TECHNICAL BACKGROUND OF THE INVENTION
The invention refers to a hand-held device according to the preamble of the patent claim 1.
Skin grafting for surgical or cosmetic purposes constitutes an essential part of surgical maneuvers, especially for broad wounds resulting from injury or from removal of a skin tumor. According to the medical indication and the recipient site, e. g. in the facial region for cosmetic purposes, skin grafts of divergent thickness, which comprise all or only some tissue layers of the skin are used. Thus, one differentiates e. g. full-thickness skin grafts (FTSG), which comprise epidermis and complete dermis from split-thickness skin grafts (STSG), which include epidermis and only a part of the dermis.
There are various procedures for graft taking, that are not of detailed concern in consideration of the invention under discussion, like the excision of the desired skin layer for grafting by mechanical or electromechanical devices (so-called dermatomes), besides the manual excision of the skin graft of desired size using a blade, knife or scalpel.
The above mentioned context and medical requirements are described in detail in the publication “Journal of the American Academy of Dermatology”, Vol. 27, No. 2, part 1 (August 1992). Different realizations of dermatomes are known in medical engineering, represented e. g. by the patent claims U.S. Pat. No. 4,690,139 and GB 774 689.
Generally, it is not possible to place the excised “raw” graft directly on the recipient site in a medically suitable way, as thickness and type of tissue layers of the skin graft require further manipulation, respectively preparation, to remove undesired tissue layers, e. g. subcutaneous fat and to adapt the underside of the skin graft to the recipient site optimally.
In the first-mentioned publication (page 155, last paragraph) a manual procedure of preparing a skin graft is described shortly: The skin graft is draped raw side up (epidermal side down) over a finger or another region of the hand of the surgeon and the undesired subcutaneous fat or subcutaneous fat and dermal tissue is trimmed with scissors until the desired skin thickness is obtained. Obviously, this conventional method to trim a skin graft is not optimal, as it depends solely on the manual skills of the surgeon and an even thickness of the whole graft is not warranted. There is also a risk of contamination for the skin graft resulting from the tight contact to the hand of the surgeon, who is at risk of injuring himself while using scissors just above the surface of his hand. Finally, a perforation of the skin graft cannot be excluded.
This basically manual and time-consuming method hence does not provide optimal requirements for successful grafting in a hygienic respect, as well.
For these reasons, different more or less complicated devices have been published to accomplish this procedure more reliably (DE 297 22 914 U1; DE 94 03 937 U1); a kind-like device is known from U.S. Pat. No. 3,364,920. A slicer-like apparatus is shown there, wherein a blade for removal of undesired tissue layers is adjustable in a certain position, wherein a given distance of the cutting level to a surface, where the skin graft is placed upon, and by this the remaining thickness of the skin graft, is maintained whilst cutting as the lateral rods of this device move along both sides of the skin graft on the surface.
Even though this device offers more reliability than the beforehand described manual preparation with scissors, it is cumbersome and the adjustment of the blade position is laborious, which is especially disadvantageous, if the once adjusted distance between the blade and the surface does not directly result in the desired remaining thickness of the skin graft. The multitude of components requires a high precision in its production and makes this known device uneconomical.
Presentation of the Invention
The task of the invention hence is to simplify the known hand-held device regarding its handling and construction with keeping a desired thickness of a skin graft.
This task is solved with the features of the patent claim 1.
The basic idea of the invention consists in keeping a definite cutting plane along the whole cutting movement solely by the handling of the device while drawing it through the graft, but also to allow corrections of the cutting plane while pulling through the blade. To realize this advantage the invented contraption is intended to be provided with two rods, with their end regions serving as variable spacers, so that according to the applicable operating angle of the device in relation to the supporting surface a definite thickness of the remaining skin tissue can be chosen quickly and easily. A removal of tissue in multiple layers is also possible with a reduction of the operating angle resulting in a lowering of the cutting plane allowing a quick and nonetheless precise “cautious” approach to the layer of the skin graft later representing the contact surface to the recipient site.
The invented device is handy, easy to use and facile to produce. The time required to trim a graft using this device, is considerably diminished, the danger of injuries and contamination is reduced.
Preferred features are represented in the subsections of the patent claim.