Patent Publication Number: US-2011077664-A1

Title: Device for processing dermal tissue

Description:
FIELD OF THE DISCLOSURE 
     The disclosed system relates a device for processing dermal tissue that has been harvested or otherwise removed from a patient. More specifically, the disclosed system relates to a device for cutting dermal tissue into particles that are suitable for transplantation into a wound on the patient. 
     BACKGROUND OF THE INVENTION 
     Skin grafting involves removing of a thin slice of dermal tissue from a donor site on a patient. The harvested tissue slice is then used to cover the site of a wound, which is typically a non-self-healing wound or a burn. The harvested tissue is frequently processed before it is applied to the recipient wound site to expand the area of the harvested tissue in order to minimize the amount of tissue that needs to be harvested from the donor site. 
     A common process called “meshing” creates a number of small, non-connected cuts in the slice of tissue. The harvested and processed tissue can then be stretched until it has the appearance of a mesh or net. Other processing methods include cutting the tissue into particles with knives, blades, or scissors. 
     Conventional devices for processing dermal tissue utilize a drum carrying a plurality of parallel blades. The strip of tissue is placed on the cutting surface, and the device is activated thereby rotating the drum and bringing the blades into contact with the underlying cutting surface. The tissue is manually translated across the cutting surface to enable the blades to slice the tissue into fine strips. The strips of tissue may then be repositioned on the cutting surface to enable the blades to cut the strips into individual particles. Unfortunately, particles may accumulate in the interstices between adjacent blades. This accumulation of tissue necessitates manual removal using a spatula or the like instrument. 
     Some devices, such as the device disclosed in U.S. patent application Ser. No. 10/789,620 titled “Method and Apparatus for Processing Dermal Tissue”, attempt to solve this problem by including separators having tines that interdigitate with blade tips. However, such devices are expensive to manufacture as they include numerous individual components. Additionally, these devices do not include any features that prevent them from being sterilized and reused by a hospital, which increases the chances of spreading diseases or infections if the device is not thoroughly sterilized. 
     Accordingly, a device for processing harvested dermal tissue that is inexpensive to manufacture and is easy and effective to use is desirable. 
     SUMMARY OF THE INVENTION 
     In some embodiments, a device for processing harvested dermal tissue is provided that includes a body having a cutting head portion with a handle portion extending from the cutting head portion. The cutting head portion defines a chamber. A cutting assembly is disposed in the chamber and includes a plurality of blades and a flexible spacer member disposed on an axle such that the blades rotate as the axle rotates. Each of the plurality of blades is separated from an adjacent blade by a spacer disposed on the axle. A grill assembly is coupled to the body and includes a grill and a grill cap. The grill has a plurality of spaced apart slots sized and configured to receive and maintain the blades in position with respect to the body. The grill cap is sized and configured to couple the grill to the cutting head portion of the body. 
     In some embodiments, another device for processing harvested dermal tissue is provided that includes a body having a cutting head portion and a handle portion, a second handle, a cutting assembly, and a grill assembly. The handle portion extends from the cutting head portion, which defines a cavity. The second handle is pivotally coupled to the cutting head portion of the body such that it pivots between a collapsed position and an extended position. The cutting assembly is rotatably disposed within the chamber of the body. The cutting assembly includes a plurality of blades disposed on an axle such that as the axle rotates about its axis each of the plurality of blades rotates about the same axis. Adjacent blades of the plurality of blades are spaced apart by a spacer member disposed on the axle. At least one flexible spacer member is disposed on the axle adjacent to one of a pair of retaining clamps. A pair of bearings are disposed on a portion of the axle and are disposed within a pair of slots defined in inner walls of the cutting head portion of the body. The grill assembly includes a grill and a grill cap. The grill has a plurality of spaced apart slots. Each of the spaced apart slots is sized and configured to receive a respective one of the plurality of blades. The grill cap is sized and configured to couple the grill to the cutting head portion of the body and deform during an autoclaving process. 
     The foregoing and other aspects will be apparent from the following description of the preferred embodiments. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration, and not limitation, a preferred embodiment. Such embodiment does not necessarily represent the full scope of the invention, and reference must therefore be made to the claims herein for interpreting the scope of the invention and its equivalents. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       These and other features and advantages of the present invention will be more fully disclosed in, or rendered obvious by the following detailed description of the preferred embodiments of the invention, which are to be considered together with the accompanying drawings wherein like numbers refer to like parts and further wherein: 
         FIG. 1  is an isometric view of an improved device for processing harvested dermal tissue; 
         FIG. 2  is an elevated side view of the device for processing harvested dermal tissue illustrated in  FIG. 1 ; 
         FIG. 3  is an elevated top side view of the device for processing harvested dermal tissue illustrated in  FIG. 1 . 
         FIG. 4  is an elevated side view of a body of the device for processing harvested dermal tissue illustrated in  FIG. 1 ; 
         FIG. 5  is an elevated bottom-side view of the body of the device for processing harvested dermal tissue illustrated in  FIG. 4 ; 
         FIG. 6  is an elevated top-side view of the body of the device for processing harvested dermal tissue illustrated in  FIG. 4 ; 
         FIG. 7  is a elevated view of the cutting head of the body of the device for processing harvested dermal tissue illustrated in  FIG. 4 ; 
         FIG. 8  is a sectional view taken along the longitudinal axis of the body of the device for processing harvested dermal tissue illustrated in  FIG. 4 ; 
         FIG. 9  is a detail view of the device for processing harvested dermal tissue illustrated in  FIG. 8 ; 
         FIG. 10  is an elevated side view of a handle of the device for processing harvested dermal tissue illustrated in  FIG. 1 ; 
         FIG. 11  is an elevated bottom-side view of the handle of the device for processing harvested dermal tissue illustrated in  FIG. 10 ; 
         FIG. 12  is an elevated top-side view of the handle of the device for processing harvested dermal tissue illustrated in  FIG. 10 ; 
         FIG. 13  is an elevated front-end view of a blade sub-assembly of the device for processing harvested dermal tissue illustrated in  FIG. 1 ; 
         FIG. 14  is an elevated view of an axle of the blade sub-assembly illustrated in  FIG. 13 ; 
         FIG. 15  is an elevated side view of the axle illustrated in  FIG. 14 ; 
         FIG. 16  is an elevated side view of a blade of the blade sub-assembly illustrated in  FIG. 13 ; 
         FIG. 17  is an elevated view of the blade illustrated in  FIG. 165 ; 
         FIG. 18  is a detail view of the blade tip of the blade illustrated in  FIG. 17 ; 
         FIG. 19  is an elevated side view of a spacer member of the blade sub-assembly illustrated in  FIG. 13 ; 
         FIG. 20  is an elevated view of the spacer member illustrated in  FIG. 19 ; 
         FIG. 21  is an elevated side view of a flexible spacer member of the blade sub-assembly illustrated in  FIG. 13 ; 
         FIG. 22  is an elevated view of the flexible spacer member illustrated in  FIG. 21 ; 
         FIG. 23  is an elevated side view of a clamp of the blade sub-assembly illustrated in  FIG. 13 ; 
         FIG. 24  is an elevated view of the clamp illustrated in  FIG. 23 ; 
         FIG. 25  is an elevated side view of a bearing of the blade sub-assembly illustrated in  FIG. 13 ; 
         FIG. 26  is an elevated view of the bearing illustrated in  FIG. 25 ; 
         FIG. 27  is an elevated view of a grill sub-assembly of the device for processing harvested dermal tissue illustrated in  FIG. 1 ; 
         FIG. 28  is an elevated view of a grill of the grill sub-assembly illustrated in  FIG. 27 ; 
         FIG. 29  is an elevated side view of the grill illustrated in  FIG. 28 ; 
         FIG. 30  is a detail view of the grill illustrated in  FIG. 28 ; 
         FIG. 31  is an elevated view of a grill cap of the grill sub-assembly illustrated in  FIG. 27 ; 
         FIG. 32  is a sectional view of the grill cap taken along line  32 - 32  in  FIG. 31 ; 
         FIG. 33  is a sectional view of the grill cap taken along line  33 - 33  in  FIG. 31 ; 
         FIG. 34  is a detail view of the grill cap illustrated in  FIG. 33 ; 
         FIG. 35  is an exploded view of the cutting assembly of the device for processing harvested dermal tissue illustrated in  FIG. 1 ; 
         FIG. 36  is a detail view of the cutting assembly installed in the cutting head portion of the device for processing harvested dermal tissue illustrated in  FIG. 1 ; 
         FIGS. 37A-37B  illustrate the device for processing harvested dermal tissue illustrated in  FIG. 1  in use; 
         FIG. 38A  illustrates the device for processing harvested dermal tissue illustrated in  FIG. 1  disposed in an autoclave; 
         FIG. 38B  illustrates the device for processing harvested dermal tissue illustrated in  FIG. 1  after being autoclaved; 
         FIG. 38C  illustrates the grill cap after autoclaving the device for processing harvested dermal tissue illustrated in  FIG. 1 ; 
         FIG. 39  is a top plan view of one example of a dermatome; 
         FIG. 40  is a side plan view of the dermatome illustrated in  FIG. 39 ; 
         FIG. 41  is a top plan view of one example of a cutting surface; and 
         FIG. 42  is a side plan view of the cutting surface illustrated in  FIG. 41 . 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     This description of preferred embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. The drawing figures are not necessarily to scale and certain features of the invention may be shown exaggerated in scale or in somewhat schematic form in the interest of clarity and conciseness. In the description, relative terms such as “horizontal,” “vertical,” “up,” “down,” “top” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms including “inwardly” versus “outwardly,” “longitudinal” versus “lateral” and the like are to be interpreted relative to one another or relative to an axis of elongation, or an axis or center of rotation, as appropriate. Terms concerning attachments, coupling and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The term “operatively connected” is such an attachment, coupling or connection that allows the pertinent structures to operate as intended by virtue of that relationship. 
     Referring now to  FIGS. 1-38 , a device for processing harvested dermal tissue is provided that may be manufactured at a lower cost compared to conventional devices, and offers enhanced safety by ensuring the device is used only once. Referring to  FIG. 1 , a disposable, handheld device  100  for processing harvested dermal tissue includes a device body  102  having a cutting head portion  104  and a handle portion  128  extending from the cutting head portion  104 . The cutting head portion  104  defines a chamber  106  sized and configured to receive and house a blade sub-assembly  156  ( FIG. 13 ) including a plurality of spaced apart blades  166  through opening  108 . Blade sub-assembly  156  may be secured inside the cutting head portion  104  by a grill sub-assembly  188  ( FIG. 27 ). A second handle  146  ( FIG. 1 ) is pivotally coupled to the cutting head portion  104  of the device body  102 . 
     Referring to  FIG. 4 , cutting head portion  104  of the device body  102  often has convex top and bottom surfaces  114 ,  118 . One skilled in the art will appreciate that cutting head portion  104  may have a variety of other geometric shapes. Referring to  FIGS. 4 and 9 , bottom surface  118  of device body  102  may include a ridge  120  around the perimeter of opening  108 . Additionally, a stop or flange  122  may project outwardly from top surface  114  of device body  102  adjacent to opening  108 . 
     Referring to  FIGS. 7 and 8 , chamber  106  of cutting head portion  104  may have a concave top wall  112  and straight side walls  110 . Each of side walls  110  of chamber  106  may include a slot  124  that projects inwardly from bottom surface  118  of device body  102 , terminating at radius R ( FIG. 8 ). In some embodiments, slots  124  have a width of approximately 8.2 mm (approximately 0.32 inch) and a depth of approximately 10.4 mm (approximately 0.41 inch) although one skilled in the art would understand that slots  124  may have other dimensions that enable receipt of bearings  184  of cutting assembly  154  as will be further described in relation to embodiments of the invention. Each of slots  124  may define a blind or through hole  126  that extends partially or through side walls  110  of cutting head portion  104 . Holes  126  may be sized and configured to receive a dowel pin  206  or other coupling device. 
     Handle portion  128  of device body  102  extends from cutting head portion  104 . Preferably, handle portion  128  extends from the device body at an angle with respect to an axis defined by slots  124  ( FIG. 8 ) of from between 0 and 90 degrees, and preferably between 20 and 70 degrees, and more preferably between 50 and 60 degrees. Referring to  FIGS. 5 and 6 , handle portion  128  may include a slight taper near its proximal end  130  adjacent to cutting head portion  104  and terminate in a curved distal end  132 . A shallow depression  138  may be formed on top surface  134  of handle portion  128  adjacent to a view port  142  ( FIGS. 6 and 8 ) so as to provide an ergonomic shape. A stiffener rib  144  may extend longitudinally along the length of handle portion  128 . Referring to  FIG. 5 , stiffener rib  144  may be disposed on the underside of handle portion  128  approximately along its center to provide additional structural integrity to handle portion  128  while maintaining light weight and keeping to a minimum the amount of raw materials necessary to fabricate device body  102 . Device body  102  may be injection molded, machined, or otherwise fabricated from polyethylene, polypropylene, or any other polymeric, plastic, or metallic material suitable for injection molding, machining, and medical device applications. 
     In some embodiments, the device  100  may include a second handle  146 , which may also be injection molded, machined, or otherwise fabricated from polyethylene, polypropylene, polymeric, plastic, or metallic material such that it has a similar shape to handle portion  128  of device body  102 . However, one skilled in the art will appreciate that handle  146  may also have a shape that substantially differs from handle portion  128 . Descriptions of the features of second handle  128  that are similar or identical to the features of the handle portion  128  are not repeated here. Referring to  FIGS. 10-12 , handle  146  includes a pair of arms  148  that extend from proximal end  130  of handle  146  at an angle with respect to an axis defined by the longitudinal portion of handle  146 . Arms  148  are sufficiently spaced apart to receive cutting head portion  104  of device body  102  therebetween. A flange or stop  150  may extend from proximal end  130  of handle  146  between arms  148 . A blind or through hole  152  may be formed near the end of each of arms  148  for pivotally coupling handle  146  to cutting head portion  104  of device  100  ( FIG. 10 ). As best seen in  FIG. 3 , viewing ports  142  defined by each of handles  128 ,  146  are located on each of handles  128 ,  146 , such that they do not normally align with one another when device  100  is in the folded position, e.g., when handles  128 ,  146  are disposed in abutting relationship ( FIGS. 2 and 3 ). Locating viewing ports  142  such that they do not align with one another when in a folded position encourages a physician or user of device  100  to employ the device in an open or extended position ( FIG. 1 ). 
     The cutting assembly  154  includes a blade sub-assembly  156  and a grill sub-assembly  188 . Turning now to  FIGS. 13 and 14 , blade sub-assembly  156  comprises an arbor or axle  158 , a plurality of rotary blades  166  and spacers  172  alternately disposed on axle  158 , one or more flexible spacer members  176 , a pair of clamps  180 , and a pair of bearings  184 . Axle  158  may include a first region  160  having a substantially circular cross-sectional geometry and an undercut region  162  also having a substantially circular cross-sectional geometry, but having a smaller diameter than the diameter of first region  160 . A central region  164  extending between regions  160  and  162  may have a polygonal cross-sectional geometry. In some embodiments, axle  158  has an overall length of approximately 1.012 inches with a diameter of first region  160  being approximately 4 mm (approximately 0.16 inch), which may be the same as the width of polygonal region  164 . In some embodiments, the first cylindrical region  160  may have a diameter that is less than the thickness of the polygonal region  164  to facilitate the loading of the blades  166  onto the axle  158 . Under-cut region  162  may have a diameter of approximately 2.95 mm (approximately 0.12 inch), although one skilled in the art will understand that the three regions of axle  158  may have different dimensions. Polygonal region  164  may be triangular, rectangular, pentagonal, hexagonal, or any other polygon. In some embodiments, polygonal region  164  may have a substantially circular cross-sectional area having a flat, a key, or other like feature for engaging rotary blades  166 . Axle  158  may be formed from stainless steel or any other material suitable for use in medical device applications including, but not limited to, titanium, aluminum, and brass. Axle  158  may be injection molded, extruded, machined, or otherwise fabricated as will be understood by one skilled in the art. In alternative embodiments, the axle,  158 , blades  166 , and spacers  172  monolithically formed by turning down a single piece of material. 
       FIGS. 16-18  illustrate one example of a rotary blade  166  where each rotary blade  166  may have a substantially circular outer shape and define a central aperture  170  having a complementary shape with the shape of polygonal region  164  of axle  158 . In some embodiments, each rotary blade is formed from stainless steel and has an outer diameter of approximately 18 mm (approximately 0.71 inch) and a thickness of approximately 3 mm (approximately 0.12 inches). Referring to  FIG. 18 , each blade  166  may have a blade tip  168  having a length of approximately 4.8 mm (approximately 0.19 inches), although the blade tips may have other lengths that are sufficiently long to cut through harvested dermal tissue as will be understood by one skilled in the art. Additionally, the blades  166  may have a variety of configurations including, but not limited to, notches in the blade tips or multiple blade tips per blade that are separated by a channel. Each of blades  166  may define a central key hole or aperture  170  sized and configured to receive polygonal region  164  of axle  158 . For example, central aperture  170  may have a hexagonal cross-sectional geometry with a width of approximately 0.160 to slidingly receive polygonal region  164  of axle  158  therein. 
     Adjacent rotary blades  166  of blade sub-assembly  156  are separated by spacers or washers  172  ( FIGS. 19 and 20 ). Spacers  172  often have an outer diameter that is less than the outer diameter of rotary blades  166 . In some embodiments, spacers  172  may have a diameter of approximately 7.87 mm (approximately 0.31 inch) and a width of approximately 5 mm (approximately 0.2 inch). One skilled in the art would understand that the width of spacers  172  may be adjusted to cut the harvested dermal tissue to the desired width. Additionally, the outer diameter of spacers  172  may also be adjusted depending upon the depth of slots  124  formed in side walls  110  of device body  102  such that spacers  172  do not interfere with the attachment of grill sub-assembly  188 , but allow blade sub-assembly  156  to float, e.g., vertically move along slots  124  in cutting head portion  104 . Spacers  172  may define an aperture  174  that is often substantially circular ( FIG. 19 ) or may have a shape that is complementary to the cross-sectional shape of polygonal region  164  of axle  158 . Spacers  172  may be manufactured from stainless steel, titanium, aluminum, brass, a polymer, plastics, or the like. 
     The alternating arrangement of blades  166  and spacers  172  is often secured on axle  158  by a combination of clamps  180 . One or more flexible spacer members  176  may be disposed on axle  158  adjacent to one of clamps  180  to compensate for tolerance stack-up of blades  166  and spacers  172  along axle  158 . Flexible spacer member  176  may be a wave spring ( FIGS. 21 and 22 ) having a thickness of approximately 0.15 mm (approximately 0.0059 inch), an outer diameter of approximately 6.2 mm (approximately 0.24 inch), and an inner diameter of approximately 5 mm (approximately 0.2 inch). One skilled in the art will understand that the size and shape of the spacer may be adjusted. The inclusion of one or more flexible spacer members  176  between clamps  180  and the arrangement of alternating blades  166  and spacers  172  enables blades  166  and spacers  172  to shift along the axis defined by axle  158 . Once device  100  is assembled, blades  166  are held in place by slots  192  in grill  190 . 
     Referring to  FIGS. 23 and 24 , clamp  180  is sized and configured to engage undercut region  162  of axle  158 . In some embodiments, clamp  180  may have an outer diameter of approximately 7.2 mm (approximately 0.28 inch), an inner diameter of approximately 3 mm (approximately 0.12 inch), and a thickness of approximately 0.6 mm (approximately 0.024 inch), although clamp  180  may have other dimensions and shapes. Flexible spacer members  176  and clamp  180  may each be fabricated from stainless steel or any other sufficiently resilient medical-grade materials. 
     Bearings  184  are sized and configured to be disposed on first region  160  of axle  158  and enable axle  158  to rotate about an axis when blade sub-assembly  156  is disposed in cutting head portion  104  of device body  102 . In some embodiments, bearings  184  may be polyethylene bearings having an inner diameter of approximately 4 mm (approximately 0.16 inch), an outer diameter of approximately 8 mm (approximately 0.31 inch), and a thickness of approximately 3 mm (approximately 0.12 inch). One skilled in the art would understand that other polymers may be used to form these parts. Polyethylene bearings  184  are less expensive and have a longer shelf-life compared to ball bearings that are implemented in conventional devices for processing harvested dermal tissue. Additionally, polyethylene or soft polymer bearings  184  are more susceptible to sterilization compared to conventional ball bearings implemented in dermal processing devices. 
       FIGS. 27-30  illustrate one example of a grill sub-assembly  188  including a grill  190  and a frame or cap  196 . Grill  190  often includes a plurality of parallel, spaced apart slots  192  separated by parallel, spaced apart bars  194 . Each of slots  192  is sized and configured to receive a portion of a blade  166  yet provide sufficient clearance such that the blade may rotate about an axis defined by the axle  158  as the device  100  is translated across a cutting surface  216 . In one embodiment, slots  192  have a length of approximately 16.5 mm (approximately 0.65 inch), a width of approximately 0.4 mm (approximately 0.016 inches), and be spaced apart from adjacent slots  192  by approximately 8.5 mm (approximately 0.33 inch) measured from center-to-center. Each end of slots  192  may include a radius of approximately 0.135 mm (approximately 0.0053 inch). Grill  190  may be formed from a hardened stainless steel, e.g., ASTM A276 type 302 stainless steel or ASTM A167 type 304 stainless steel. Hardening the stainless steel provides additional rigidity and resilience that reduces the likelihood of bars  194  deforming and causing blades  166  to lock up as blades  166  rotate about axle  158 . 
     Referring to  FIGS. 31-34 , a grill frame or cap  196  has a substantially rectangular shape defining a rectangular window  198 . Grill frame  196  curves along its width ( FIGS. 31-32 ). The curvature of grill frame  196  complements the curvature of bottom surface  118  of cutting head portion  104  of device body  102 . Grill frame  196  includes a recessed shelf  200  sized and configured to support grill  190  and detent or energy director  202  spaced apart from first shelf surface  200 . The grill  190  and grill frame  196  are dimensioned such that the grill  190  may be press fit against the recessed shelf  200 . The energy director  202  ( FIGS. 33 and 34 ) is sized and dimensioned such that it melts during an ultrasonic welding process to secure the grill sub-assembly  188  to the cutting head portion  104  of the device body  102 . In some embodiments, the energy director  202  inwardly extends from the interior portion of the grill frame  196  approximately 0.13 mm (approximately 0.005 inches) in the form of an equilateral triangle, although one skilled in the art will understand that the energy director may have various sizes and geometries. Grill frame  196  includes a second shelf surface  204  that is sized and configured to complement ridge  120  disposed around opening  108  located in bottom surface  118  of device body  102 . Grill cap  196  may be injection molded from polyethylene, polypropylene, or any other material suitable for injection molding and that may be ultrasonically welded to device body  102 . 
     To assemble device  100 , second handle  146  is coupled to cutting head portion  104  of device body  102  by inserting a pin  206  into holes  152  formed in arm  148  of second handle  146  and into holes  126  in cutting head portion  104 . The assembly of blade sub-assembly  156  and grill sub-assembly  188  is illustrated in the exploded assembly view in  FIG. 35 . The blade sub-assembly  156  may be formed by clamping a clamp  180  onto one of undercut regions  162  of axle  158 . A first flexible spacer member  176  may be slid along axle  158  until it abuts clamp  180 . A first blade  166  may be slid onto axle  158  followed by a first spacer  172  or vice versa. A second blade  166  and a second spacer  172  may then be slid onto axle  158 . Additional blades  166  and spacers  172  are alternately slid onto axle  158  until a predetermined number of blades  166  have been placed on axle  158 . A second flexible spacer member  176  may then be slid onto axle  158  and secured by clamping a second clamp  180  onto undercut region  162  of axle  158 . 
     First and second bearings  184  are slid onto first region  160  of axle  158  and blade sub-assembly  156  may then be disposed in cutting head portion  104  of device body  102  by sliding bearings  184  into corresponding slots  124  formed in side walls  110  of cutting head portion  104  of device body  102  ( FIG. 36 ). Grill sub-assembly  188  is assembled by inserting grill  190  into grill frame  196  until the edges of grill  190  are received past detent  202 . When installed, grill  190  has a curvature that matches the curvature of grill frame  196  ( FIG. 32 ). Grill sub-assembly  188  is then placed over blade sub-assembly  156  disposed within cutting head portion  104  of device body  102  such that blades  166  are received within slots  192  of grill  190 . Second shelf surface  204  is disposed adjacent to ridge  120  around opening  108  located in bottom surface  118  of device body  102 . Grill frame  196  may be ultrasonically welded to cutting head portion  104  of device body  102  to secure blade sub-assembly  156  inside chamber  106  of device body  102 . In some embodiments, grill frame  196  may be secured to the cutting head portion  104  of device body  102  by using an adhesive or glue or by using set screws or other attachment means as will be understood by one skilled in the art. 
     Device  100  for processing harvested dermal tissue may be sold in a kit including a dermatome  208  and a cutting mat  216  ( FIGS. 39-42 ). Dermatome  208  may include a razor blade  210  that is coupled to a housing  212  having a handle  214 . Razor blade  210  is secured to housing  212  such that blade  210  extends below a surface of housing  212  by a predetermined distance that corresponds to the desired thickness of dermal tissue to be harvested from a patient. 
     The cutting mat  216  ( FIGS. 41 and 42 ) is preferably fabricated from polypropylene although other materials including, but not limited to, metals and polyethylene may be used. The upper and lower surfaces  218  may include a plurality of convex protrusions  220  or other structures for increasing the friction of top and/or bottom surfaces  218  of cutting mat  216  such as, for example, pyramidal protrusions, concave dimples, cross-hatching, or the like. 
     Referring  FIGS. 37A-37B , the method of using device  100  for processing harvested dermal tissue includes placing a slice of harvested dermal tissue on a surface  218  of cutting mat  216 . The dermal tissue may be harvested using a dermatome  208  ( FIG. 39 ). With the dermal tissue disposed on cutting mat  216 , the user may pivot second handle  146 , if the device  100  includes a second handle, from the substantially collapsed position in which the second handle is disposed adjacent to handle portion  128  of device body  102  to the extended position as indicated by the arrow C in  FIG. 37A . In the extended position, the flange or stop  150  disposed between arms  148  of handle  146  engages flange or stop  122  that extends from top surface  114  of cutting guide portion  104  of device body  102 . 
     The user may then grip device  100  with both hands, e.g., one hand on handle portion  128  and a second hand on handle  146 , and arrange device  100  such that blades  166  contact cutting mat  216 . The user may then move device  100  in a first direction (arrow A in  FIG. 37A  or arrow B in  FIG. 37B ) while maintaining blades  166  engaged with cutting mat  216 . Note that the second handle  146  is not shown in  FIG. 37B  to simplify the figure. As device  100  is moved, the engagement of blades  166  with cutting mat  216  causes blades  166  and axle  158  to rotate. The user may continue to apply a downward force on handles  128 ,  146  of the device while moving device  100  in the first direction until blades  166  engage harvested dermal tissue  222 . Blade tips  168  slice harvest dermal tissue  222  as the user continues to move device  100  in the first direction. Bars  194  of grill  190  disposed between adjacent blades  166  prevent sliced dermal tissue from wrapping around spacers  172  between blades  166 . 
     After passing once through the harvested dermal tissue and creating sliced dermal tissue, the user may repeat the steps described above to further slice the tissue at an angle with respect to the initial slice. For example, the user may pass device  100  through the dermal tissue orthogonally with respect to the direction of the initial slice to create squares of dermal tissue, at a 45 degree angle to create diamond-shaped pieces of dermal tissue, or at any other angle to create further sliced tissue. Once the harvested dermal tissue has been processed, device  100  may be thrown away. To prevent device  100  from being sterilized and reused, grill fame  196  is often ultrasonically welded to cutting head portion  104  of device body  102  and will deform if the device is autoclaved. 
       FIGS. 38A-38C  illustrate a device  100  before and after it has been autoclaved. As shown in  FIG. 38B , cap  196  is severed from the device body  102  after having been autoclaved due to cap  196  being deformed during autoclaving. In this manner, improved device  100  for processing harvested dermal tissue increases the safety by ensuring a single use of the device and preventing hospitals from attempting to sterilize and reuse the device which could lead to cross-contamination as sliced dermal tissue may get stuck between adjacent blades. 
     The invention has been described in connection with what are presently considered to be the most practical and preferred embodiments. However, the present invention has been presented by way of illustration and is not intended to be limited to the disclosed embodiments. Accordingly, those skilled in the art will realize that the invention is intended to encompass all modifications and alternative arrangements included within the spirit and scope of the invention, as set forth by the appended claims.