SURAL PERFORATOR FLAP: ASSESSMENT OFTHE POSTERIOR CALF REGION AS DONOR SITE FORA FREE FASCIOCUTANEOUS FLAP

FUMIAKI SHIMIZU, M.D.,* AIKO KATO, M.D., HARUAKI SATO, M.D., and HIROKO TANEDA, M.D.

Three kinds of free fasciocutaneous flap from the posterior calf region have been described in the literature: the medial sural perforatorflap, the lateral sural perforator flap, and the traditional posterior calf fasciocutaneous flap that is supplied by superficial cutaneous vessels.Moreover, it has been reported that superficial cutaneous vessels are of a suitable size for microanastomosis when deep musclocutaneousperforators are absent or relatively tiny. To establish a safe technique for free fasciocutaneous flap elevation from the posterior calf region,we examined the number and location of the musculocutaneous perforators and the size of superficial cutaneous vessels at their originfrom the popliteal artery in six formalinized cadavers. We found that all legs had at least one perforator either from the medial sural arteryor the lateral sural artery. By contrast, we failed to find superficial cutaneous vessels of suitable size for microanastomosis in three legs,and there was no significant inverse relationship between the diameter of the superficial cutaneous artery and the number of musculocuta-neous perforators. Our results suggest that the medial sural perforator flap and the lateral sural perforator flap might be the surgeon’s firstand second choice, respectively. The traditional posterior calf fasciocutaneous flap should be the third choice because our study suggeststhat its availability is doubtful. Another site is recommended, when preoperative Doppler study suggests that the existence of musculocuta-neous perforator is in doubt. Two clinical cases, with a medial sural perforator flap and a lateral sural perforator flap, respectively, are pre-sented. VVC 2009 Wiley-Liss, Inc. Microsurgery 29:253–258, 2009.

The medial sural (medial gastrocnemius) perforator free

flap, which has a long and larger-caliber pedicle and can

be elevated as a thin piece of tissue without any donor-site

morbidity, is considered to be one of the best choices for

reconstruction of a distal extremity or the head and neck

region.1–5 Previous anatomical studies have shown that

�90% of limbs have the potential for elevation of this

flap, whereas 10% of limbs do not have sufficient perfora-

tors for elevation of this flap.3 In the absence of medial

sural perforators, use has been recommended of a tradi-

tional posterior calf fasciocutaneous flap, which is supplied

by the median superficial or the lateral superficial sural

arteries and can be elevated as a second choice at the

same donor site.2,3,5 However, some authors do not recom-

mend this flap for use as a free flap because of the small-

caliber pedicle and numerous anatomical variations.6 Satoh

et al.6 reported that no vessel was found in two of 17

cases. Shaw et al.7 reported that, in their clinical experi-

ence, there seemed to be an inverse relationship between

the superficial cutaneous system and deeper systems of

musculocutaneous perforators with respect to the blood

supply to the posterior calf (see Fig. 1). In some cases, the

deep system was more prominent and in others the superfi-

cial system was predominant. Their experience suggests

that it is possible that a traditional posterior calf fasciocu-

taneous flap might be of sufficiently large caliber and

might be suitable as a second choice of free flap when the

medial sural perforator flap is not suitable because of the

absence of musculocutaneous perforators. Clinical cases

treated with a lateral sural perforator flap have been

reported.8 If the presence of medial sural perforators or of

lateral sural perforators could be guaranteed and if there

are inverse relationship were to exist between the superfi-

cial cutaneous system and deeper systems of musculocuta-

neous perforators, there would be three possibilities for

elevation of a free fasciocutaneous flap from a single pos-

terior calf region. The purpose of this study was to investi-

gate anatomical variations and relationship between

namely the traditional posterior-calf fasciocutaneous flap,

which is supplied by the superficial cutaneous system, and

the medial and lateral sural perforator flaps, which are sup-

plied by deep musculocutaneous perforators. Our goal was

to establish a safe surgical technique for elevation of a

free fasciocutaneous flap from the posterior calf region.

METHODS

Using 12 lower limbs of six formalinized cadavers,

we determined the number and location of the musculo-

cutaneous perforators that presented through the deep fas-

cia to the subcutaneous tissue. First, each cadaver was

placed in the prone position and the posterior calf region

was dissected subcutaneously. Then, we counted the

number of perforators of larger than 1 mm in diameter.

In addition, we measured the distance from the midpoint

of the popliteal crease to the point of emergence of each

perforator. Finally, we dissected the superficial cutaneous

system subcutaneously and measured each diameter of

Department of Plastic Surgery, Oita University, Oita, Japan

*Correspondence to: Fumiaki Shimizu, M.D., Department of Plastic Surgery,Faculty of Medicine, Oita University, Idaigaoka, Hasamamachi, Yufu, Oita879-5593, Japan. E-mail: fumi@med.oita-u.ac.jp

Received 1 July 2008; Accepted 25 November 2008

Published online 18 March 2009 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/micr.20626

VVC 2009 Wiley-Liss, Inc.

the median superficial sural artery and lateral superficial

sural artery at its point of origin from the popliteal artery

(see Fig. 2).

Statistical Analysis

Correlation and statistical difference between the size

of the median or lateral superficial sural artery and the

number of musculocutaneous perforators were assessed

with rank difference correlation coefficient. Statistical

analysis was performed with Graph Pad Prism 4 software

(Graphpad software, San Diego). Significance was

accepted at the P value of less than 0.05.

Surgical Techniques for Elevation of

a Medial Sural Perforator Flap

Musculocutaneous perforators were identified preoper-

atively with an Doppler probe. The outline of the flap was

centered on a perforator. The flap was elevated with the

patient either supine or prone. The prone position was

ideal for flap elevation, as Hallock and Sano mentioned

previously,3 because the approach to the posterior calf

region is much easier than when the patient is supine.

When the flap was elevated with the patient in the supine

position, the hip joint was abducted and the knee joint was

flexed and rotated 90 degrees externally prior to dissection.

Use of a tourniquet without exsanguinations of the leg

facilitated dissection. Dissection of the flap was begun

from the anterior aspect of the flap, and an incision was

made anteriorly through the medial gastrocnemius muscle

of the deep fascia, with confirmation of the perforators.

Dissection within the muscle was continued along the pre-

viously confirmed main pedicle until a pedicle of sufficient

length was obtained.

The blood flow condition of the elevated flap was

confirmed, and the subdermal plexus was retained while

the thickness and volume of the flap were being taken

into account. Whenever the width of the flap did not

exceed 5 cm, primary closure was performed at the donor

site; when the width exceeded 5 cm, a skin graft was per-

formed.

RESULTS

We dissected 12 legs of six cadavers. We found perfo-

rators (average, 2.0 6 1.2 perforators; range, 0 to 4 perfo-

rators) from the medial sural artery in 11 of 12 legs (92%

of legs), and one leg lacked a medial sural artery perfora-

tor. The most of medial sural artery perforators were found

located at distances of 8 cm and 11 cm from the popliteal

crease (Table 1 and Fig. 3). We found perforators (aver-

age, 1.4 6 1.2 perforators; range, 0 to 3 perforators) from

the lateral sural artery in nine of 12 legs (75% of legs),

and three legs lacked a lateral sural artery perforator. No

statistically significant pattern of location of lateral sural

artery perforators was evident (Table 1 and Fig. 3). All

legs had at least one perforator either from the medial

Figure 1. Anatomy of the superficial cutaneous system and deep

musculocutaneous perforators of the posterior calf region. m.s.s.,

Median superficial sural artery; l.s.s., lateral superficial sural artery;

m.s., medial sural artery perforator; and l.s., lateral sural artery per-

forator.

Figure 2. The leg of a formalinized cadaver. The perforators were

counted and the distance from the midpoint of the popliteal crease

to the point of emergence of each perforator was measured. The

diameter of the median superficial sural artery and of the lateral su-

perficial sural artery was measured at the point of origin from the

popliteal artery. m.s., Medial sural artery perforator; and l.s., lateral

sural artery perforator.

254 Shimizu et al.

Microsurgery DOI 10.1002/micr

sural artery or from the lateral sural artery. We found a su-

perficial cutaneous artery with a diameter of suitable size

for microanastomosis (greater than 0.8 mm) in nine of 12

legs (75% of legs), either from the median or the lateral

superficial sural artery (Table 1), while no suitable superfi-

cial cutaneous system was found in three legs. The rank

difference correlation coefficient between the size of the

median or lateral superficial sural artery and the number of

musculocutaneous perforators was 0.233 (P 5 0.47). There

was no significant inverse relationship between the diame-

ter of the median or lateral superficial sural artery and the

number of musculocutaneous perforators. In the case of

four legs that lacked a medial sural perforator or a lateral

sural perforator, no superficial cutaneous artery with a di-

ameter of suitable size for microanastomosis was found in

two of the four legs.

CASE REPORT

Case 1: Medial Sural Perforator Flap

In January 2005, a nine-year-old boy sustained a

severe pressure injury to his left great toe. He presented

at our hospital one year later. During this period, the

wound had been treated conservatively. By the time the

patient presented at our hospital, the wound had already

healed and there was a severe hypertrophic scar, with

scar contracture, on his left great toe. The IP and MP

joint of the great toe exhibited medial deviation because

of scar contracture. Scar revision and free medial sural

perforator flap transfer were performed in March 2006.

Following scar revision, a 3 3 7 cm free medial sural

perforator flap was elevated from the same leg, based on

a single perforator, with a pedicle length of 7 cm. The

flap was transferred to the left dorsalis pedis artery and

the superficial cutaneous vein of the dorsal foot. The do-

nor site was closed with primary closure. One year post-

operatively, a secondary revision was performed with Z

plasty. One year after the second surgery, it was evident

that the medial deviation of the great toe had been suc-

cessfully corrected and the patient remained happy with

the outcome (see Fig. 4).

Case 2: Lateral Sural Perforator Flap

A 74-year-old woman presented with a malignant mel-

anoma on her left cheek. Initially, extensive excision of

her tumor was performed with a 2 cm measurable margin.

After excision of the tumor, an ipsilateral 4 3 7 cm

medial sural perforator flap was designed around the point

at which the vascular flow of a perforator had been

detected. However, no medial sural perforator was encoun-

tered after subfascial dissection. Dissection was advanced

to the lateral side and a lateral sural perforator was found.

The flap was redesigned around the lateral perforator and

the leg was repositioned. The knee joint was flexed 135

degrees, the hip joint was flexed 60 degrees, and leg was

rotated internally. The flap, with an 8-cm pedicle of lateral

sural artery, was transferred to the site of the defect on the

patient’s left cheek. The vascular pedicle was anastomosed

to the superficial temporal artery and vein. The flap

showed good circulation for 16 hours. However, the flap

failed because of arterial thrombosis which had occurred

at 16 hour after arterial anastomosis and the defect was

recovered with a local flap. The local flap survived without

partial necrosis, but the healed site was sunken in appear-

ance because of the insufficient volume of soft tissue (see

Fig. 5). Although the flap failed, this case provided us

with the concept that a lateral sural perforator flap could

Table 1. Location, in Cadavers, of Medial and Lateral Sural Artery

Perforators and Diameters of Median and Lateral Superficial Sural

Arteries at the Site of Origin from the Popliteal Artery

Leg

Numbers of perforators

Diameters of medial and lateral

superficial arteries (mm)

Medial

sural artery

perforator

Lateral

sural artery

perforator

Median

superficial

sural artery

Lateral

superficial

sural artery

01 1 0 – –

02 1 0 1.3 1.8

03 3 1 2.5 2

04 3 3 1.2 2.5

05 1 0 – –

06 0 1 1.4 –

07 2 3 0.8 0.4

08 4 1 0.9 0.5

09 2 3 – –

10 1 2 2.7 2

11 3 2 2.4 –

12 3 1 – 2.3

–, No arteries large enough for microanastomosis were found.

Figure 3. Points of emergence of perforators. Y axis: Distance from

the popliteal crease. Medial, Medial sural artery perforator; and Lat-

eral, lateral sural artery perforator.

Sural Perforator Flap 255

Microsurgery DOI 10.1002/micr

be elevated, as a second choice, form the same donor site

when no medial sural perforator is found.

DISCUSSION

A free fasciocutaneous flap from the posterior calf

region depends, classically, on superficial cutaneous ves-

sels that arise from the popliteal artery.6,7,9,10 The disad-

vantage of such a ‘‘traditional’’ posterior calf fasciocuta-

neous flap is its small diameter and the possible anatomi-

cal variations among pedicles. In some cases, a free flap

cannot be elevated because of the absence of a suitable

pedicle.6 Previous anatomical studies revealed variations

in the origin of the median superficial cutaneous vessel,

which arises from the popliteal artery in 65% of cases,

from the medial sural artery in 20%, and from the lateral

sural artery in 8.3%. It was also reported that the average

diameter of the median sural artery is 1 mm and that of

the lateral sural artery is 0.5 mm.10 Satoh et al. reported

that in two of 17 cases no vessel was found.6

The medial sural (medial gastrocnemius) perforator

free flap, with a long and larger-caliber pedicle that can

be elevated as a thin piece of tissue without any donor-

site morbidity, was introduced recently as one of the best

choice for reconstruction of a distal extremity or the head

and neck region.1–5 The medial sural perforator free flap

was introduced by Cavadas et al.1 in 1996. Subsequent to

their report, further anatomical studies were performed by

Hallock et al.2,3 and Kim et al.4 Cavadas et al. reported

that there were musculocutaneous perforating branches

from the medial sural artery at mean distances of 11.8

cm (range, 8.5–15 cm) and 17 cm (range, 15–19 cm)

from the popliteal crease, and they found at least one

medial sural perforator in all specimens.1 Hallock et al.

also found one or two perforators from the medial sural

artery in their study of cadavers. They reported that these

perforators tended to arise from the distal half of the

medial head of the gastrocnemius muscle.2,3 In 2006,

Kim et al. performed a clinical and anatomical study and

reported that perforators from the medial sural artery

were observed at a distance of 9.7 6 1.1 cm (range, 8–

11.5 cm) and 15 6 1.8 cm (range, 13–17.5 cm), respec-

tively, from the midpoint of the popliteal crease.4 How-

ever, in their study of cadavers, Kim et al. found no

medial sural perforators in one of the legs examined,

even though perforators were found in all of 21 clinical

cases.4 In this study, we found at least one perforator

from the medial sural artery was found in 11 of 12 legs

(92% of legs). The numbers of medial sural artery perfo-

rators were higher at distances of 8 cm and 11 cm from

the popliteal crease and our results were similar to those

in previous studies. Thus, a medial sural perforator flap

Figure 4. Case 1. (a) The patient had sustained a severe pressure injury to his left great toe. (b) One year after the injury, the IP and MP

joints of the great toe exhibited medial deviation because of scar contracture. (c) Free medial sural perforator flap transfer was performed.

(d) One year after the second surgery, it was clear that the medial deviation of the great toe had been corrected successfully.

256 Shimizu et al.

Microsurgery DOI 10.1002/micr

seems to be available in most cases even though, rarely,

a perforator cannot be found (Table 2).

When no medial sural artery perforators are available

for flap elevation, some authors recommend the use of a

traditional posterior calf fasciocutaneous flap from the

same donor site.2,3,8 However, there is a possibility that

no fasciocutaneous flap can be elevated from the poste-

rior calf region when musculocutaneous perforators have

not been found and superficial cutaneous arteries are too

small for microsurgical anastomosis. Shaw et al.7

reported, from their clinical experience, that there seemed

to be an inverse relationship between the superficial cuta-

neous system and deeper systems of musculocutaneous

perforators for blood supply to the posterior calf. In some

cases, the deep system was more prominent and in others

the superficial system was predominant. Their experience

suggested that a traditional posterior calf fasciocutaneous

flap might have a large-caliber pedicle and might be suit-

able for use as a free flap, as a second choice, when the

medial sural perforator flap is not suitable because of the

absence of musculocutaneous perforators. However, in

this study, no inverse relationship between the diameter

of the median or lateral superficial sural artery and the

number of musculocutaneous perforators was found. Fur-

ther studies with much larger numbers of cadavers are

necessary to confirm our conclusions.

Figure 5. Case 2. (a) A case of malignant melanoma on the left cheek; the tumor was excised with a measurable margin of 2 cm. (b) Ini-

tially, a 4 3 7 cm medial sural perforator flap was designed for reconstruction. However, there was a lateral sural perforator but no medial

sural perforator, so the flap was redesigned around the lateral perforator and the leg was repositioned. (c) A lateral sural perforator flap

was successfully elevated with a 6-cm pedicle. (d) Unfortunately, the flap failed because of arterial thrombosis and the defect was repaired

with a local flap.

Table 2. The Results from Previous Anatomical Studies and the Present Study with Respect to Medial Sural

and Lateral Sural Artery Perforator

Study

Medial sural artery perforators Lateral sural artery perforators

Number

of legs

Average number

of perforators

Number of cases

with no perforators

Average number

of perforators

Number of cases

with no perforators

Cavadas et al.1 2.0 0/10 0.4 8/10 10

Hallock et al.2,3 2.3 6 1.1 1/10 1.7 6 1.0 1/10 10

Kim et al.4 1.7 6 0.5 1/40 – – 40

Present study 2.0 6 1.2 1/12 1.7 6 1.2 3/12 12

–, No study.

Sural Perforator Flap 257

Microsurgery DOI 10.1002/micr

Three cases in which a lateral sural perforator flap

was used were reported in 2003 by Kashiwa et al.8 How-

ever, in previous studies, lateral sural artery perforator

seemed to less frequent than a medial one. Cavadas et al.

demonstrated the absence of a lateral sural artery perfora-

tor in 8 of 10 legs. Hallock et al. also performed an ana-

tomical study of lateral sural perforators, and they found

the absence of a lateral sural perforator in one of ten

legs.2 In this study, we also assessed musculocutaneous

perforators from the lateral sural artery and 25% of legs

lacked a lateral sural perforator (Table 2).

A review of previous studies together with our results

suggest that the potential for free fasciocutaneous flap ele-

vation from the posterior calf region is high because there

are two possibilities such for free perforator flap eleva-

tions: a medial sural perforator flap; and a lateral perfora-

tor flap. Our anatomical study indicated that all legs had at

least one perforator, either from the medial sural artery or

from the lateral sural artery. A medial sural perforator flap

should be the first choice because there are fewer anatomi-

cal variations than there are in the case of lateral sural per-

forator flaps. Therefore, free fasciocutaneous flap elevation

can be recommended, using the technique that is summar-

ized below.

First, a skin incision is made through the fascia, on

one side of the flap only, and dissection is continued below

the fascia for localization of the medial sural perforator(s).

When no medial sural artery perforator is found, dissection

is advanced to the lateral side until a lateral sural perfora-

tor(s) is found. If a lateral sural perforator is found, the leg

is repositioned and the skin flap is redesigned to put the

perforator in the center of the flap. When the patient is in

the prone position, repositioning of the donor leg is not

necessary. When the patient is in the supine position, the

knee joint is flexed 135 degrees, the hip is flexed 60

degrees, and the leg is rotated internally (see Fig. 5). If

there are no perforators either from the lateral or the

medial sural artery, a traditional posterior calf fasciocuta-

neous flap, as discussed by Hallock et al.,2,3 can be ele-

vated as a third choice. However, care must be taken

because the possibility remains that no vessels suitable for

microsurgical anastomosis are present in such a situation.

No inverse relationship between the number of perforators

and the dimensions of the superficial cutaneous system

was found in our study of cadavers. Therefore, preopera-

tive assessment of another possible donor site is recom-

mended, for insurance, when the existence of perforators

is in doubt after a preoperative Doppler study.

CONCLUSION

The posterior calf region appears to be an ideal

region for use as the donor site for a free fasciocutaneous

flap for reconstruction of a distal extremity or the head

and neck region. The surgeon has two choices for suc-

cessful elevation of a free perforator flap: a medial sural

perforator flap and a lateral sural perforator flap. A tradi-

tional posterior calf fasciocutaneous flap can be elevated

as a third choice. However, care must be taken because

the possibility remains that no superficial cutaneous ves-

sels of suitable size for microsurgical anastomosis are

present. Preparation of another donor site is recom-

mended when the existence of perforators is doubtful

after a preoperative Doppler study.

REFERENCES

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2. Hallock GG. Anatomical basis of the gastrocnemius perforator-basedflap. Ann Plast Surg 2001;47:517–522.

3. Hallock GG, Sano K. The medial sural medial gastrocnemius perfo-rator free flap: An ideal prone position skin flap. Ann Plast Surg2004;52:184–187.

4. Kim HH, Joeng JH, Seul JH, Cho BC. New design and identificationof the medial sural perforator flap: An anatomical study and its clini-cal applications. Plast Reconstr Surg 2006;117:1609–1618.

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