OUTIL DE PREPARATION DE GREFFE CUTANEE

SKIN GRAFT PREPARATION TOOL

Abrégé anglais

A tool for preparing a skin graft which can be expanded to form a mesh,
includes a handle to be grasped by the hand of the operator and a circular bladefreely rotatably mounted to the handle. The blade has a sharp cutting edge
around its periphery, the blade periphery being notched at circumferentially
spaced intervals to provide cutting sections between the notches of a selected
length in the circumferential direction. A skin section placed on a hard backingsurface may thus be provided with a selected array of spaced cuts by the
operator by rolling the blade on the skin surface along successive parallel paths
while pressing the blade cutting edge into the skin section and toward the
backing surface.

Revendications

-8-
CLAIMS
1. A tool for preparing a skin graft which can be expanded to form a mesh,
said tool comprising:
a handle to be grasped by the hand of the operator;
a circular blade freely rotatably mounted to said handle;
said blade having a sharp cutting edge around its periphery;
the blade periphery being notched at circumferentially spaced intervals
to provide cutting sections between the notches of a selected length in the
circumferential direction;
whereby a skin section placed on a hard backing surface may be
provided with a selected array of spaced cuts by the operator by rolling the
blade on the skin surface along successive parallel paths while pressing the
blade cutting edge into the skin section and toward the backing surface.
2. The tool according to claim 1 wherein said notches are at least about
3mm deep in the radial direction.
3. The tool according to claim 1 or 2 wherein said notches are spaced to
provide cutting sections therebetween having a length from about 5mm to about
10mm in the circumferential direction.
4. The tool according to any one of claims 1-3 wherein said notches are
semi-circular in outline shape.
5. The tool according to any one of claims 1-4 wherein a single said
circular blade is mounted to said handle by a bracket having a spaced pair of

-9-
forks having an axle fixed to a distal end thereof and on which said blade is
mounted for rotation between said forks.
6. A method for preparing a skin graft which can be expanded to form a
mesh comprising the steps of:
(a) providing a tool as recited in any one of claims 1-5;
(b) placing a skin section on a backing surface;
(c) rolling the blade on the skin surface along a path of travel while
pressing the blade cutting edge into the skin section toward the backing surfaceto produce a series of linearly arranged spaced cuts in said skin section;
(d) repeating step (c) along successive paths of travel parallel to the first
mentioned path while indexing said blade before starting along each path such
that the cuts along each of said paths are staggered relative to the cuts in thepath(s) next adjacent thereto.
7. A method of preparing a skin graft comprising effecting the steps
recited in claim 6 and then applying stretching forces to the skin section
generally normal to the direction of said paths to cause the cuts to open and the
skin section to expand and form a meshed skin graft.

Description

- ' - CA 022207~ 1997-11-10
SKIN GRAFT PREPARATION
BACKGROUND OF THE INVENTION
The present invention relates to the preparation of skin grafts,
particularly skin grafts prepared in such a way that a relatively small area of
skin may be expanded to form a mesh which is then grafted over a larger area
on the patient.
Mechanical skin expanders have become the state of the art
instrumentation for the efficient expansion and application of large skin grafts.
This has reduced donor site areas. Graft meshing has also increased skin graft
take particularly in areas difficult to dress where fluid accumulation can occur,
or where there is a high incidence of sepsis. The skin expansion instruments
currently available are expensive and require expensive upkeep to maintain
their effective operation. Because of this they have not yet found wide spread
application or acceptance in Third World work. Indeed when harvesting small
areas of skin the set up time for these instruments and the mechanical problems
that can occur often result in the surgeon choosing to work with a more
traditional meshing technique wherein the skin graft is mechanically perforated
by a scalpel blade, or an osteotome used on a wood backing. Some degree of
expansion can be achieved by these traditional techniques, although it will be
less than optimal compared to that obtainable mechanical expander.
SUl\/~MARY OF THE INVENTION
It is a basic object of the present invention to provide an improved tool
and method for preparing skin grafts which can be expanded to form a mesh
and which is particularly useful in Third World conditions and which invention
achieves many of the benefits of currently available mechanical skin expanders
but without the substantial cost and maintenance problems associated therewith.

. - CA 022207~ 1997-11-10
Accordingly, the invention in one aspect provides a tool for preparing a
skin graft which can be expanded to form a mesh, said tool comprising: a
handle to be grasped by the hand of the operator; a circular blade freely
rotatably mounted to said handle; said blade having a sharp cutting edge
around its periphery; the blade periphery being notched at circumferentially
spaced intervals to provide cutting sections between the notches of a selected
length in the circumferential direction; whereby a skin section placed on a hardbacking surface may be provided with a selected array of spaced cuts by the
operator by rolling the blade on the skin surface along successive parallel paths
while pressing the blade cutting edge into the skin section and toward the
backing surface.
In a further aspect of the invention said notches are at least about 3mm
deep in the radial direction.
In a still further aspect of the invention said notches are spaced to
provide cutting sections therebetween having a length from about Smm to about
1 Omm in the circumferential direction.
Preferably and in a further aspect of the invention said notches are semi-
circular in outline shape.
In the preferred form of the invention a single said circular blade is
mounted to said handle by a bracket having a spaced pair of forks having an
axle f1xed to a distal end thereof and on which said blade is mounted for
rotation between said forks.
An improved method of preparing the graft is also described and
claimed herein.
These and other objects, aspects and features of the present invention
will be better understood from the following detailed description of a preferredembodiment of same when read in conjunction with the appended drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. lA is a somewhat diagr~mm~tic representation of a skin section

. - -' CA 022207~ 1997-11-10
-4 -
provided with a plurality of spaced apart parallel rows of staggered cuts;
Fig. lB is a diagr~mm~tic representation ofthe skin sample after it has
been stretched to form a mesh;
Fig. 2 is an elevation view of a skin graft tool in accordance with the
present invention showing the blade edge-on;
Fig. 3 is a further elevational view of the tool taken at right angles to the
circular blade.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring firstly to Figs. 2 and 3 there is shown a typical tool 10 for
preparing a skin graft which can be expanded to form a mesh. The tool
includes an elongated handle 12 of a convenient size and shape for grasping by
the hand of the surgeon. A relatively thin circular blade 14 is freely rotatablymounted adjacent one end of the handle by a bracket 16 defining a spaced pair
of forks. Bracket 16 includes an axle 18 which extends through the distal ends
of the bracket forks and through a suitably sized aperture at the centre of blade
14 thereby mounting blade 14 for free rotation between the bracket forks. A
guard 20 is disposed at the interface between bracket 16 and the end of handle
12 with the guard 20 extending laterally outwardly as best seen in Fig. 3 by a
sufficient distance in both directions as to assist in preventing the hand of the
user from coming into contact with the sharp cutting edge of the blade 16.
Blade 16 has a sharp cutting edge around its periphery with the blade
periphery being provided with notches 22 at circumferentially spaced intervals
thereby to provide cutting sections 24 between the notches, which cutting
sections are of a selected length in the circumferential direction.
The tool as described above preferably comprises a modified simple
piza cutter, preferably a strong high quality model such as made by Henckel of
Germany. As described above it has only one moving part (blade 16) and its
cutting edge can be maintained razor sharp by a simple means such as a fine
grit abrasive film. This tool is well suited for third world conditions as it can be

CA 022207~ 1997-11-10
readily modified in any simple shop using a chain saw file (which is of circularcross section) or a pattern file or a diamond bit as will be described in more
detail hereinafter.
In the course of modifying the pizza cutter referred to above it is best to
5 sharpen the cutting edge ofthe blade 14 first and this is done most easily by
using a one inch wide sanding belt sharpening system. This is relatively quick
and efficient and avoids loss of blade temper as a result of the heating that
could occur if a grindstone is used. The final cutting edge is achieved using 0.5
micron CRO 2 film or equivalent.
The circular cutting blade of a typical Henckel pizza cutter as referred to
above has an overall diameter of about 60mm and is approximately lmm thick.
The notches 22 are typically provided by holding the blade 14 secure in a vice
and using either a hand drill with a diamond burr or alternatively a chain saw
file or a round pattern file to achieve a series of evenly spaced notches
15 (preferably of semi-circular outline) the notches being at least about 3mm deep
in the radial direction. These notches 22 in a typical case would also be
approximately 3mm wide at the perimeter of the cutting blade and in the
embodiment shown, with the notches being cut at approximately 13mm centre-
to-centre distances, this provides cutting sections 24 between the notches which20 are about 1 Omm long in the circumferential direction. This arrangement is
capable of producing a well meshed graft that expands about 2 to 3 times its
original size. The degree of expansion depends upon how far apart the parallel
cuts are made in the skin graft. For a more finely meshed graft with about l.S
times expansion the notches are more closely spaced to provide 5mm-6mm
25 long cutting sections or intervals between the notches on the circular blade 14.
The blade 14 can be used to cut skin on any wooden or plastic surface running
parallel to the grain to ensure uniform and total skin perforation. Woods of
moderate density seem best suited. The blade will dull less quickly than with
an exceptionally hard wood. Very soft wood will wear and become ridged

- CA 022207~ 1997-11-10
quickly.
Skin strips which are some 4 or 5mm wide will allow for the suturing of
the graft down with ease. Narrower skin strips can also be cut to allow
increased expansion with 2 to 3mms being optimal. In order to allow custom
5 meshed grafts to be made for all likely areas, the surgeon should have on handat least two such tools 10, the first one having notches 22 on the circular blade
which are sized and spaced to provide cutting sections or intervals in the orderof Smm-6mm long while the other tool is provided with notches 22 sized and
spaced to provide cutting sections or intervals in the lOmm length range. These
10 dimensions are not absolutely critical and some practitioners may find that
slight deviations from the suggested dimensions given above still yield good
results. For additional inforrnation in this area reference may be had to the
publication of Vandeput, J.J., Tanner, J.D., and Beswick J. titled
"Implementation of Parameters in the Expansion Ratio of Mesh Skin Grafts",
15 Plastic and Reconstructive Surgery, Sept. 1997.
The preparation of the skin graft involves placing a skin section of the
desired size on a backing surface as described above. The tool 10 described
above is then utilized by rolling the blade on the skin surface along a fairly
straight line path of travel while pressing the blade cutting edge into the skin20 section against the backing surface to produce a series of linearly arranged
spaced cuts in the skin section. This last mentioned step is then repeated alongsuccessive paths of travel parallel to the first mentioned path while at the same
time indexing or rotating the cutting blade slightly before starting along each
path such that the cuts along each such path are staggered relative to the cuts in
25 the path(s) next adjacent thereto. This provides the staggered array of cuts as
depicted in Fig. lA giving optimal expansion.
Following the above procedure, the skin graft preparation is completed
by applying stretching forces to the skin section generally at right angles to the
direction of the cut lines thereby to cause the cuts to open and the skin section

-~ CA 022207~ 1997-11-10
to expand and form a mesh skin graft, this procedure being well known per se
in the art.
For best results, the blade 10 should be kept as sharp as reasonably
possible at all times. Minor resharpening of the blade is usually required
5 following preparation of some 10 to 15 grafts depending of course on graft size
and possibly other circumstances.
As noted previously, the extreme simplicity of the tool described above,
its very low initial cost and ease of maintenance, makes the tool ideally suitedfor work in the Third World although the invention is not limited to use in such10 applications. Various modifications and adjustments to the tool and the
techniques used may be made without departing from the spirit and scope of the
invention.

Dessin représentatif