INTRODUCTION
Flap surgery is a fundamental reconstruction method for covering a defect. The recent popularization of microsurgery has rapidly increased the areas to which flap surgery is applicable. Reconstruction using microsurgery, or free flap surgery, is increasingly common, and has become an important area of reconstructive surgery. While these procedures have increased in frequency, quality improvement is necessary. To meet this need, it is important to choose an appropriate donor site and to cover the defect completely [
1].
As a donor site, the peroneal flap was introduced by Taylor et al. [
2] in 1975. It was mainly used for grafting the vascularized fibula, and a cutaneous flap served only as a skin paddle or a buoy for the blood circulation. Peroneal flap surgery remains an important method of vascularized bone grafting. The cutaneous flap was introduced by Yoshimura et al. [
34] in the 1980s, and many other types of flaps, including island and free flaps, have been used since then.
We have applied peroneal flaps to many different sites. We have used island flaps for reconstructing a lower limb around the donor site, retrograde flaps for reconstructing the lower third of a lower limb and an ankle, and anterograde flaps for reconstructing the upper third of a lower limb and a knee. We have used free flaps for upper-limb reconstruction, including a hand, as well as lower-limb reconstruction, and found them to be particularly useful in reconstructing a defect caused by the removal of head and neck carcinoma.
By applying several types of peroneal flaps to clinical cases, we were able to determine their definite advantages and disadvantages and, based on this information, to present some indications for their use. To use peroneal flaps flexibly, it is essential to have the appropriate anatomical knowledge, particularly about the peroneal artery and its perforators. We obtained the required anatomical information by examining cadavers. This paper reports the results of a cadaveric study and clinical research, along with a literature review.
DISCUSSION
Of the blood vessels primarily responsible for the blood supply in the lower limbs, the peroneal artery is one of the best areas to elevate a perforator flap not only because it serves as a feeding artery in the fibula but also because it supplies blood to the skin in the lateral part of the lower limb through a number of musculocutaneous and septocutaneous perforators originating in the fibula [
56]. The peroneal artery originating in the posterior tibia artery travels downward along the posterointerior side of the fibula and generates several perforators to supply blood to the fibula, neighboring muscles, and the skin on the lateral surface along the travel path. Thus, it supplies blood to the area ranging from the middle third to the lower third of the lateral side of the lower limb [
7]. Musculocutaneous perforators, which supply the skin with blood through the peroneus longus or soleus, are distributed from the upper distal third to the middle third. Septocutaneous perforators, which supply blood directly to the skin through the septum between the peroneus longus and soleus, are distributed from the middle third to the lower third [
38]. In our cadaveric study, only musculocutaneous perforators were found in the upper part, only septocutaneous perforators in the lower part, and both types of perforators in the middle part.
The lateral part of the lower limb usually contains 3 to 8 perforators [
59], most of which originate in the peroneal artery, whereas proximal perforators do not always originate in the peroneal artery [
10]. In our cadaveric study, 4 of the 19 perforators were musculocutaneous perforators, which originated in the posterior tibial artery; 3 of them were distributed in the upper third, and 1 in the middle third. Retrograde island peroneal flap surgery can be performed only when the major vessel used as a pedicle is the peroneal artery. It is important to note that some perforators, particularly musculocutaneous perforators, in the upper and middle parts may not originate in the peroneal artery.
The perforators in the peroneal artery average about 5 cm in length, although this measurement has been reported to vary in the literature [
11]. In our cadaveric study, the length ranged from 3.5 to 7.5 cm (mean, 4.8 cm). The perforators in the lower third were shorter than those in the middle and upper parts, and musculocutaneous perforators tended to be longer because of their complicated travel path. It is therefore desirable to design a flap in the middle and upper parts with the aim of securing the length of the pedicle during free flap surgery.
Partial flap necrosis occurred as a complication in 5 cases. A problem related to the blood circulation was found in 3 cases of anterograde island peroneal flap surgery and in 2 cases of retrograde island peroneal flap surgery (5 of 16). In free flap surgery, however, no partial flap necrosis occurred (0 of 13). Thus, an island flap is at a higher risk of causing a problem related to the blood circulation than a free flap. This is probably because an island flap, which needs a long pedicle to travel up to the defect through a subcutaneous tunnel, can develop inhibited blood circulation due to postoperative edema. In the case of trauma, it may be difficult to elevate a flap from the same trauma site.
It is most desirable to close a donor site directly, taking aesthetics into account. However, the possibility of direct closure varies by donor site location and according to the room, elasticity, and resilience of the skin, all of which are affected by the patient's age. In the lower third of a lower limb, the flaps ranged from 4.0 to 4.5 cm in diameter, and each case required skin grafting. In the upper and middle third of a lower limb, direct closure was possible when a flap was <4.5 cm in diameter, and even when it was 5 cm in diameter in some cases.
Peroneal flaps have many advantages, none of which are found in other types of flaps. They are very thin and flexible, and require no additional surgery for thinning; therefore, they are very effective in the reconstruction of the head and neck, particularly in the partial reconstruction of the tongue and in hand or foot reconstruction. The donor site can be closed directly, taking into account the flap size, patient age, and so on, and minimum donor site morbidity occurs. A peroneal flap can also be used as a composite flap, which contains bones, muscles, and nerves. A free flap makes it easy to perform dissection up to a major vessel and causes no injury to the major vessels in a lower limb. Another major advantage is the possibility of tightening a tourniquet during surgery.
These techniques have several disadvantages. With the continuing increase of diabetes and aging in the population, it is essential to preserve the major vessels of lower limbs. Injuring the peroneal artery, one of the major vessels in a lower limb, however, is unavoidable when a pedicled flap is used. Therefore, we considered other methods, such as true perforator flaps, prior to major vessel sacrifice. If such methods were impossible, we used a peroneal flap. Failed direct closure of the donor site, which is exposed, can produce very unsatisfactory results aesthetically. The patient needs to be in a prone position, or at least in a lateral position, to expose the peroneal artery, which is medial to the fibula. As a result, it is necessary to change the patient's position, and the location of the vessel makes it difficult to dissect intraoperatively. When a retrograde island peroneal flap is selected, it is necessary to determine the major vessel from which the perforator originates. Our anatomic study showed that some perforators originated in the posterior tibial artery. This uncertainty causes major difficulties, and makes it necessary to select another type of surgery when the perforator originates in any major artery other than the peroneal artery. Furthermore, when variations and malformations of the vessels are present, a preoperative evaluation using angiography is recommended [
1213].
If the surgical method and indications are properly determined to overcome the limitations of the clinical application of island flaps and the disadvantages of a donor site on the basis of a good anatomical understanding of the peroneal artery and its perforators, peroneal flap surgery can be considered a good method to reconstruct diverse sites, resulting in a lower morbidity rate at the donor site.