermoplastic polymer may be relatively high, typically at least 1 ,800 Pas at 70 °C, 1/10 s. The viscosity can be of the order of 8,000 to 13,000 Pas at 70 °C, 1/10 s (dynamic viscosity, measured from melt phase).

The modulus (Young's modulus) at ambient temperature of the thermoplastic polymer component may be greater than 300 MPa. By compounding the thermoplastic polymer with the wood particles, the modulus will increase to about 350 to 2000 MPa for the composite material.

The thermoplastic polymer may have a melt flow index of between 0.3 and 2.3 g/min (at 80°C; 2.16 kg). The thermoplastic polymer may have a melt flow index less than 7g/10 min (at 160oC, 2.16 kg standard die).

The thermoplastic polymer may be present in the composite material in an amount of 5 to 99 wt% (based on the amount of thermoplastic polymer and wood particles). It may be present in an amount between 40 to 99 wt%.

In some preferred embodiments showing particularly good shock absorption, the thermoplastic polymer is present in an amount of around 60 wt% i.e. the weight ratio of wood particles to thermoplastic polymer in the composite layer may be 2:3.

Preferably, the wood particles have a granular or a generally plate-like structure. Typically, the wood particles are greater in size than a powder.

Particulate or powdered material is characterised typically as material of a size in which the naked eye can no longer distinguish unique sides of the particle. Plate-like particles are easily recognizable as one dimension is recognizable by the naked eye as being larger than another. Granular particles, while having substantially equal dimensions, are of such dimension that their unique sides can be determined by the naked eye and oriented.

More particularly, particulate or powdered materials are of such a small or fine size that they cannot be easily oriented with respect to their neighbors. Granular and plate-like particles are of such a size that their sides are recognizable and can be orientated.

The wood particles orientate in two dimensions in the thermoplastic polymer matrix and provide a self-reinforcement effect. As a result, the composite foot support provides a good dimensional stability, good shock absorbance and good puncture resistance. The wood particles may be present in the composite material forming the composite foot support in an amount of 1 to 95 wt% (based on the amount of thermoplastic polymer and wood particles). They may be present in an amount between 1 to 70 wt% or 1 to 60 wt% or 10 to 60 wt% or 20 to 60 wt%. In some preferred embodiments, the wood particles may be present in an amount of around 40 wt% i.e. the weight ratio of wood particles to thermoplastic polymer in the composite material forming the composite layer may be 2:3.

The wood particles may be present in the composite material forming the composite layer in an amount of 15 to 50 % (based on the volume of thermoplastic polymer and wood particles). They may be present in an amount between 25 to 50 %, by volume.

Before the wood particles are mixed with the thermoplastic polymer they can be surface treated, e.g. sized, with agents, which modify their properties of hydrophobicity/- hydrophobicity and surface tension. Such agents may introduce functional groups on the surface of the wood particles to provide for covalent bonding to the matrix. The wood particles can also be surface treated with polymer e.g. PCL.

The wood particles can be also coated or treated with anti-rot compound e.g. vegetable oil to improve its properties against aging and impurities.

The wood particles can be dehydrated to make them lighter before mixing with thermoplastic polymer. The mechanical and chemical properties of the wood particles can be improved with heat treatment, which is known to decrease swelling and shrinkage.

The size and the shape of the wood particles may be regular or irregular. Typically, the particles have an average size (of the smallest dimension) in excess of 0.02 mm, advantageously in excess of 0.1 mm, 0.4 mm or 0.5 mm, for example in excess of 0.6 mm or 1 mm, suitably about 0.6 to 40 mm, in particular about 1.2 to 20 mm, preferably about 1 .5 to 10 mm, for example about 1 to 7 mm. For the plate-like wood particles having a length, width and thickness, the smallest dimension will be the thickness.

The length of the particles (longest dimension of the particles) can vary from a value of greater than 0.6 mm (e.g. greater than 0.75 mm or 1 mm or 1 .8 mm or 3 mm) to value of up to about 200 mm, for example up to about 50 mm or 21 mm. The wood particles can be granular i.e. having a substantially cubic shape, plate-like or a mixture of both. Wood particles considered to be granular have a cubic shape whose ratio of general dimensions are on the order of thickness : width : length = 1 : 1 : 1 . In practice it is difficult to measure each individual particle to determine if it is a perfect cube. Therefore, in practice, particles considered to be granular are those where one dimension is not substantially different than the other two.

Wood particles considered to be plate-like means that they have generally a plate-shaped character. The ratio of the thickness of the plate to the smaller of the width or length of the plate's edges is generally 1 :2 to 1 :500 or 1 :100 or 1 :20 such that the thickness of the plate- like particles is smaller than the width/length.

The plate-like wood particles may have at least two dimensions greater than 1 mm and one greater than 0.02 mm (e.g. greater than 0.1 mm), the average volume of the wood particles being generally at least 0.02 mm³ (e.g. at least 0.1 mm³ or at least 1 mm³). Suitable wood particles have typical dimensions of 2 mm x 2 mm x 1 mm, for example. The specific weight of the wood particles may be between 180-200 kg/m³.

"Derived from platy wood particles" designates that the wood particles may have undergone some modification during the processing of the composition. For example, if blending of the thermoplastic polymer and wood particles is carried out with a mechanical melt processor, some of the original plate-like wood particles may be deformed to an extent. Typically more than 70 % and preferably up to 100% of the wood particles are greater in size than powder, which particles may be granular or platy.

The wood species can be freely selected from deciduous and coniferous wood species alike: beech, birch, alder, aspen, poplar, oak, cedar, Eucalyptus, mixed tropical hardwood, pine, spruce and larch tree for example. The wood particles can be derived from wood raw-material typically by cutting or chipping of the raw-material. Wood chips of deciduous or coniferous wood species are preferred.

The desired composition of the wood particles can be achieved by sifting wood particles through one or more meshes having one or more varying qualities. The desired composition can also be accomplished by other well-known techniques in the art for sorting and separating particles in to desired categories. The desired composition may be the resultant composition of one sifting or separating process. The desired composition may also be a mixture of resultant compositions from several sifting or separation processes.

A particularly interesting raw-material comprises wood particles, chips or granules, of any of the above mentioned wood species having a screened size of greater than 0.6 mm up to about 3.0 mm, in particular about 1 to 2.5 mm on an average.

In addition to wood particles and thermoplastic polymer, the composite foot support can contain reinforcing fibrous material, for example cellulose fibers, such as flax or seed fibers of cotton, wood skin, leaf or bark fibers of jute, hemp, soybean, banana or coconut, stalk fibers (straws) of hey, rice, barley and other crops and plants including plants having hollow stem which belong to main class of Tracheobionta and e.g. the subclass of meadow grasses (bamboo, reed, scouring rush, wild angelica and grass).

In addition, inorganic particulates or powdered materials such as mica, silica, silica gel, calcium carbonate and other calcium salts such as tricalcium orthophosphate, carbon, clays and kaolin may be present or added. In some embodiments, the composite material further comprises an elastic or soft polymer. Such a polymer can be homogenously distributed within the composite material or can be concentrated within regions of the composite foot support.

This improves the fit and comfort of the total contact cast.

"Soft" when used in the context of a polymer means that the polymer, either a thermoplastic or thermosetting polymer, has Shore D hardness 27 or less at ambient temperature. "Ambient temperature" stands for a temperature of about 10 to 30 C, in particular about 15 to 25 °C.

"Region" when used in connection of elasticity or softness of the composite foot support denotes a portion of the composite foot support. The region may extend only to a limited depth of the composite foot support or it may extend through the composite foot support in at least one dimension. The region may comprise an elongated, essentially integral area. The region may also comprise one or several isolated portions of, for example, material different from the material surrounding the isolated portion(s). "Region" may also be a portion evenly distributed throughout the composite foot support. Thus, a soft or elastic polymer can be homogeneously blended or mixed with the thermoplastic polymer to extend the region of elasticity or softness to cover essentially the whole superficial area of composite foot support.

A property of "elasticity" or "softness" can be measured by a ring stiffness test, and such a property will be manifested in a greatly reduced stiffness. Typically the stiffness will be at least 20 % lower, preferably at least 30 % lower than for a corresponding material, wherein the same (± 10 %) volume as taken up by the soft or flexible polymer is formed by the thermoplastic polymer, for example and typically by the thermoplastic polyester or other polymer having melting point or softening point below 70 C and higher or equal to about 55 C. The elastic/soft polymer is a different polymer than the thermoplastic polymer. The elastic/soft polymer can be thermoplastic or thermosetting polymer. The elastic/soft polymer can be used to partly replace the thermoplastic polymer to maintain the total volume of polymer in the composite layer at least essentially unaltered.

The composite foot support will have a longitudinal and lateral axis and the soft (or elastic) polymer rich regions are generally unidirectional either along the longitudinal or lateral axis. The soft (or elastic) polymer rich regions can also be in form of a grid, mesh or web.

Typically, the soft/elastic polymer is a polymer having a Shore D hardness of 27 or less, in particular 25 or less, at ambient temperature or a thermoplastic elastomer.

Other examples of soft polymers include polymers exhibiting Shore A of 0 to 70 and Shore OO of 0 to 90.

The soft/elastic polymer can be formed by a polymer selected from the group of thermoplastic polyolefin blends; polyurethanes; co-polyesters; polyamides; unsaturated or saturated rubbers, including natural rubber, silicone, and copolymers of olefins; and natural or synthetic soft material, including soft gelatin, hydrogels, hydrocolloids and modified cellulose. The elastic or soft polymer does not need to have melting range in same range as the thermoplastic polymer. Typically, the soft/elastic polymer has a melting range outside that of the thermoplastic polymer, in particular the melting point of the soft/elastic polymer is higher than the melting point of the thermoplastic polymer.

In one embodiment, the soft/elastic polymer is miscible with thermoplastic polymer forming a homogenous matrix when processed at elevated temperatures. In another embodiment, the soft/elastic polymer is immiscible with the thermoplastic polymer forming phase-separated zones or regions within the thermoplastic polymer.

Based on the above, in one embodiment, the composite material forming the composite foot support comprises: - 10 to 70 parts by weight of thermoplastic polymer e.g. a biodegradable polyester;

- 25 to 60 parts by weight of wood particles; and

- 5 to 40 parts by weight of a soft or elastic polymer.

The soft or elastic polymer together with the thermoplastic polymer (e.g. biodegradable polyester) may make up a majority of the composite foot support (i.e. more than 50 % by weight of the total weight of the composite foot support).

In one embodiment, the soft or elastic polymer together with the thermoplastic polymer (e.g. biodegradable polyester) make up at least 53 % and up to 70 %, for example 55 to 70 %, by weight of the total weight of the composite foot support. The soft or elastic polymer generally forms 5 to 50 %, in particular 10 to 40 %, for example 15 to 30 %, by weight of the total weight of the thermoplastic polymer (e.g. biodegradable polyester) together with the soft or elastic polymer.

It is possible to incorporate further polymers into the composite material. In one embodiment, the composite material comprises 3 to 30 parts by weight, of a further polymer comprising a thermoplastic polymer different from that of the first and the soft/elastic polymer. Such a component can be used for achieving improved mechanical properties of the composite foot support. It is also possible to use a fourth polymer to modify the surface properties (for example properties of adhesion) of the composite foot support.

Suitable polymers for the soft/elastic polymer and the further polymer are as described in WO2015/059354. The composite foot support may a thickness of about 1 to 50 mm, in particular about 1 .5 to 30 mm, for example 1 .5 to 20 mm. The composite foot support may have a thickness greater than 1.5 mm.

A typical thickness is about 2 to 6 mm, for example between 3 and 4 mm or about 4 mm. The thickness of the composite foot support may vary. For example, the composite foot support may be increase in thickness from its periphery to its centre. For example, the composite layer may have a thickness of between 4-6 mm e.g. around 4 mm at its centre decreasing to between 2-4 mm e.g. around 2 mm at its peripheral edges. The composite foot support is preferably a unitary support.

The composite foot support preferably has a plantar portion and a calf portion, the two portions being joined by a heel portion, the three portions forming the unitary composite foot support.

The plantar portion is positioned under the sole of the wearer's foot and preferably extends the length of the wearer's foot i.e. from the heel to the end of the toes (and optionally beyond the toes). The plantar region of the composite foot support preferably comprises upturned edges which are contoured to match the lateral and medial sides of the wearer's foot.

The heel portion is contoured to match the wearer's heel and the calf portion is contoured to match the wearer's calf i.e. has a substantially U-shaped profile. The calf portion preferably extends to proximal the wearer's knee. The composite foot support is dimensioned such that the wearer's ankle bones (malleoli) are exposed.

The composite foot support may comprise at least one region formed with openings/apertures. For example, the heel portion may be formed with openings/apertures.

The shape of the openings or apertures can be, for example, round, rectangular, square, diamond, hexagonal, oval, slot or ornamental perforation. The surface area of one hole should be generally about 3 to 30 mm² and the number of the holes is preferably kept between 20 holes/10 cm² and 100 holes/10 cm². The total open area is less than 10% of the whole surface area of the contact support.

The composite foot support preferably comprises a single layer i.e. a single layer of composite material. In some embodiments, the total contact cast further comprises a wrapping layer wrapped around an outer surface of the composite foot support (i.e. around the surface facing away from the wearer). The wrapping layer is provided to encircle the wearer's leg so that the composite foot support is held in position by contact (either direct or indirect) with the outside surface of the composite foot support. Preferably, the wrapping layer is shaped to substantially match the contour of the wearer's leg/foot.

Preferably, the wrapping layer is formed by wrapping a tape/bandage/ribbon component around the wearer's foot/leg and the composite foot support (adjacent the outer surface). The wrapping layer may comprise multiple (overlapping) layers of the tape/bandage/ribbon component.

The bandage component may comprise a fabric bandage. For example, the fabric bandage may be a fabric bandage manufactured by HERO healthcare, e.g. cohesive inelastic compression bandage HERO H-2 Layer2 or Comprilan. In some embodiments, the wrapping layer may be a rigid layer e.g. forming a hard/rigid outer shell for the total contact cast. This may be achieved by using a plaster casting tape such as Johnson & Johnson's Specialist® fast setting plaster bandage or Gypsona®. This is wetted and wrapped around the wearer's leg/foot and the composite foot support to secure the composite foot support and, once dried and hardened to form the wrapping layer provides further support and protection for the wearer's foot/leg.

Alternatively, the tape/bandage/ribbon component may be a synthetic e.g. fibreglass casting tape which comprises a fibreglass substrate impregnated with a water activated polyurethane resin which also sets hard after wetting and wrapping to form the wrapping layer. For example, it may be Delta-cast® Soft casting tape. In preferred embodiments, the wrapping layer comprises the composite material as described above for the composite foot support (although the composite material forming the wrapping layer and the composite foot support need not be identical).

For example, the wrapping layer may be formed of a tape/bandage/ribbon component comprising the composite material. The tape/bandage/ribbon component may comprise the composite material and may have a thickness that is less than the thickness of the composite foot support e.g. it may have a thickness of 2 mm or less, e.g. around 1 mm. In some embodiments, the tape/bandage/ribbon component may be Wood cast® 1 mm Ribbon.

The tape/bandage/ribbon component may be as described in WO2012/032226.

In these embodiments, the tape/bandage/ribbon component comprises a first layer formed of the composite material and a second layer formed of a textile material. Preferably, the first layer is bonded only to one surface of the second layer. The first layer may have a thickness of 0.5 to 1 .5 mm, e.g. around 1 mm.

The second, textile layer may be formed of a gauze or felt and may be elastic. It may be formed of natural fibres (e.g. cotton, flax, hemp, jute) or it may be formed of synthetic fibres (e.g. polyester, polyamide, polyurethanes, polypropylene etc.)

In some embodiments, the total contact cast further comprises one of more fixing elements for securing the composite foot support to the wearer's leg, the fixing elements encircling the wearer's foot/leg. The fixing element(s) may be interposed between the composite foot support and the wrapping layer. There may a plantar fixing element encircling the wearer's foot and the outer surface of the plantar region of the composite foot support.

There may be a lower calf fixing element encircling the wearer's lower calf (proximal the ankle) and the outer surface of the calf region of the composite foot support.

There may be an upper calf fixing element encircling the wearer's upper calf (proximal the knee) and the outer surface of the calf region of the composite foot support.

The fixing elements may be formed of composite material. They may have a thickness less than the composite foot support e.g. they may have a thickness of 0.5 mm to 3 mm e.g. around 1 mm or 2 mm. They may be formed, for example, of Wood cast® 1 mm ribbon.

Where the total contact cast includes one or more fixing elements, the wrapping layer may be as described above e.g. it may be a fabric bandage or a casting tape.

In some embodiments, the total contact cast further comprises a padding layer radially inwards of the composite foot support.

The padding layer is to cushion the wearer's foot/leg and to prevent abrasion by the composite foot support. The padding layer may completely encircle the wearer's foot/leg or it may be a discontinuous layer provided only at protuberances or areas prone to abrasion (e.g. at the ankle bones). The padding layer may comprise a felt or foam padding material such as HERO Healthcare foam elastic bandage (e.g. HERO H-2 Layer 1 ). The padding layer may be impregnated with aloe (for moisturising) and/or cyclodextrin (for de-odourising).

The padding layer may be a spacer fabric e.g. a polyester spacer fabric. A suitable polyester spacer fabric is that manufactured by Baltex™.

The padding material may have a thickness of between 1 and 5 mm e.g. around 3mm. It may have a weight between 200-400 g/m² e.g. around 300 g/m².

In some embodiments, the total contact cast further comprises a lining layer/stockinette layer radially inwards of the composite foot support. The lining/stockinette layer may be adjacent the composite foot support e.g. the lining/stockinette layer may be interposed between the composite foot support and the padding layer (especially where the padding layer is a foam layer).

In these embodiments, the lining/stockinette layer acts to prevent the padding layer adhering to the composite foot support. In other embodiments, the padding layer may be interposed between the composite foot support and the lining/stockinette layer (especially where the padding layer is a 3D spacer fabric).

It is preferably formed of a loosely knitted, stretch fabric.

In some embodiments, the total contact cast includes a wound surface dressing radially innermost.

The wound surface dressing may be provided only at the site of the ulceration.

The wound surface dressing may comprise a sterile non-adhesive dressing such as Optifoam™, SOF-FOAM, 3M Foam or a sterile gauze dressing. It may be a hydrogel or hydrocolloid dressing. It may comprise an absorptive filler. It may be impregnated with silver ions.

Further suitable wound surface dressings are Molnlycke® wound care dressings e.g. Lyofoam® Max, Mepilex ® Border AG or Mextra® superabsorbent. In a second aspect, the present invention provides a method of applying a total contact cast to a wearer's foot, the method comprising:

moulding a composite blank formed of a composite material comprising wood particles within a thermoplastic matrix about a portion of the wearer's foot and leg to form a composite foot support that is shaped to substantially match the contour of a portion of the wearer's foot and leg.

The composite material forming the composite blank (and thus the composite foot support) may be as described above for the first aspect. The composite foot support may be as described for the first aspect. The blank may be a planar blank e.g. it may be a rectangular plate. It is preferably substantially rigid/non-flexible at room temperature.

The blank may comprise at least one region formed with incisions, in particular unidirectional incisions/perforations.

By introducing lengthwise/longitudinal incisions in regions (or across the entirety) of the composite blank, aeration can be achieved through the composite foot support by merely widening the composite blank in widthwise/transverse direction during molding to form the composite foot support.

The incisions are located such that they are kept "closed" in the areas of the composite foot support requiring maximum strength so as not to impair mechanical strength. Typically the areas requiring maximal strength are subjected to longitudinal forces, i.e. forces which act along the length of the composite foot support (i.e. parallel to the wearer's calf). Thus, in one preferred embodiment, the incisions are longitudinally directed, and they will therefore not be opened by the action of such longitudinal force. By orientating the incisions longitudinally, the incisions will remain closed under the influence of longitudinal forces, and the material will exhibit mechanical strength and rigidity directly derivable from the structure of the composite foot support.

The incisions in the blank may be formed by straight (linear) incisions or cuts. Preferably there are lines formed with a plurality of incisions. In particular there is a plurality of such lines, which preferably are parallel. In a particular embodiment, the incisions in adjacent lines are off-set such that no two adjacent incisions are located along the same transversal line. Examples of suitable perforations are shown in WO2015/059355.

It has been found that incisions having a length of generally more 20 mm may cause tearing of the composite foot support when exposed to strong twisting and strain. On the other hand, incisions which are less than 5 mm in length do not sufficiently open during molding of the blank onto the wearer's foot/leg to allow for proper aerating.

Further, the space between each incision in longitudinal direction must preferably exceed 5 mm to mitigate tearing of the material and be less than 20 mm to achieve sufficient level of aerating.

The space between each incision line transversally to the linear incision may exceed 10 mm to avoid tearing and be less than 25 mm to achieve sufficient level of aerating. The incisions may be manufactured into the composite blank with an incision device, examples of suitable equipment include a rolling cylinder or a press equipped with blades, water jet, and laser cutting.

Typically, the incisions have a width of 0.1 to 1 mm, preferably 0.3 to 0.8 mm, and a length of 4 to 20 mm, e.g. 5-10 mm.

The incisions can be made with a blade, the surface area of which incisions being on the blade ingoing side about 1 to 10 mm², preferably 2.5 to 8 mm². The number of incisions per 10 cm² may be generally 20 to 100, preferably 30 to 70.

The particular advantage of incorporating incisions into the composite blank is that upon forming the composite foot support by molding the blank, the incisions will yield openings which give the composite foot support properties of breathability, especially around the heel/calf portion of the composite foot support where lateral stretching of the composite blank will be high.

When subjected to the stretching laterally, the incisions will form the openings/apertures. Typically, the perforated composite blank will allow stretching at least 5 %, typically up to 75 %, in particular about 10 to 50 %.

After stretching, the heel region and/or the calf region of the composite foot support may have pore area which is 2x to lOOx, typically 2.5x to 15x greater that than pore area of any non- incised region. The pore area can be about 2.5 to 30 % of the total area of the heel region/calf region, for example about 3 to 20 %, for example about 5 to 15 %.

The blank may comprise at least one region formed with apertures or openings. This will also assist in aeration through the composite foot support. In some embodiments, the method comprises heating the composite blank to a temperature of between 50 and 70°C and molding it about the wearer's foot and calf such that it closely matches the anatomical contours of the wearer's body.

With the composite material still pliable and moldable, it can be contoured to fit the wearer's foot and calf nearly or exactly. Additionally, if the initial placement is not desirable, the blank can be moved while still moldable to a more desirable location. If the composite layer has lost its desired moldability, then it can be reheated and likewise moved to the new location. A blank formed of PCL and wood particles typically remains moldable for up to 5 minutes. One of the particular advantages of the composite material is that it can be heated and cooled many times without degrading its mechanical properties. When the blank is located properly and molded to the desired form, then it can be allowed to cool to a temperature where it can maintain its shape. The cooling may be accomplished by allowing the ambient conditions to reduce the temperature of the material or the cooling may be aided by spraying the material with water or another chemical to speed up the cooling. Additionally, solid cooling means can be used to cool the material such as a cold pack or ice place directly against the composite material.

In some embodiments, the method comprises molding the composite blank into a unitary composite support having a plantar portion, a heel portion and a calf portion. The method preferably comprises molding the plantar portion such that it extends up the lateral and medial sides of the wearer's foot. In some embodiments, the method comprises stretching the composite blank in a transverse direction during molding to form openings at least in the heel portion and optionally in the calf portion.

In some embodiments, the method further comprises forming a wrapping layer around wearer's foot and leg and around the outer surface of the composite foot support.

The wrapping layer may be as described above for the first aspect. The method may comprise wrapping a tape/bandage/ribbon component around the outer surface of the composite foot support and the wearer's foot/leg to encase the wearer's foot/leg.

Where the wrapping layer is plaster or synthetic casting tape, the method comprises wetting the tape and wrapping it around the outer surface of the composite foot support and the wearer's foot/leg to encase the wearer's foot/leg.

Where the wrapping layer comprises a tape/bandage/ribbon component comprising the composite material (and optionally a second textile layer), the method may comprise heating the tape/bandage/ribbon to between 50 and 70°C and wrapping it around the outer surface of the composite foot support and the wearer's foot leg to encase the wearer's foot/leg. The wrapping layer will, in these embodiments, harden upon drying/cooling to form a rigid outer shell to the total contact cast.

In some embodiments, the method further comprises applying one or more fixing elements encircling the wearer's leg, radially outwards of the composite foot support and radially inwards of the wrapping layer. The fixing element(s) may be as described above for the first aspect.

In some embodiments, the method may comprise providing a plantar fixing element encircling the wearer's foot and the outer surface of the plantar region of the composite foot support.

In some embodiments, the method may comprise providing a lower calf fixing element encircling the wearer's lower calf (proximal the ankle) and the outer surface of the calf region of the composite foot support.

In some embodiments, the method may comprise providing an upper calf fixing element encircling the wearer's upper calf (proximal the knee) and the outer surface of the calf region of the composite foot support.

Where the fixing element(s) is/are formed of composite material, the method may comprise providing one or more fixing element blanks, heating it/them to around 50-70°C and molding it/them about the wearer's leg/foot.

In some embodiments, the method further comprises a applying a padding material radially inwards of the composite foot support to form a padding layer, i.e. the padding material will be applied before the composite foot support is moulded to match the contour of a portion of the wearer's foot and leg.

The padding layer may be as described above for the first aspect.

The padding layer may be provided to cover the entire of the wearer's foot/lower leg or it may be provided only on bony protuberances e.g. over the ankle bones.

In some embodiments, the method further comprises applying a lining layer e.g. a stockinette radially inwards of the composite foot support.

The lining/stockinette layer may be provided adjacent the composite foot support e.g. the method may comprise providing the lining/stockinette layer interposed between the composite foot support and the padding layer (especially where the padding material is a foam material).

In other embodiments, the padding layer may be interposed between the composite foot support and the lining/stockinette layer (especially where the padding material is a 3D spacer fabric).

The lining/stockinette may be as described for the first aspect.

In some embodiments, the method comprises (as a first step) applying a wound surface dressing radially inwards of the padding layer to cover the diabetic ulcer.

The wound surface dressing may be as described for the first aspect.

Accordingly, in a first preferred embodiment, the method comprises:

1 ) applying the wound surface dressing to cover the ulcer:

2) applying the padding material (e.g. a foam padding material) to form a padding layer;

3) fitting the lining/stockinette layer over the padding material;

4) moulding the composite blank around the wearer's foot and calf to form the composite foot support;

5) optionally moulding one or more composite fixing blanks to provide one or more fixing elements radially outwards of the composite foot support; and 6) wrapping the outer surface of the composite foot support (and optionally the fixing element(s) e.g. with a tape/ribbon/bandage component to form the wrapping layer.

In a second preferred embodiment, the method comprises:

1 ) applying the wound surface dressing to cover the ulcer;

2) fitting the lining/stockinette layer;

3) applying the padding material (e.g. a 3D spacer fabric) to form a padding layer;

5) optionally moulding one or more composite fixing blanks to for one or more fixing elements radially outwards of the composite foot support; and

6) wrapping the outer surface of the composite foot support (and optionally the fixing element(s) e.g. with a tape/ribbon/bandage component to form the wrapping layer.

The total contact cast will remain in place until removed by a medical clinician. When removal is required, the wrapping layer can be cut or removed and the composite foot support separated from the remaining components of the total contact cast.

When the total contact cast is reapplied, the composite foot support can be re-heated e.g. to 50-70°C and remoulded to be reused again.

In a third aspect, the present invention comprises a kit for a total contact cast for protecting a wearer's foot, the kit comprising:

a moldable composite blank, the composite blank being formed of a composite material comprising wood particles within a thermoplastic polymer matrix, the composite blank being mouldable to substantially match the contour of a portion of the wearer's foot and leg.

The composite material may be as described for the first aspect. The composite blank may be as described above for the second aspect.

In some embodiments, the kit further comprise a wrapping material for wrapping around the outer surface of the composite foot support once moulded to form a wrapping layer.

The wrapping material/layer may be as described for the first aspect. For example, the wrapping material may be a tape/ribbon/bandage component such as a plaster or a synthetic casting tape or textile bandage or it may be formed of the composite material (optionally with a second textile layer). The tape/ribbon/bandage component may be Woodcast® 1 mm Ribbon.

In some embodiments, the kit further comprises one or more composite fixing element blanks formed of the composite material for encircling the wearer's foot/leg radially outwards of the composite foot support and radially inwards of the wrapping layer.

The fixing element blank may be a rigid, planar blank or may be a tape (e.g. Woodcast® 1 mm Ribbon). It may have a thickness of between 0.5 mm and 3 mm e.g. around 1 mm or 2 mm. It may comprise incisions or apertures as described above for the composite foot support. The kit may comprise a plantar fixing element blank for encircling the wearer foot radially outwards of the plantar region of the composite foot support. The kit may comprise a lower calf fixing element blank for encircling the wearer leg proximal the ankle radially outwards of the calf region of the composite foot support. The kit may comprise an upper calf fixing element blank for encircling the wearer leg proximal the knee radially outwards of the calf region of the composite foot support.

In some embodiments, the kit further comprises a padding material for forming a padding layer radially inwards of composite foot support.

The padding material/layer may be as described for the first aspect.

In some embodiments, the kit further comprises a lining material or stockinette for forming a lining/stockinette layer radially inwards of composite foot support.

The lining/stockinette layer may be as described for the first aspect.

In some embodiments, the kit further comprises a wound surface dressing for applying to the ulcer.

The wound surface dressing may be as described for the first aspect. For example, the wound surface dressing may be a sterile non-adhesive dressing such as Optifoam™, SOF-FOAM, 3M Foam or a sterile gauze dressing. It may be a hydrogel or hydrocolloid dressing. It may comprise an absorptive filler. It may be impregnated with silver ions. Further suitable wound surface dressings are Molnlycke® wound care dressings e.g. Lyofoam® Max, Mepilex ® Border AG or Mextra® superabsorbent.The kit is preferably sealed in a package. The kit preferably include instructions for forming the total contact cast using the method described in the second aspect. Brief description of Drawings

Figure 1 shows a first embodiment of a total contact cast; and

Figure 2 shows a second embodiment of a total contact cast.

Detailed description of the invention

Figure 1 shows a side view of a total contact cast 1 . A wound dressing (not shown) selected from Molnlycke® wound care dressings e.g.

Lyofoam® Max, Mepilex ® Border AG or Mextra® superabsorbent is first applied to cover the wearer's ulcer.

Next, a padding material (HERO Healthcare foam bandage (H-2)) is wrapped around the wearer's foot and calf to form a padding layer 2). A stockinette 3 is then fitted over the padding layer 2. The stockinette covers the entire of the patient's foot and lower leg and lines the padding layer 2.

Next a rectangular, planar composite blank is provided. The blank is formed of a composite material comprising a 3:2 ratio of PCL and wood particles. The wood particles were aspen wood particles having an average size of 2 x 2 x 1 mm. The PCL had an Mn of 80,000g/mol. The composite blank comprises incisions which are formed into parallel, longitudinally extending rows with incisions in adjacent rows offset such that no two adjacent incisions are located on the same transversal line. The incisions may have a width of 0.3-0.8 mm and a length of 5-10 mm.

The composite blank is heated to a temperature of between 50-70°C at which temperature, the blank becomes pliable and moldable. The blank is moulded about the wearer^'s foot and lower leg to form a composite foot support 4 which substantially matches the anatomical contours of the wearer's foot/lower leg. After cooling under ambient conditions, the composite foot support 4 forms a rigid, hard support for the wearer's foot and transfers pressure to the lower leg.

During molding of the composite blank, lateral/transverse stretching of the blank results in the formation of openings 5 in the heel region 6 and calf region 7 of the composite foot support 4. This allows aeration of the heel and lower leg.

The unitary, single layer composite foot support 4 further comprises a plantar region 8 which is moulded against the sole of the wearer's foot. The plantar region 8 comprises upturned edges 9 which are moulded to the lateral and medial edges of the wearer's foot.

Next a tape comprising the composite material (e.g. Wood cast® 1 mm Ribbon) is heated to 50-70°C so that it becomes pliable and moldable. The tape is then wrapped around the wearer's leg/foot and the outer surface of the composite foot support 4 to form a wrapping layer (not shown) which encases the entire of the wearer's foot/lower leg and cools to form a rigid shell.

When removal and replacement of the total contact cast is required, at least the composite foot support can be removed and reused by re-heating and re-molding. It may also be possible to reuse the (composite) wrapping layer.

Figure 2 shows a side view of a second embodiment of the total contact cast 1 '.

A wound dressing (not shown) selected from Molnlycke® wound care dressings e.g.

Next, a stockinette (not shown) is fitted over the wearer's foot and calf.

A padding layer 10 is then formed by positioning pieces of a padding material (Baltex™ 100% polyester spacer fabric, weight: 300g/m², thickness: 3mm) at locations prone to rubbing e.g. over the ankle bones and around the toes. Next a rectangular, planar composite blank is provided. The blank is formed of a composite material comprising a 3:2 ratio of PCL and wood particles. The wood particles were aspen wood particles having an average size of 2 x 2 x 1 mm. The PCL had an Mn of 80,000g/mol. The composite blank comprises incisions which are formed into parallel, longitudinally extending rows with incisions in adjacent rows offset such that no two adjacent incisions are located on the same transversal line. The incisions may have a width of 0.3-0.8 mm and a length of 5-10 mm. The composite blank is heated to a temperature of between 50-70°C at which temperature, the blank becomes pliable and moldable. The blank is moulded about the wearer's foot and lower leg to form a composite foot support 4 which substantially matches the anatomical contours of the wearer's foot/lower leg. After cooling under ambient conditions, the composite foot support 4 forms a rigid, hard support for the wearer's foot and transfers pressure to the lower leg.

Next a tape comprising the composite material (e.g. Wood cast® 1 mm Ribbon) is heated to 50-70°C so that it becomes pliable and moldable. The tape is then applied as fixing elements 1 1 a, 1 1 b, 1 1 c a) around the wearer's foot and the plantar region 8 of the composite foot support (plantar fixing element 1 1 a), b) around the wearer's lower leg just above the ankle bone and around the calf region 7 of the composite foot support 4 (lower calf fixing element 1 1 b), and c) around the wearer's lower leg just below the knee and around the calf region 7 of the composite foot support 4 (upper calf fixing element 1 1 c). A fabric bandage is then wrapped around the wearer's leg/foot and the outer surface of the composite foot support 4 (over the fixing element 1 1 a, 1 1 b, 1 1 c to form a wrapping layer (not shown) which encases the entire of the wearer's foot/lower leg.

When removal and replacement of the total contact cast is required, the composite foot support 4 and composite fixing elements 1 1 a, 1 1 b, 1 1 c can be removed and reused by reheating and re-molding.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention. All references referred to above are hereby incorporated by reference.

Claims

1. A total contact cast for protecting a wearer's foot, the total contact cast comprising: a composite foot support, the composite foot support being formed of a composite material comprising wood particles within a thermoplastic polymer matrix, the composite foot support being moulded to substantially match the contour of a portion of the wearer's foot and leg.

2. A total contact cast where the thermoplastic polymer comprises polylactide, polyglycolide, polycaprolactone (PCL), mixtures/blends thereof and copolymers thereof and has a melt flow index of less than 7 g/10 min and/or an intrinsic viscosity of 1.5 to 2.5 dl/g and/or a molecular weight (Mn) of 75.000 to 100,000 g/mol.

3. A total contact cast wherein the wood particles are plate-like wood particles having a ratio of the thickness of the plate to the smaller of the width or length of 1 :2 to 1 :500

4. A total contact cast according to any one of the preceding claims wherein the composite foot support has a plantar portion and a calf portion, the two portions being joined by a heel portion, the three portions forming a unitary composite foot support.

5. A total contact cast according to claim 4 wherein the plantar region of the composite foot support preferably comprises upturned edges which are contoured to match the lateral and medial sides of the wearer's foot.

6. A total contact cast according to claim 4 or 5 wherein at least the heel region is formed with openings/apertures.

7. A total contact cast according to any one of the preceding claims wherein the composite foot support comprises a single layer of composite material.

8. A total contact cast according to any one of the preceding claims further comprising a wrapping layer wrapped around an outer surface of the composite foot support, the wrapping layer shaped to substantially match the contour of the wearer's leg/foot.

9. A total contact cast according to claim 8 wherein the wrapping layer is formed by wrapping a tape/bandage/ribbon component around the wearer's foot/leg and the composite foot support.

10. A total contact cast according to claim 9 wherein the tape/ribbon/bandage component comprises the composite material and optionally a textile layer.

1 1 . A total contact cast according to any one of the preceding claims further comprising at least one composite fixing element radially outwards of the composite foot support, selected from a plantar fixing element, an upper calf fixing element and a lower calf fixing element, the or each fixing element formed of the composite material.

12. A total contact cast according to any one of the preceding claims further comprising one or more of:

a wound dressing in contact with the ulcer;

a padding layer radially inwards of the composite foot support; and

a lining layer radially inwards of the composite foot support

13. A method of applying a total contact cast to a wearer's foot, the method comprising: moulding a composite blank formed of a composite material comprising wood particles within a thermoplastic matrix about a portion of the wearer's foot and leg to form a composite foot support that is shaped to substantially match the contour of a portion of the wearer's foot and leg.

14. A method according to claim 13 comprising heating the composite blank to between 50 and 70°C and molding it against the wearer's foot and calf.

15. A method according to claim 13 or 14 comprising providing selecting a composite blank having incisions and laterally stretching the composite blank during molding across the heel of the foot to form openings in at least a heel portion of the composite foot support.

16. A method according to any one of claims 13 to 15 comprising molding the composite blank to form a unitary, single layer composite foot support having a plantar region, a heel region and a calf region.

17. A method according to claim 16 comprising molding the composite blank such that the plantar portion of the composite foot support is molded around the lateral and medial sides of the wearer's foot.

18. A method according to any one of claims 13 to 17 further comprising forming a wrapping layer around wearer's foot and leg and around the outer surface of the composite foot support.

19. A method according to claim 18 comprising wrapping a tape/bandage/ribbon component around the outer surface of the composite foot support and the wearer's foot/leg to encase the wearer's foot/leg.

20. A method according to claim 19 comprising heating and wrapping a tape/bandage/ribbon component comprising the composite material and optionally a textile layer around the outer surface of the composite foot support and the wearer's foot leg to encase the wearer's foot/leg.

21 . A method according to any one of the preceding claims comprising moulding at least one composite fixing element blank formed of the composite material about the wearer's leg/foot radially outwards of the composite foot support.

22. A method according to any one of claims 13 to 21 comprising

1 ) applying a wound surface dressing to cover the ulcer;

2) applying a padding material to form a padding layer;

3) fitting a lining/stockinette layer either before or after forming the padding layer;

5) optionally moulding at least one composite fitting element blank radially outwards of the composite foot support; and

5) wrapping the outer surface of the composite foot support with a tape/ribbon/bandage component to form a/the wrapping layer.

23. A kit for a total contact cast for protecting a wearer's foot, the kit comprising:

24. A kit according to claim 23 wherein the composite blank is a rigid, planar blank.

25. A kit according to claim 23 or 24 wherein the composite blank comprises at least one region formed with incisions.

26. A kit according to any one of claims 23 to 25 further comprising a wrapping material for wrapping around the outer surface of the composite foot support once moulded to form a wrapping layer.

27. A kit according to claim 26 wherein the wrapping material is a tape/ribbon bandage component formed of the composite material optionally with a second textile layer.

28. A kit according to any one of claims 23 to 27 further comprising at least one composite fixing element blank formed of the composite material.

29. A kit according to any one of claims 23 to 27 further comprising one or more of: a wound dressing;

a padding material for forming a padding layer; and

a lining material/stockinette for forming a lining/stockinette layer.