WO2017063036A1 - Remplissage de plaie pour traitement de plaie par pression négative - Google Patents

Remplissage de plaie pour traitement de plaie par pression négative Download PDF

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Publication number
WO2017063036A1
WO2017063036A1 PCT/AU2016/050956 AU2016050956W WO2017063036A1 WO 2017063036 A1 WO2017063036 A1 WO 2017063036A1 AU 2016050956 W AU2016050956 W AU 2016050956W WO 2017063036 A1 WO2017063036 A1 WO 2017063036A1
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WO
WIPO (PCT)
Prior art keywords
wound
fill material
wound filler
stiffener
filler according
Prior art date
Application number
PCT/AU2016/050956
Other languages
English (en)
Inventor
Jianhu SHEN
Arash GHAEDIZADEH
Yi Min Xie
Original Assignee
Rmit University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AU2015904144A external-priority patent/AU2015904144A0/en
Application filed by Rmit University filed Critical Rmit University
Publication of WO2017063036A1 publication Critical patent/WO2017063036A1/fr

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/05—Bandages or dressings; Absorbent pads specially adapted for use with sub-pressure or over-pressure therapy, wound drainage or wound irrigation, e.g. for use with negative-pressure wound therapy [NPWT]

Definitions

  • the present invention generally relates to a wound filler and associated wound closure arrangement for negative pressure wound therapy.
  • the invention is particularly applicable to treating a wound with negative pressure wound therapy system and it will be convenient to hereinafter disclose the invention in relation to that exemplary application.
  • the abdominal fascia can be closed primarily at the end of most surgical incisions into a patient's abdominal cavity. However, sometimes full fascial closure is not possible and the operating surgeon is forced to leave the abdomen open. Different techniques are employed in order to effect temporary abdominal closure. It should be noted that after temporary abdominal closure, the abdominal fascia must be closed primarily [See for example references 1 , 8 to 13].
  • NPVVT negative pressure wound therapy
  • the wound dressing typically comprises a non-adherent dressing film covering organs in a body (for example, in the abdomen) with a dressing or filler material seated on top of the film and fitted to the contours of a wound which is then sealed with a transparent film.
  • a drainage tube is connected to the dressing through an opening of the transparent film.
  • the vacuum pump is then used to apply sub-atmospheric pressure to the local wound environment and in some cases remove infective fluid and material from the wound thereby reducing the swelling size and removing exudates. This turns an open wound into a controlled, closed wound while removing excess fluid from the wound bed to enhance circulation and remove wound fluids.
  • NPVVT systems and associated NPVVT wound closure arrangements are currently known and used in clinical practice.
  • International patent publication no. WO2013/175309A1 teaches a negative pressure wound closure system and methods for using such a system.
  • the exemplified system comprises a porous wound fill material; and a plurality of stiffener elements configured to extend vertically when the wound filler is positioned within a wound bed, the stiffener elements being made of a more rigid material than the porous wound fill material.
  • the wound filler Upon application of negative pressure to the wound filler, the wound filler is configured to contract horizontally with the stiffener elements reducing vertical movement of the wound filler.
  • NPVVT systems which include a mechanical support member and a cover member positionable over the wound in use.
  • the support member comprises a hingable framework having moveable arms which extend over the cover member to support at least a middle portion of the cover member above a surface of the wound and define a space between the wound cover and the wound.
  • the drawback of these and other existing NPWT systems include: (1 ) high cost of the device; (2) invasiveness of the procedure; (3) detrimental pressure on the abdominal contents from the bow stringing effect; and (4) poor cosmesis of the healed wound geometric complexity. Accordingly, the use of NPWT systems in wound therapy applications is still very limited.
  • a first aspect of the present invention provides a wound filler for use in treating a wound with negative pressure comprising:
  • porous wound fill material having an inner side designed to face a wound and an opposite outer side;
  • stiffener elements located within the wound fill material, the stiffener elements extending between the inner side and the outer side of the wound fill material and arranged in a two dimensional pattern across the width and length of the wound fill material, the stiffener elements comprising a more rigid material than the porous wound fill material,
  • stiffener elements are arranged between 5 to 25 degree angle to the vertical within the wound fill material when the wound filler is positioned within a wound bed.
  • This first aspect of the present invention therefore comprises a wound filler useful in treating large wounds, such as abdominal wounds, with negative pressure wound therapy (NPWT), where closure and approximation of the wound edges are challenging.
  • the wound filler is configured to provide selective stiffness and deformation.
  • Desired closure deformation of a wound is lateral contraction, without changing the height of the wound.
  • the present invention provides vertical stiffness to avoid vertical or height deformation of the wound closure arrangement using a specific matrix of stiffener elements with specific shapes and a cover member of foam which is positionable inside the wound in use. In the absence of stiffener elements, the lack of enough stiffness would cause the top and bottom surfaces of the wound filler to draw into the cavity and the height of the wound to change.
  • the stiffener elements support at least a middle portion of the foam cover member above a surface of the wound.
  • the angled stiffener elements can advantageously impart a negative linear compressibility (NLC) property to the wound filler when positioned within a wound bed, in which the wound filler expands vertically when laterally (or horizontally) compressed when negative pressure is applied.
  • NLC negative linear compressibility
  • compressibility is a measure of the relative volume change of a solid or fluid as a response to a pressure change. Usually a material contracts in all directions when the pressure increases. However, there are some exceptional materials which expand under hydrostatic pressure in one or two directions. Such phenomena are known as negative linear compressibility (NLC) and negative area compressibility (NAC), respectively.
  • the term “horizontal,” when referring to a wound and the associated wound bed indicates a direction or plane generally parallel to the skin surrounding the wound.
  • vertical when referring to a wound and associated wound bed, generally refers to a direction extending perpendicular to the horizontal plane.
  • longitudinal when referring to a wound and associated wound bed, generally refers to a direction in the horizontal plane taken in a direction along which the wound is longest.
  • lateral when referring to a wound and associated wound bed, generally refers to a direction in the horizontal plane perpendicular to the longitudinal direction.
  • the angle of the stiffener elements to the vertical direction is important to the NLC property of the wound filler.
  • the angle is preferably an acute angle.
  • the stiffener elements are arranged between a 5 to 20 degree angle, preferably a 5 to 15 degree angle to the vertical within the wound fill material when the wound filler is positioned within a wound bed.
  • the stiffener elements are arranged at about a 10 degree angle to the vertical within the wound fill material when the wound filler is positioned within a wound bed.
  • each angled stiffener element can be optimised relative to compression direction in a wound bed to provide an advantageous NLC property.
  • the wound filler is configured to be laterally compressed, and each stiffener element is preferably angled within the wound fill material along an axis which extends parallel to the axis of compression of the wound filler when the wound filler is positioned within a wound bed.
  • the axis of compression of the wound filler generally aligns with the axis of closure of the wound (i.e. the horizontal axis of the wound and wound bed).
  • each stiffener element is preferably angled within the wound fill material along an axis which extends parallel to the axis of closure of the wound filler when the wound filler is positioned within a wound bed.
  • the axis of compression is aligned with the general direction of closure of a wound (and thus the axis of closure of the wound). This direction of closure is generally perpendicular to the longitudinal length of a wound.
  • the filler material has a longitudinal axis generally aligned with the length of a wound bed and a lateral (or horizontal) axis generally aligned with the width of a wound bed, each stiffener element being preferably angled within the wound fill material along an axis which extends parallel to the lateral axis of the filler material. This alignment locates each angled stiffener element along the wound closure direction.
  • the wound filler contracts horizontally (generally along the lateral axis).
  • the stiffener elements become more vertical, resisting vertical movement of the wound fill material.
  • the alignment of each angled stiffener element ensures that compaction of the wound filler along the lateral axis impacts each angled stiffener element, forcing each stiffener element to undergo torsional forces along its length.
  • the acute angle i.e.
  • each stiffener element ensures that each stiffener element twists or rotates in the compacted wound filler towards the surfaces of the inner and the outer sides of the porous wound fill material resulting in a negative linear compression property in the wound filler.
  • the stiffener elements comprise an element, preferably an elongate element which is more rigid than the fill material. In some embodiments, the stiffener elements are between 1 to 2 times, between 2 to 4 times, between 4 to 6 times, between 6 to 8 times, or 8 times or more rigid than the porous wound fill material. The stiffener elements may also be denser than the wound fill material. In some embodiments, the stiffener elements are between 1 to 2 times, between 2 to 4 times, between 4 to 6 times, between 6 to 8 times, or 8 times or more dense than the wound fill material. In some embodiments, each stiffener element preferably has a stiffness of at least 80 kPa, preferably at least 100 kPa. In one preferred embodiment, stiffener elements have a stiffness of 5 to 10 times that of the porous wound fill material.
  • the stiffener elements can be made from; rigid plastics, such as polystyrene, polycarbonate, poiy(meth)acrylates; semirigid materials, such as silicone; rigid foams; or felted flexible foams.
  • felted flexible foams can be made by subjecting flexible foams, e.g. those used as the porous compressible filler, to heat and pressure to produce a dense, semi-rigid foam that is still porous. Such a configuration can also enhance horizontal movement so as to permit greater wound closure.
  • the stiffener elements can have any suitable configuration.
  • the stiffener elements are elongate.
  • the stiffener elements may comprise struts, rods, planks, slabs, columns or tiles.
  • the stiffener elements may be parallel or substantially parallel to one another, and may be spaced apart either equally or unequally. In horizontal cross-section each of the stiffener elements may have the same thicknesses, or alternatively, they may have different thicknesses. In vertical cross-section, the stiffener elements may have the same vertical height or length, or may have different vertical heights or lengths,
  • the stiffener elements function to resist vertical (height) compression of the wound fill material when laterally compressed.
  • the porous wound fill material preferably surrounds and extends between each of the stiffener elements.
  • the stiffener elements are preferably configured to engage or be bonded to the surrounding porous wound fill material.
  • each stiffener element includes at least one attachment arrangement for engagement with the porous wound fill material. This enables the stiffener element to attach and/or engage with the surrounding porous wound fill material.
  • Each stiffener element can include any number of attachment arrangements of a variety of configurations and forms.
  • the attachment arrangement comprises a plurality of engagement portions spaced apart along the length of the stiffener.
  • Suitable engagement portions include a bump, bunch, eaves, extension, hook, jut, knob, ledge, outthrust, point, prolongation, prominence, protrusion, protuberance, ridge, rim, shelf, sill, spine, spur, step or swelling.
  • the engagement portion comprises at least one of a ledge, hook, flange, bulb, protrusion, spur, step, ridge, bump, spine or projection, including radial or annular projections.
  • the stiffener elements can be housed within a slit or aperture within the porous wound fill material. This allows the stiffener elements to be formed separately to the porous wound fill material and then be inserted or otherwise located into the slit or aperture formed within the porous wound fill material.
  • the stiffener elements can be adhered with the wound fill material using an adhesive. Suitable adhesives would be selected to be compatible with the porous wound fill material.
  • the stiffener elements can be positioned in any suitable two dimensional pattern (for example, an array) across the width and length of the wound fill material.
  • the locations of the stiffeners in the array can be identified from Archimedean Lattices, in which all polygons are regular and each vertex is surrounded by the same sequence of polygons.
  • the stiffener elements are positioned in a two dimensional array or across the width and length of the wound fill material. A number of different arrays are possible, including (but not limited to) a honeycomb pattern, a triangular pattern, a kagome pattern, a snub square pattern or a rhombitrihexagonal pattern.
  • the porous wound fill material may comprise a material which does not provide sufficient compressibility to provide a suitable wound closure ratio (which is typically greater than 50%).
  • a softer and/or more compressible porous wound fill material could be selected or alternatively the construction/configuration of the wound filler could be modified.
  • the wound filler can further include a plurality of apertures extending through the wound fill material between the inner side and the outer side of the wound fill material, the apertures arranged about the stiffener elements across the width and length of the wound fill material in a complementary pattern to the two dimensional pattern of stiffener elements. The apertures assist in horizontal contraction/ compression of the fill material.
  • the apertures are preferably positioned in the wound fill material between the stiffener elements to facilitate lateral movement of the stiffener elements towards each other upon lateral compression of the wound fill material.
  • lateral compression of the wound filler is enhanced when the wound filler, positioned within a wound bed, is placed under negative pressure.
  • the apertures can be positioned in the wound fill material between the stiffener elements in any suitable configuration which assists horizontal or lateral compression of the wound filler.
  • the plurality of stiffener elements and the plurality of apertures are arranged in respective complementary two dimensional arrays across the width and length of the wound fill material. These respective complementary arrays preferably position the apertures proximate respective stiffener elements to counteract the negative effect of proximate stiffener elements on closure ratio of the wound filler.
  • a number of different arrays are possible, including (but not limited to) a honeycomb pattern, a triangular pattern, a kagome pattern, a snub square pattern or a rhombitrihexagonal pattern.
  • each stiffener element is spaced apart from an adjoining stiffener within the wound fill material by at least one aperture. Each aperture therefore counteracts the effects of each adjoining stiffener element.
  • Each aperture preferably extends vertically through the wound fill material between the inner side and the outer side of the wound fill material when the wound filler is positioned within a wound bed.
  • each aperture comprises a substantially perpendicular opening relative to the surface plane of the inner and outer sides extending through the thickness of the wound fill material.
  • the apertures can have a variety of shapes and configurations.
  • the apertures comprise a plurality of slits.
  • the apertures comprise at least one of a rectangular, square, circular, oval, ellipse, arch, lens, crescent, stadium or trapezium shape.
  • the apertures have a width to height ratio of greater than 1 .5: 1 , preferably greater than 2:1 , more preferably greater than 3: 1.
  • the apertures can be formed as discontinuous voids throughout the height of the porous wound fill material.
  • the aperture can therefore comprise two or more voids extending through the height of the porous wound fill material configured to facilitate lateral movement of the stiffener elements towards each other upon lateral compression of the wound fill material.
  • the wound filler is configured to be laterally compressed, and the width of the apertures are arranged along an axis which extends parallel to the axis of compression of the wound filler when the wound filler is positioned within a wound bed. Compression of the wound filler along the compression axis of the material (and closure axis of the wound) causes the apertures to expand about their height and contract about their width, enhancing compression and deformation of the wound filler.
  • the term "fill material” comprises, in a non- limiting manner, porous wound fill materials and flexible materials.
  • compressible materials are included within the scope of flexible materials.
  • the wound fill material can comprise open-celled and reticulated foam.
  • the wound fill material comprises polymer foam, preferably polyurethane, silicone or polyvinyl alcohol.
  • at least a portion of the wound fill material has a pore size of from 200 to 600 Mm, preferably from 200 to 500 Mm, more preferably from 400 to 600 Mm. This pore size is suitable for liquid suction. Examples of a suitable foam based wound fill material are commercially available as medical grade black foam from Smith&Nephew or V.A.C Granufoam.
  • a second aspect of the present invention provides a wound filler for use in treating a wound with negative pressure comprising:
  • porous wound fill material having an inner side designed to face a wound and an opposite outer side;
  • stiffener elements located within the wound fill material, the stiffener elements extending between the inner side and the outer side of the wound fill material and arranged in a two dimensional pattern across a width and length of the wound fill material, the stiffener elements comprising a more rigid material than the porous wound fill material;
  • a plurality of apertures extending through the wound fill material between the inner side and the outer side of the wound fill material, the apertures arranged about the stiffener elements across the width and length of the wound fill material in a complementary pattern to the two dimensional pattern of stiffener elements.
  • This second aspect of the present invention also comprises a NPWT wound filler useful in treating large wounds, such as abdominal wounds, where closure and approximation of the wound edges is challenging.
  • the wound filler is configured to provide selective stiffness and deformation. Improved wound closure can be obtained by limiting vertical deformation of the wound filler and enhancing the horizontal collapse of the wound filler using apertures.
  • desired closure deformation of a wound is lateral contraction, without changing the height of the wound filler and hence the height of the wound.
  • the present invention provides vertical stiffness to avoid vertical or height deformation of the wound closure arrangement using a specific matrix of stiffener elements with specific shapes and a cover member of foam which is positionable inside the wound in use. Again, the stiffener elements support at least a middle portion of the cover member above a surface of the wound.
  • the porous wound fill material also contains regular specific matrix vertical apertures designed to counteract the negative effect of stiffener elements on the closure ratio of the wound filler.
  • the wound closure arrangement which includes the wound filler
  • the wound filler contracts horizontally with the stiffener elements resisting vertical movement of the wound fill material and the aperture assisting horizontal contraction/compression of the wound closure arrangement.
  • the angle to the vertical of the stiffener elements is reduced; that is, the stiffener elements become more vertically aligned as the wound filler is laterally compressed.
  • the apertures are positioned in the wound fill material to counteract the negative effect of stiffener elements on the closure ratio of the wound filler.
  • the apertures are preferably positioned in the wound fill material between the stiffener elements to facilitate lateral movement of the stiffener elements towards each other upon lateral compression of the wound fill material.
  • lateral compression of the wound filler is enhanced when the wound filler is positioned within a wound bed and is placed under negative pressure.
  • the apertures can be positioned in the wound fill material between the stiffener elements in any suitable configuration which assists horizontal or lateral compression of the wound filler.
  • the plurality of stiffener elements and the plurality of apertures are arranged in respective complementary two dimensional arrays across the width and length of the wound fill material.
  • the respective complementary arrays preferably position each aperture proximate respective stiffener elements to counteract the negative effect of proximate stiffener elements on the closure ratio of the wound filler.
  • a number of different arrays are possible, including (but not limited to) a honeycomb pattern, a triangular pattern, a kagome pattern, a snub square pattern or a rhombitrihexagonal pattern.
  • each stiffener element is spaced apart from an adjoining stiffener within the wound fill material by at least one aperture. Each aperture therefore counteracts the effects of each adjoining stiffener element.
  • Each aperture preferably extends vertically through the wound fill material between the inner side and the outer side of the wound fill material when the wound filler is positioned within a wound bed.
  • each aperture comprises a substantially perpendicular opening relative to the surface plane of the inner and outer sides extending through the thickness of the wound fill material.
  • the apertures can be formed as discontinuous voids throughout the height of the porous wound fill material. The aperture can therefore comprise two or more voids extending through the height of the porous wound fill material configured to facilitate lateral movement of the stiffener elements towards each other upon lateral compression of the wound fill material.
  • the apertures can have a variety of shapes and configurations.
  • the apertures comprise a plurality of slits.
  • the apertures comprise at least one of a rectangular, square, circular, oval, ellipse, arch, lens, crescent, stadium or trapezium shape.
  • the apertures have a width to height ratio of greater than 1 .5: 1 , preferably greater than 2: 1 , more preferably greater than 3: 1 .
  • the wound filler is configured to be laterally compressed, and the width of the apertures are arranged along an axis which extends parallel to the axis of compression of the wound filler when the wound filler is positioned within a wound bed. Compression of the wound filler along the compression axis of the material (and closure axis of the wound) causes the apertures to expand about their height and contract about their width, enhancing compression and deformation of the wound filler.
  • fill material comprises, in a non-limiting manner, porous wound fill materials and flexible materials.
  • compressible materials are included within the scope of flexible materials.
  • the wound fill material can comprise an open-cell and reticulated foam.
  • the wound fill material comprises polymer foam, preferably polyurethane, silicone or polyvinyl alcohol.
  • at least a portion of the wound fill material has a pore size of from 200 to 600 pm, preferably from 200 to 500 pm, more preferably from 400 to 600 pm. This pore size is suitable for liquid suction.
  • suitable foam based wound fill materials are commercially available as medical grade black foam from Smith&Nephew or V.A.C Granufoam.
  • the stiffener elements may be orientated in any orientation within the porous wound fill material.
  • the stiffener elements are preferably arranged between 0 to 25 degree angle to the vertical within the wound fill material when the wound filler is positioned within a wound bed.
  • the stiffener elements are configured to extend vertically when the wound filler is positioned within a wound bed.
  • the stiffener elements extend at an angle from the horizontal or vertical plane of the wound.
  • stiffener elements extend at between 5 to 25 degree angle, preferably 5 to 15 degree angle to the vertical within the wound fill material when the wound filler is positioned within a wound bed.
  • the 5 to 25 degree angle to the vertical advantageously imparts a NLC property to the wound filler, in which the wound filler expands vertically when laterally (or horizontally) compressed when negative pressure is applied when positioned within a wound bed.
  • the stiffener elements are arranged at about 10 degree angle to the vertical within the wound fill material when the wound filler is positioned within a wound bed.
  • the wound filler is preferably configured to be laterally compressed, and each stiffener element is therefore preferably angled within the wound fill material along an axis which extends parallel to the axis of compression of the wound filler when the wound filler is positioned within a wound bed.
  • the axis of compression is aligned with the general direction of closure of a wound.
  • the above stiffener element alignment locates each angled stiffener element along the direction of closure of the wound.
  • the wound filler contracts horizontally (generally along the lateral axis) with the stiffener elements resisting vertical movement of the wound fill material.
  • the alignment of each angled stiffener element ensures that compaction of the wound fill material along the lateral axis impacts each angled stiffener element, forcing each stiffener element to undergo torsional forces along its length.
  • the acute angle i.e.
  • each stiffener element ensures that each stiffener element twists or rotates in the compacted wound filler towards the surfaces of the inner and outer sides of the porous filler material resulting in a negative linear compression property in the wound filler.
  • the present invention also relates to a wound closure arrangement which incorporates the wound filler of the present invention.
  • a third aspect of the present invention provides a wound closure arrangement for negative pressure wound therapy comprising:
  • a dressing film sized and configured to cover a selected wound
  • a wound filler according to the first or second aspect of the present invention sized to fit to the contours of the wound and seated on top of the dressing film
  • the wound closure arrangement further comprises a connection for connecting the wound cover to a source of negative pressure.
  • the wound closure arrangement further comprises a negative pressure source configured to be connected to the wound cover to provide negative pressure to the wound filler when placed within the wound bed.
  • a negative pressure source for example a vacuum pump
  • a vacuum pump can be fitted to control the pressure in the abdomen cavity of a patient having the wound to be treated.
  • the present invention also relates to a method of treating a wound using the wound filler of the present invention.
  • a fourth aspect of the present invention provides a method of treating a wound, comprising:
  • Figures 1 (a) to 1 (c) provide a cross-sectional schematic diagram of a wound filler according to an embodiment of the present invention showing: 1 (a) the elements of the wound filler; 1 (b) loading of the wound filler when negative pressure is applied in normal (or expanded) state; and 1 (c) configuration of the wound filler in a compressed state, i.e. when compressed by the forces shown in 1 (b).
  • Figure 2A shows an abdomen wound which can be treated using a wound treatment arrangement which includes a wound filler of the present invention.
  • Figure 2B shows a schematic diagram of the wound filler shown in Figure 1 used in-situ in a wound as temporary wound closure using NPVVT.
  • Figure 3 provides a photograph of a black foam made by Smith&Nephew which can be used as a wound fill material in the wound filler shown in Figures 1 and 2.
  • Figure 4A illustrates the shape of a first form of stiffener element which can be used in a wound filler of the present invention.
  • Figures 4B and 4C show different views of the stiffener element of Figure 4A.
  • Figures 5A and 5B illustrates the shape of still other forms of stiffener element which can be used in a wound filler of the present invention.
  • Figure 6 is a photograph showing two stiffener elements placed inside the black foam shown in Figure 3; the stiffener elements are placed in the foam block with a 10 degree angle to the vertical.
  • Figures 7A to 7E provide examples of the layout pattern of stiffener elements within the porous wound fill material, specifically: (7A) a honeycomb pattern (or array); (7B) a kagome pattern; (7C) a triangular pattern; (7D) a snub square pattern; and (7E) a rhombitrihexagonal pattern.
  • Figures 8A to 8D illustrate: (8A) a top view of the matrix or array of apertures; (8B) a top view of the matrix or array of stiffener elements; (8C) a top view when the arrays of apertures and stiffener elements are combined; and (8D) a lateral cross-sectional view of the wound filler according to one embodiment of the wound filler according to the present invention.
  • Figure 9 provides a photograph of a first experimental form of the wound filler according to the present invention.
  • Figures 10A to 10C illustrate a finite element (FE) model and deformation features of a simplified wound filler according to the present invention when placed under uniform external pressure, showing: (10A) a quarter model; (10B) a full model without pressure; and (10C) a model deformed under pressure loading.
  • FE finite element
  • Figure 1 1 illustrates a NPWT procedure for an open abdomen using the wound filler according to the present invention.
  • Figure 12 shows the loading condition and preferred deformation pattern for a wound filler according to the present invention when used in the NPWT procedure shown in Figure 1 1 .
  • Figures 13A to 13D illustrate a wound simulation arrangement for testing a wound filler using a NPWT procedure, in which a wound shaped cut is made into a cavity of a silicone block, showing the steps of: (13A) drawing a straight line which represents the length of the wound; (13B) cutting along the straight line; (13C) pulling the edges of the wound apart to identify the appropriate shape and size of the mimetic wound; and (13D) finding a template for the wound cavity.
  • Figures 14A to 14E show: (14A) a schematic view of a silicone wound model and the position of an elliptical cavity inside it; (14B) a front view of the silicone wound model and the position of a hole in which to place a plastic connector; (14C) a dimensioned template for making the cavity inside the wound model; (14D) a final shape of a mimetic silicone wound; and (14E) a closure pattern of the mimetic silicone wound.
  • Figure 15 illustrates the experimental set-up of the wound simulation arrangement shown in Figures 13A to 13D.
  • Figure 16 illustrates the cutting process of an experimental wound filler specimen for use in the experimental set-up of the wound simulation arrangement shown in Figure 15.
  • Figures 17A to 17F show the closure pattern of test specimens in the wound simulation arrangement shown in Figure 15 under negative pressure of approximately 100 mmHg, showing: ( Figure 17A) - a simple black foam before testing; ( Figure 17B) - a stiff square metalic plate inside the wound before testing; ( Figure 17C) - a black foam with stiffeners and voids before testing; ( Figure 17D) - the arrangement of Figure 17A under pressure of 100 mmHg; ( Figure 17E) - the arrangement of Figure 17B under pressure of 100 mmHg; and (Figure 17F) - the arrangement of Figure 17C under pressure of 100 mmHg.
  • Figure 18 provides a plot of the variation of closure ratio of the silicone wound filled with the wound fillers shown in Figures 3, 9, 10 and 17B under different negative pressures.
  • wound is to be broadly construed and encompasses open and closed wounds in which skin is torn, cut or punctured, or where trauma causes a contusion, or any other superficial or other conditions or imperfections on the skin of a patient or otherwise that benefit from reduced pressure treatment.
  • a wound is thus broadly defined as any damaged region of tissue where fluid may or may not be produced.
  • wounds include, but are not limited to, acute wounds, chronic wounds, surgical incisions and other incisions, subacute and dehisced wounds, traumatic wounds, flaps and skin grafts, lacerations, abrasions, contusions, burns, diabetic ulcers, pressure ulcers, stoma, surgical wounds, trauma and venous ulcers or the like.
  • the components of the negative pressure treatment system described herein can be particularly suited for incisional wounds that exude a small amount of wound exudate.
  • reduced or negative pressure levels represent pressure levels that are below standard atmospheric pressure, which corresponds to 760 mmHg (or 1 atm, 29.93 inHg, 101 .325 kPa, 14.696 psi, etc.).
  • a negative pressure value of -X mmHg reflects absolute pressure that is X mmHg below 760 mmHg or, in other words, an absolute pressure of (760-X) mmHg.
  • negative pressure that is "less” or "smaller” than X mmHg corresponds to pressure that is closer to atmospheric pressure (e.g., -40 mmHg is less than -60 mmHg).
  • Negative pressure that is "more” or "greater” than -X mmHg corresponds to pressure that is further from atmospheric pressure (e.g., -80 mmHg is more than -60 mmHg).
  • the present invention provides a wound filler, and a wound closure arrangement which includes the wound filler for use in treating a wound with reduced pressure, known as negative pressure wound therapy (NPWT).
  • NGWT negative pressure wound therapy
  • the present invention encompasses the wound filler, associated wound dressing components, pump, apparatus and related arrangements.
  • the wound filler of the present invention has two important aspects:
  • the wound filler of the present invention relates to a wound filler which includes a porous wound fill material having an inner side designed to face a wound and an opposite outer side and a plurality of stiffener elements located within the wound fill material.
  • the stiffener elements comprise a more rigid material than the porous wound fill material extending between the inner side and the outer side of the wound fill material to provide vertical stiffness to avoid vertical or height deformation of the wound closure arrangement.
  • the stiffener elements are arranged in a two dimensional pattern, preferably a two dimensional array across the width and length of the wound fill material and are arranged between 5 to 25 degree angle to the vertical within the wound fill material when the wound filler is positioned within a wound bed.
  • Each stiffener element is also preferably angled within the wound fill material along an axis which extends parallel to the axis of closure of the wound filler when the wound filler is positioned within a wound bed.
  • each stiffener element When negative pressure is applied to a wound closure arrangement, which includes the wound filler, the wound filler contracts horizontally with the stiffener elements resisting vertical movement of the wound fill material.
  • the acute angle (i.e. 5 to 25 degrees to the vertical within a wound bed) of each stiffener element ensures that each stiffener element twists or rotates in the compacted wound filler towards the surfaces of the inner and outer sides of the porous wound fill material resulting in a negative linear compression property in the wound filler. That is, the acute angle of the stiffeners reduces when the wound filler contracts horizontally.
  • the wound filler of the present invention relates to a wound filler which includes a porous wound fill material having an inner side designed to face a wound and an opposite outer side and a plurality of stiffener elements located within the wound fill material.
  • the stiffener elements comprise a more rigid material than the porous wound fill material extending between the inner side and the outer side of the wound fill material to provide vertical stiffness to avoid vertical or height deformation of the wound closure arrangement.
  • a plurality of apertures is also provided which extend through the wound fill material between the inner side and the outer side of the wound fill material.
  • the apertures are arranged about the stiffener elements across the width and length of the wound fill material in a complementary pattern to the two dimensional pattern of stiffener elements.
  • the apertures are positioned in the wound fill material to counteract the negative effect of stiffener elements on a closure ratio of the wound filler.
  • Each of these aspects of the present invention provides a wound filler with improved closure properties.
  • the first aspect of the present invention provides a wound filler with a NLC property.
  • the second aspect of the present invention provides a wound filler having improved closure properties.
  • each aspect of the present invention and the associated embodiments including the wound fillers described herein may be used in combination with a negative pressure system comprising at least one drape or wound cover placed over the wound filler.
  • a vacuum source such as a pump, may be connected to the cover, for example, through one or more tubes connected to an aperture or port made in, or under the cover.
  • the apparatuses and components comprising the wound overlay and packing materials, if any, are sometimes collectively referred to herein as dressings. Examples of these systems are published in United States patent publication nos. US201 1/0213287 and US201 1/0282309, the contents of which should be understood to be incorporated into the present specification by these references.
  • FIG. 1 there is shown a series of width wise cross- sectional views of a wound filler 100 according to one embodiment of the present invention for use in treating a wound with negative pressure.
  • the illustrated wound filler comprises a number of interacting elements, namely:
  • a block of porous wound fill material 102 A block of porous wound fill material 102;
  • a specific matrix of elongate stiffener elements 104 which extend through the porous wound fill material 102 between an upper side 106 and a lower side 108 thereof at an angle (between 5 and 20 degrees, and more preferably about 10 degrees) positioned and configured to maintain the vertical height of the wound filler;
  • a specific matrix of vertical apertures or voids 1 10 which extend through the porous wound fill material 102 between the upper side 106 and the lower side 108 thereof and are positioned and configured to counteract the negative effect of stiffener elements on a closure ratio.
  • Sufficient wound closure ratio of preferably above 50%.
  • the minimum closure ratio requirement is preferably 50% at a pressure of 120 mmHg;
  • the wound filler 100 is used for negative pressure wound therapy of a wound; for example, an abdominal wound 120 is shown in Figure 2A and the abdominal wound with wound filler inserted in the wound is shown in Figure 2B.
  • this type of abdominal wound 120 has a longitudinal direction or axis L which follows the length of the wound 120, a horizontal direction or axis H which is generally perpendicular to the longitudinal axis L and defines the direction of desired closure of the wound, and as shown in Figure 2B a vertical height or axis V, defining the depth of the wound within a patient.
  • Figure 2B shows a wound filler 100 placed within a wound 120 such that the edges of the wound 120 surround and contact the edges of a wound closure arrangement which includes the wound filler 100.
  • the wound filler 100 shown in Figures 1 (a) to 1 (c) and Figure 2B is used in a layered structure in a wound (for example, abdominal wound 120) where the wound filler 100 is placed between a wound bed layer (not shown) which contacts the wound and a wound cover layer (also not shown) which extends over the top of the wound filler 100.
  • a negative pressure is then applied to the wound cover layer.
  • the application of negative pressure causes the wound filler 100 to contract horizontally with the stiffener elements 104 reducing vertical movement of the wound fill material 102 and the apertures 1 10 assisting horizontal contraction/compression of the wound filler 100.
  • the net pressure on the wound filler 100 is the combination of the pressures induced by negative pressure and the forces from the wound bed layer and wound cover layer surrounding the wound filler 100.
  • Figure 1 (b) when negative pressure is applied in a normal (or expanded) state, loading of the wound filler is from the wound bed layer below 1 14, the wound cover layer above 1 15 and wound edges from the side 1 16.
  • Figure 1 (c) shows the configuration of the wound filler 100 in a compressed state, i.e. when compressed by the forces shown in Figure 1 (b).
  • each angled stiffener element 104 is angled within the wound filler 100 and corresponds with the horizontal axis H and direction of closure of the wound (as shown in Figure 2A).
  • a wound closure arrangement which includes the wound filler 100 as shown in Figures 1 (b) and 1 (c)
  • the wound filler 100 contracts horizontally (generally along the width or lateral axis) with the stiffener elements 104 resisting vertical movement of the wound fill material 102.
  • the alignment of each angled stiffener element 104 ensures that compaction of the wound fill material 102 along the lateral axis impacts each angled stiffener element, forcing each stiffener element to undergo torsional forces along its length.
  • each stiffener element 104 results in each stiffener element twisting or rotating in the compacted wound filler towards the surfaces of the lower 108 and the upper 106 sides of the wound fill material 102 resulting in a NLC property in the wound filler 100.
  • each stiffener element 104 ends up in a substantially vertical orientation within the wound fill material 102 as shown in Figure 1 (c).
  • the wound fill material 102 is preferably constructed from a porous material, for example foam, that is soft, resiliently flexible, and generally conformable to the wound site.
  • Suitable foam materials include open-celled and reticulated foam. These foams can be made, for example, of a polymer, such as, for example, polyurethane, silicone, and polyvinyl alcohol foams.
  • Foam is one of the best dressings used in wound management because it can be used for lightly, moderately or heavily exuding wounds. Foams offer advantages over traditional gauze dressings because they do not shed particles and can be left in place for several days without causing maceration.
  • a foam fill material has the following advantages: (1 ) it removes excess exudate and toxic components; (2) it maintains high humidity at the wound/dressing interface; (3) it permits gaseous exchange; (4) it provides thermal insulation protection from secondary infection; (5) it protects from particulate or toxic contamination; and (6) it allows removal without trauma at dressing changes.
  • the foam used in the present invention preferably has at least a portion having a pore size suitable for liquid suction.
  • the size of the pores for the uniformed wound filler should be in the range of 200 to 600 Mm, preferably 200 to 500 pm.
  • only a portion of the foam includes pores having the above size requirement, with the remainder being formed from other materials, for example, a large void or voids or a solid material or blocks.
  • Suitable foam wound fill materials are commercially available for negative pressure wound therapy, for example, V.A.C.® Therapy available from KCI and RenasysEZ available from Smith&Nephew.
  • One suitable product shown in Figure 3 is a black foam 130 made by Smith&Nephew.
  • the stiffener elements 104 of the wound filler 100 typically comprise an elongate element which is more rigid than the fill material, and preferably a material that is denser than the fill material. Suitable materials include: rigid plastics, such as polystyrene, polycarbonate and poly(meth)acrylates; semi-rigid materials, such as silicone; rigid foams; and felted flexible foams.
  • the stiffener elements are formed from plastic having a stiffness of at least 80 kPa. In an alternate preferred embodiment, the stiffener elements are 5 to 10 times the stiffness of the wound fill material. However, it should be appreciated that other materials could be used which have sufficient stiffness and are produced to a suitable medical grade.
  • FIGs 4 and 5 illustrate embodiments of stiffener elements 104 used in the wound filler 100 of the present invention.
  • the stiffener elements 104A, 104B, 104C may have a rectangular cross- section in both horizontal and vertical cross-section, where the horizontal length is greater than the thickness, and the vertical height is greater than the thickness.
  • the stiffener elements 104A and 104B illustrated in Figures 4A and 4B comprise a rectangular element.
  • the stiffener elements may comprise solid rectangular bars 124 (as shown in Figure 4B, top two stiffener elements) or (for example, 104A) may include a plurality of apertures 125 (as also shown in Figure 4B, bottom two stiffener elements).
  • the stiffener elements 104A, 104B, 104C may include tapered ends 121 (shown only in Figure 4A) to assist insertion into the wound fill material 102.
  • the stiffener elements 104A, 104B shown in Figures 4A and 4B are preferably bonded with the wound fill material, such as the black foam 130, using an adhesive, for example cling film adhesive produced by Smith&Nephew.
  • stiffener elements 104 can be specially designed to increase the bond between the stiffener elements and the black foam.
  • the stiffener elements may be attached to the fill material, such as with barbs, VelcroTM or other attachment mechanisms.
  • the designed shape of the stiffener element 104D (shown in Figure 5) allows the stiffener element 104D to be simply inserted into the wound fill material 102.
  • the stiffener elements 104D comprise an elongate rod or spine 122 and a plurality of spaced apart flanges or protrusions 123 running along the length of the spine 122. The protrusions 123 are used to engage with the wound fill material 102 once the stiffener element 104D is inserted therein.
  • the stiffener element 104D may include tapered ends 121 to assist insertion into the wound fill material 102.
  • the stiffener elements may be inserted into slits or areas for insertion of the fill material and be connected by friction, an interference fit, a slight expansion of the stiffener elements, or other mechanical forces.
  • the fill material contains slits or areas for the insertion of stiffener elements.
  • the stiffener elements can be inserted after the wound filler 100 has been placed in the wound, !n other embodiments, the stiffener elements are placed within the wound filler 100 prior to insertion into the wound.
  • the slits or areas for insertion can be made after the wound filler 100 has been placed in the wound.
  • the slits or areas for insertion are made before the wound filler 100 is placed in the wound.
  • the slits may be open to a top surface and/or a bottom surface of the fill material to allow the stiffener elements to be inserted.
  • each stiffener element 104 is placed within the wound fill material 102, 130 at an acute angle, preferably from 5 to 25 degrees to the vertical.
  • stiffener elements 104 are placed at a 10 degree angle to the vertical axis of the wound filler, in the vertical direction of the wound 120 ( Figure 2B) and aligned along the closure direction or horizontal direction of the wound ( Figure 2A). This angle advantageously imparts a NLC property to the wound filler, in which the wound filler expands vertically when laterally (or horizontally) compressed when negative pressure is applied when positioned within a wound bed.
  • the stiffener elements 104 can be arranged in a variety of different arrangements in the foam material.
  • the stiffener elements are arranged in a pattern or array.
  • the locations of the stiffeners in the array can be identified from Archimedean Lattices, in which all polygons are regular and each vertex is surrounded by the same sequence of polygons.
  • Figure 7 provides examples of the layout patterns of stiffener elements within the porous wound fill material following this principle, specifically: ( Figure 7A) is a honeycomb pattern (or array); ( Figure 7B) is a kagome pattern; ( Figure 7C) is a triangular pattern; ( Figure 7D) is a snub square pattern; and ( Figure 7E) is a rhombitrihexagonal pattern.
  • Other patterns are also possible, and it should be understood that the present invention should not be limited to only those patterns exemplified.
  • the wound filler also includes a plurality of apertures or voids 1 10 extending through the wound fill material 102 between the lower side 108 of the wound fill material 102 (to be placed facing inside the wound) and the upper side 106 of the wound fill material 102 (to be placed facing out of the wound).
  • the apertures are arranged about the stiffener elements across the width and length of the wound fill material in a complementary pattern to the two dimensional pattern of stiffener elements 104.
  • the apertures can be arranged using Archimedean Lattices, in which all polygons are regular and each vertex is surrounded by the same sequence of polygons as described above for the stiffener elements.
  • each aperture 1 10 is positioned in the wound fill material 102 between the stiffener elements 104 to facilitate lateral movement of the stiffener elements towards each other upon lateral compression of the wound fill material.
  • each aperture 1 10 comprises a substantially perpendicular opening which extends vertically through the wound fill material 102 between inner side 108 and outer side 106 of the wound fill material 102 when the wound filler 100 is positioned within a wound 120.
  • the apertures 1 10 can have a variety of shapes and configurations. In the illustrated embodiment, the apertures 1 10 comprise a plurality of rectangular slits. However, a variety of other shapes are also possible.
  • Figures 8A to 8D illustrate one example of a complementary array of apertures 1 10 and stiffener elements 104 which achieve the required deformation pattern and achieve the prescribed closure ratio described above when applied to the black foam 130 shown in Figure 3.
  • Figures 8A and 8B show respectively, a top view of the matrix of apertures 140 and a top of view of the matrix of stiffener elements 145. The positions of apertures 1 10 and stiffener elements 104 are defined by guideline coordinates.
  • the combined matrix is shown as a top view in Figure 8C and a cross-sectional front view (across the width of the wound filler 100) in Figure 8D.
  • Figure 8D illustrates the angled placement of the stiffener elements 104 (80 degrees from the horizontal or 10 degrees from the vertical) within the wound filler 100 when using the matrix 145 shown in Figure 8B.
  • FIG. 9 An example of a wound filler 100 produced using the matrix patterns 140 and 145 shown in Figures 8A to 8D is illustrated in Figure 9.
  • the overall panel illustrated in Figure 9 has a dimension of 250 mm ⁇ 150 mm ⁇ 35 mm.
  • the size of each aperture is 10 mm ⁇ 10 mm ⁇ 35 mm.
  • the size of each stiffener element is 5 mm ⁇ 10 mm ⁇ 35.5 mm.
  • FIG. 1 Treatment of a wound with negative pressure in certain embodiments uses a negative pressure wound closure arrangement 298 as illustrated schematically in Figure 1 1 .
  • a wound site 305 illustrated in Figures 2A, 2B and 1 1 as an abdominal wound site, may benefit from treatment with negative pressure.
  • Such abdominal wound sites may be a result of, for example, an accident or due to surgical intervention.
  • medical conditions such as abdominal compartment syndrome, abdominal hypertension, sepsis, or fluid oedema may require decompression of the abdomen with a surgical incision through the abdominal wall to expose the peritoneal space, after which the opening may need to be maintained in an open, accessible state until the condition resolves.
  • the application of reduced or negative pressure to a wound site has been found to generally promote faster healing, increased blood flow, decreased bacterial burden, increased rate of granulation tissue formation, to stimulate the proliferation of fibroblasts, stimulate the proliferation of endothelial cells, close chronic open wounds, inhibit burn penetration, and/or enhance flap and graft attachment, among other things. It has also been reported that wounds that have exhibited positive response to treatment by the application of negative pressure include infected open wounds, decubitus ulcers, dehisced incisions, partial thickness burns, and various lesions to which flaps or grafts have been attached. Consequently, the application of negative pressure to a wound site 305 can be beneficial to a patient.
  • the wound filler 100 of the present invention is used as part of a wound closure arrangement for negative pressure wound therapy.
  • this wound closure arrangement 298 comprises a wound contact layer (or dressing film) 300 sized and configured to cover a selected wound 305; a wound filler 100 according to the present invention sized to fit to the contours of the wound and seated on top of the dressing film; and a sealing film 310 sealed over the wound filler 100.
  • the wound contact layer 300 is placed over the wound site 305.
  • the wound contact layer 300 is preferably a thin, flexible material which will not adhere to the wound site or the exposed viscera in close proximity.
  • polymers such as polyurethane, polyethylene, polytetrafluoroethylene, or blends thereof may be used.
  • the wound contact layer is permeable.
  • the wound contact layer 300 can be provided with openings, such as holes, slits, or channels, to allow the removal of fluids from the wound site 305 or the transmittal of negative pressure to the wound site 305.
  • step 2 Figure 1 1
  • the wound filler 100 of the present invention is then disposed over and seated on the wound contact layer 300.
  • the pores and apertures of the wound filler 100 can channel wound exudate and other fluids through itself when negative pressure is applied to the wound.
  • a sealing film or drape 310 is used to seal the wound site 305.
  • the sealing film 310 can be at least partially liquid impermeable, such that at least a partial negative pressure may be maintained at the wound site.
  • Suitable materials for the sealing film 310 include, without limitation, synthetic polymeric materials that do not significantly absorb aqueous fluids, including polyolefins such as polyethylene and polypropylene, polyurethanes, polysiloxanes, polyamides, polyesters, and other copolymers and mixtures thereof.
  • the materials used in the drape may be hydrophobic or hydrophilic. Examples of suitable materials include Transeal® available from DeRoyal and OpSite® available from Smith&Nephew.
  • the drapes in certain embodiments are at least partly breathable, such that water vapour is able to pass through without remaining trapped under the dressing.
  • An adhesive layer may be provided on at least a portion the underside of the sealing film 310 to secure the sealing film 310 to the skin of the patient, although certain embodiments may instead use a separate adhesive or adhesive strip.
  • a release layer may be disposed over the adhesive layer to protect it prior to use and to facilitate handling the sealing film 310; in some embodiments, the release layer may be composed of multiple sections.
  • an aperture 320 is formed in the sealing film 310.
  • a vacuum fitting 315 is then fitted to sealing film 310 via aperture 320 to control the pressure in the selected wound 305 through the wound closure arrangement 298.
  • Negative pressure can then be applied to the wound closure arrangement 298 (or wound cover) when the vacuum fitting 315 is connected to a source of negative pressure, for example a pump (not illustrated).
  • a pump is the Renasys EZ pump available from Smith&Nephew.
  • a container or other storage unit may be interposed between the source of negative pressure and vacuum fitting 315 to permit wound exudate and other fluids removed from the wound site to be stored without entering the source of negative pressure.
  • Certain types of negative pressure sources for example, peristaltic pumps, may also permit a container to be placed after the pump.
  • Some embodiments may also use a filter to prevent fluids, aerosols, and other microbial contaminants from leaving the container and/or entering the source of negative pressure.
  • FIG. 1 may also include a shut-off valve or occluding hydrophobic and/or oleophobic filter in the container to prevent overflow; other embodiments may include sensing means, such as capacitive sensors or other fluid level detectors that act to stop or shut off the source of negative pressure should the level of fluid in the container be nearing capacity.
  • sensing means such as capacitive sensors or other fluid level detectors that act to stop or shut off the source of negative pressure should the level of fluid in the container be nearing capacity.
  • At the pump exhaust it may also be preferable to provide an odour filter, such as an activated charcoal canister.
  • the net pressure on the wound filler 100 in this wound closure arrangement 298 is the combination of the pressures induced by pumps and the forces from enveloping layers (that is, the wound contact layer 300 and the sealing film 310) and sides of the wound as shown in Figure 12.
  • the stiffener elements 104 maintain the vertical height of the wound filler 100 whilst still allowing the horizontal contraction of the wound as shown in Figure 2.
  • FIG. 10 illustrates a FE model and deformation features of a simplified wound filler according to the present invention when placed under uniformed external pressure, showing (A) a quarter model; (B) full model without pressure; and (C) a model deformed after pressure loading.
  • ABAQUS/Explicit solver was used for the non-linear analysis to take into account effects of large deformations and complex interaction between stiffener elements and the black foam.
  • Quadratic solid elements of the secondary accuracy (element C3D10R with a mesh sweeping seed size of 0.4 mm) were used.
  • FIG. 10C shows a compacted wound filler 200.
  • the stiffener elements (not illustrated, but internal within the compacted wound filler 200) twist or rotate in the compacted wound filler 200 towards the surfaces of the inner 208 and outer 206 sides of the wound fill material, slightly expanding the height of the wound filler 200, as shown by peaks or bumps 21 1 in the surfaces of the inner 208 and outer 206 sides of the fill material. This is achieved by a negative linear compression property in the wound fill material 102.
  • each stiffener element ends up in a generally vertical orientation within the wound filler 200, thereby creating the peaks or bumps 21 1 .
  • a silicone wound model was fabricated to assess the performance of existing materials and wound fillers according to embodiments of the present invention.
  • the wound model was also used to test and validate newly designed cellular metamaterials with appropriate stiffness and deformation capability for use in wound fillers.
  • the wound filler test provides information on the performance of wound fillers quantified by the closure ratio of a wound model under negative pressure.
  • the illustrated silicone wound model comprises a block of silicone 400 which is cut following normal surgical practises to mimic a wound.
  • the silicone wound model is formed from "Polymould 10 A RTV2 Flexible” produced by Polymech Pty Ltd.
  • the product consists of rubber and a clear silicone catalyst.
  • the ratio of mixture (silicone rubber to silicone catalyst) is 100:2 by weight.
  • the accurate weights of both components are measured by digital scale and the mixture of the two components is cast in the container.
  • the normal de-moulding time at room temperature (25 °C) is approximately 5 to 6 hours.
  • a suitably sized plastic container is used to make the silicone wound model, which is approximately 240 ⁇ 300 ⁇ 45 mm 3 (length ⁇ width ⁇ depth).
  • FIGs 13A to 13D illustrate a method of forming an accurate wound shape template using the silicone block.
  • a straight line 405 is drawn on the silicone block 400. This is assumed to represent the mean length of a wound.
  • the silicone block 400 is cut along the line 405 to create a mimetic wound 41 OA.
  • edges 415, 416 of the wound 41 OA are pulled apart by hand as shown in Figure 13C.
  • four corners of the torn silicone mimetic wound 41 OA are fixed using clamps 420, as shown in Figure 13D. It should be noted that the cavity shall be fully penetrated without leaving any silicone in the cavity region.
  • Figure 14 represents a final shape of the mimetic wound 41 OA that is formed.
  • the dimensions of the formed mimetic wound 41 OA (shown in Table 1 below) can be used as a template to cut the cavity inside the silicone wound model and cut a wound filler in an appropriate size, as shown in Figures 14A to E.
  • the mimetic wound 410 used in testing is formed by cutting an elliptic cavity 460 into and all the way through the silicone wound model 400 as shown in Figure 14. Care must be taken to ensure that when removing the cavity the base of the silicone wound model 400 is cut through completely.
  • a hole 470 with diameter of 10 mm is made at a position shown in Figure 14B.
  • a RENASYS EZ Plus pump 480 is connected via this hole 470 as shown in Figure 15.
  • the final shape of the mimetic silicone wound and closure pattern of the mimetic wound are shown in Figures 14D and 14E, respectively.
  • the experimental set-up used for experimental procedures for testing the wound filler 100 and associated wound closure arrangement 298 is illustrated in Figure 15.
  • the experimental set up includes the silicone block 400 and formed mimetic wound 410 with a digital camera 450 positioned perpendicularly above the mimetic wound 410.
  • the wound closure arrangement 298, described above, can then be fitted within the mimetic wound 410 and negative pressure applied using a vacuum pump 480, for example a RENASYS EZ Plus pump as shown in Figure 15.
  • the RENASYS EZ Plus pump 480 is a negative pressure device that provides a solution for high volume output wounds while still offering flexibility in treating a variety of acute and chronic wounds.
  • This machine is made by Smith&Nephew and has straightforward controls for easy operation.
  • the pressure control range of the machine is between 40 to 200 mmHg and it weighs approximately 7.4 lbs or 3.3 kg.
  • the wound fill material is cut to match the cavity shape (see Figures 16A and 16B) and is placed inside the wound.
  • a dressing is applied to the top and bottom of the wound model and covered with a transparent plastic sealing film (in this case, RENASYS F/AB transparent adhesive film, available from Smith&Nephew).
  • a wound covering arrangement is therefore formed comprising a dressing applied to the top and bottom of the wound filler and a transparent plastic sealing film.
  • the transparent plastic sealing film consists of two layers, a top protective layer which is to be removed and an adhesive bottom layer which is attached to the top and bottom surfaces of the wound filler so that it covers the cavity. Any air bubbles must be removed completely from the adhesive bottom layer when applied to the wound filler.
  • the silicone wound model is connected to the RENASYS negative pressure pump via hole 470 or a port formed in the top surface of the wound covering arrangement.
  • the deformation of the silicone wound model under different negative pressures is presented as shown in Figure 18 (described in further detail below); the negative pressure device sucks out the air from inside the cavity.
  • the silicone wound model is placed on a surface.
  • the experimental results of the silicone wound model can be influenced by the effect of friction between a bottom surface of the silicone wound model and the surface that it is placed on during testing. Therefore, to reduce the effect of friction, the silicone wound model is preferably seated on a smooth surface during testing. This is not an issue in reality because the wound is in the body, for example, the abdominal cavity.
  • the deformation process of the silicone wound model is captured by a camera. Images may be acquired by a digital camera or a conventional film camera. Images acquired from a digital camera are not scaled for one-to-one (1 : 1 ) life-size output. Photographs taken with a camera (film or digital) involve variable distances from lens to object. The pictures or images need to be calibrated and this can be achieved as follows..
  • a calibration scale (of a known length and 2D area) is used with photographs to ensure that each photograph can be accurately compared.
  • the first photograph is taken from above the silicone wound model, after that, the calibration scale is removed and another photograph is taken without changing the position of camera.
  • the number of pixels in the wound area in the first photograph are counted and termed the pixel number in a known area.
  • the number of pixels corresponding to the cavity is counted from the second photograph and termed the pixel number in an unknown area.
  • the closest pixel number among known areas to the unknown area is chosen and divided by its area per square millimetre. This number represents the number of pixels per square mm for resolution. Thus all unknown areas can be estimated by using this ratio and counting the pixel number of unknown areas. number of pixels of known area . . .
  • the wound closure ratio can thus be calculated using the following formula:
  • Figure 17A shows a wrapped silicone mimetic wound with a black foam prototype 505 placed in the cavity of the silicone wound 410 in before application of negative pressure from the RENASYS negative pressure pump.
  • Figure 17D shows the wrapped silicone mimetic wound of Figure 17A after application of negative pressure from the RENASYS negative pressure pump.
  • Deformation of the prototype under negative pressures shows that the foam 505 was sucked concavely into the cavity of the mimetic wound while: the sealed side (that is, the side where the sealing film 310, illustrated in Figure 1 1 - step 3, was placed) wrinkled; the centre region cupped; and the edge region swelled.
  • the cross-sectional thickness of the wound is not consistent under negative pressure. Therefore, it cannot sufficiently help to close the wound.
  • Figure 17B shows a wrapped silicone wound with a stiff metallic plate 508 sitting vertically inside the cavity of the mimetic wound 410 prior to the application of negative pressure.
  • Figure 17E shows the wrapped silicone wound of Figure 17B after application of negative pressure.
  • the stiff plate 508 was placed inside the wound 410 to mimic the stiffness of the wound filler of the present invention along parallel walls of the wound 410. According to test results, the closure mechanism of the wound model was complete and the height of the wound was constant under negative pressure.
  • Figure 17C shows a wrapped silicone mimetic wound with a wound filler prototype 509 as shown in Figures 9 and 16 placed into the wound 410 before the application of negative pressure.
  • Figure 17F shows the wrapped silicone mimetic wound of Figure 17C after application of negative pressure.
  • the wound filler prototype 509 is cut to match the cavity of the wound 410 and inserted therein. After application of negative pressure the pattern of the reinforcement stiffener elements has a significant effect on the closure performance of the wound under negative pressure; as shown in Figure 17F the space between the sides of the silicone wound model has significantly decreased when compared to Figure 17C.
  • Figure 18 shows the closure ratio of the silicone wound under different negative pressures when the silicone wound is filled with: (i) the wound filler shown in Fig 10 which uses the stiffening elements shown in Figure 5; (ii) the wound filler having a stiffener and void pattern as shown in Figure 9; (iii) the wound filler shown in Figure 3 (wound filler (only black foam)); and (iv) a stiff metalic plate, as shown in Figure 17B.
  • the large black triangle signifies the wound closure ratio when black foam is used; the large black circle signifies the required wound closure ratio when a wound filler shown in Figure 10 (having siffening elements shown in Figure 5) is used at an applied pressure of 120mmHg.
  • closure ratio satisfies the requirement for wound closure using the NPWT system, though it is lower than when the stiff metalic plate inserted in the middle of the wound ( Figures 17B and 17E) was tested. It is also worth noting that the variation of closure ratio between 50 mmHg and 200 mmHg is larger than 40%.

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Abstract

La présente invention concerne un remplissage de plaie pour utilisation dans le traitement d'une plaie avec une pression négative comprenant : un matériau de remplissage de plaie poreux ayant un côté interne conçu pour faire face à une plaie et un côté externe opposé ; et une pluralité d'éléments raidisseurs situés à l'intérieur du matériau de remplissage de plaie, les éléments raidisseurs s'étendant entre le côté interne et le côté externe du matériau de remplissage de plaie et étant agencés dans un motif bidimensionnel de part et d'autre de la largeur et la longueur du matériau de remplissage de plaie, les éléments raidisseurs comprenant un matériau plus rigide que le matériau de remplissage de plaie, les éléments raidisseurs étant agencés à un angle compris entre 5 et 25 degrés par rapport à la verticale à l'intérieur du matériau de remplissage de plaie lorsque le remplissage de plaie est positionné dans le lit d'une plaie.
PCT/AU2016/050956 2015-10-12 2016-10-12 Remplissage de plaie pour traitement de plaie par pression négative WO2017063036A1 (fr)

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AU2015904144A AU2015904144A0 (en) 2015-10-12 Wound filler for negative pressure wound therapy

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Cited By (14)

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US10575991B2 (en) 2015-12-15 2020-03-03 University Of Massachusetts Negative pressure wound closure devices and methods
USD878609S1 (en) 2018-04-09 2020-03-17 Kci Licensing, Inc. Compressive layer for abdominal wound dressing
US10814049B2 (en) 2015-12-15 2020-10-27 University Of Massachusetts Negative pressure wound closure devices and methods
WO2021046360A1 (fr) 2019-09-05 2021-03-11 Tautona Group Ip Holding Company, L.L.C. Dispositifs et procédés pour réduire l'apparition de cellulite
US11040127B2 (en) 2018-04-09 2021-06-22 Kci Licensing, Inc. Abdominal dressing with mechanism for fascial closure
US11083631B2 (en) 2012-07-16 2021-08-10 University Of Massachusetts Negative pressure wound closure device
US11160917B2 (en) * 2020-01-22 2021-11-02 J&M Shuler Medical Inc. Negative pressure wound therapy barrier
US11166726B2 (en) 2011-02-04 2021-11-09 University Of Massachusetts Negative pressure wound closure device
WO2022008998A1 (fr) * 2020-07-09 2022-01-13 Kci Licensing, Inc. Pansement à pression négative avec contraction latérale préférentielle
US11241337B2 (en) 2012-05-24 2022-02-08 Smith & Nephew, Inc. Devices and methods for treating and closing wounds with negative pressure
US11419767B2 (en) 2013-03-13 2022-08-23 University Of Massachusetts Negative pressure wound closure device and systems and methods of use in treating wounds with negative pressure
US11439539B2 (en) 2015-04-29 2022-09-13 University Of Massachusetts Negative pressure wound closure device
US11471586B2 (en) 2015-12-15 2022-10-18 University Of Massachusetts Negative pressure wound closure devices and methods

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US11166726B2 (en) 2011-02-04 2021-11-09 University Of Massachusetts Negative pressure wound closure device
US11241337B2 (en) 2012-05-24 2022-02-08 Smith & Nephew, Inc. Devices and methods for treating and closing wounds with negative pressure
US11083631B2 (en) 2012-07-16 2021-08-10 University Of Massachusetts Negative pressure wound closure device
US11564843B2 (en) 2012-07-16 2023-01-31 University Of Massachusetts Negative pressure wound closure device
US11419767B2 (en) 2013-03-13 2022-08-23 University Of Massachusetts Negative pressure wound closure device and systems and methods of use in treating wounds with negative pressure
US11439539B2 (en) 2015-04-29 2022-09-13 University Of Massachusetts Negative pressure wound closure device
US11471586B2 (en) 2015-12-15 2022-10-18 University Of Massachusetts Negative pressure wound closure devices and methods
US10814049B2 (en) 2015-12-15 2020-10-27 University Of Massachusetts Negative pressure wound closure devices and methods
US10575991B2 (en) 2015-12-15 2020-03-03 University Of Massachusetts Negative pressure wound closure devices and methods
WO2018237206A3 (fr) * 2017-06-21 2019-02-21 University Of Massachusetts Dispositifs et méthodes de fermeture de plaie par pression négative
USD878609S1 (en) 2018-04-09 2020-03-17 Kci Licensing, Inc. Compressive layer for abdominal wound dressing
US11040127B2 (en) 2018-04-09 2021-06-22 Kci Licensing, Inc. Abdominal dressing with mechanism for fascial closure
WO2021046360A1 (fr) 2019-09-05 2021-03-11 Tautona Group Ip Holding Company, L.L.C. Dispositifs et procédés pour réduire l'apparition de cellulite
EP4025147A4 (fr) * 2019-09-05 2024-01-03 Tautona Group IP Holding Company, L.L.C. Dispositifs et procédés pour réduire l'apparition de cellulite
US11160917B2 (en) * 2020-01-22 2021-11-02 J&M Shuler Medical Inc. Negative pressure wound therapy barrier
US20220193325A1 (en) * 2020-01-22 2022-06-23 J&M Shuler Medical Inc. Negative pressure wound therapy barrier
US11766514B2 (en) 2020-01-22 2023-09-26 J&M Shuler Medical Inc. Negative pressure wound therapy barrier
WO2022008998A1 (fr) * 2020-07-09 2022-01-13 Kci Licensing, Inc. Pansement à pression négative avec contraction latérale préférentielle
US20230248896A1 (en) * 2020-07-09 2023-08-10 Kci Licensing, Inc. Negative-pressure dressing with preferental lateral contraction

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