The PA narrowing is only the result of the tissue mobilization needs, regardless of the flap size or the anatomical area in which it is designed. In this series, dissections >90% (PA < 10%) were successfully performed on the face, back, thorax, arms, hands, and legs. Whenever possible, the PA should be located on the so-called hot spots. KFs with narrow PAs presented a different behavior. Initially, they showed a period of variable duration with evident venous congestion followed by a vasoconstriction or “white phase,” which was always sorted without compromising the KF vitality (Fig. 3). In the authors’ experience, the progress achieved with these flaps is proportional to the depth of the tissues affected and the amount of tissue lifted from its bed. Therefore, according to each clinical requirement, the advance can be sequentially increased via 3 ways:
The vascular safety of these flaps is such that, within the same KF, it was possible to carve different densities ranging from thick fasciocutaneous segments to delicate dermofat segments of a few millimeters thick. This allowed reconstructing complex defects with variable contours, filling dead spaces, and covering sensitive areas such as the perineum or the eyelids8,28 (Figs. 2 and 4).
During the closure, it is not necessary to dissect the tissues adjacent to the defect.36 Only in exceptional cases, a second flap is required to facilitate closure.8 Depending on the flap thickness or if points of above average tension are perceived, closure by planes is preferred. A Hemming suture is used in cases of considerable tension; otherwise, a continuous suture is made with absorbable material for children and polypropylene for adults.
The advantages of locoregional reconstruction have been widely discussed in the existent literature.8 The aesthetic results of stable coverage with tissues adjacent to the initial defect are extremely superior to those of techniques that transport distant tissues, which lack the desired “like to like” effect51 and require nerve repair to obtain protective sensitivity.54
Due to its versatility, the KF has been used in defects of varied etiology and in all age groups.4,6,8,37,28,57–59 They have allowed coverage that, given their extension, would require free flaps or classic perforator flaps.36,37,40,42,51,28,60–64 (See video, Supplemental Digital Content 3 which displays the defect secondary to parotid oncological resection covered with a Keystone flap. This video is available in the “Related Videos” section of the Full-Text article on PRSGlobalOpen.com or at http://links.lww.com/PRSGO/B15.)
The concept of pedicular area contributes to the KF biomechanical efficiency. The fact that extensive tissue areas, supplied in tiny random pedicles and supported by ubiquitous microperforators, survive without any vascular damage breaks the anatomical paradigms of local flaps and raises questions about the dynamics of tissue perfusion.
Of course, the KF technique has limitations. Its efficiency in intraoral and intranasal coverage has not been sufficiently proven. Its fasciocutaneous and musculocutaneous nature lacking bone components63 excludes them from scenarios with these specific requirements. Besides, due to its vascular dependence on perforators, caution should be exercised in areas surgically or traumatically dissected. As in any other technique, the design of the island must be careful to avoid transgression of natural folds or scar location on areas of excessive pressure. To do so, it is recommended to design larger islands as previously mentioned.
In sum, KF’s versatility, functional and aesthetic results, and low complication rate (3%–4.6%)5,36 have far exceeded the expectations of any random perforator or flap. The KF allows reconstruction in a single surgical time5,36 and is a relatively easy and fast technique28 for the beginner and the experienced surgeon. Economic considerations are not a minor issue in a context of financial sustainability of the health system of countries such as Colombia. Nowadays, there is an underestimation of techniques such as the one discussed here.
Plastic surgeons have come a long way to find a reconstructive strategy that (1) provides similar tissues in terms of function, texture, color, and sensitivity; (2) is versatile for any reconstructive requirement; (3) provokes minimal or no aesthetic or functional morbidity of donor areas; (4) entails short surgical times; and (5) is replicable, with short learning curves and without large infrastructure requirements.
Without ignoring the abovementioned limitations, the KF satisfies practically all of these requirements. The concept of ubiquitous microperforators, not detectable by conventional techniques and capable of supplying extensive segments of soft tissues, breaks the paradigm of fixed, anatomically identifiable pedicles. It opens the way to what we might call “freestyle pedicles” or “random pedicular area,” free of the complex and expensive technical requirements of the perforator or free flaps.
However, given the heterogeneity of the age groups, comorbidities, and anatomical areas considered adverse to flap perfusion, new cohorts with a larger number of patients and more strict inclusion criteria are necessary to validate our conclusions.
We believe that the development of microsurgery is an elegant and sophisticated response to previously insoluble problems. However, it is no less true that there is a current increasing overindication of these procedures with a parallel disdain for techniques with better cost-effectiveness.
In short, more studies are needed to better understand the physiological adaptations of KF. However, the clinical evidence is irrefutable and supports its use in many reconstructive scenarios, which undoubtedly allows the decentralization of health care and provides an invaluable tool with superior results.
1. Behan F, Wilson I. The principle of the angiotome, a system of linked axial pattern flaps. Paper presented at the Sixth International Congress of Plastic and Reconstructive Surgery; 1975; Paris.
2. Behan FC. The keystone design perforator island flap in reconstructive surgery. ANZ J Surg. 2003;73:112–120.
3. Behan FC, Rozen WM, Kapila S, et al. Two for the price of one: a keystone design equals two conjoined V-Y flaps. ANZ J Surg. 2011;81:405–406.
4. Pelissier P, Gardet H, Pinsolle V, et al. The keystone design perforator island flap. Part II: clinical applications. J Plast Reconstr Aesthet Surg. 2007;60:888–891.
5. Moncrieff MD, Bowen F, Thompson JF, et al. Keystone flap reconstruction of primary melanoma excision defects of the leg-the end of the skin graft? Ann Surg Oncol. 2008;15:2867–2873.
6. Hu M, Bordeaux JS. The keystone flap for lower extremity defects. Dermatol Surg. 2012;38:490–493.
7. Shayan R, Behan FC. Re: the “keystone concept’: time for some science. ANZ J Surg. 2013;83:499–500.
8. Mohan AT, Rammos CK, Akhavan AA, et al. Evolving concepts of keystone perforator island flaps (KPIF): principles of perforator anatomy, design modifications, and extended clinical applications. Plast Reconstr Surg. 2016;137:1909–1920.
9. Douglas CD, Low NC, Seitz MJ. The keystone flap: not an advance, just a stretch. Ann Surg Oncol. 2013;20:973–980.
10. Pauchot J, Chambert J, Remache D, et al. Geometrical analysis of the V-Y advancement flap applied to a keystone flap. J Plast Reconstr Aesthet Surg. 2012;65:1087–1095.
11. Hessam S, Sand M, Bechara FG. The keystone flap: expanding the dermatologic surgeon’s armamentarium. J Dtsch Dermatol Ges. 2015;13:70–72.
12. Douglas C, Morris O. The ‘keystone concept’: time for some science. ANZ J Surg. 2013;83:498–499.
13. Penington T. Science and the keystone flap. ANZ J Surg. 2013;83:496–497.
14. Findlay MW, Kleid S. The keystone concept: a time for good science. ANZ J Surg. 2014;84:194–195.
15. Saint-Cyr M, Wong C, Schaverien M, et al. The perforasome theory: vascular anatomy and clinical implications. Plast Reconstr Surg. 2009;124:1529–1544.
16. Braverman IM. The cutaneous microcirculation. J Investig Dermatol Symp Proc. 2000;5:3–9.
17. Manchot C. The Cutaneous Arteries of the Human Body. 1983.1st ed. New York: Springer-Verlag.
18. Salmon M. Arteries of the Skin. 1988.1st ed. London: Livingstone, Churchill.
19. Taylor GI, Palmer JH. The vascular territories (angiosomes) of the body: experimental study and clinical applications. Br J Plast Surg. 1987;40:113–141.
20. Sinna R, Boloorchi A, Mahajan AL, et al. What should define a “perforator flap”? Plast Reconstr Surg. 2010;126:2258–2263.
21. Kostopoulos E, Casoli V, Agiannidis C, et al. The keystone perforator island flap in nasal reconstruction: an alternative reconstructive option for soft tissue defects up to 2 cm. J Craniofac Surg. 2015;26:1374–1377.
22. Behan FC, Rozen WM, Wilson J, et al. The cervico-submental keystone island flap for locoregional head and neck reconstruction. J Plast Reconstr Aesthet Surg. 2013;66:23–28.
23. Behan FC, Lo CH, Sizeland A. The interpretation of vascular changes observed in keystone island flaps: a hypothesis. J Plast Reconstr Aesthet Surg. 2010;63:e215–e216.
24. Behan FC, Lo CH. Vascular dynamics of the keystone island flap: ongoing observations similar to sympathectomy. ANZ J Surg. 2009;79:861.
25. Pelissier P, Santoul M, Pinsolle V, et al. The keystone design perforator island flap. Part I: anatomic study. J Plast Reconstr Aesthet Surg. 2007;60:883–887.
26. Chaput B, de Bonnecaze G, Lopez R, et al. Modified keystone island flap design for lateral nasal defect: aesthetic subunit consideration. Plast Reconstr Surg Glob Open. 2014;2:e213.
27. Rubino C, Coscia V, Cavazzuti AM, et al. Haemodynamic enhancement in perforator flaps: the inversion phenomenon and its clinical significance. A study of the relation of blood velocity and flow between pedicle and perforator vessels in perforator flaps. J Plast Reconstr Aesthet Surg. 2006;59:636–643.
28. Behan FC, Lo CH, Sizeland A, et al. Keystone island flap reconstruction of parotid defects. Plast Reconstr Surg. 2012;130:36e–41e.
29. Behan FC, Rozen WM, Azer S, et al. ‘Perineal keystone design perforator island flap’ for perineal and vulval reconstruction. ANZ J Surg. 2012;82:381–382.
30. Behan F, Sizeland A, Porcedu S, et al. Keystone island flap: an alternative reconstructive option to free flaps in irradiated tissue. ANZ J Surg. 2006;76:407–413.
31. Moncrieff MD, Thompson JF, Stretch JR. Extended experience and modifications in the design and concepts of the keystone design island flap. J Plast Reconstr Aesthet Surg. 2010;63:1359–1363.
32. Pikturnaite J, Mashhadi S. Enhanced robustness and mobility of the keystone flap. Dermatol Surg. 2014;40:1054–1056.
33. Stone JP, Webb C, McKinnon JG, et al. Avoiding skin grafts: the keystone flap in cutaneous defects. Plast Reconstr Surg. 2015;136:404–408.
34. Abraham JT, Saint-Cyr M. Keystone and pedicle perforator flaps in reconstructive surgery: new modifications and applications. Clin Plast Surg. 2017;44:385–402.
35. Mohan AT, Sur YJ, Zhu L, et al. The concepts of propeller, perforator, keystone, and other local flaps and their role in the evolution of reconstruction. Plast Reconstr Surg. 2016;138:710e–729e.
36. Khouri JS, Egeland BM, Daily SD, et al. The keystone island flap: use in large defects of the trunk and extremities in soft-tissue reconstruction. Plast Reconstr Surg. 2011;127:1212–1221.
37. Rao AL, Janna RK. Keystone flap: versatile flap for reconstruction of limb defects. J Clin Diagn Res. 2015;9:PC05–PC07.
38. Behan FC. The fasciocutaneous island flap: an extension of the angiotome concept. Aust N Z J Surg. 1992;62:874–886.
39. Mešić H, Kirkebøen KA, Bains R. The importance of a skin bridge in peripheral tissue perfusion in perforator flaps. Plast Reconstr Surg. 2012;129:428e–434e.
40. Gutman MJ, Goldschlager T, Fahardieh RD, et al. Keystone design perforator island flap for closure of myelomeningocele. Childs Nerv Syst. 2011;27:1459–1463.
41. Kostopoulos E, Agiannidis C, Konofaos P, et al. Keystone perforator island flap as an alternative reconstructive option for partial thickness alar defects up to 1.5 centimeters. J Craniofac Surg. 2016;27:1256–1260.
42. Aguilera-Sáez J, Sanz-Gil F, Palao-Domènech R, et al. Reconstrucción de defectos amplios en tronco mediante colgajo de perforante en piedra clave. Rev Latinoam Cir Plast. 2014;40:403–411.
43. Shipkov CD, Mojallal A. The keystone island and pedicle flap: a handy local flap for soft tissue reconstruction. Ann Surg Oncol. 2008;15:3625.
44. Milton SH. Experimental studies on island flaps. 1. The surviving length. Plast Reconstr Surg. 1971;48:574–578.
45. Lo CH, Menezes H, Behan F. The island perforator flap design augments vascularity. Plast Reconstr Surg. 2013;132:468e–469e.
46. Behan FC, Sizeland A. Reiteration of core principles of the keystone island flap. ANZ J Surg. 2006;76:1127–1129.
47. Lo CH, Nottle T, Mills J. Keystone island flap: effects of islanding on vascularity. Plast Reconstr Surg Glob Open. 2016;4:e617.
48. Behan FC, Lo CH, Shayan R. Perforator territory of the keystone flap—use of the dermatomal roadmap. J Plast Reconstr Aesthet Surg. 2009;62:551–553.
49. Behan FC, Lo CH, Findlay M. Anatomical basis for the keystone island flap in the upper thigh. Plast Reconstr Surg. 2010;125:421–423.
50. Hamahata A, Saitou T, Ishikawa M, et al. Usefulness of keystone island flap for circumferential defect around a urostomy. Int Cancer Conf J. 2013;2:188–190.
51. Behan FC, Paddle A, Rozen WM, et al. Quadriceps keystone island flap for radical inguinal lymphadenectomy: a reliable locoregional island flap for large groin defects. ANZ J Surg. 2013;83:942–947.
52. Jackson IT. The keystone design perforator island flap in reconstructive surgery. ANZ J Surg. 2003;73:261.
53. Behan FC, Rozen WM, Lo CH, et al. The omega - Ω - variant designs (types A and B) of the keystone perforator island flap. ANZ J Surg. 2011;81:650–652.
54. Behan F. Evolution of the fasciocutaneous island flap leading to the keystone flap principle in lower limb reconstruction. ANZ J Surg. 2008;78:116–117.
55. Sliesarenko SV, Badiul PO, Sliesarenko KS. Extensive mine-shrapnel and gunshot wound closure using keystone island perforator flaps. Plast Reconstr Surg Glob Open. 2016;4:e723.
56. Findlay MW, Sinha S, Rotman A, et al. The keystone perforator island flap in head and neck reconstruction: indications and outcomes from 200 flaps. Plast Reconstr Surg. 2013;132:8–9.
57. Taleb M, Choi L, Kim S. Safety and efficacy of the keystone and rhomboid flaps for immediate reconstruction after wide local excision of non-head and neck melanomas. World J Surg Oncol. 2016;14:269.
58. Wong C. Review: the keystone perforator island flap concept. Plast Reconstr Surg. 2013;131:427.
59. Al-Busaidi AA, Semalesan N, Al-Busaidi SS. Keystone design sliding skin flap for the management of small full thickness burns. Sultan Qaboos Univ Med J. 2011;11:412–414.
60. Behan FC, Findlay M, Lo CH. The Keystone Perforator Island Flap Concept. 2012.Sidney: Churchill Livingstone.
61. Magliano J, Falco S, Agorio C, et al. Modified keystone flap for extremity defects after Mohs surgery. Int J Dermatol. 2016;55:1391–1395.
62. Sinha S, Yip MJ, Gill S, et al. A giant fungating metastatic basal cell carcinoma of the back and novel reconstruction using two large keystone design island perforator flaps. J Plast Reconstr Aesthet Surg. 2013;66:1015–1018.
63. Chen HC. Precautions in using keystone flap. J Plast Reconstr Aesthet Surg. 2010;63:720.
64. Behan FC, Rozen WM, Tan S. Yin-Yang flaps: the mathematics of two keystone island flaps for reconstructing increasingly large defects. ANZ J Surg. 2011;81:574–575.
65. Loh IW, Rozen WM, Behan FC, et al. Eyelid reconstruction: expanding the applications of the keystone perforator island flap concept. ANZ J Surg. 2012;82:763–764.