Surgery – Instruments – Means for removal of skin or material therefrom
Reexamination Certificate
1999-07-22
2001-06-19
Smith, Jeffrey A. (Department: 3732)
Surgery
Instruments
Means for removal of skin or material therefrom
Reexamination Certificate
active
06248114
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for forming skin grafts by cutting skin present an a carrier, which carrier is present in a holder, using cutting means, and furthermore to such a holder to be used in forming skin grafts, a carrier, a contra carrier, a cutting table, clamping means and ejecting means to be used therewith. The present invention furthermore relates to a method for applying skin grafts to a burn.
BACKGROUND
Such a method for cutting skin by using cutting means in order to form skin grafts is known from International patent application WO 84/02464. According to FIG. 3 of WO 84/02464 the skin to be cut into skin grafts is placed between a cutting frame and a baseplate, after which the skin is stretched on said baseplate by stretching means fitted with a stretching screw. The cutting operation is carried out by means of a knife which is pulled across the cutting frame. In order to improve the fixation of the skin to be cut pins are provided in the baseplate in regularly spaced-apart relationship, so that the skin cannot move during cutting. In addition to that a cutting foil is present under the skin to be cut, in order to prevent the knives from coming into direct contact with the baseplate. A special drawback of this method is that the pins project into the skin to be cut, which makes it impossible to achieve a 100% yield. In other words, it is not possible to convert 100% of the skin used as the starting material into skin grafts, since a certain amount of skin will be lost as a consequence of being pierced by the pins. Although other methods are mentioned for holding the, skin to be cut in position on the baseplate, for example by using an adhesive, the fixation of the skin to be cut by using a sub-atmospheric pressure or underpressure cannot be derived therefrom.
A method of this kind for forming skin grafts by cutting skin present on a carrier, using cutting means, is already known from the academic dissertation “De techniek van de behandeling van brandwonden” (the technique for treating burns) by R. P. Hermans, published by Stafleu's Wetenschappelijke Uitgeversmaatschappij N. V. of Leiden (see pp. 50-55). According to the said method it is also possible to cover defects caused by burns taking up more than 15-20% of the total surface area of a human body with auto transplants. Split-skin grafts that have been harvested by means of an electro dermatome in a manner which is normal to a person skilled in this field are placed on cork plates which have been immersed in a physiological saline solution. An apparatus known from U.S. Pat. No. 3,076,462, which was specially designed for this purpose, is used to cut said transplants into strips having a width of about 3 mm by means of rotating knives functioning as cutting means, whereby the knives cut through the skin but not through the cork plate, which merely functions as a base. Then the transplant-carrying cork plate is passed through the apparatus anew, but now turned through 90°, so that small squares of about 3×3 mm are formed. The skin grafts thus cut are adhered to gauze, which has been pre-folded in two directions in advance (pleat), by means of a special glue. After the glue has dried the folded gauze is stretched in two directions, as a result of which the skin grafts are spread. This has led to the situation wherein the small squares, viz. the cut skin grafts, are arranged in regularly spaced-apart (about 5 mm) relationship, with the cutting side facing upwards. Then the folded bandage is laid loosely on the excided area, provided with perforations for drainage, and subsequently fixed in position by means of gauze. In this manner an increase in area of about nine times the original dimension is obtained. One drawback of such a method is that after about one week the gauze is removed under an anaesthetic and can be replaced by donor skin. Another drawback is the fact that it takes a considerable amount of routine to be able to carry out such a method. After all, it frequently happens that the skin grafts are detached from the cork plate by the rotating knives and stick to the knives. This problem can be solved, however, by applying a small amount of paraffin to the knives, but this results in insufficient adherence of the skin grafts to the pre-folded gauze. In addition to that it is of paramount importance that the glue be allowed to dry sufficiently long before it is attempted to remove the cork plate from the gauze, as otherwise the skin will not properly adhere to the gauze. Because of the fact that the gauge cannot be removed until after about one week, the healing process, that is, the closing of the wound, will take a period of three to four weeks. In practice such a long healing period is undesirable.
SUMMARY OF THE INVENTION
Now a method for forming skin grafts has been found which does not exhibit the drawbacks of the prior art referred to above. In addition to that the method according to the present invention makes it possible to shorten the healing period by one week, so that the wound will already have closed after a period of two to three weeks.
According to the present invention the method as referred to in the introduction is characterized in that the skin is placed on a porous carrier, whereby a sub-atmospheric or reduced pressure is generated in the holder on the side of the carrier remote from the skin, after which the skin is cut into skin grafts by cutting means.
Although the use of a sub-atmospheric pressure for fixing skin is known from German Gebrauchsmuster No. 94 03 937, it is not known from said document to place the skin on a porous carrier in order to form skin grafts, whereby a sub-atmospheric pressure is generated in the holder, on the side of the carrier remote from the skin, in order to cut the skin thus fixed into skin grafts by cutting means. German Gebrauchsmuster No. 94 03 937 is aimed at the sub-epidermal thinning out of skin for reconstructive purposes, whereas the method according to the present invention comprises a complete cutting through of the skin in order to obtain separate skin grafts.
According to the present invention the term skin is to be understood to mean autologous skin as well as donor skin. In practice it has become apparent, however, that autologous skin “adheres” better than donor skin. In addition to that the term “porous” is understood to mean that a sub-atmospheric pressure can be applied, that is, the carrier is provided with apertures or perforations.
The carrier used according to the present invention is essentially different from the carrier used in U.S. Pat. No. 3,076,462, because the former carrier needs to be porous in connection with the application of a sub-atmospheric pressure, whereas such a requirement is not made of the carrier according to U.S. Pat. No. 3,076,462. Hereafter the term carrier will in all cases be understood to mean a porous carrier.
The carrier used in accordance with the present invention is preferably provided with apertures, in particular conical apertures, whereby the smallest dimension of the cone is located on the side carrying the skin. As a result of the presence of these apertures the generation of a sub-atmospheric pressure in the holder will cause the skin to adhere to the porous carrier, whereby it should be noted that the dimensions of the apertures on the side-carrying the skin are smaller than those of the skin grafts to be cut. If the dimensions of the apertures would exceed those of the skin grafts to be cut, the skin grafts would be sucked out through the apertures of the carrier as a result of the presence of said sub-atmospheric pressure.
In a special embodiment a so-called contra carrier is placed under the apertured or perforated carrier. A contra carrier is a plate provided with protrusions, whereby the diameter of said protrusions is selected to make them fit the apertures of the carrier. The combination of carrier and contra carrier functions to reduce the cross-sectional area of an aperture of the carrier over which the sub-atmospheric pressure is
Burncare B. V.
Robert Eduardo C.
Smith Jeffrey A.
LandOfFree
Method for forming skin grafts does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for forming skin grafts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for forming skin grafts will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2461262