Delayed autografting in the face and hands: The role of allografts in burn wound bed preparation

Abstract

Introduction

Burn injuries affecting specialised areas such as the face and hands require durable skin coverage and complete graft “take” to prevent scarring and functional impairment. Failure to achieve these outcomes can lead to long-term complications. This presentation aims to describe an approach of delayed autografting in these regions, following a "trial of allograft" to optimise wound bed preparation. We hypothesize that a trial of allograft prior to autografting improves graft take, and hence aesthetic and functional outcomes in specialised burn areas.

Materials and methods

Four patients with burns involving the hands (N = 3) and face (N = 2) were treated using allografts. The patients presented with TBSA burns of 60 %, 60 %, 55 %, and 2 %, respectively. In three cases, the primary indication for this approach was to prioritise life-saving coverage through the use of micrografts, while temporarily allografting the hands for three weeks. Skin exchange with sheet autografts was performed after re-excision of any non-viable areas, except in one patient who succumbed to pneumonia due to inhalation injuries. For facial burns, serial tangential excision was performed followed by allograft application to assess the viability of the wound bed, as indicated by their take.

Results

Initial allograft take was 80 %. After re-preparation of non-take areas, autograft adherence reached 100 %. One patient expired before skin exchange could be performed.

Two patients who successfully underwent skin exchange regained full ROM and independent ADLs. The facial burn patient achieved minimal scarring and full mimetic function, with preserved cosmetic subunits.

Conclusion

Delayed autografting of specialised areas facilitated optimal wound bed preparation, ensuring a 100 % take of the autograft.

Introduction

Burn injuries affecting specialised areas such as the face and hands present unique challenges as these areas hold significant functional and aesthetic value. For a favourable outcome, they require coverage with high-quality sheet skin grafts that integrate with the wound bed in a stable fashion.¹ Complete skin graft take in these regions is critical for restoring both form and function, particularly in the hands and face where fine motor skills and facial expression respectively are paramount.² Poor graft take leads to residual wounds which need to be regrafted or actively managed to achieve healing by secondary intention. Ultimately, they result in scarring and loss of function.

However, in major burns exceeding 60 % TBSA, autologous sheet grafting of specialised areas, though critical, is subordinate to expansive life-saving coverage using meshed grafts and micrografts.^3,4 The reasons are twofold: firstly, sheet skin grafting expends too much skin and does little to accomplish early rapid coverage. Secondly, owing to haemodynamic instability in the acute phase, wounds tend to convert despite adequate excision. Thus sheet grafts often do not take completely and are wasted.

The purpose of this paper is to describe our technique of delayed autografting of specialised areas through the temporary application of sheet allografts after total burn excision. We hypothesise that a trial of allograft prior to autografting ensures complete graft take at the second stage, and hence aesthetic and functional outcomes in specialised burn areas.

Materials and methods

Four patients were admitted to the Singapore General Hospital Burn Centre with total body surface area (TBSA) burns of 60 %, 60 %, 55 %, and 2 %, involving specialised areas including the face and hands. Each patient was treated using the "trial of allograft" approach. In the first three cases, the primary indication for this approach was to prioritise life-saving coverage using micrografts, while temporarily applying allografts to the hands for a period of two to three weeks. After this interval, skin exchange with sheet autografts was performed, following the re-excision of any non-viable (non-take) areas. The third patient expired from inhalational injuries before skin exchange could be carried out.

In the case of facial burns, serial tangential excisions were conducted according to cosmetic units. Allografts were initially applied and were subsequently replaced with autografts after successful graft take.

The patients underwent a standardised rehabilitation protocol. Hand therapy was initiated seven to ten days post-grafting depending on graft stability. Initial rehabilitation involved active range of motion exercises and intrinsic-plus splinting to prevent contractures. The splints were typically kept for a month and adjusted accordingly. Subsequently, to increase the range of movement, passive ranging over and above active ranging was instituted as tolerated. Pressure garments and silicone gel sheets were applied after two weeks and continued for two years. For facial burns, rehabilitation involved the application of the facial pressure mask and silicone gel sheets, as well as exercises to improve oral competence and eye closure. Maintenance of skin moisturisation and pliability were accomplished using emollients and scar massage.

At six months post-discharge, hand and facial reconstruction outcomes were assessed. Hand functional outcomes were evaluated using both objective functional measures and subjective patient-reported outcomes. Objective measurements included range of motion (ROM) and grip-pinch strength, with total active motion (TAM) calculated to assess ROM. Subjective outcomes were measured using the Michigan Hand Questionnaire (MHQ), which evaluates six domains: overall hand function, activities of daily living (ADLs), work performance, pain, aesthetics, and satisfaction. MHQ scores range from 0 to 100, with higher scores indicating better patient-perceived hand function.⁵ Key facial functions including sensation, animation, oral competence and eyelid function were assessed.

Surgical technique

Hands

Tangential excision of the hands was performed using an air-powered Zimmer dermatome set to a depth of 10 thousandths of an inch. Over the joints, pre-infiltration with saline was done to facilitate smooth passage of the dermatome. The procedure was carried out under tourniquet control to maintain a bloodless field. After excision, the tourniquet was released to evaluate the wound bed. The presence of punctate bleeding confirmed that excision was adequate. The tourniquet was then re-inflated, and slow-acting fibrin tissue glue applied to promote adhesion of the skin grafts. Perforated sheet allografts were applied in the standard fashion and secured with bulky dressings to ensure optimal contact with the wound bed. The grafted hands were inspected on the fifth postoperative day, and thereafter every other day for maintenance. After one week, well-prepared beds typically demonstrated allograft adherence. In the second week, converted areas would typically declare themselves and these were marked. Between two and three weeks, allograft rejection became apparent and they were replaced with sheet autografts after re-excising “converted” areas.

Face

For the case of facial scalds, tangential excision of deep burns was performed using a Goulian knife set to a depth of 8 thousandths of an inch. In areas not amenable to excision with the Goulian knife (eg, the eyelids, nasojugal fold, and lips), a #10 blade was used instead. Adequacy of excision was assessed by the presence of punctate bleeding. Once adequate excision was done, medium-thickness allografts were applied immediately and secured using fine quilting sutures. The excision and grafting were performed according to cosmetic units. Postoperatively, the grafts were managed using an open grafting technique where the grafts were lightly dressed and inspected 2 hourly until they were adherent.

Autografting of the face was typically performed after 5 to 7 days, depending on operating room availability. Donor sites for autografts included the scalp (for the eyelids and lips) and the thigh (for the cheeks). During the autografting procedure, the wound bed was reassessed, and areas of conversion re-excised before sheet grafting. Reconstruction of the nose was later completed using a forehead flap.

Results

Allografts applied to the hands and face achieved 80 % stake in the initial 3 weeks. Sheet autografts applied to the hands and face achieved 100 % take without complications. The patient with TBSA 55 % expired a month after admission from inhalation injuries before the scheduled skin exchange could be performed on his hands. The two patients who successfully underwent skin exchange achieved normal ROM in the fingers, thumb and wrist. They regained the ability to perform all activities of daily living (ADLs) independently. Their outcomes and follow-up periods are summarised in Table 1. In the patient with facial burns, there was minimal scarring and disruption to the cosmetic subunits of the face. All critical functions such as sensation and mimetic function were restored. He was followed-up for a year before he returned to his country of origin. Patients 1 and 2 were followed-up for four years and a year respectively. Both continue to wear pressure garments on their hands and have returned to work without the need for secondary surgery.

Table 1.

Summary of clinical outcomes following a trial of allograft in burn patients.

Case	TBSA (%)	Initial allograft take (%)	Autograft take (%)	Survival	Hand function outcomes	MHQ score (Hand)	Facial outcomes	Follow up (Years)
1	60 %	80 %	100 %	Survived	Normal ROM, Independent ADLs	88	Minimal scarring, preservation of cosmetic units and mimetic function	4
2	60 %	80 %	100 %	Survived	Normal ROM, Independent ADLs	92	N/A	1
3	55 %	80 %	Not performed	Deceased	N/A	N/A	N/A	N/A
4	2 %	80 %	100 %	Survived	N/A	N/A	Minimal scarring, facial sensation and animation restored	1

Illustrative case reports

Case 1

A 33-year-old man presented with 60 % TBSA burns, including deep burns to the face, torso, back, thighs and hands, following an explosion in the workplace (Figure 1A). The above mentioned surgical technique was performed on the face and hands (Figure 1B). Skin exchange was performed at 3 weeks following the application of the trial of allografts (Figure 1C). Autograft take achieved 100 % take.

Figure 1A.

Patient of case 1. This 35-year-old male sustained 60% TBSA burns involving the torso, back, thighs, face, and upper extremities in a workplace explosion. The left hand shown here has deep burns.

Figure 1B.

The hand was covered with allografts after initial excision. One week postoperatively, the hand was still oedematous owing to fluid overload.

Figure 1C.

Skin exchange using sheet autografts 3 weeks after allograft placement. Notice the hand is well decompressed after successful fluid management in critical care.

The patient underwent rehabilitation with physiotherapy and occupational therapy following discharge. At six months post-operation, the patient achieved normal range of motion in the fingers, wrist, and thumb, and regained the ability to perform essential activities of daily living (ADLs) independently (Figure 1D). Hand reconstruction outcomes are summarised in Table 1.

Figure 1D.

Appearance of the left hand 1 year postoperatively.

Case 4

A 20-year-old man presented with 2 % TBSA scald involving his face. He had an epileptic fit while cooking, causing him to fall onto spilled oil, resulting in scalds to his face (Figure 2A). Excision and grafting were performed according to the aforementioned technique. Skin exchange with autografts was performed stage-wise when allografts demonstrated “take”. The cheek, chin and lips were the first to demonstrate successful allograft take and hence autografted first (Figure 2B). Skin exchange of the eyelid was performed after another 4 days (Figure 2C). Donor sites for the autografts included the thigh (for the cheek and chin) and the scalp (for the eyelid and lips). The grafts were managed using an open grafting technique which allowed regular maintenance. There was 100 % take. A forehead flap was performed at a third stage to reconstruct the nose.

Figure 2A.

Patient of case 4. This 20-year old male sustained deep 2% hot oil scalds over his face. The scalds over the cheek, nose and upper lip, including parts of the eyelids were full thickness in depth.

Figure 2B.

Staged tangential excision of his face and temporary application of sheet allografts according to cosmetic units.

Figure 2C.

Skin exchange with sheet autografts over the right cheek, lips and chin. The allografts on the nose and upper eyelid remained ‘taken’ and were reconstructed later.

At six months postoperatively, facial sensation and animation were restored. Eyelid function was normal with no ectropion and contractures. Scarring was minimal with no disruption to aesthetic units of the face (Figure 2D).

Figure 2D.

Appearance of the patient 6 months postoperatively. The nose was reconstructed with a forehead flap.

Discussion

Allografts are critical tools in the management of extensive burn injuries.⁶ They serve as temporary biological skin transplants, promoting wound healing by 'taking' to the wound bed.⁷ Physiologically, allografts form an adherent barrier that minimizes fluid and protein loss, thus preventing wound desiccation and promoting revascularization at the level of the dermis.⁸ In addition, they prevent infection and wound hypergranulation, ultimately creating optimal wound healing conditions.⁹.

Studies have in fact shown that the dermal component (which is less immunogenic) has a potential of permanent “take” onto the wound bed.¹⁰ In non-specialised areas, we combine sheet allografts with autologous micrografts to achieve 1:9 to 1:16 skin expansion for rapid expansive coverage.^11,12 The allografts provided a temporary cover for the micrografts during their nesting phase. At 3 weeks, the allografts slough off exposing an epithelialising bed of micrografts.

However in the face and hands, where quality coverage is paramount, the allograft strategy employed was more nuanced. Initial sheet graft take is unpredictable owing to haemodynamic instability in the acute phase owing to extensive burns. This is particularly true for the hands which are in the peripheral zone of systemic circulation. Commonly, the hands become oedematous from fluid overload, ultimately resulting in burn conversion. We have observed that burn conversion occurs despite adequate excision resulting in poor skin graft take. Hence in these cases, the hands were temporarily sealed with allografts for 3 weeks while the patients were being stabilized (cases 1–3). In the face where skin grafting is performed according to cosmetic units, 100 % graft take is desirable for cosmesis.¹¹ Skin graft loss owing to inadequately prepared wound beds results in a patchwork appearance with scarring. A “trial of allograft” ensured that the bed was completely ready for autologous grafting (cases 1 and 4).

The advantages of this approach are that it reduces skin graft wastage from non-take. Furthermore, it reduces surgical trauma inflicted on the patient from the repeat harvest of quality sheet grafts. Delayed autologous grafting allows for an undivided attention to life-saving coverage whilst conserving skin for later coverage of specialised areas. This concept is illustrated in Case 3 where no sheet autografts were harvested while he was critically ill with acute respiratory distress syndrome. Sheet allografts had remained “taken” on his hands till the time of his demise.

While our present approach focuses on extensive TBSA burns with limited donor sites, it is equally applicable to moderate burns since a trial of allograft is always beneficial to test the bed and ultimately, to ensure complete autograft take, particularly in specialised areas. This concept is exemplified in the 2 % facial burn case.

The drawbacks of this approach are the extra cost and time incurred in the staged surgeries. In addition, skin banking facilities are paramount for this method. Lastly, this small clinical series with heterogeneity in TBSA is insufficient to draw definitive conclusions regarding its benefits. Future studies with larger sample sizes are required to validate our clinical outcomes.

Conflict of interest statement

The authors declare no conflicts of interest related to this study.