Skin bed, to decrease shearing forces, and
Skin GraftingSkin grafting, or, the transplanting of skin and other underlying tissues types to another location has been used for almost three thousand years. It originally began with the Hindu Tilemaker Caste System where skin grafting was used to reconstruct noses that had been amputated as punishment. Over time, it evolved, and in this contemporary age we possess two major means by which to transplant skin: split-thickness skin grafting and full-thickness skin grafting. In split-thickness skin grafts, the skin graft includes only the epidermis and a portion of the dermis.
The thickness of the slice can be broken down further into a thin layer (.008-.012 mm), a medium layer (.
012-.018 mm), and a thick layer (.018-.030 mm).
This type of skin grafting is used primarily when cosmesis, or, the concern for the appearance of the patient, is not a key concern, or when the defect is too large for the use of a full-thickness skin graft. Split-thickness skin grafts are employed in various situations including: chronic non healing cutaneous ulcers, temporary coverage to allow for the observation of a possible tumor reoccurrence, surgical correction of depigmenting disorders, and coverage of burn areas to accelerate wound healing and reduce the loss of fluids. The procedure for harvesting and transplanting split-thickness grafts begins with the measurement of the skin defect. A purse-string placed around the defect reduces its size and thus also the size of the graft that must be harvested from the donor. Effective donor sites include thighs, buttocks, and upper arms. Then the donor site is lubricated with sodium chloride and a sterile tongue depressor is placed across the donor site to create a flat surface. The surgeon then applies the dermatome to the donor site and slices off the necessary layer of skin.
The newly harvested skin is placed in a sodium chloride solution and is prepared to be meshed. Meshing is advantageous when one wants to increase the ratio of the skin graft. By placing it in the mesher, the graft becomes flatter and obtains a diamond plate appearance. Keep in mind that while it is acceptable to trim the graft to fit the recipient site, it is better to have some overlapping between the donor tissue and the recipient bed. The slight-thickness skin graft is secured by staples and a bolster may be applied to encourage graft apposition to the recipient bed, to decrease shearing forces, and to maintain a moist environment for the graft.
The donor wound is now known as the partial-thickness wound, or the secondary defect. While full-thickness skin grafting does not require the use of various surgical instruments, slight-thickness skin grafting does. The two types of instruments may be separated into two groups: free hand and powered dermatomes. Free hand instrument include scalpel blades, and double-edged knives.
Only are these instruments truly effective when the graft is a small slight-thickness skin graft and the surgeon is consistent with thickness. Powered dermatomes, such as the davol dermatome, is more productive in harvesting large areas while producing accurate thickness, however, the quality remains dependent on the surgeon. In full-thickness skin grafts, the skin graft includes the full thickness of the skin and the subcutaneous tissue. Appropriate donor sites would include areas with similar color and texture. Once again, a purse-string suture decreases the size of the graft that must be harvested for the defect. A template of the defect is created by using a flexible material like Telfa, and the template is then transposed to the donor site.
The donor tissue is then excised and placed in a sodium chloride solution where it will remain viable for about 24 hours. After harvesting the graft, the secondary defect should be closed and the full-thickness skin graft should be defatted. The yellow globular adipose is removed by iris scissors and its removal allows more efficient revascularization. No matter which way the harvesting occurs the assimilation of the graft will follow the same three stages. Stage one, plasmatic imbibition, begins 24-48 hours after the placement of the graft on the recipient. The graft is white and maybe edematous at this point. Thinner grafts would survive better because the fibrin network encourages vascular buds from the recipient bed to extend into the graft.
Stage two is dubbed inosculation and this is where revisualization actually takes place and a erythemous blush is apparent has the red blood cells come into the area. The final step of the assimilation is one in which lymphatic development and vascular in growth occurs from the relatively highly vascularized recipient bed across the avascular base– vascular bridging. When the patient returns for a check-up, ideally, there will be a slight pink appearance in the graft and minimal crusting surrounding it. The newly grafted skin will be sensitive to trauma such as excessive heat (i.e. the sun), and strenuous exercise.
Complications include infection from staphylococcal, streptococcal, and gram-negative bacteria, and hematoma and seroma formation– the accumulation of fluids caused by burst blood vessels. The future holds promising prospects for skin grafting. Synthetics skins such as cadaver allograft skin, porcine xenograft skin, and bioengineer substitutes have been used to replace skin lost as a result of surgery, chronic wounds, and burns. Advantages to the usage of synthetic materials include the elimination of the necessity to produce a second surgical wound, the relative abundance of the materials, and the immediate presence and availability of the transplantable tissue. Disadvantages exist as well, and they include possible graft rejection and potential for disease transmission. Overall, these delicate procedures have been very helpful to mankindBibliography1.
Brady, JG. Skin Grafting. http://www.emedicine.com/derm/topic867.
htm C 2005, eMedicine.com, Inc.2.
Chinese University Bulletin. “Improved Skin Grafting Techniques Bring Hope to Burn Patient.” http://www.cuhk.hk/puo/bulletin/issue/199602/english/skin.htm3. Rustom, Al.
Skin and Laser Clinic. http://www.skin-and-laser.com/Vitiligo_FAQ.html