EmBOssEd AUTOdERmOTRANsPLANTs: ThEORETIcAL sUBsTANTIATION ANd PRAcTIcAL UsAgE

Background. It is established that granulation wound has uneven bumpy surface and modern electric dermatomes cut skin with a smooth internal surface. Therefore there is no tightly contact between the smooth surface of a graft and granulation tissue. Objective. The method of harvesting by split-skin grafts with variable thickness (embossed) is proposed. Methods. an embossed skin graft with sinusoidal surface of inner side was obtained by modified dermatome with special technological plate. The embossed autografting of skin was applied in 16 patients (21–60 years old) with deep burns of 7–9% of body. For clinical comparison the part of granulating wounds in each patient was covered with embossed transplants and the other part with smooth split-thickness grafts. Results. During ultrasound doppler examination of grafts on the fifth postop day the active blood flow in embossed transplants with 4–6 blood outbreaks and only 2–3 flashes in smooth graft were found. clinically the embossed transplants were engraftment on 6–7th day. On 18–21st day the roughness of grafts surface disappeared. In two months the graft together with subcutaneous fatty tissue was taken in crease. Donor wound: on 14–15th day its surface was like “slate” but on 25–30th day the undulation of the re-epithelisation skin disappeared. Conclusions. The improvement of dermatome design with technological plate allows cutting scalloped split-skin grafts of varied thickness (embossed). Split-thickness embossed grafts combine anatomic and physiological features of skin cover granulation wound to adhere tightly because of the enlargement of area of their internal surface without retraction and/or secondary shrinkage. Donor wounds, after the harvesting of embossed skin grafts, contain the morphological elements of dermis which contribute to their complete spontaneous healing.


Introduction
Skin transplantation is a method of choice in the treatment of patients with deep burns.In order to do this procedure, split-thickness skin grafts are harvested from donor areas.The donor wound regrows epithelium within two weeks [1][2][3]5].Sometimes there are complications with transplant skin engraftment to a granulating wound, sometimes areas of donor wounds suppurate [4,6,7,11].
Important aspect of skin graft healing is wound contraction that may present serious functional and cosmetic concerns, depending on the location and severity.Myofibroblasts may cause contraction.The ability of a skin graft to resist contraction is related to the thickness of deep dermal component included in the graft, not just the absolute thickness of the graft.This deep dermal component is able to suppress myofibroblast function.The severity of wound contraction from the least to the most is as follows: fullthickness skin graft cause least contraction, then thick and thin split-thickness skin graft, and finally the open wound has the most contraction [14].
Modern electric dermatomes cut skin with a smooth internal surface, in the meantime granulation wound has uneven bumpy surface [1,12].In certain cases there is no close contact between the smooth surface of a skin graft and granulation tissue; there are gaps and voids, where discharge from the wound collects, colonies of microorganisms form, which may cause hematomas or seromas and local inflam matory complications [4,8,9,11].
Thus, for successful healing by a skin graft without contraction of the wound, it is necessary to have the surface adapted to the granulating The question we are aiming to address is to find out if it is possible to cut skin graft with an uneven embossed surface, similar to the relief of granulations.
The study is aimed to introduce a method of harvesting the split-skin grafts of variable thickness.

Material and Methods
Theoretical consideration.The upper boundary of granulation tissue on the tentative vertical cut of the wound is a sinusoid with smaller or larger range, depending on which granulations (small-, medium-, or largegrained) fill the wound.Theoretically these granulations should be covered with analogic sinusoidal surface (Fig. 1).Obviously, the larger is the surface of granulations contact with the graft, the faster graft retention will be.Optimal configuration of internal surface of skin graft with spacing between ledges of π/2, π/4, π/8 mm (equals to 1.57 mm, 0.78 mm and 0.39 mm) is proved mathematically.
Technical solution.To obtain split-skin grafts with variable thickness (embossed) it is sug gested to add a so called technological plate with embossed surface [10].A technological plate is made of plastic mass or metal and consists of a base and shaped elements on it which have ledges of rectangular or other geometric figure shapes (Fig. 2).
Method of embossed skin graft cutting.Instruments and donor area do not differ from regular grafting.The technological plate is fixed to the base of the dermatome.The embossed surface of the plate should adjoin the skin of donor area tightly.Technological plate should be chosen according to the size of granulation on the wound: small, medium and large grained.Fig. 3 shows embossed skin graft harvest of the variable thickness and donor wound with sinusoidal surface.
An embossed skin graft has sinusoidal surface from the inner side, which considerably enlarges area of its contact with granulations on the wound (Fig. 4).e.g., the inner surface is embossed skin graft with 0.78 mm space between ledges is larger by 29.3% if compared to a smooth graft.
Full-scale adhesion to wound surface contributes to a quick engraftment of dermal transplant and minimizes the local postoperative comp lications.The epithelisation of donor wound is not affected because all skin appendages are preserved.
Clinical application.The embossed autografting of skin was applied for 16 patients with deep burns of 7-9% of the body.The patients aged 21-60 years, 13 mail (81.0%), and 3 female (19.0%).Part of granulating wounds in each patient was covered with embossed transplants, and part of them with smooth splitthickness grafts.Thus it was possible to conduct a clinical comparison of survival of two types of grafts.Next day after the surgery the surface of the embossed skin grafts was of different colours -pale and cyanotic lines along the grafts.On the second or third day cyanosis    decreased, and on 4-5 th days the colour of the embossed grafts became even.Clinically the embossed transplants were engrafted on 6-7 th day.On 18-21 st day the roughness of grafts surface disappeared.In two months the graft together with subcutaneous fatty tissue was taken in the crease.Donor wound: on 14-15 th day its surface was like "slate", but on 25-30 th day the undulation of the re-epithelized skin disappeared.
Ultrasound Doppler (Siemens G60S) examination of grafts was performed on the 5 th day.Active blood flow was found in some parts of the embossed transplants, there were on average 4-6 blood outbreaks on the length of the linear sensor (l10-5; 7.5-10.0MHz), but in smooth graft, which was still swelling, there were only 2-3 flashes.Therefore, variable thickness skin graft integrated with granulation tissue faster.Thus, our clinical study proved the use of embossed skin grafts in closing the granulating wounds.

Results and Discussion
The embossed epidermo-dermal transplants with variable thickness contain morphological elements of dermis which the thin smooth split-thickness skin grafts do not have.The thin part of the sinusoidal graft is represented by the epidermis; the thick part contains papillary and reticular dermis.So there are all structures of the skin: loose and dense connective tissue containing blood and lymphatic capillaries and vessels, elastic and collagen fibres, reticular layer with fibroblasts, nerve endings, and epidermal appendages in the gel-like ground substance.The same components are also in donor sites and play a crucial role in its re-epithelialization.That is why after placement of sinusoidal graft, its initial adherence to the wound bed via a fibrin binding is favourable if compared to the straight skin graft.
It is established that the smooth split skin grafts shrink along fibres on cleavage lines and in transverse directions after cutting.Moreover, shrinkage along the cleavage lines is almost twice as much as transverse shrinkage.Convolution of split-thickness skin grafts to internal surfaces is its characteristic feature [1,6].
Because of the embossed surface the shrinkage of epidermo-dermal transplant decreases considerably and the preserved morphological structure of dermis contributes to fast healing of burn wound as well as regeneration of functions of the transplanted skin.
The choice of skin grafts thickness is very important for successful autodermoplastic surgeries.Autodermoplastics with thin grafts have several advantages: the transplant survives for an average of 3-4 days, and the donor wound epithelizes for 12-14 days.However, this method has its deficiencies as well.Secondary shrinkage of the transplant occurs with usage of thin split grafts for wound covering; besides fatty tissue does not grow under this type of transplant [6,8,13].
Usage of full-thickness skin grafts has distinct advantages.They withstand mechanical loads, full fatty tissue grows under them, thanks to the renewed skin integument, which receives the functional and dynamic features.long term retraction and retention of full-layer grafts are significant disadvantages.They suppurate and are rejected more often.The usage of such grafts creates problems for the treatment of a do nor wound, which has to be covered with local tissues or autodermotransplants [1,7,9,12,14].iSSN 2413-6077.iJMMr 2016 Vol. 2 issue 2 epidermis of various topographical anatomical body areas is different in terms of relief, color and thickness (0.5-0.2 mm).Human skin thickness varies from 0.4 up to 4.0 mm.Thickness of the skin's dermal layer varies from 0.35 up to 4.0 mm and is a significant resource for harvesting split flaps [1,14].
Opposite to the smooth split grafts, embossed dermotransplants with variable thickness retain anatomical and physiological features of skin in monofunctional structural integrity; herewith there is no substantial trans plant shrinkage.The area of contact of transplant and wound increases because of the positioning of surface granulations, which hasten the process of its engraftment.

Conclusions
The improvement of dermatome design with technological plate allows cutting scalloped split-skin grafts of varied thickness (embossed).
Split-thickness embossed grafts combine anatomic and physiological features of skin cover granulation wound to adhere tightly because of the enlargement of area of their internal surface without retraction and/or secondary shrinkage.
Donor wounds, after the harvesting with the embossed skin grafts, contain the morphological elements of dermis which contributes to their complete spontaneous healing.