like reference numbers refer to corresponding parts throughout the drawings , description and examples . to create the wound dressing of example 1 , a perforated sheet of polyurethane film was applied to the wound contact surface of a sheet of 4 mm depth polyurethane foam ( allevyn , smith & amp ; nephew medical limited ). the wound contact surface is that surface which is placed adjacent to or in direct contact with the wound . the non - wound contact surface is that surface which is remote from or opposite the wound contact surface . a cutter of specification shown in fig2 ( cutter blade with 15 mm length blades , linear spacing 5 mm , vertical spacing 5 mm ) was used to cut slits in the sheet of polyurethane foam to form a lattice . the cutting action also formed slits in the polyurethane film . following cutting , an extensive force was applied to the lattice in a direction perpendicular to the longitudinal axis of the cuts or slits to produce an open lattice as shown in fig3 . a moisture permeable top - film was heat laminated to the non - wound contact layer or surface of the open lattice . to the top - film , a polymeric film release sheet of sufficient mechanical stiffness to resist the contractile force of the open lattice was applied . after applying the release sheet the extensive force applied to the lattice was removed and the extended or open lattice was retained in the open lattice conformation by the release sheet . to create the wound dressing of example 2 , a perforated sheet of adhesive polyurethane film was applied to the wound contact surface of a sheet of 4 mm depth polyurethane foam ( allevyn , smith & amp ; nephew medical limited ). the adhesive surface of the film was covered by a siliconised release paper . a cutter of specification shown in fig2 ( cutter blade with 15 mm length blades , linear spacing 5 mm , vertical spacing 5 mm ) was used to cut slits in the sheet of polyurethane foam to form a lattice . the cutting action also formed slits in the polyurethane film and siliconised release paper . the wound contact surface is that surface which is placed adjacent to or in direct contact with the wound . the non - wound contact surface is that surface which is remote from or opposite the wound contact surface . following cutting , the siliconised release paper was removed and an extensive force was applied to the lattice in a direction perpendicular to the longitudinal axis of the cuts or slits to produce the open lattice pattern as shown in fig3 . a new sheet of siliconised release paper was then attached to the wound contact surface of the perforated adhesive film . a moisture permeable top - film was heat laminated to the non - wound contact layer or surface of the open lattice . to the top - film , a polymeric film release sheet of sufficient mechanical stiffness to resist the contractile force of the open lattice was applied . after applying the release sheet the extensive force applied to the lattice was removed and the extended or open lattice was retained in the open lattice conformation by the release sheet . to demonstrate the effectiveness of the wound dressing of example 2 , the siliconised release paper was removed from the perforated adhesive film and placed , adhesive side down , upon intact skin . the polymeric film release sheet was then removed . a uni - directional contractile force was generated on the skin , upon removal of the polymeric film release sheet , and in a direction perpendicular to the axis of the cuts . to create the wound dressing of example 4 , a perforated sheet of polyurethane film was applied to the wound contact surface of a sheet of 4 mm depth polyurethane foam ( allevyn , smith & amp ; nephew medical limited ). a cutter of specification shown in fig4 ( cutter blade with 15 mm length blades , linear spacing 5 mm , vertical spacing 2 . 5 mm ) was used to cut slits in the sheet of polyurethane foam to form a lattice . the cutting action also formed slits in the polyurethane film and siliconised release paper . the wound contact surface is that surface which is placed adjacent to or in direct contact with the wound . the non - wound contact surface is that surface which is remote from or opposite the wound contact surface . following cutting , the lattice was extended along two axes , x and y , as shown in fig4 . the extensive force was applied perpendicular and parallel to the longitudinal axis of the slits to produce an open lattice structure . a moisture permeable top - film was heat laminated to the non - wound contact surface of the open lattice . to the top - film , a polymeric film release sheet of sufficient mechanical stiffness to resist the contractile force of the open lattice was applied . after applying the release sheet the extensive force applied to the lattice was removed and the extended or open lattice was retained in the open lattice conformation by the release sheet . to create the wound dressing of example 5 , a perforated sheet of adhesive polyurethane film was applied to the wound contact surface of a sheet of 4 mm depth polyurethane foam ( allevyn , smith & amp ; nephew medical limited ). the adhesive surface of the film was covered by a siliconised release paper . a cutter of specification shown in fig4 ( cutter blade with 15 mm length blades , linear spacing 5 mm , vertical spacing 2 . 5 mm ) was used to cut slits in the sheet of polyurethane foam to form a lattice . the cutting action also formed slits in the polyurethane film and siliconised release paper . the wound contact surface is that surface which is placed adjacent to or in direct contact with the wound . the non - wound contact surface is that surface which is remote from or opposite the wound contact surface . following cutting , the siliconised release paper was removed and the lattice was extended along two axes , x and y , as shown in fig4 . the extensive force was applied perpendicular and parallel to the longitudinal axis of the slits to produce an open lattice structure . a new sheet of siliconised release paper was then attached to the wound contact surface of the perforated adhesive film . a moisture permeable top - film was heat laminated to the non - wound contact layer or surface of the open lattice . to the top - film , a polymeric film release sheet of sufficient mechanical stiffness to resist the contractile force of the open lattice was applied . after applying the release sheet the extensive force applied to the lattice was removed and the extended or open lattice was retained in the open lattice conformation by the release sheet . the lattice of the wound dressing of example 5 , having the polymeric film release sheet removed , it shown in fig5 . to demonstrate the effectiveness of the wound dressing of example 5 , the siliconised release paper was removed from the perforated adhesive film and placed , adhesive side down , upon intact skin . the polymeric film release sheet was then removed . upon removal of the polymeric film release sheet , a contractile force was generated on the skin acting towards the centre of the dressing . a similar process to that described for the wound dressing of example 5 is employed to create the wound dressing of example 7 . however , in this case , a cutter of specification shown in fig6 and 7 was used to cut the slits . as can be seen from fig6 , the blades have three cutting edges . a long cutting edge of 15 mm in length bridging two shorter cutting edges of 7 mm in length . the two shorter cutting edges being parallel to each other and perpendicular to the longer cutting edge . each blade has a spacing with an adjacent blade which describes a square area having a side length of 3 . 75 mm . this spacing is demonstrated by the shaded square portion in fig6 . the lattice of the wound dressing of example 7 , having the polymeric film release sheet removed , it shown in fig8 . an array of blades ( 10 ) mounted on a board is shown in fig1 . each blade ( 12 ) is a straight thin blade 30 mm long , and having a depth of approximately 30 mm . the blades are arranged in 20 parallel linear series of blades ( 16 , 18 ), each series comprising a row of blades ( 12 ) arranged longitudinally , with a gap ( 14 ) of 3 mm between each blade ( 12 ) in the series . each series is spaced from the adjacent series by a 3 mm spacing ( 15 ). furthermore , adjacent series ( 16 , 18 ) are staggered relative to one another such that the gap between the blades on one series ( 16 ) aligns with the midpoint in the adjacent series ( 18 ). accordingly , the blades within the array ( 10 ) are arranged like the bricks in a wall . given this offset arrangement , it is convenient that at the end of a series where a full 30 mm blade would extend beyond the dimension to be cut , blades of 15 mm length are provided ; this allows for a neater array — once more , this is akin to half bricks at the end of a row in a wall . full length blades could be used at the ends , provided they would not be problematic in the cutting process . a body of npwt foam ( 20 ) measuring 200 × 125 × 30 mm is cut using the array ( 10 ). it is cut by driving the array of blades ( 10 ) through the body ( 20 ) in a die cutting operation . this can be achieved using a press , typically a hydraulic press ( not shown ), also known as a clicker press . the blades are driven perpendicularly into and through the largest face of the body ( 20 ), and perpendicular thereto , to form a plurality of slits therein . the slits ( 21 ) formed are arranged in a plurality of parallel linear series ( 26 , 28 ) of slits , each comprising slits ( 21 ) 30 mm long separated by gaps ( 22 ), where material is left un - cut , which are 3 mm long . each series is separated by a spacing ( 24 ) 3 mm in width . when the body ( 20 ) is curved , as shown in fig1 , the slits ( 21 ) open up to form a lattice structure . tension in the outer region of the body ( 20 ) as a result of the curving process is relieved through deformation of the body ( 20 ) which is facilitated by the slits ( 21 ) provided therein . the arrangement of parallel offset linear series of linear slits is particularly suited to this as it form a regular lattice structure , as shown in fig1 . in the embodiment shown in fig1 , an additional partial cut ( 30 ) has been made running the length of the middle of the largest face of the body ( 20 ), perpendicular to the slits . this allows the body ( 20 ) to be easily split in two if this is desirable . fig1 shows another body ( 40 ) cut using the array of blades of fig1 , this time without the additional cut ( 30 ). the body has been curved in a different manner to that in fig1 . in this case the body has been bent back on itself along its longest side , i . e . the 200 × 300 mm face has been curved back on itself . the body ( 40 ) has opened via the slits ( 42 ) into an open lattice structure . this type of curving of the body ( 40 ) is not generally useful for a wound dressing application , but does serve to demonstrate the flexibility and strength of the body ( 40 ). fig1 further demonstrates the ability of a body according to the present invention ( 40 ) to drape over a surface , in this case a leg , when compared to an uncut body ( 46 ). fig1 shows an array ( 50 ) of blades adapted to form cuts in a body of foam in two orientations , the orientations being perpendicular to each other . as with the array ( 10 ) in fig1 , the blades have a depth of 30 mm . however , in the array ( 50 ) comprises h - shaped blades ( 52 ) comprising a first blade element 30 mm long ( 54 ) ( also termed “ cross - piece ”), with second ( 56 ) and third ( 58 ) blade elements ( also termed “ sides ”) 15 mm long located at the end of the first blade element ( 54 ), each end of the first blade element intersecting with the midpoint of the second and third blade elements , thus defining a “ wide h - shaped ” blade . the array is made up of first set of eleven parallel linear series of h - shaped blades in a first orientation ( called x for convenience ) and a second set of eleven parallel linear series of h - shaped blades in a second , perpendicular orientation ( called y for convenience ). adjacent series within each set are offset in exactly the same manner as for linear blades . as can be seen from fig1 , the blades are spaced and arranged such that a close packing of the blades as achieved , but each blade is always approximately 5 mm or so from the nearest neighbouring blade . it can be seen that the “ side ” of a blade in the x - orientation nests within the region defined by the “ cross - piece ” and “ sides ” of a blade in the y - orientation . such an array is suited to forming slits in a body to allow draping in two planes . fig1 shows a body ( 60 ) formed by cutting with the array of fig1 . the slits ( 62 ) are formed by pressing the array of blades ( 50 ) through the body ( 60 ) in the same manner as described above . h - shaped slits ( 62 ) are formed in the body ( 60 ) corresponding to the array of blades ( 50 ). as shown in fig1 , the body ( 60 ) is well adapted to curving in complex shapes . it should be noted that the present description has focused on bodies formed by a batch die cutting process . there are of course numerous ways of forming cuts in a body of porous material ( e . g . laser cutting , high pressure liquid cutting ), or the cuts could formed when the body itself is formed ( e . g . during a moulding process ). furthermore , these methods could be applied in a flow process rather than a batch ; this might be more efficient for large production runs . all such variations are within the scope of the present invention . furthermore , it should be noted that , while the exemplified embodiments form particularly preferred embodiments with excellent drapeability , it is quite possible that other arrangements of cuts will provide satisfactory results .
embodiments disclosed within herein relate to a wound dressing , suitable for use in negative pressure wound therapy , comprising a body of porous material , the body of porous material comprising a plurality of cuts which provide regions of flexibility within the body . further embodiments relate to methods of manufacturing and method of use of such wound dressings . in addition , the wound dressing can comprise a retaining mechanism removably coupled to the material and configured to retain the material in the expanded conformation .