Adequate soft tissue reconstruction in large defects of extremities is particularly important to avoid unnecessary amputation and to aid in recovery of function. The advent of perforator flaps has allowed for a more “like for like” replacement of full-thickness skin defects with the same tissue type, even with large defects. They permit low morbidity of the donor site, versatility in flap design, and muscle preservation with less functional deficits; additionally, the texture is similar to that of the recipient site, which provides good aesthetic results [7, 8]. Selection of a perforator flap is determined by factors including reliable vasculature, acceptable donor site, reproducibility, and efficiency of procedure and complication rates [9-13]. In this study, we applied the classic DIEP flap, which has been frequently used for BR without design verification, similar to that in other studies. We recommend it for large defects after some prior surgical requirements: preoperative planning for perforator selection to avoid unexpected complications; preoperative design to support zone IV and lateral extension of the flap; preoperative confirmation of donor site closure in the standing position; intraoperative meticulous dissection of perforators; additional vascular support with additional anastomosis; and individualized defatting for the defect.
The DIEP flap has become the first choice for autologous BR since it was introduced by Koshima et al in 1992 [14]. It provides a large amount of tissue, relatively easy dissection during flap elevation and minimal donor site morbidity with concealed scar at lower abdomen [13, 15-18]. Despite these advantages, it has rarely been used in areas other than the breast according to previous literature; it has been rarely reported for extremity reconstruction since the 2000s. A case study introduced a reconstruction with a DIEP flap in diabetic foot ulceration in 2005 [19]. In the same year, Masuoka et al. introduced the method for foot reconstruction, successfully using an exterior pedicle in two cases [20]. Landuyt et al. presented 25 cases of DIEP flaps in lower extremity reconstruction including a pedicled flap. They conducted the largest study using DIEP flaps, proving that apart from its merits in BR, it offers diverse opportunities. In the 2010s, several case series reported good results of the DIEP flap for extremity reconstruction in children [21-23]. A study that used the chimeric DIEP flap for the reconstruction of post-traumatic drop foot deformity, inter alia, reported that two patients recovered active dorsiflexion of the ankle after the surgery [23]. Two studies that compared DIEP and other free flaps (anterolateral thigh perforator flap) [24] and circumflex scapular artery perforator flap [25] for the reconstruction of lower extremities in pediatric patients concluded that the DIEP flap might be a good alternative for foot reconstruction; however, other flaps showed better morpho-functional outcomes than the DIEP flap. They embraced it as a second option for selected cases in extremity reconstruction and don’t explain the technical details.
DIEP might not be primarily selected to reconstruct large defects of the extremities and we considered several technical details to overcome the weaknesses of the DIEP flap, including the relatively high rate of perfusion-related problems which result in flap necrosis, and its bulkiness, which required “thickness-controlling.”
Unless you are a breast surgeon, vascular anatomy might be unfamiliar territory, which may lead to perfusion-related problems and disadvantages due to bulkiness. When DIEP flaps are used, discarding tissue with unreliable perfusion is crucial to prevent perfusion-related complications. Classically, the so-called Hartlampf perfusion zone is commonly used to decide the discarded zone (Figure 5). Holm et al recommended new perfusion zones based on their clinical fluorescent studies and suggested that zones II and III be reversed (Figure 5). Recently, Saint-CYR et al. introduced a perfusion zone concept that varies depending on location, rows, and quality of the perforators [26]. They showed that medial and lateral row perforators have different perfusion patterns. The classical Hartlampf concept for the medial perforator trace and the Holm’s concept for the lateral row perforators have been recommended. It is the latest model for perfusion pattern analysis of the DIEP flap after minor modifications [27, 28] that should be considered to perform safe DIEP flap coverage.
After understanding of these concepts, the circulatory problems of DIEP flap can be sufficiently overcome with an additional surgical procedure. Providing additional vascular flow between pedicles enables us to augment the territory of the flap. As a result, an extra-arterial inflow (bilateral pedicles or combination with superficial epigastric vessels) can be charged to incorporate more lateral skin without any circulatory problems. Understanding of the circulatory zone of the DIEP flap and the design of flap should be individualized according to the location of the perforators (medial or lateral). These procedures could allow for an extended skin flap by supporting zone IV, which can be planned before the surgery.
Another major reason the DIEP flap is not widely chosen is its “bulkiness.” If an appropriate defatting procedure is not achieved, a flap larger than the defect might be needed and aesthetic insetting will not be possible. Defatting, or thinning procedure, means the removal of tissue in the deep subcutaneous fat layer, superficial fascia system and part of the superficial subcutaneous fat layer, except the area around the perforators [29]. The superficial fascial system supports the fat and holds the skin onto the underlying tissues [30]. Thus, disruption of the superficial fascial system could change the integrity of the superficial fat layer and the flap becomes more pliable and stretchable. We performed conventional perforator flap elevation at the suprafascial plane and flap defatting was performed with scissors in what is known as the lobule-by-lobule technique after micro-anastomosis, according to the required thickness[31]. This procedure allows a flap to be insetted favorably to curved defects in the extremities without needing to design a larger flap. Controlling flap thickness is an essential procedure to overcome the weaknesses of the DIEP flap and to provide successful coverage in large defects. Furthermore, it results in high patient satisfaction with substantial aesthetic improvement [29].
Although this study includes successful functional and aesthetic results with DIEP flaps for large extremity defects through long term follow-up, the limitations of a retrospective study and a small number of patients exists.