Anterolateral Thigh Perforator Flap

Abstract

With the increasing knowledge about the vascular anatomy and the blood supply of the skin and the refinement of surgical skills and instruments, sophistication of free tissue transfer could further develop. The first precise descriptions about the structure of the integument and its vessels were given by Spateholz in 1893 [506], who even then made a distinction between direct and indirect cutaneous vessels (perforators), branching off from a source vessel. A detailed analysis of the fine blood vessels of the skin was already published some years before by Manchot in 1889 [324]. He introduced vascular territories of the individual skin vessels, which later were further objectified by radiographic studies using lead oxide tincture injections [48]. On the basis of this knowledge, Esser was the first to build island flaps in which only the fine cutaneous perforators were preserved [48].Whereas in times when cutaneous flaps were raised without the knowledge of the specific anatomy of the skin as random pattern flaps, the vessel course at the skin was taken into consideration by Mc Gregor, who described the first axial pattern skin flaps [48, 352]. Moreover, the significance of the muscles as carriers for cutaneous vessels was pointed out by Orticochea [48, 401], and the blood supply of the skeletal muscles of the human body was classified into five types by Mathes and Nahai [338]. They already noticed that in muscles having a dominant proximal pedicle (type I), a cutaneous side branch often can be found close to the muscle hilum. A further important contribution for the understanding of skin perfusion was made by Ponten [48]. In his paper, he emphasized the relevance of the deep fascia for skin perfusion and introduced the definition of fasciocutaneous flaps. A first classification of this type of flaps was proposed by Cormack and Lamberty, who differentiated four types of fasciocutaneous flaps according to the number and course of the perforators, including osteomyofascial flaps (type D). An even more detailed definition of six different patterns of perforating vessels was provided by Nakajima, giving a description of the different vessel courses through muscle, septa, and subcutaneous fatty tissue [388]. Based on detailed anatomical dissections, dye injections, and radiographic investigations, Taylor and Palmer introduced the angiosome concept, in which the blood supply of three-dimensional blocks of tissue is correlated with specific vessels. They described an angiosome as a composite block of tissue that is supplied anatomically by source vessels that span between the skin and bone. In addition to supplying the deep tissues, the source vessel of these angiosomes supplies branches to the overlying skin, which pass either between the deep tissues or through the deep tissues, usually muscle, to pierce the outer layer of the deep fascia. Hence, perforator flaps, when dissected to the underlying source vessels, involve tracing vessels either between the deep tissues, whether muscle, tendon, or bone, or through the deep tissues, usually muscle [526]. Thus, these three-dimensional tissue blocks can consist of all possible tissue components but are perfused by one single source vessel. Like vascular territories of the skin, adjacent angiosomes are connected by fine vascular anastomoses (choke anastomotic vessels).