Indications and features of skin allotransplantation
Allotransplantation is used in clinical situations where autoplasty (transplantation of one's own tissues) is impossible. Most commonly, this occurs with extensive burn injuries or an extremely severe general condition of the patient accompanied by pronounced intoxication and sepsis.
As plastic material, surgeons use both fresh and preserved skin allografts.
Features of the procedure:
- Timing: the intervention is performed at an early stage of burn disease (typically days 14–21) or immediately after radical excision of necrotic areas.
- Purpose: the transplanted foreign skin serves as a kind of biological dressing. It is a short-term cover that functions for about 2–3 weeks.
- Outcome: temporary wound closure significantly reduces fluid loss, decreases intoxication, and thereby improves the recipient's general condition.
In clinical practice, allotransplantation is rarely used in isolation. It is frequently combined with autologous skin transplantation (autotransplantation) and animal tissue transplantation (xenotransplantation).
Bretoplasty
A specific variant of alloplasty is bretoplasty — the transplantation of skin harvested from a stillborn fetus.
The main limitation in selecting donor material is the gestational age: it must be no more than 6 months. A critical condition for the successful engraftment and function of such a graft is strict adherence to isoserological compatibility. The donor and recipient must share the same blood type.
Free transplantation with microvascular anastomosis
For complete and long-term closure of large tissue defects, a modern method is used: the transplantation of a free segment comprising skin and subcutaneous adipose tissue.
Essence of the technique:
- The surgeon harvests the donor flap along with its feeding vessels.
- The flap is transferred to the defect.
- Using specialized microsurgical technique under an operating microscope, a vascular anastomosis is created — the arteries and veins of the donor flap are sutured to the vessels of the recipient bed.
Criteria for donor flap quality: For the transplanted tissues to survive, they must have adequate blood supply. To achieve this, the flap must have a well-pulsating artery (for blood inflow) and at least one vein of sufficient diameter. It is the vein that provides the necessary drainage capacity, meaning the ability to effectively drain blood from the transplanted segment, preventing edema and necrosis.
Briefly: answers to topical questions
What methods of skin allograft preservation are used in combustiology?
The sources list the following tissue preservation methods used to maintain transplant material:
- Chilled solutions — placing tissues in solutions containing antiseptics or antibiotics, plasma, or the recipient's blood.
- Freezing — rapid freezing at temperatures from −183 to −273 °C followed by storage at −25…−30 °C.
- Lyophilization — freezing followed by vacuum drying; the source indicates the use of this method for bones.
- Chemical preservation — immersion in paraffin or aldehyde solutions, including formaldehyde and glutaraldehyde.
What types of free flaps by tissue composition are used in plastic microsurgery?
In transplantation with microvascular anastomosis, a free segment of skin and subcutaneous adipose tissue is used. The source also categorizes free skin flaps by thickness: thin, split-thickness, and full-thickness.
For a microsurgical flap, remember a simple rule: "Artery pulses — Vein drains." Without adequate venous drainage capacity, the flap will not survive.
Class and exam questions
Why is an allograft transplanted for only 2–3 weeks?
This is foreign tissue that is inevitably rejected by the recipient's immune system. Its main goal is to give the patient a temporary respite, reduce intoxication, and prepare the wound for autologous skin transplantation.
When is allotransplantation preferred over autotransplantation?
In situations where the patient lacks resources for autologous tissue transplantation: in extensive burns (insufficient donor sites) or severe sepsis, where the additional trauma of harvesting autologous skin could be fatal.
What is drainage capacity in free transplantation?
This is the ability of the venous bed of the transplanted flap to adequately drain blood. To achieve this, at least one vein of sufficient diameter must be isolated in the flap and anastomosed to the recipient's vein.
What else to study on this topic
- Methods of skin allograft preservation
- Technique of surgical excision of necrosis in burns
- Indications and materials for xenotransplantation
- Combined methods of burn wound closure (auto- + alloplasty)
Master the entire topic in the "General Surgery" course
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