The evolution of acute burn care - retiring the split skin graft

Abstract

The skin graft was born in 1869 and since then, surgeons have been using split skin grafts for wound repair. Nevertheless, this asset fails the big burn patient, who deserves an elastic, mobile and robust outcome but who receives the poorest possible outcome based on donor site paucity. Negating the need for the skin graft requires an autologous composite cultured skin and a material capable of temporising the burn wound for four weeks until the composite is produced. A novel, biodegradable polyurethane chemistry has been used to create two such products. This paper describes the design, production, optimisation and evaluation of several iterations of these products. The evaluation has occurred in a variety of models, both in vitro and in vivo, employing Hunterian scientific principles, and embracing Hunter's love and appreciation of comparative anatomy. The process has culminated in significant human experience in complex wounds and extensive burn injury. Used serially, the products offer robust and elastic healing in deep burns of any size within 6 weeks of injury.

Keywords: Biodegradable polyurethane; Biodegradable temporising matrix; Bioreactor; Composite cultured skin; Skin graft replacement.

Figure 1

Day 0 (prior to biodegradable temporising matrix [BTM] insertion): Radial forearm free flap donor site just after flap harvest. The pedicle wound has been closed (proximal). The tendon of the flexor carpi radialis muscle runs across the wound bed from proximal to distal. Day 484: After BTM integration and skin graft application at day 36, the result at 16 months is shown.

Figure 2

Patient 5 sustained complete full-thickness back burns and biodegradable temporising matrix (BTM) was applied. The patient was nursed supine on the intensive care unit. BTM integration was followed by delamination and graft application when donor sites became available. The result at 10 months was excellent.

Figure 3

A 66-year-old, 75% full-thickness burn patient whose head and neck were burned sparing only the midface. Gentle debridement resulted in a clean wound by day 40 but complete exposure of the calvarium. The calvarial outer table was burred to diploe, and biodegradable temporising matrix (BTM) was applied to the whole burn and diploe (like a bathing cap). BTM delamination and graft application followed on day 89. Successful integration and grafting is clear by day 115.

Figure 4

A: Necrotising fasciitis of the neck following infection in the left parotid gland resulted in aggressive debridement with muscle and salivary gland exposure. By day 11, after negative pressure wound therapy, biodegradable temporising matrix (BTM) was applied. B: Integration and delamination was followed by application of a fenestrated sheet graft. C: At 86 days following grafting, the result is flexible, soft, mobile and robust. (See also video available online.)

Figure 5

Complete bioreactor in incubator with software controlled pump array and media fridge. A mock up of a bioreactor tower (10 cassettes, each capable of containing a 25cm × 25cm composite cultured skin, are divided between two ‘shoes’ in the full tower) is shown in the foreground.

Figure 6

With 9 days of culture left before day 28 is reached, epidermal confluence is nearly complete over the cultured neodermis.