WO2014016385A1

WO2014016385A1 - Cushioning device

Info

Publication number: WO2014016385A1
Application number: PCT/EP2013/065751
Authority: WO
Inventors: Christian Stephenson
Original assignee: Crawford Healthcare Ltd
Priority date: 2012-07-25
Filing date: 2013-07-25
Publication date: 2014-01-30
Also published as: EP2877136A1; GB201213192D0

Abstract

A conformable cushioning device for application to a human or animal body, with a plurality of channels running between the proximal face of the cushioning device, which in use is in direct or indirect contact with the skin of the human or animal body, and the opposing distal face. The device may be used for relieving pressure on and cushioning pressure-sensitive parts of the body, and for the prophylaxis and treatment of wounds and wound precursors. The plurality of channels make the cushioning device less prone to cause excessive sweating in the tissue underlying the device, facilitate sweat evaporating normally therefrom, and mitigates any consequent maceration therein, without excessively drying it.

Description

Cushioning Device

The present invention relates to a cushioning device, as defined herein, a method for the preparation of such a cushioning device, and a method of prophylactic and therapeutic use of the device. It relates more specifically to a conformable, flexible and elastic cushioning device for relieving pressure on and cushioning pressure-sensitive parts of the body, and its use in the prophylaxis and treatment of wounds and wound precursors as defined herein, on or in the skin of humans and animals or in the underlying tissue.

The term 'absorbent component' as used herein refers to any conformable component comprised in a absorbent device, which may be used in the treatment or prophylaxis of acute or chronic wounds or wound precursors, as defined herein, on or in the skin of humans and animals, or in the tissue underlying it. It often comprises a synthetic absorbent material that is substantially insoluble in a relevant bodily fluid,

The term 'antimicrobial' as used herein in relation to a therapeutically active material includes materials which have

antibacterial activity, for example against Methicillin-resistant Staphylococcus aureus (MRSA), Clostridium difficile, Salmonella typhimurium, Leigonella, Listeria monocytogenes and Escherichia coli,

antimycotic activity, including against one or more of Aspergillus niger and Candida albicans, and/or

antiviral activity,

both in vitro and in vivo, and in particular when comprised in a cushioning device for relieving pressure on and cushioning pressure-sensitive parts of the body, when in use in the prophylaxis and treatment of wounds or wound precursors as defined herein.

When used herein, the term "biocompatible" refers to any material which when in contact with the cells, tissues or body fluids of a human or other animal does not induce adverse effects such as immunological reactions and/or rejections and the like. Reference herein to a 'cushioning device' of the present invention is to a solid and substantially water-insoluble, soft and conformable lamellar device for relieving pressure on affected parts of the body and/or for the prophylaxis and treatment of wound precursors and wounds, including pressure sores and/or ulcers.

Reference herein to a 'shaped cushioning device' of the present invention is to a device' of the present invention which is shaped to conform in use to the body over an affected area to which it is applied.

Reference herein to an 'unshaped cushioning device' of the present invention is to a device' of the present invention which is not shaped to conform in use to the body over an affected area to which it is applied. Reference herein to a 'proximal face' of a cushioning device of the present invention is to the face that in use is proximal to the patient, that is, towards or in direct or indirect contact with the skin of the human or animal body, and the 'distal face' is the opposite face of the cushioning device, distal to the patient. By the term 'substantially water-insoluble' herein in the context of any material in a cushioning device is meant that the material is soluble in an aqueous medium to the extent of less than 5%, such as 1 %, for example 5% w/w.

Reference herein to a 'spacer layer' is to an integer in the form of at least one layer or sheet, often of a fabric or device, used with a cushioning device of the present invention between its proximal face and the skin of the human or animal patient body

The term "wound precursor" herein means any condition on or in the skin of a human or animal, or in the tissue underlying it, which in the absence of prophylactic treatment is at substantial risk of developing into tissue of compromised integrity, such tissue including wounds, often chronic wounds, including pressure sores and ulcers; and infected wounds. No statements made on belief herein, in particular as to the nature, physical form and physical properties of any material or of any device, in particular any wound dressing comprising such a material, or of any process for the manufacture thereof, shall be construed as in any way as limiting the scope of the present invention. .

It is known that a wound precursor on the body of a patient, as referred to above can be treated with a pressure-relieving, soft conformable lamellar cushioning device.

It may be a shaped cushioning device, that is one that is shaped to conform in use to the body over an affected area to which it is applied, and is often held in position over the affected parts, for example in the foot by conforming footwear, or in other parts of the body, for example over the sacrum by clothing.

Alternatively, the cushioning device may be an unshaped cushioning device, that is, not shaped to conform in use to the body over an affected area, and is often held in position over the affected parts, for example on each side of the torso and/or the back, by a layer of pressure-sensitive adhesive around its periphery.

Known cushioning devices for the relief of pressure are often made of a soft, almost viscous fluid-like plastics material, which, for example, can consist of a silicone-based gel or an appropriate elastomer. Such known cushioning devices are suitable for the prophylaxis and treatment of wound precursors and wounds, in particular for use on patients who are known to have, or are at substantial risk of developing, them, for example those patients who are known to have, or are at substantial risk of developing, inter alia arthritis, diabetes or cardiovascular conditions and/or who are chairbound or bedridden, inter alia with paralysis

It is a however a problem that the materials used for known cushioning devices are often very prone to cause excessive sweating in the tissue underlying the cushioning device and to prevent the sweat from evaporating normally, and moisture vapour escaping adequately. As a result, the known cushioning devices can be a source of irritation and can, at worst, cause maceration of the underlying tissue and potentially wounds or wound precursors on or in the skin of the patients who may already be at risk. . Known cushioning devices for the relief of pressure have been provided with features to try to address this major problem for the patient, for example by providing indentations in the surface of the cushioning device in direct or indirect contact with the skin with a series of grooves running to the periphery of the cushioning device to facilitate the sweat evaporating normally. However, the result of such measures is that such cushioning devices still fail to adequately mitigate the problems of sweating and the consequent maceration of the underlying tissue and potentially sores and/or ulcers. On the other hand, the environment under the cushioning device during use of the cushioning device should not be too dry for any sustained period of prophylaxis or therapy on the patient. This can lead to cracking of the skin, or in the tissue underlying it, of a patient at special risk, for example in the foot of those with diabetes who are not bedridden to which the device is applied, which may lead to ulcers. Additionally, the healing of chronic wounds, including ulcers and infected wounds, is favoured by moist wound conditions at a typical patient body temperature, and dry conditions may hinder the healing of such wounds.

It is also known to use medical devices, such as cushioning devices as a source of topical therapeutic agents, such as topical antimicrobials; topical antibiotics, and topical anaesthetics, attached to and/or dispersed in the material of the cushioning device for prophylaxis or therapy of the patient during use of the cushioning device. These may be released sustainedly from the cushioning device. . .

However, in some cases, for example if the cushioning device is used in contact with wound exudate, it may be desirable, in particular to minimise any additional regulatory burden, that any topical therapeutic agent, such as a topical antimicrobial and/or a topical antibiotic, remains attached to and/or dispersed within the cushioning device, and is not released sustainedly from the cushioning device.

This presents a technical problem where the desired topical therapeutic agent, such as a topical antimicrobial and/or a topical antibiotic is water-soluble and would be released sustainedly to the patient during treatment with the cushioning device. An object of the present invention is to devise an improved form of cushioning device for the relief of pressure at points or areas of the body which can be used in everyday life as normal convenient prophylaxis or treatment of wound precursors, as defined herein, and/or wounds in the skin of a patient, or in the tissue underlying it, for the patients at special risk discussed above, for example those with arthritis, diabetes, cardiovascular conditions and/or paralysis. .

Another object of the present invention is to devise an improved form of cushioning device which facilitates sweat evaporating normally from the tissue underlying the cushioning device by having a high moisture vapour permeability (MVP), and thus mitigates the problems of consequent maceration of the underlying tissue and the substantial risk of developing wound precursors and/or chronic wounds, including pressure sores, ulcers and infected wounds, Yet another object of the present invention is to provide an improved form of cushioning device which provides prophylactic and/or therapeutic treatment of the surface of the patient's body and/or the tissue underlying it, against disorders such as inflammation, pain or microbial infection in affected parts of the human or animal body.

Yet another object of the present invention is to provide a cushioning device which provides an environment under the cushioning device during use which is not too dry for any sustained period of prophylaxis or therapy on the patient and/or provides moist wound conditions at a typical patient body temperature to favour the healing of chronic wounds, such as ulcers.

A further object of the present invention is to devise an improved form of cushioning device with a topical therapeutic agent, such as a topical antimicrobial and/or a topical antibiotic, which is attached to or dispersed within it and is otherwise water-soluble, to be applied to a patient in prophylactic and/or therapeutic treatment, which will not release the therapeutic agent to any significant extent into a wound and/or the tissue immediately surrounding it during such treatment. These objects are achieved by embodiments of the present invention, Accordingly, in a first aspect the present invention provides a conformable cushioning device for application to a human or animal body, characterised by a plurality of channels running between the proximal face of the cushioning device, which in use is in direct or indirect contact with the skin of the human or animal body, and the opposing distal face.

The plurality of channels running between the proximal face of the present lamellar cushioning device and the opposing distal face makes the cushioning device much less prone to cause excessive sweating in the tissue underlying the cushioning device.

It also facilitates sweat evaporating normally from the tissue underlying the cushioning device, and mitigates the problems of consequent maceration of the underlying tissue and the substantial risk of developing wound precursors and/or chronic wounds, including pressure sores, ulcers and infected wounds,

It does so in a more effective manner than known cushioning devices for the relief of pressure provided with features such as a series of grooves in the surface of the cushioning device in contact with the skin running to the periphery of the cushioning device to try to address this major problem for the patient.

The plurality of channels running within the cushioning device between the proximal face and its opposing distal face open in a plurality of pores respectively on the proximal face and its opposing distal face.

The plurality of pores opening respectively on the proximal face and its opposite distal face and the channels running through the cushioning device may suitably be in any form or shape that is compatible with their function of facilitating sweat evaporating normally, moisture vapour escaping adequately, and mitigating consequent maceration and the substantial risk of developing wound precursors and/or chronic wounds, including pressure sores, ulcers and infected wounds.

The channels in the cushioning device may suitably all be substantially straight. Where they open into pores in a surface that is substantially planar, in preferred forms of the cushioning device, they are substantially at right angles to that surface, and so substantially parallel to each other. They are preferably of substantially the same cross-sectional area as each other. The pores in the proximal face and the opposite distal face and the channels in the cushioning device are frequently round, but not necessarily regularly round, such as circular, elliptical or oval in cross-section. The pores in the proximal face and the opposite distal face, and the channels in the cushioning device, may suitably have a mean cross-sectional area of less than 6 mm², for example from 1 to 5 mm². In preferred forms of the cushioning device according to the present invention they will have a mean cross-sectional area of less than 5 mm², for example from 2 to 4 mm².

They may suitably be present at a mean area density of from 0.5 to 60 cm^"2, for example from 1 to 30 cm^"2. In preferred forms of the cushioning device according to the present invention they will be present at a mean area density of from 1 .5 to 15 cm^"2, for example from 3 to 7 cm^"2.

Clearly, the higher mean density values, for example 60 cm^"2, will correlate with lower mean cross-sectional area values, for example from 1 mm², such that the total cross-sectional open area of the pores in a surface of the cushioning device i does not exceed the area of that surface pierced by the pores.

The total cross-sectional open area of the pores in a surface is typically from 5 to 25% of the area of that surface pierced by the pores, for example 10 to 20% in preferred forms of the cushioning device according to the present invention. The conformable cushioning device of the present invention may suitably be in any form or shape that is compatible with its functions of facilitating sweat evaporating normally and moisture vapour escaping (preferably with a moisture vapour permeability (MVP) in the range of 250 to 10 000 g/m²/24hr, more preferably with a moisture vapour permeability (MVP) in the range of 250 to 4 500 g/m²/24hr, most preferably with an MVP) in the range of 250 to 2 500 g/m²/24hr), cushioning the relevant part of the body, and preferably taking up as little space and causing as little inconvenience as possible so that Ίπβ cushioning device can be worn under ordinary human clothing or footwear (shoes etc.), or bedclothes without inconveniencing the patient. For those who are bedridden or chairbound, in particular bedridden, for example with paralysis, parts of the body, for example on each side of the torso and the back tend to be pressure-sensitive parts of the body, at risk of developing wound precursors and/or chronic wounds, including pressure sores, ulcers and infected wounds.

Cushioning devices of the present invention may suitably be used on pressure- sensitive parts of the body, for example on each side of the torso and the back of such a patient who is known to be at risk of developing pressure sores and/or ulcers.

Because of the variety of the points on the human or animal body where the cushioning device is used, and the relative flatness of some, for example on the back of the patient who is potentially at risk, such a cushioning device of the present invention cannot then usefully be shaped to conform in use to the body over a given area.

The lower parts of the body, for example the soles and heels of the feet and the sacrum, tend to be particularly pressure-sensitive parts of the body, where the risk of developing wound precursors and/or wounds referred to above tends to occur. This is especially the case in those patients with arthritis, diabetes or cardiovascular conditions who are not bedridden or chairbound.

Such cushioning devices are usually shaped to conform in use to, and to be in direct or indirect contact with, a relevant body part when used in cushioning, relieving pressure on, and cushioning pressure-sensitive parts of the body such as the soles and heels of the feet and the sacrum, and protecting them against wound precursors and/or chronic wounds, including pressure sores, ulcers and infected wounds.

The present invention extends mutatis mutandis to conformable cushioning devices for relieving pressure which are shaped to conform during use to any required position on the body and to those which are not shaped to conform in use to the body. Accordingly, in a first embodiment of the first aspect of the present invention, the conformable lamellar cushioning device for application to a human or animal body is not shaped to conform to affected areas to which it is applied. It is thus usually provided in a versatile lamellar form, and in a shape that is compatible with its functions referred to above.

Such cushioning devices are usually in the form which comprises a conformable component, or consists essentially of such a component in the form of at least one layer or sheet of a absorbent material.

Such structures have channels in them, running within the layer between its proximal face and its opposite distal face opening in a plurality of pores on its faces.

Such structures often have a shape such as an elongate strip, band or ribbon, a quadrilateral, such as a rectangle or oblong, or an equilateral, such as a square, or a round, but not necessarily regularly round, disc such as circular, elliptical or oval disc such as circular, elliptical or oval cushioning device.

Suitable and preferred mean density values and mean cross-sectional area values for such pores in the surfaces of this embodiment of the first aspect of the present invention are as so described hereinbefore for the generic cushioning device of the present invention.

This embodiment of the first aspect of the present invention will typically have a thickness that tends to be constant and towards the lower figures in the ranges given hereinbefore for the thickness of the general cushioning device of the present invention; that is in the ranges of from 0.1 to 1 .5 cm, for example from 0.2 to 1 cm, such as from 0.3 to 0.5 cm.

As described hereinafter in greater detail, such cushioning devices may comprise a material which characteristically has a good permeability to water vapour, and at least part of the proximal face of which is inherently self-adhesive to skin, thus avoiding any need for a layer of pressure-sensitive adhesive around the periphery of its proximal face, or retaining strapping or other means of attachment. Such self-adhesion is usually relatively unaggressive, which is among the especially advantageous properties of a cushioning device with a proximal face comprising such a material. Alternatively or additionally, the present cushioning device may suitably be provided with conventional (generally pressure-sensitive) adhesive around the periphery of its proximal face, or retaining strapping or other appropriate means for it to be secured, which are well-known to the skilled person, or are described further in the patent or literature prior art.

Such means of attachment should not of course block the pores in the surfaces of this embodiment to such an extent that the moisture vapour permeability (MVP) of the cushioning device on the relevant part of the body is impaired, and in particular falls below 250 g/m²/24hr. Such a reduction in MVP could cause maceration of the underlying tissue and a substantial risk of developing wound precursors or chronic wounds, including pressure sores, ulcers and infected wounds.

Thus any layer of pressure-sensitive adhesive around the periphery of the proximal face, should be a discontinuous layer of adhesive, with apertures though it, preferably of the same mean cross-sectional area as, and in register with the channels through the cushioning device at corresponding parts.

Alternatively or additionally, the present cushioning device may suitably be provided with conventional moisture vapour permeable strapping means for it to be secured. Such means are well-known to the skilled person, but include those made of closed-cell foamed plastics material, closed-cell foam natural rubber or another closed-cell foam material with channels in them, much as described hereinbefore for the cushioning device. Suitable such materials characteristically have a good permeability to water vapour, and include thermoplastic polyurethane closed-cell foams.

As noted above, the cushioning device of the present invention as defined herein may suitably be used not only on pressure-sensitive parts of the body, for example on parts of the body of a patient who is bedridden or chairbound, but also on parts of the body that are not pressure-sensitive, for example on a patient who is mobile. In the latter case, the cushioning devices of the invention may be used primarily for the prophylaxis and treatment of wound precursors and/or chronic wounds, including pressure sores, ulcers and infected wounds, by acting as a source of topical therapeutic agents, such as topical antimicrobials; topical antibiotics, and topical anaesthetics, attached to or dispersed in the material of the cushioning device.

As described hereinafter in greater detail, the or each therapeutic agent may be released to a controlled or diminished degree and rate of release by such cushioning devices, but in particular (as noted hereinbefore) to a negligible degree when applied over a wound and exposed to a highly aqueous medium such as wound exudate, at a typical patient body temperature. As described hereinbefore in greater detail, the cushioning device may be inherently self-adhesive to skin, or may need retaining strapping or other means of attachment.

A second embodiment of the first aspect of the present invention is a shaped cushioning device, that is one that is shaped to conform in use to the body over an affected area to which it is applied.

It may suitably be used on pressure-sensitive parts of the body, for example on parts of the body of a patient who is not bedridden, but mobile or chairbound, and is known to be at risk of developing pressure sores and/or ulcers. Such a conformable, flexible cushioning devices of the present invention is in general shaped to conform to, for example, the foot or the sacrum. Suitable and preferred mean density values and mean cross-sectional area values for such pores in the surfaces of this embodiment of the first aspect of the present invention are as so described hereinbefore for the general cushioning device of the present invention. The thickness of such a cushioning device of the present invention tends to range between the lowest and highest figures in these ranges, that is in the ranges of from 0.3 to 5 cm, for example from 0.5 to 3 cm, such as from 1 to 1 .5 cm. Where the proximal face conforms in use to, for example the arch of the foot, the cushioning device has an increased thickness at the point where it is required to cushion the arch, or where the proximal face conforms in use to, for example the soft tissue over the sacrum, the cushioning device has an increased thickness at that point where it is required to cushion the sacrum.

In both cases, the opposite distal face does not conform in use to the same extent to the relevant part of the human body if at all. Such structures have channels in them, running within the layer between its proximal face and its opposite distal face opening in a plurality of pores on its faces.

A cushioning device of this embodiment of the first aspect of the present invention will generally not need to be provided with means for it to be secured to the body of a patient who is potentially at risk, over the affected areas to which it is applied. As described hereinafter in greater detail, such cushioning devices are in general held in position over the affected parts, in the foot by conforming footwear, or in other parts of the body, for example over the sacrum, by clothing. As is well-known to the skilled person, it thus does not normally need to be provided with conventional adhesive or strapping means for it to be secured

However, as noted above, some materials which characteristically have a good permeability to water vapour and are coincidentally inherently self-adhesive to skin, thus further holding the cushioning device in place.

Any conforming footwear or clothing should not of course block the pores in the surfaces of this embodiment to such an extent that the moisture vapour permeability (MVP) of the cushioning device on the relevant part of the body is impaired, and in particular falls below 250 g/m²/24hr, and thus put a patient at risk of developing wound precursors and/or chronic wounds, including pressure sores, ulcers and infected wounds.

In all embodiments of the first aspect of the present invention, the conformable cushioning devices may suitably be made of a soft, pliable plastics material. Suitable materials for use in the cushioning devices the first aspect of the present invention include synthetic polymeric materials, with a good permeability to water vapour, such as

gels, for example preferably a silicone-based gel;

elastomers, for example one based on one or more alkylenes, such as ethylene, propylene and butylene, and styrene and combinations thereof,

thermoplastic polyurethanes (also preferred materials),

certain copolyesters and polyamides, and combinations thereof; and

closed-cell foamed plastics materials, for example a thermoplastic polyurethane closed-cell foam, closed-cell foamed natural rubber or any other closed-cell foam material

In the cushioning devices of the present invention that are shaped to conform to affected areas to which they are applied, for example the foot or the sacrum, it is preferred that the cushioning device be made of a soft, pliable, almost viscous fluid-like plastics material. Preferably the cushioning device is made of a conformable gel of this type.

Preferred silicone-based gel materials include crosslinked polydimethylsiloxanes

Each of such gels may optionally comprise up to 90 wt%, for example up to 60 wt%, such as up to 40 wt% of an oil, for example a silicone oil, for example a linear polydimethylsiloxane .

These gels have high durability and a useful level of tack, and are characteristically extremely soft and pliable, and can readily be shaped to conform in use to the body.

In the cushioning devices of the present invention that are not shaped to conform to affected areas to which they are applied, for example each side of the torso and the back, it is preferred that the cushioning device be made of a soft, pliable plastics material, but one that is not almost viscous fluid-like.

Suitable silicone-based gel materials include crosslinked polydimethylsiloxanes. Such gels are often inherently self-adhesive to skin, thus holding the cushioning device in place and avoiding any need for a layer of pressure-sensitive adhesive, for example around the periphery of the proximal face, or retaining strapping or other means of attachment, and are particularly useful on pressure-sensitive parts of the body in a patient who is bedridden, and known to be at risk of developing pressure sores and/or ulcers on the side of the torso and/or the back. Such self-adhesion is usually relatively unaggressive, which is among the especially advantageous properties of the cushioning device for use with those patients with diabetes and/or who are elderly, (in contrast to adhesive strapping or other means of attachment). Such patients tend to have delicate, fragile skin with which the cushioning device is in direct contact in use, which is easily broken on removal of strapping or other means of attachment with more aggressive adhesive.

In all embodiments of the first aspect of the present invention, the conformable cushioning devices may suitably be made of the other plastics materials listed above.

Suitable elastomers for use in the cushioning device according to the first aspect of the present invention include for example ones based on a combination of one or more alkylenes, such as ethylene, propylene and butylene, and styrene, in particular styrene ethylene butylene styrene (SBES).

All of the plastics materials listed above are characteristically extremely soft and pliable. Alternatively or additionally, the present cushioning device may suitably be made of a closed-cell foam, in which none of the pores in the material will form the plurality of channels running between its proximal face and the opposite distal face. The closed-cell foam in the cushioning device is provided with a plurality of channels running between the proximal face and its opposite distal face opening in a plurality of pores respectively on the proximal face and its opposing distal face. Suitable and preferred mean density values and mean cross-sectional area values for such pores in the surfaces of this form of the first aspect of the present invention are as so described hereinbefore for the general cushioning device of the present invention.

Suitable materials include closed-cell foamed plastics materials, closed-cell foamed natural rubber and other closed-cell foams, including thermoplastic polyurethane closed-cell foams. These are characteristically extremely soft and pliable.

In a third embodiment of this first aspect of the present invention, the cushioning device is used in conjunction with a conformable spacer layer which in use lies between the cushioning device and the skin of the body, and conforms to the body over all areas where cushioning is needed.

Such a spacer layer serves to further cushion pressure-sensitive parts of the body, and may also facilitate sweat evaporating from the tissue underlying the cushioning device and moisture vapour escaping. It preferably has the same or a higher figure in the ranges given hereinbefore for the moisture vapour permeability (MVP) of the cushioning device.

Such a spacer layer may suitably be in any form or shape that is compatible with these functions and with conforming to the relevant pressure-sensitive parts of the body. However, it is in use often roughly coterminous with the cushioning device.

The spacer layer may suitably be in the form of at least one layer of woven, non- woven or knitted fabric. Such structures have inherent channels in them, much as described hereinbefore for the cushioning device, running within the cushioning device layer between its proximal face and its opposite distal face opening in a plurality of pores respectively on the proximal face and its opposing distal face. The spacer layer may also suitably be in the form of at least one layer of woven, non- woven or knitted fabric, contained in a fabric container, often also of a woven or knitted fabric, the structure of which also has inherent channels in it. The or each layer is optionally attached to another and/or to the cushioning device, or the distal face of the spacer layer container device may also optionally be attached to the cushioning device. Any attachment may be by thermal welding, adhesion or other appropriate method. Where one layer of, typically woven or knitted fabric, is attached to another, they may be knitted together to form a three-dimensional spacer fabric, with one component layer optionally attached to the cushioning device

The spacer layer may suitably be made of a textile of yarns, threads or filaments of cotton, linen, silk or wool, polymers of one or more alkylenes, such as ethylene, propylene and butylene, and styrene and combinations thereof, thermoplastic polyurethanes, and copolyesters and polyamides, and combinations thereof. The spacer layer may suitably have a thickness of from 0.1 to 2 cm, such as from 0.2 to 0.5 cm.

Where the layer is of woven or knitted fabric, a plurality of channels running between its proximal face and its opposite distal face, may be formed by the conventional apertures though the spacer fabric. This is sufficient to achieve the object of the present invention of providing an improved form of cushioning device which facilitates sweat evaporating from the tissue underlying the cushioning device, thus mitigating the problems of consequent maceration of the underlying tissue and the substantial risk of developing wound precursors or chronic wounds, including pressure sores, ulcers and infected wounds.

Preferably, however, the spacer layer also has a plurality of channels running between its proximal face and its opposite distal face, which channels should be in register with those through the cushioning device at the same part of the human or animal body.

Suitable and preferred mean density values and mean cross-sectional area values for such channels are as so described hereinbefore for the channels in the cushioning devices of the first aspect of the present invention.

The spacer layer tends to be used with a cushioning device of the second embodiment of the first aspect of the present invention, that is, a shaped cushioning device, shaped to conform in use to the body over an affected area to which it is applied. In such cases, the cushioning device often has an increased thickness at the point where it is required, for example to cushion the arch of the foot or where it is required to cushion the sacrum. The spacer layer may then suitably have a thickness that tends to be constant and between 0.1 to 0.5 cm.

Alternatively, such a cushioning device may not conform fully to the areas to which it is applied, for example the arch of the foot or the sacrum, although the cushioning device may have an increased thickness at the point where it is required to cushion the arch or the sacrum. In such cases, the spacer layer on the present cushioning device will conform fully to the areas to be cushioned, and will have an increased thickness at the area. The thickness may often be a variable thickness ranging between from 0.2 to 2 cm. Alternatively, the cushioning device may be a conformable lamellar cushioning device of the first embodiment of the first aspect of the present invention, that is, an unshaped cushioning device which is not shaped to conform in use to the body over an affected area, and which is often held in position over the affected parts, for example on each side of the torso and/or the back, by a layer of pressure-sensitive adhesive around its periphery. The spacer layer may then suitably have a thickness that tends to be constant and between 0.1 to 0.5 cm.

The cushioning device may be held in position over the affected parts by a discontinuous layer of pressure-sensitive adhesive around its periphery. In such case, the layer of pressure-sensitive adhesive should have apertures in register with the channels through the cushioning device at the same part, and preferably of the same mean cross-sectional area.

In a fourth embodiment of this first aspect of the present invention, the cushioning device also comprises one or more topical therapeutic agents, attached to or dispersed within it, to provide a further prophylactic and therapeutic effect on the surface of the patient's body and/or the underlying tissue.

As described hereinafter in greater detail, the or each therapeutic agent, attached to or dispersed within the cushioning device may be intended to be released sustainedly to the patient during treatment by diffusion from the cushioning device, or preferably to remain attached to or dispersed within the cushioning device and act by the cushioning device being held in contact with the surface of the patient's body and/or the underlying tissue.

In the latter case, the cushioning devices of the invention may exhibit a surprising and advantageously diminished or negligible degree and rate of release by water of the or each therapeutic agent, in particular when it is exposed to a highly aqueous medium, such as wound exudate, at a typical patient body temperature.

Where there is no open wound, for example an ulcer, on the patient's body underlying the cushioning device in use, it may be intended that the topical therapeutic agents, such as emollients, soothing therapeutic agents, topical antimicrobials, topical antibiotics, and topical anaesthetics be released sustainedly to the patient during treatment by diffusion from the cushioning device, and whilst the rate and degree of release should be controlled, it is in particular not necessary that the rate and degree of release be minimised or prevented.

Where there is an open wound, for example an ulcer, on the patient's body underlying the cushioning device in use, the rate of release of any topical therapeutic agents into the wound on the patient during treatment by diffusion from the cushioning device should normally be minimised. Release of any such therapeutic agents into the wound should preferably be prevented, in particular to minimise any regulatory burden, for example by the agents being attached to molecules of the material of the cushioning device in its surface or bulk.

Depending on the type of material of which the cushioning device is made, the therapeutic agent may be attached to a solid substantially water-insoluble cushioning device by hydrogen bonding and/or pairing of ions of opposite charges, and/or by covalent bonding, optionally with condensation and/or cross- linking. The or each therapeutic agent should be pharmaceutically acceptable, and may suitably be any of the following pharmaceutically acceptable ingredients: emollients, such as skin lipids and sterols, oils, for example lightweight oils, such as cetyl alcohol, or silicone-derived oils, such as cyclomethicone, and heavier oils, such as grape seed oil or dimethicone, and petrolatum;

antioxidants;

lubricants;

soothing ingredients, such as chamomile and aloe vera;

topical antimicrobials; for example tea tree oil; antimicrobial metals and their compounds; biocompatible quaternary ammonium and guanidine-based cationic antimicrobials:

topical antibiotics, for example bacitracin, neomycin, mupirocin, and polymyxin B; in particular for the healing of sores and/or ulcers:

topical analgesics, such as ibuprofen, diclofenac and capsaicin; to treat pain in combination with the soothing effect of the present cushioning device (optionally in relation to cushioning devices for relieving pressure on painful arthritic joints, such as fallen arches of the foot, for longer-term pain relief);

topical anaesthetics, such as lidocaine to numb affected parts of the human or animal body; and/or

topical antiinflammatories, such as steroids, such as Cortisol;

or other appropriate therapeutic agents.

These therapeutic agents may be incorporated in the material of the cushioning device according to the present invention during the process for the preparation of the cushioning device. The. material of the cushioning device may for example consist of a silicone- based gel or a thermoplastic polyurethane, copolyester, polyamide, or combinations thereof, or an appropriate elastomer. It is convenient to disperse one or more pharmaceutically acceptable therapeutic agents throughout the cushioning device according to the present invention. This is the case, whether it is intended that they be released sustainedly to the patient during treatment by diffusion from the cushioning device, or remain attached to or dispersed within the cushioning device and act by the cushioning device being held in contact with the surface of the patient's body and/or the underlying tissue. The cushioning device according to this embodiment may comprise up to 10 wt%, for example up to 3 wt%, such as up to 1 wt% total of one or more of the pharmaceutically acceptable therapeutic agents. Again, this is the case, whether it is intended that they be released sustainedly to the patient in use or not.

Favoured pharmaceutically acceptable therapeutic agents in this embodiment of the cushioning device include topical antibiotics, for example bacitracin, neomycin, mupirocin, and polymyxin B.

More favoured pharmaceutically acceptable therapeutic agents in this embodiment of the cushioning device include topical antimicrobials, preferably antimicrobial metals, such as silver, which is in particular effective in inhibiting the development and formation of biofilm, and including colloidal silver and silver nanoparticles, which are in particular effective in inhibiting the development or destroying gram-negative bacterial species: antimicrobial metal salts, such as silver sulfadiazine and silver nitrate, and antimicrobial metal oxides, such as silver oxides, in particular when the silver is in one of its higher oxidation states, such as 2 or 3.

These are substantially water-insoluble and/or remain attached to the cushioning device, for example by pairing of ions of opposite charges, even when the cushioning device is exposed to a highly aqueous medium, such as wound exudate, at a typical patient body temperature, and are particularly effective in those conditions.

Favoured forms of this embodiment of the cushioning device include silicone- based gel materials, such as one or more pharmaceutically acceptable crosslinked linear polydimethylsiloxanes which comprise up to 10 wt%, for example up to 3 wt%, such as up to 1 wt% of silver, including colloidal silver and silver nanoparticles, silver salts, such as silver sulfadiazine and silver nitrate, and silver oxides, in particular when the silver is in one of its higher oxidation states, such as 2 or 3.

Examples of pharmaceutically acceptable therapeutic agents in this embodiment of the cushioning device also include biocompatible quaternary ammonium salts, which are derivatised by being N-substituted by a tris(hydrocarbyl or hydrocarbyloxy)-silylhydrocarbyl group. These are believed to remain attached to the cushioning device, for by hydrogen bonding and/or pairing of ions of opposite charges, and/or by covalent bonding, optionally with condensation and/or cross-linking. Favoured forms of this embodiment of the cushioning device comprise up to 10 wt%, for example up to 3 wt%, such as up to 1 wt% of one or more pharmaceutically acceptable, biocompatible derivatised quaternary ammonium salts. Biocompatible quaternary ammonium salts are characteristically water-soluble, and would for example be readily released to the patient during treatment by diffusion into sweat evaporating normally on, and moisture vapour escaping from, the skin of the body over the areas which the cushioning device covers, or by other well-known physiological processes. These disadvantageous properties make known quaternary ammonium salts less suitable for use as antimicrobial materials in antimicrobial devices such as the cushioning device.

In favoured forms of this embodiment of the cushioning device, such biocompatible quaternary ammonium salts preferably remain attached to or dispersed within the cushioning device and are not released sustainedly to the patient during treatment by diffusion.

In preferred forms of this embodiment of the cushioning device, such biocompatible derivatised quaternary ammonium salts which remain attached to or dispersed within the cushioning device include a derivatised quaternary ammonium salt, wherein the quaternary ammonium salt is N-substituted by i) a group of formula (I)

R¹ (R²) (R³) Si(R⁴) - (I) wherein

each of R¹, R² and R³ is an optionally substituted hydrocarbyl group, and

R⁴ is an optionally substituted hydrocarbylene group,

and

ii) a group R⁵ , which is an optionally substituted hydrocarbyl group, The derivatised quaternary ammonium salt is highly advantageous for use as an antimicrobial material in the cushioning device of this embodiment of the first aspect of the present invention. These cushioning devices exhibit a surprising and advantageously diminished or negligible degree and rate of release by water of the derivatised quaternary ammonium salt from the cushioning device, in particular when in contact with wound exudate at a typical patient body temperature and/or at the pH levels found in chronic and burn wounds.

The rate and degree of release can be minimised in particular by the choice of a) the derivatised quaternary ammonium salt, and

b) the material(s) of the solid substantially water-insoluble cushioning device, in particular when the derivatised quaternary ammonium salt and solid substantially water-insoluble cushioning device may be linked by covalent bonding, optionally with condensation and/or cross-linking.

Treatment or prophylaxis of microbial infections using an antimicrobial cushioning device according to this embodiment of the first aspect of the present invention does not cause microbial resistance, for example by

bacteria, such as Staphylococcus aureus (MRSA), Clostridium difficile, Salmonella typhimurium, Leigonella, Listeria monocytogenes and Escherichia coli,

mycotic species, including Aspergillus niger and Candida albicans, and/or viruses. In formula (I):

Each of R¹, R², R³ and R⁴ may independently be oxa-substituted, preferably to produce R¹, R² and R³ optionally substituted hydrocarbyloxy groups, and, for example to produce an R⁴ optionally substituted hydrocarbylene group with an internal ether linkage.

Each of R¹, R² and R³ independently may be an optionally oxa-substituted alkyl group, preferably a lower alkyl group with 1 to 6 carbon atoms, such as a methyl, ethyl, propyl or butyl group, preferably a methyl group. Any propyl or butyl group is preferably attached in the 1 -position to the silicon atom. Each of R¹, R² and R³ is preferably a hydrocarbyloxy residue, for example a lower alkoxy group with 1 to 6 carbon atoms. Each of R¹, R² and R³ may thus suitably be, for example, a methoxy, ethoxy, propoxy, isopropoxy or butoxy group, preferably a methoxy group. Any component propyl or butyl group group is preferably attached in the 1 -position to the oxygen atom.

Most preferably, such R¹, R² and R³ groups are the same. The most preferred R¹, R² and R³ residue is a methoxy group. R⁴ may be an optionally oxa-substituted alkanediyl group, preferably a lower alkylene group with 1 to 6 carbon atoms, such as a methylene, ethan-1 ,2-diyl, propan-1 ,3-diyl or butan-1 ,4-diyl group, preferably a propan-1 ,3-diyl group.

R⁵ is an optionally substituted hydrocarbyl group, which may be oxa-substituted, for example to produce an R⁵ optionally substituted hydrocarbyl group with an internal ether linkage.

R⁵ may be an optionally oxa-substituted alkyl group, preferably a higher alkyl group with 8 to 22 carbon atoms, such as an octyl, decyl, dodecyl, tetradecyl, hexadecyl (cetyl or palmityl), octadecyl or eicosyl group.

The alkyl moiety may be branched or unbranched, and oxa-substituted, for example to produce an R⁵ optionally substituted unsaturated hydrocarbyl group with an internal ether linkage.

Examples include 3,6-dioxa-substituted higher alkyl groups with 8 to 22 carbon atoms.

Each of the two remaining N-substituents other than the tris(hydrocarbyl or hydrocarbyloxy)-silylhydrocarbyl group of formula (I) and R⁵ may independently be an alkyl group, preferably an optionally substituted lower alkyl group with 1 to 6 carbon atoms, such as a methyl, ethyl or propyl, preferably methyl. The alkyl moiety may be branched or unbranched, and hence suitable propyl may be n- propyl or iso-propyl. One of the groups may be an aralkyl group, such as benzyl, in which case, if the remaining N-substituent is a methyl group, the derivatised quaternary ammonium salts is a derivatised benzalkonium salt. Most preferably, the groups are the same and are methyl groups.

Less preferably they may also independently be an aryl group, such as phenyl or tolyl, preferably phenyl.

The anion of the derivatised quaternary ammonium salt for use in antimicrobial cushioning devices of this embodiment of the first aspect of the present invention may be any pharmacologically acceptable anion. Such an anion of the derivatised quaternary ammonium salt may be selected from the anion of:

an inorganic acid, such as chloride, bromide, hydrogen sulphate, dihydrogen phosphate and/or hydrogen difluorophosphate, or

an organic acid, such as acetate, propionate, isobutyrate, iodobutyrate, valerate, caproate, alpha-hydroxyisobutyrate, glucoheptonate, benzoate, cinnamate, mandelate, isophthalate, 2-hydroxynapthoate, lactate, ascorbate, gluconate, salicylate, isethionate, succinamate, methanesulphonate, glucoheptonate, hydrogen tartrate, hydrogen adipate, hydrogen maleate hydrogen malate, hydrogen malonate, hydrogen glutamate, dihydrogen citrate, hydrogen succinate, hydrogen pamoate and/or hydrogen diglycolate, or

a pharmacologically acceptable dianion selected from a dianion of any of the above diacids.

Preferred derivatised quaternary ammonium salts for use in antimicrobial medical cushioning devices of this embodiment of the first aspect of the present invention include derivatised quaternary ammonium salt, wherein the quaternary ammonium salt is N-substituted by

i) a group of formula (I)

R¹ (R²) (R³) Si(R⁴) - (I)

wherein

each of R¹, R² and R³ is a methoxy, ethoxy, propoxy, isopropoxy or butoxy group, preferably a methoxy group, and any component propyl or butyl group group is preferably attached in the 1 -position to the oxygen atom.

R⁴ is a methylene, ethan-1 ,2-diyl, propan-1 ,3-diyl or butan-1 ,4-diyl group, preferably an ethan-1 ,2-diyl group,

and b) a group R⁵ , which is a dodecyl, tetradecyl, hexadecyl, octadecyl or eicosyl group, which may be branched or unbranched and/or oxa-substituted to produce a higher alkyl group with an internal ether linkage. More preferred derivatised quaternary ammonium salts for use in antimicrobial cushioning devices of this embodiment of the first aspect of the present invention include derivatised quaternary ammonium salts such as

N,N-dimethyl-N-octadecyl-N-2-(trimethoxysilyl)propylammonium chloride, N,N-dipropyl-N-octadecyl-N-2-(trimethoxysilyl)propylammonium hydrogen sulphate

N,N-dimethyl-N-octadecyl-N-2-(trimethoxysilyl)propylammonium dihydrogen phosphate,

N,N-dipropyl-N-octadecyl-N-2-(trimethoxysilyl)propylammonium acetate, N,N-dimethyl-N-octadecyl-N-2-(trimethoxysilyl)propylammonium benzoate, and in particular N,N-dimethyl-N-octadecyl-N-2-(trimethoxysilyl)propylammonium chloride,

More favoured pharmaceutically acceptable therapeutic agents in this embodiment of the cushioning device also include at least one derivatised quaternary ammonium-based antimicrobial, together with at least one biocompatible guanidine-based cationic antimicrobials, including guanidine- based compounds, diguanidine-based compounds and polymeric guanidine- based compounds, optionally and/or at least one underivatised quaternary ammonium-based antimicrobial.

Biocompatible guanidine-based cationic antimicrobials, are characteristically water-soluble, and would for example be readily released to the patient during treatment by diffusion into sweat evaporating normally on, and moisture vapour escaping from, the skin of the body over the areas which the cushioning device covers, or by other well-known physiological processes. These disadvantageous properties make known guanidine-based cationic antimicrobials less suitable for use as antimicrobial materials in antimicrobial devices such as the cushioning device. In more favoured forms of this embodiment of the cushioning device, such biocompatible guanidine-based cationic antimicrobials preferably remain attached to or dispersed within the cushioning device and are not released sustainedly to the patient during treatment by diffusion.

The or each guanidine-based cationic antimicrobial or underivatised quaternary ammonium-based antimicrobial is believed may remain attached to the cushioning device, for example

by hydrogen bonding and/or pairing of ions of opposite charges, and/or by being trapped by one or more derivatised quaternary ammonium salts, as defined herein.

Such biocompatible guanidine-based cationic antimicrobials will have a pharmacologically acceptable anion, which may be selected from that of an inorganic acid, such as chloride, bromide, hydrogen sulphate, dihydrogen phosphate and/or hydrogen difluorophosphate, or

a pharmacologically acceptable dianion selected from a dianion of any of the above diacids. Which materials of the cushioning device and topical therapeutic agents, attached to or dispersed within it are mutually compatible are either well-known to the skilled person, or so described in the patent or literature prior art, or readily ascertained by the skilled person without undue experimentation. Similarly, less polar or apolar device materials, such as silicone-based gel materials, will be known to the skilled person as being likely to be more compatible with less polar or apolar topical therapeutic agents, dispersed within them. The cushioning device of this fourth embodiment of the the present invention may further comprise one or more surfactants. Such a surfactant will often be residues of a surfactant used in the process for producing the cushioning device. In a second aspect of the present invention, there is provided a process for the preparation of the cushioning device according to the first aspect of the present invention, characterised by reactive injection moulding or reactive casting of a monomeric or oligomeric precursor of the material of the cushioning device according to the present invention.

In a favoured embodiment of this second aspect of the present invention, the process for the preparation of the cushioning device is characterised by the crosslinking of a non-crosslinked monomeric or oligomeric precursor of the material of the cushioning device in the course of reactive injection moulding or casting.

The precursors of the materials of the cushioning device, may be based on non-crosslinked polydimethylsiloxanes which may optionally comprise a silicone oil, for example a linear polydimethylsiloxane,

SBES precursors that are alkylene oligomers of styrene, ethylene and butylene.

Favoured embodiments of the process are characterised by the crosslinking of a non-crosslinked, or monomeric or oligomeric precursor of a silicone-based gel material, such as one comprising one or more pharmaceutically acceptable crosslinked linear polydimethylsiloxanes, in the course of reactive injection moulding or casting. In the second embodiment of the first aspect of the present invention, where the cushioning device is shaped to conform in use to the body over a given area where cushioning device is needed, the cushioning device is often relatively thick. It may have an increased thickness at the point where it is required, for example to cushioning device the arch of the foot or where it is required to cushioning device the sacrum.

Advantageously, the process for the preparation of the cushioning device according to the first aspect of the present invention is then characterised by reactive injection moulding, for example of a room-temperature curing fluid precursor system, Where the cushioning device is made of a silicone-based gel, the process for the preparation of the cushioning device according to the first aspect of the present invention is then characterised by reactive injection moulding of a room- temperature curing fluid precursor system, such as a high purity catalyst-cure silicone.

Such a precursor system is typically supplied in two parts, with one of the parts containing the catalyst, which are then mixed with any other therapeutic agents which may be required, before injection moulding. The room-temperature curing fluid precursor system may be based on non-crosslinked polydimethylsiloxane, and may optionally comprise a platinum cure catalyst. The mould into which the fluid precursor system, such as a high purity platinum-cure silicone, is injected typically has proximal faces that are shaped to conform to the proximal face and the opposite distal face of the desired form of the cushioning device, and is often in two co-operating parts.

Where the cushioning device is not shaped to conform in use to the body over a given area where cushioning device is needed, the cushioning device is often relatively thin, and may have an essentially constant thickness. Advantageously, the process for the preparation of the cushioning device according to the first aspect of the present invention is then characterised by reactive casting, for example of a room-temperature curing fluid precursor system. Again, where the cushioning device is made of a silicone-based gel, the process for the preparation of the cushioning device according to the first aspect of the present invention is then also characterised by reactive casting of a room- temperature curing fluid precursor system, such as a high purity catalyst-cure silicone, typically supplied in two parts, with one of the parts containing the catalyst, which are then mixed with any other therapeutic agents which may be required, before casting.

The platen onto which the fluid precursor system, such as a high purity platinum- cure silicone, is cast typically has a flat face with a raised periphery or other appropriate means for containing the fluid precursor system shaped to conform to the desired form of the cushioning device. In either embodiment of the process for the preparation of the cushioning device according to the first aspect of the present invention, the plurality of channels running between the proximal face of the cushioning device and the opposite distal face, which facilitate improved sweat evaporation and diffusion through the cushioning device, may be formed in the material of the cushioning device according to the present invention by conventional processes which are well- known to the skilled person, or are described further in the patent or literature prior art. In particular, the proximal face of one of the parts of a two-part injection mould into which the fluid precursor system is injected, or the face of a platen onto which the fluid precursor system is cast, is typically provided with a plurality of elongate aciform (needle- or spike-like) extensions. These extensions respectively run between that proximal face of the two-part injection mould and the opposite proximal face of the other part of the mould when assembled for use, or project upwards from the face of the platen onto which the fluid precursor system is cast.

In both cases, the plurality of elongate aciform extensions thus form a negative facsimile of the desired plurality of channels in the cushioning device

As noted above, the cushioning device of the present invention may suitably comprise one or more therapeutic agents, preferably attached to or dispersed within the cushioning device, which preferably remain attached to or dispersed within the cushioning device and are not released sustainedly to the patient during treatment.

Any desired appropriate pharmaceutically acceptable therapeutic agents may conveniently be incorporated into the precursor of the material of the cushioning device according to the present invention. This is of course provided that any such precursor, for example of a silicone-based gel, thermoplastic polyurethane materials (which are preferred materials) or of an appropriate elastomer, is compatible with these pharmaceutically acceptable therapeutic agents. Favoured pharmaceutically acceptable therapeutic agents in the cushioning device include topical antimicrobials which remain attached to or dispersed within the cushioning device, and are not released sustainedly to the patient during treatment.

Accordingly, one embodiment of the process of the second aspect of the present invention, for the preparation of a cushioning device according to the first aspect of the present invention which comprises one or more topical therapeutic agents, attached to or dispersed within it, is characterised by

i) impregnating a cushioning device produced according to the above process of the present invention with one or more topical therapeutic agents, optionally in a fluid medium, or

ii) dispersing one or more topical therapeutic agents in a, typically fluid, precursor of the cushioning device, followed solidification of the precursor to form the cushioning device according to the above process of the present invention.

In the first variant above, where the cushioning device of the first aspect of the present invention is impregnated with the one or more therapeutic agents, this may be carried out by adding the one or more therapeutic agents to a length of the cushioning device, which is then passed through nip rollers, which impregnate the cushioning device with the one or more therapeutic agents, and remove any excess optional fluid from the cushioning device. In the second variant above, the one or more therapeutic agents are dispersed in a, typically fluid, precursor of the carrier, followed solidification of the precursor of the cushioning device to form the cushioning device, as described hereinbefore for the general preparative process of the second aspect of the present invention.

The process mixture in the general preparative process of the second aspect of the present invention in all its variants, preferably comprises one or more surfactants, to promote wetting of the carrier. Such a surfactant will often be a non-ionic surfactant with internal ether linkages, such as an alkylated polyglycoside or a polyalkoxylated alcohol, often one with 7 to 12 carbon atoms. Favoured surfactants thus include nonionic surfactants, such as polymeric material of which the largest part (by weight) consists of homo- or copolymers of oxyolefins such as oxyethylene, oxypropylene, oxybutylene or oxy-4-methyl-l- pentene. These may be polyoxyethylene alkyl ethers (Brij), for example of the formula: CH₃-(CH₂)io-i6-(O-C₂H₄) _25-OH, such as octaethylene glycol monododecyl ether and pentaethylene glycol monododecyl ether; and polyoxypropylene glycol alkyl ethers, for example of the formula: CH₃-(CH₂)io-i6-

Such nonionic surfactants preferably comprise residues of an oligosaccharide with alkylated hydroxyl functions, typically oligoglucoside alkyl ethers, for example decyl glucoside, dodecyl glucoside, octyl glucoside and decyl octyl glucoside (APG). These are often formed by an alkylation reaction between a function such as the anion of an alkali metal oxide, such as a sodium oxide group, in the oligosaccharide.

The precursor of the material of which the cushioning device is made, the therapeutic agent and the conditions of the process for the preparation of the cushioning device according to the first aspect of the present invention, should be chosen for the desired properties in use of the cushioning device for the release, or non-release, for example into a wound, of the therapeutic agents. This may be readily be done by means well-known to the skilled person and/or as described further hereinbefore for the corresponding cushioning devices of the present invention.

In a third aspect of the present invention, there is provided a method of treatment of pressure-sensitive parts of the human or animal body, characterised by applying a cushioning device according to the first aspect of the present invention to the body of a human or animal patient.

In one embodiment of a third aspect of the present invention, there is provided a method of treatment of pressure on pressure-sensitive parts of the human or animal body, characterised by applying a cushioning device according to the first aspect of the present invention to the body of a human or animal patient. In another embodiment of the third aspect of the present invention, there is provided a method of prophylaxis or treatment of wound precursors and/or chronic wounds, including pressure sores, ulcers and infected wounds, on or in the skin of humans or animals, or in the underlying tissue, characterised by applying a cushioning device according to the first aspect of the present invention to the body of a human or animal patient.

In a further embodiment of the third aspect of the present invention, there is provided a method of treatment of pressure on pressure-sensitive parts of the human foot, characterised by applying a cushioning device according to the first aspect of the present invention to the foot of a patient.

In another embodiment of the third aspect of the present invention, there is provided a method of prophylaxis or treatment of wound precursors and/or chronic wounds, including pressure sores, ulcers and infected wounds, on or in the human foot, characterised by applying a cushioning device according to the first aspect of the present invention to human foot.

In a further embodiment of the third aspect of the present invention, there is provided a method of prophylaxis or treatment of wound precursors and/or chronic wounds, including pressure sores, ulcers and infected wounds on or in the skin of humans and animals, or in the underlying tissue, characterised by applying a cushioning device according to the first aspect of the present invention to body of a human or animal patient, which cushioning device comprises one or more topical therapeutic agents, attached to or dispersed within it.

Preferably, the one or more topical therapeutic agents attached to or dispersed within the cushioning device are topical antimicrobials

It is desirable to minimise any microbial bioburden on or in the skin of humans and animals, or in the underlying tissue, which are in a particularly pressure- sensitive part of the body at risk of developing a wound precursor or wound on or in that skin or in the underlying tissue, by applying a topical antimicrobial and/or a topical antibiotic to that part of the body. Accordingly, in a yet further embodiment of the third aspect of the present invention, there is provided a method of prophylaxis or treatment of microbial infections on or in the skin of humans and animals, or in the underlying tissue, or wounds and wound precursors on or in the skin or in the underlying tissue, characterised by applying a cushioning device according to the first aspect of the present invention comprising one or more topical therapeutic agents attached to or dispersed within the cushioning device which are topical antimicrobial agents.

In another embodiment of the third aspect of the present invention, the cushioning device comprises one or more of the following pharmaceutically acceptable therapeutic agents: Cortisol; lidocaine; ibuprofen, diclofenac and capsaicin; bacitracin, neomycin, mupirocin, and polymyxin B;

In another embodiment of the third aspect of the present invention, the cushioning device comprises one or more of the following pharmaceutically acceptable therapeutic agents: emollients, antioxidants; lubricants; soothing therapeutic agents, topical antimicrobials; topical antibiotics, topical analgesics, topical anaesthetics and/or topical antiinflammatories.

The preparation of a cushioning device with a pharmaceutically acceptable therapeutic agent attached to and/or dispersed in the cushioning device, and the advantageous properties of cushioning devices according to the first aspect of the present invention are illustrated in the following Example:

Example

The moisture vapour permeability (MVP) of silicone gel cushioning devices of the present invention with a plurality of channels running within the cushioning device between the inner face and its opposite outer face and opening in a plurality of pores respectively on the inner face and its opposing outer face of the following mean density values and mean cross-sectional area values:

5 per cm² 1 mm²

2 5 per cm² 3.14 mm² were comparison tested against a corresponding cushioning device of the prior art with no such plurality of channels running within the cushioning device between the inner face and its opposite outer face and opening in a plurality of pores respectively on the inner face and its opposing outer face: .

Method

The temperature of an oven was set to 37°C, and its humidity was reduced using silica bags. Each dermal pad (cushioning device) sample was cut into discs of approximately 5cm in diameter. Paddington cups were labelled and the pads affixed to the upper flange with the wound contact surface facing inwards. The retaining ring was placed on each cup and secured. The empty cup and sample were then weighed (W-i) Solution A was then made up using the following measurements:

The cups were then filled with 10ml of Solution A, the base fixed in position and then were re-weighed (W₂). The cups were placed in the oven for 24 hours facing upwards to allow moisture vapour transmission. After 20 hours the cups were removed and able to equilibrate at room temperature for 30 minutes. The temperature of the oven was also recorded. Each sample was then re-weighed to give W₃. The results were then used to calculate the MVTR of each sample.

Results

Conclusion

The cushioning devices of the present invention have substantially higher moisture vapour permeability (MVP) in the range of 250 to 10 000 g/m²/24hr, than the corresponding cushioning device of the prior art with an MVP of 40 g/m²/24hr.

Claims

1 . A conformable cushioning device for application to a human or animal body, characterised by a plurality of channels running between the proximal face of the cushioning device, which in use is in direct or indirect contact with the skin of the human or animal body, and the opposite distal face.

2. A cushioning device as claimed in claim 1 , characterised in that the channels in the cushioning device are present at a mean area density of from 0.5 to 60 cm^"2

3. A cushioning device as claimed in claim 1 , characterised in that the channels in the cushioning device are present at a mean area density of from 3 to 7 cm ^"2.

4. A cushioning device as claimed in claim 1 , characterised in that the channels in the cushioning device have a mean cross-sectional area of from 1 to 5 mm².

5. A cushioning device as claimed in claim 1 , characterised in that the channels in the cushioning device have a mean cross-sectional area of from 2 to 4 mm².

6. A cushioning device as claimed in claim 1 , characterised in that the total cross-sectional open area of the pores in a surface into which the channels in the cushioning device open is from 5 to 25% of the area of that surface.

7. A cushioning device as claimed in claim 8, characterised in that the total cross-sectional open area of the pores in a surface into which the channels in the cushioning device open is from 10 to 20% of the area of that surface.

8. A cushioning device as claimed in claim 1 , characterised in that the channels in the cushioning device are all substantially straight.

9. A cushioning device as claimed in claim 1 , characterised in that the where the channels in the cushioning device open into pores in a surface that is substantially planar, they are all substantially at right angles to that surface, and so substantially parallel to each other.

10. A cushioning device as claimed in claim 1 , characterised in that the channels in the cushioning device are of substantially the same cross-sectional area as each other.

1 1 . A cushioning device as claimed in claim 1 , characterised in that the cushioning device has a thickness of from 0.1 to 5 cm.

12. A cushioning device as claimed in claim 1 , characterised in that the cushioning device has a moisture vapour permeability (MVP) in the range of 250 to 10 000 g/m²/24hr

13. A cushioning device as claimed in claim 1 , characterised in that the cushioning device has a moisture vapour permeability (MVP) in the range of 250 to 4 500 g/m²/24hr.

14. A cushioning device as claimed in claim 1 , characterised in that the cushioning device has a moisture vapour permeability (MVP) in the range of 250 to 2 500 g/m²/24hr.

15. A cushioning device as claimed in claim 1 , characterised in that the cushioning device has a thickness of from 0.1 to 5 cm.

16. A cushioning device as claimed in claim 1 , characterised in that the cushioning device is not shaped to conform in use to the body over a given area where cushioning is needed.

17. A cushioning device as claimed in claim 15, characterised in that the cushioning device has an essentially constant thickness in the range of from 0.3 to 0.5 cm.

18. A cushioning device as claimed in claim 1 , characterised in that the cushioning device is shaped to conform in use to the body over a given area where cushioning is needed.

19. A cushioning device as claimed in claim 18, characterised in that the cushioning device has a variable thickness ranging between from 0.3 to 5 cm.

20. A cushioning device as claimed in claim 1 , characterised by the cushioning device being made of a soft, almost viscous fluid-like plastics material.

21 .A cushioning device as claimed in claim 10, characterised in that it is made of a silicone-based gel.

22. A cushioning device as claimed in claim 10, characterised in that it is made of an elastomer based on a copolymer of styrene ethylene butylene styrene .

23. A cushioning device as claimed in claim 1 , characterised in that it is a conformable, relatively thin lamella of an essentially constant thickness, and is made of a silicone-based gel, a thermoplastic polyurethane, copolyester, polyamide, or combinations thereof, or an elastomer.

24. A cushioning device as claimed in claim 1 , characterised in that it is inherently self-adhesive to the skin of a human or animal patient.

25. A cushioning device as claimed in claim 1 , characterised in that it is shaped to conform in use to the body of a human or animal patient over a given area where cushioning device is needed.

26. A cushioning device as claimed in claim 1 , for use on the heel of the human foot, characterised by being shaped to extend in use from behind the heel and below both ankle protuberances and pass forwards under the heel.

27. A cushioning device as claimed in claim 1 , for use on the sole of the human foot, characterised by being shaped to extend in use from the lower back of the heel and below both ankle protuberances and pass forwards under the heel and the arch of the foot.

28. A cushioning device as claimed in claim 18, characterised by one or more pharmaceutically acceptable therapeutic agents attached to and/or dispersed in the cushioning device.

29. A cushioning device as claimed in claim 28, characterised in that the agent remains attached to or dispersed within the cushioning device in use.

30. A cushioning device as claimed in claim 1 , characterised in that the one or more pharmaceutically acceptable therapeutic agents are emollients, antioxidants; lubricants; soothing therapeutic agents, topical antimicrobials; topical antibiotics, topical analgesics, topical anaesthetics and/or topical antiinflammatories.

31 . A cushioning device as claimed in claim 1 , characterised in that it comprises one or more of Cortisol; lidocaine; ibuprofen, diclofenac and capsaicin; bacitracin, neomycin, mupirocin, and polymyxin B; chamomile and aloe vera; tea tree oil; skin lipids and sterols, cetyl alcohol, cyclomethicone, grape seed oil, dimethicone, and/or petrolatum.

32. A cushioning device as claimed in claim 1 , characterised in that the one or more pharmaceutically acceptable therapeutic agents are topical antimicrobials.

33. A cushioning device as claimed in claim 32, characterised in that the one or more topical antimicrobials are silver, silver salts, silver oxides, biocompatible quaternary ammonium salts, quaternary ammonium salts derivatised by being N-substituted by a tris(hydrocarbyl or hydrocarbyloxy)-silylhydrocarbyl group, and/or salts of guanidine-based compounds, diguanidine-based compounds and polymeric guanidine-based compounds.

34. A cushioning device as claimed in claim 32, characterised in that the one or more topical antimicrobials are colloidal silver, silver nanoparticles, silver sulfadiazine, silver nitrate, and/or silver oxides where the silver is in one of its higher oxidation states, 2 or 3.

35. A process for the preparation of a cushioning device according to claim 1 , characterised by reactive injection moulding or casting of a monomeric or oligomeric precursor of the material of the cushioning device according to the present invention.

36. A process according to claim 35, characterised by the crosslinking of a non- crosslinked monomeric or oligomeric precursor of the material of the cushioning device in the course of reactive injection moulding or casting.

37. A process according to claim 35, characterised by the crosslinking of a non- crosslinked monomeric or oligomeric precursor of a silicone-based gel material, comprising one or more pharmaceutically acceptable uncrosslinked linear polydimethylsiloxanes in the course of reactive injection moulding or casting.

38. A process according to claim 35, characterised by

i) impregnating a cushioning device produced according to the process of claim 34 with one or more topical therapeutic agents, optionally in a fluid medium, or

ii) dispersing one or more topical therapeutic agents in a fluid, precursor of the cushioning device, followed solidification of the precursor to form the cushioning device according to the process of claim 35.

39. A process according to claim 35, characterised by the presence of one or more surfactants.

40. A method of treatment of pressure on pressure-sensitive parts of the human or animal body, characterised by applying a cushioning device according to claim 1 to the body of a human or animal patient.

41 .A method of prophylaxis or treatment of wounds and wound precursors on or in the skin of a human or animal, or in the underlying tissue, characterised by applying a cushioning device according to claim 1 to body of a human or animal patient.

42. A method of treatment of pressure on pressure-sensitive parts of the human foot, characterised by applying a cushioning device according to claim 1 to the foot of a patient.

43. A method of prophylaxis or treatment of microbial infections on or in the skin of a humans or animal, or in the underlying tissue, or wounds and wound precursors on or in the skin or in the underlying tissue, characterised by applying a cushioning device according to claim 1 comprising one or more topical therapeutic agents attached to or dispersed within the cushioning device which are topical antimicrobial agents.