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 fig5 . 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 fig5 . 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 , is 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 .
a wound dressing , a method of manufacturing a wound dressing , and in particular to a material for use as and in a wound dressing . a wound dressing can comprise a material movable between an initial conformation and an expanded conformation resulting from applying an extensive force to the material , such that removal of the extensive force can cause a contraction of the material toward a center of a wound . 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 .