Since the skin graft becomes incorporated into the recipient bed, it undergoes three predictable stages of graft "take." The first stage, plasmatic imbibition, consists of simple diffusion of nutrients from the recipient bed towards the skin graft. Lasting 24-48 hours, imbibition prevents the graft from becoming dry and keeps the graft vessels patent so that the graft can survive the immediate postgraft ischemic period. Grafts appear plump during this time and can add as much as 40% for their pregraft weight through fluid movement from recipient bed to graft.
After 48 hours, the second phase, inosculation, and also the third phase, revascularization, happen to restore blood circulation towards the graft. During inosculation, capillary buds in the recipient bed fall into line with graft vessels to create open channels.
This establishes blood flow and allows your skin graft to become pink. The connection between graft and host vessels develops further as the graft revascularizes and recently formed vascular connections differentiate into afferent and efferent vessels between days four and seven. Lymphatic drainage is present by the fifth or sixth postgraft day, and also the graft begins to lose weight until it reaches its pregraft weight through the ninth day.
Once your skin graft is harvested, it also starts to shrink. Primary contraction is passive and occurs immediately after harvest. A FTSG loses about 40% of its original area; a medium-thickness skin graft about 20%; along with a thin STSG about 10%. Secondary contraction takes place when the skin graft is used in the recipient bed, and it is only seen in STSG. The amount of wound contraction is determined by the quantity of dermis in the skin graft.
The more dermis there's in a skin graft, the less the wound bed will contract. Secondary contraction is minimal in a FTSG, that is able to develop after it heals. Wound contraction can be handy in reducing wound size, but a contracted wound can also be tight and immobile, leading to distortion of surrounding normal tissue.
As the skin graft heals, it reinnervates and undergoes color changes. Nerves come to be skin grafts from the wound margins and recipient bed, and skin grafts can start to show sensory recovery anywhere from 4-5 weeks to 5 months postgraft.
Full return of two-point sensation is usually complete by 12-24 months, but temperature and pain sensation may never return. Regarding color, grafts from the abdomen, buttocks and thigh often darken with time, whereas grafts from the palm often lighten. Thin grafts will also be usually darker than thick ones.
Depending on thickness, skin grafts may also regain function of transferred epithelial appendages, such as sweat glands, sebaceous glands and follicles of hair. Usually, only FTSG are reliably able to sweat production, oil secretion and hair regrowth. Sweat production depends on the number of sweat glands transferred during grafting and the extent of sympathetic reinnervation. The graft will sweat based on incoming sympathetic nerve fibers so that a graft on the abdomen sweats in reaction to physical activity while exactly the same graft on the palm will sweat in response to emotional stimuli.
With regard to oil secretion, sebaceous gland activity is visible in both full- and split-thickness grafts, but they are not often functional in thin STSG. Similarly, FTSG produce hair, while STSG produce little or no hair. In addition, inadequate revascularization or disruptions in graft take will damage graft follicles of hair and result in sparse, random and unpigmented hair growth.
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Note: This article was sent to us by: Patricia Phillips at 02102011
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