Introduction

Severe full-thickness burns or major injuries that severely damage the skin can impede natural regeneration and threaten patient survival. Prompt intervention is crucial to restore normal skin function. When donor skin is available, an autograft is widely regarded as the most effective solution ^[1].

Skin grafts are primarily classified into three basic types: full-thickness skin grafts (FTSG), split-thickness skin grafts (STSG), and composite grafts. FTSGs include both the epidermis and the entire thickness of the dermis. In contrast, STSGs comprise the entire thickness of the epidermis and only a portion of the dermis, and they can be further subdivided into thin, medium, and thick grafts ^[2].

The healing process of skin grafts typically involves three stages: anchorage, inosculation, and maturation. While split-thickness autografts are preferred, the limitation of available donor sites has driven the search for alternative solutions ^[3].

Converting both split and full-thickness grafts into micrografts transforms them into individual units that promote regeneration and release growth factors to support the healing process ^[4].

Microskin grafts (MSG) are thin split-thickness grafts that come in different sizes and thicknesses. Smaller grafts tend to heal faster because they have more active edges, which accelerate regeneration ^[5].

Cells in the basal layer of microskin form epithelial islands that expand outward, connecting to the wound surface's epidermis and creating an epidermal cyst structure. Autologous micrografts are rich in progenitor cells, growth factors, and extracellular matrix particles derived from the patient's own tissue ^[6].

The amniotic membrane (AM), which is the innermost part of the placenta, has been used in therapeutic applications for the past century. Its thickness ranges from 0.02 mm to 0.5 mm and it is composed of three primary histological layers: the epithelial layer, the thick basement membrane, and the avascular mesenchymal tissue ^[7].

Applying an amniotic membrane in burn treatment promotes rapid healing and re-epithelialization by mitigating several harmful factors. Covering microskin grafts with a hu-man amniotic membrane accelerates wound ^[8].

The amniotic membrane significantly shortens the duration for complete graft take, making it especially suitable for children or burns on the extremities. The graft is applied to the wound bed, and the amniotic membrane is wrapped around the grafted extremity, followed by dressing. The membrane adheres to itself when wrapped around the extremity. Using an amniotic membrane as a graft fixator is associated with accelerated re-epithelialization and recovery ^[9].

Aim of the work

To assess the impact of applying human amniotic membrane at the recipient site of micro-autogenous split-thickness skin grafts for covering post-burn raw areas, as regard to:

1. The graft take percentage.
2. Infection rates.
3. Time required for complete wound healing.
4. The expansion ratio of the recipient site to the graft donor site.
5. Scar evaluation of the graft.

Patient and Methods

1. Technical Design

This prospective controlled clinical study was conducted on 20 patients at the Plastic Surgery Department of Minia University Hospitals. The study involved the application of human amniotic membrane at the recipient site of micro-autogenous split-thickness skin grafts.

Inclusion Criteria:

• Age: pediatrics & adults (2: 40 years old).
• Both sexes
• Post burn raw areas.

Exclusion Criteria:

• Exposed bone, tendon, nerve, cartilage.
• Clinically infected recipient area.
• Uncontrolled DM
• Immune-compromised patients
• Uncooperative patients.
• Drug abuse

1. Operative Design:

All patients will be subjected to:

• An informed consent was taken from all patients or their guardians
• Complete history taking:
• Personal history
• Any complaint
• Past medical history and past surgical history
• Family history
• Complete physical examination
• General examination
• Vital signs (Blood pressure, Temperature, Heart rate, Respiratory rate)
• Microskin grafts are applied over the whole raw area, then the raw area was divided into two parts, and amniotic membrane is applied on only on part of it.
• Preparation of the amniotic membrane:
• The preparation of amniotic membrane (AM) involves collecting the membrane from volunteer mothers who have been screened for HIV-1, HIV-2, hepatitis B, hepatitis C, and syphilis.
• The placenta is decontaminated to eliminate potential surface pathogens, followed by rinsing with sterile saline and antibiotic solutions. An antibiotic-anti-mycotic cocktail containing Ampicillin, Ceftriaxone, and Fluconazole is used to combat both Gram-positive and Gram-negative bacteria, as well as fungi. Large sections of the amniotic membrane (AM) are then removed and thoroughly rinsed to clear any blood or blood clots. It was then transferred to a container filled with 50% glycerol  and stored at -28 °C (household freezer)^[9]. Just before use, the human amniotic membrane (HAM) is defrosted and soaked in sterile saline for two hours to remove glycerol. It is then placed in a sterile stainless steel surgical bowl
• Preparation of the micro-autogenous split-thickness skin grafts:
• During preparation of raw area, thin autogenous split-thickness skin grafts is also harvested by the Zimmer® dermatome adjusted at 25mm split thickness graft setting with a ratio of 1:8 which is expansion ratio of the graft donor site to the recipient site measured by sterile steel surgical ruler.
• Preparation of micro-autogenous split-thickness skin grafts by cutting harvested skin grafts with blade 24 into small pieces on sterile wooden board.
• Application of microskin grafts on raw area covered by amniotic membrane:
• A graft split technique is used by dividing raw area into two parts by imaginary line separates the raw area.
• Microskin grafts are spread over whole of post-burn raw area using forceps and the prepared amniotic membrane is applied on top of one half of the raw area and fixated by disposable skin stapler (study group) while the other half isn’t covered by amniotic membrane (control group).
• Vaseline gauzes are applied on both parts of raw area.
• Follow up started after 5 days then every 2 days for 6 months with documentation of progression at both compared halves as regard the graft take percentage, infection rates, time required for comp-lete wound healing, the expansion ratio of the recipient site to the graft donor site, and the scar evaluation of the graft.
• Three assessors were used to assess the results to reduce bias

1. Administrative Design:

• The protocol was submitted for approval of Research Ethics Committee
• Informed consent was obtained from the patients before enrollment of the study
• All data was kept confidential
• All participants had the right to withdraw from the study without affecting their management Department

• Discussion

  In the current thesis, regarding the demo-graphic characteristics among the 20 studied cases, the mean age of the patients was 21.4±12.4 years ranged from 4 to 40 years, 12 males and 8 females.

   

  In a previous study by Agarwal et al., in 2021 aimed to use the microskin autografting for post burn raw areas, but without a cover for the microskin graft, the demographic data among 25 studies were mean age of the patient was 27.52 years ranging from 18 to 54 years, 15 males and 5 females.

   

  As regard the causes and site distribution of the studied patients we found that, the most common cause was flame burn in (55%) of the patients, followed by scald burn (30%). The most common site was lower limbs (50%), followed by upper limbs (30%).

   

  In agreement with these findings, X. L. Chen et al., in 2011 showed that the most common cause was thermal injury was flame (63.5%), followed by explosion (19.1%), scald (12.7%).

  The present study showed that, the mean healing time in study side is (25.5±4.2) which is significantly lower than the control side which is (30.8±5) and no need for another session of grafting at both sides.

   

  1. L. Chen et al., in 2011 clarified that the wound healing time was determined by evaluating the appearance or signs of epithet-

   

  lialization in the grafted areas and the wounds healing time of these 63 major burn patients was between 35 and 55 days.