“We are like dwarfs sitting on the shoulders of giants. We see more, and things that are more distant, than they did, not because our sight is superior or because we are taller than they, but because they raise us up, and by their great stature add to ours.”

                         —John of Salisbury, 1159 AD

Classic Examples of Flap and Burn Reconstruction

Perhaps one of the earliest and most notable flap reconstructive descriptions can be found in the Sushruta Samhita. Thought to have been written around 600 BC, it contains an excellent description of the reconstruction of a nose using a series of flaps, which were derived from the face and cheek.^1,2 The subsequent evolution of this nasal reconstruction methodology ultimately developed into a routinely employed series of well defined stages based on the ascending axial supratrochlear vessels, now generally referred to as the median forehead flap (Figure 1).

Antonius Branca, and later Gaspare Taglicozzi (1546–1599), formulated and developed the concept of tubed and pedicled flaps.² These flaps utilized defined patterns of delay to improve vascularity and reliability of transfer, enabling the transfer of tissue from the upper arm to reconstruct the nose (Figure 2).

Further development of these staged transfers allowed tissue to be transferred to ever more distant sites by “waltzing” the flap from recipient site to recipient site. An appreciation for flap contracture, vascular pedicle kinking, and prefabrication is described well in the description of these procedures. Examples of modern helical rim (ear) reconstructions continue to employ this methodology (Figure 3).

Understanding the Contribution of Vascular Supply in Flap Design

Flap types can be characterized by their location or pattern of transfer (eg, local, regional, and free tissue transfer), tissue component composition (muscle flap, musculocutaneous, neurocutaneous, osteocutaneous, etc.) or by their vascular supply pattern.

The history of various flaps is perhaps best reflected by the evolution in the understanding of the nature of the underlying vascular supply.³ The earliest flaps were likely random vascular pattern flaps, which preserved the subdermal vascular plexus. These geometric rearrangements of local tissue enabled the surgeon to replace or augment adjoining areas of deficit with similar tissue elements. Common examples of these random vascular pattern flaps include the Z-plasty, 4-flap, Y-V plasty, W-plasty, banner flap, bilobed flap, and rhombic flap, among others.

The Z-plasty often first attributed to Denonvillier and derived from his work with upper eyelid surgery (1808–1872), also can be attributed to Paul Berger (1845–1918) and McCurdy (1898).⁴ In rearranging available tissue locally, these flaps allow for local tissue augmentation, lengthening and reorienting the direction of a scar, as well as increasing the depth of a reconstructive release. It remains one of the most commonly employed flap rearrangements in burn surgery (Figure 4).

Tubed flaps, successfully refined by innovative and progressive reconstructive surgeons like Sir Harold Gilles, were likely first formally described in 1917 by the Russian surgeon Filatoy at the end of World War I.^5,6 The creation of these staged and tubed pedicled flaps facilitated the transfer of healthy and well-vascularized tissue over great distances. Meticulous planning and design allowed for creative and complex reconstructions (Figure 5).

It is probable that flaps such as the classic groin flap commonly employed for extremity reconstruction, were likely first designed without a formal appreciation for their axial vascular supply. In 1972, McGregor and Jackson⁷ refined the anatomical understanding for the basis of these types of flaps, contributing greatly to the ever-expanding armamentarium (Figure 6).

Musculocutaneous flaps, which carry the underlying muscle as well as the overlying skin and subcutaneous tissues, improved the reconstructive surgeon’s ability to transfer composite tissues more reliably. These flaps were perhaps best described by McCraw et al,⁸ who recognized the value of incorporating transmuscular perforators in further enhancing perfusion. These bulkier flaps proved particularly valuable when cavitary defects required well-vascularized tissue for reconstruction.

Pontén⁹ further expanded flap reconstructive options by defining and utilizing the fascial plexus, which exists between the deep fascia and the subdermal vascular plexus. In so doing, larger areas of a thinner fasciocutaneous tissue could be transferred without sacrificing the underlying muscle. A length to width transfer ratio of 3:1 was now possible. Another major advantage of these flaps is that they could be raised rather quickly, as the subfascial plane of dissection is relatively avascular and well defined. This technique proved useful not only for cross extremity applications, but could also provide a gliding surface when placed over exposed tendons and joints (Figure 7).^3,9

The ability to perform safe, reproducible, and reliable free microvascular procedures dramatically expanded the surgeon’s ability to close, replace, or augment areas of deficit and deformity. Building on the fundamental principles of vascular anastomosis developed by Nobel prize winner Dr. Alexis Carrel (1908), Jacobson (1960) and others¹⁰ began to tackle ever finer vascular diameters. This required the development of suitable atraumatic sutures in sizes of 8-0 to 10-0 as well as the availability of effective microscopes and loupes, which could be utilized in the operating theatre. Seidenberg et al¹¹ (1959) reported on the use of revascularized free jejunum segments to repair pharyngoesophageal defects; Komatsu (1968) successfully replanted a thumb.¹² Drs. McLean and Buncke¹³ covered a cranial defect with free vascularized omentum. In 1972, Drs. Daniel and Taylor¹⁴ reported the first cutaneous free microvascular transfer.
Nakajima et al,¹⁵ Song et al,¹⁶ and Wei et al,¹⁷ further refined and developed the concept of musculocutaneous perforator based flaps. Their efforts extended the length and dimension of the feeding pedicle by introducing meticulous intramuscular or intermuscular septal dissection, minimizing peripheral tissue injury while extending both local and distant applicability for a variety of reconstructive options.

The foundation of this type of flap can be predicted by applying the angiosome principle of skin flap design. A defined dominant cutaneous perforator or set of perforators when properly designed can nourish large areas of cutaneous tissue. This is particularly true when the perforators are maintained intact at opposite ends of the flap design.¹⁸ As a result, super-thin flaps could be reliably transferred to reconstruct surface area defects providing a more aesthetic contour without the need for subsequent debulking or thinning procedures. This generally pedicled flap design often requires microvascular supercharging to improve vascularization when transferring large areas of tissue. Examples of the benefit of this pliable advancement is evident in the excellent results obtained in facial and neck contoured reconstructions (Figure 8).^15–17

Tissue Expansion

Tissue expansion has long been used to provide additional tissue for reconstruction in a fashion similar to that seen in the gravid abdomen (Neumann¹⁹ and Radovan²⁰). By progressively expanding overlying tissue, this tissue is not only stretched but mitotic rates are increased resulting in the development of new, available and uninjured tissue. The overlying epidermis is thickened, the dermis is thinned and the underlying capsule demonstrates an increased vascular pattern improving perfusion.^21,22 An appreciation of these elegant consequences led to the development of creative reconstructive options as evident in the work by Sasaki and Pang,²² and Foyatier et al²³ (Figure 9).

Recently, the combination of pre-expansion and transfer of perforator-based flap have allowed the reconstructive surgeon to transfer even larger patterns of thin, uninjured tissue to adjoining sites. An excellent example of this methodology can be seen in the execution of pre-expanded supraclavicular flaps for neck and lower face reconstruction as described by Spence²⁴ (Figure 10).

Tsai,²⁵ Masser,²⁶ Kenney et al,²⁷ and others^28,29 have combined the technique of pre-expansion with that of free tissue transfer gaining even further reconstructive utility and application. The addition of a free microvascular supply permits distant transport to areas where surrounding tissues would not be suitable for expansion. In so doing, venous outflow is optimized and arterial inflow can similarly be augmented.^25–28

The Future

Facial and extremity transplantation are no longer theoretical options for complex reconstructive challenges, having been performed with notable success in a number of centers around the world. To date, no burn survivor has undergone facial transplantation, although it remains a likely option in the near future. Tissue and organ engineering technologies continues to evolve with several impressive gains made within the last decade. Increased funding and a collaborative international experience with various lines of stem cell development will likely yield benefits for future constructs.

While recent and expected near future advances in reconstructive options make this a particularly exciting time for burn reconstructive surgeons, it is difficult to avoid the reality of an ever-present shortage and maldistribution of burn reconstructive specialists. As survival rates have improved, the challenge of securing state of the art reconstruction for our patients will be even more evident.  

Acknowledgement

The authors thank Trisha Lane for her help in preparing this review.