Free Tissue Transfer to the Lower ExtremityA Paradigm Shift in Flap Selection for Soft Tissue Reconstruction

Rahim S. Nazerali, MD, MHS, and Lee L.Q. Pu, MD, PhD

Introduction: The free anterolateral thigh (ALT) skin perforator f lap hasgained enormous popularity as a free skin perforator f lap. Currently beingused for various reconstructions primarily in Asia, its routine application forsoft-tissue reconstruction of the lower extremity remains unknown in theUnited States. The purpose of the present study was to review the current trendof f lap selection for soft tissue reconstruction of the lower extremity.Methods: We performed a retrospective review of a single-surgeon caselog between 2007 and 2011 in a tertiary academic medical center. Inclusioncriteria were patients who underwent free tissue transfer for lower extremityreconstruction regardless of sex or age. Exclusion criteria were limited topatients with a body mass index greater than 35 kg/m2. A total of 20 patientsunderwent reconstruction with a free tissue transfer for soft tissue coverageof the lower extremity wound were identified.Results: Fourteen free ALT and 6 free muscle f lap reconstructions wereperformed over a 4-year period. Good reconstructive outcomes resulting inreliable soft tissue coverage were achieved in all patients. It was noted thatmore ALT flaps were used in the last 2 years and less muscle f laps (0/8 vs 6/12,P = 0.042) when compared with the years prior.Conclusions: Although technically more challenging to perform, the freeALT flap has recently been used significantly more for lower extremity re-construction because of its minimal donor-site morbidity, reliable coverage,and improved contour. This represents a paradigm shift in f lap selectionthat is being highlighted as surgical proficiency in f lap dissection techniqueimproves.

Key Words: perforator flap, free tissue transfer, anterolateral thigh flap,ALT, soft tissue reconstruction, free flap

(Ann Plast Surg 2013;70: 419Y422)

With improvements in medical care, the need for improved re-constructive surgery for complex lower extremity defects have

become more critical. Muscle f laps previously used because of theirimportant function as carriers of blood to the skin and subcutaneoustissue are now left in place to serve their original function. The per-forator, supplying the skin and subcutaneous tissue, is evolving tobecome the free tissue of choice, providing contoured coverage ofwounds while minimizing donor morbidity.1Y5

The wide choice of skin perforators has increased the abilityof surgeons to use adjacent soft tissue to reconstruct lower extremitywounds. Theoretically, perforator f laps can be designed and harvestedbased on any dominant and clinically significant perforator adjacentto a wound. Because there are more than 350 perforators in the body,a large number of f laps can be harvested when a proper perforatoris selected.5

The free anterolateral thigh (ALT) skin perforator f lap hasgained enormous popularity as a free skin perforator f lap for variousreconstructions. The flap has reasonably consistent vascular anatomy, along pedicle with a suitable diameter, and a large skin paddle.1,2,6Y12

In addition, the donor site can be closed primarily with a minimal scar.As such, the free ALT skin perforator f lap has become a primary re-constructive tool for soft tissue reconstruction of a complex lower ex-tremity wound.

Skin perforator f laps have gained much popularity for variousreconstructions primarily in Asia, but their routine application forsoft-tissue reconstruction of the lower extremity remains unknown inthe United States.4,5,11,12 The purpose of the present study was toreview the current trend of f lap selection for soft-tissue reconstruc-tion of the lower extremity at an academic medical center in theUnited States.

METHODSWe performed a retrospective chart review of a single-surgeon

case log (L.P.) from November 2007 to October 2011. Included pa-tients were all those who underwent free tissue transfer for lowerextremity reconstruction within the timeframe reviewed. Excludedwere smokers or obese patients with a body mass index greater than35 kg/m2. These patients were excluded from the study because theircomorbidities altered our approach in wound coverage.

The study was divided into half to compare the 2 groupsagainst one another. The type of f lap used for coverage and associ-ated complications were reviewed. A Fisher exact test was performedto evaluate the type of f lap used based on the time frame in whichthe f lap was performed. The null hypothesis was that no differenceexisted between the type of f lap performed between the first timeframe (2007Y2009) and second time frame (2009Y2011). A 2-tailedP value that was statistically significance was set at P G 0.05.

RESULTSA total of 20 patients were identified requiring free tissue

transfer for lower extremity reconstruction (Table 1). There was nof lap loss in this series, and good reconstructive outcomes with reli-able soft tissue coverage were achieved in all patients. Fourteen ALTflap and 6 muscle f lap reconstructions were performed. On review,it was noted that all muscle f laps were performed in the first timeframe, and no muscle f laps were performed in the second time frame.

A Fisher exact 2-tailed P value calculated comparing the firsthalf with the second half of the study revealed a P value equal to0.04. This indicates a statistically significant difference indicatingthat the free ALT perforator f lap was used statistically more than thefree muscle f lap for soft tissue reconstruction of a lower extremitywound in the senior author’s academic practice.

CASE EXAMPLES

Case 1Case 1 is a 70-year-old man who had a chronic left distal leg

wound with exposed bone and a spacer. He required the soft tissuecoverage to his exposed distal leg wound. A free rectus abdominusmuscle was chosen with a split thickness skin graft (Fig. 1).

CLINICAL ARTICLES

Annals of Plastic Surgery & Volume 70, Number 4, April 2013 www.annalsplasticsurgery.com 419

Received December 9, 2012, and accepted for publication, after revision, January26, 2013.

From the Division of Plastic Surgery, University of California Davis Medical Center,Sacramento, CA.

Conflicts of interest and sources of funding: none declared.Reprints: Lee L.Q. Pu, MD, PhD, Division of Plastic Surgery, University of California

Davis Medical Center, 2221 Stockton Blvd, Suite 2123, Sacramento, CA 95817.E-mail: lee.pu@ucdmc.ucdavis.edu.

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Case 2Case 2 is a 30-year-old man who had a left open tib-fib frac-

ture who developed a chronic wound over his fracture site. A freeanterolateral thigh perforator f lap was chosen to cover the defect. Anend-to-end anastomosis was performed to the anterior tibial artery,and a 2.5-mm coupler was used for the venous anastomosis (Fig. 2).

Case 3Case 3 is a 28-year-old man who had an avulsion injury of

the medial aspect of the left foot with exposed bone secondary tomotor vehicle accident. He also had bony loss and lack of continuityof bony structure. An ALT perforator f lap was then designed to fillthe defect (Fig. 3).

DISCUSSIONPlastic surgeons have always focused on transplanting new

healthy tissue for the restoration of missing parts. Reconstructivemicrosurgery has been a rapidly changing reconstructive tool to helpachieve this goal. Free tissue transfers, introduced merely 3 decadesago, were fraught with challenges and disappointments. Dedicationand recent advancements in the field have changed complicationsand frustrations to success. We have moved beyond being able tomerely cover wounds to refining reconstructive surgery, optimizingcontour, and minimizing donor morbidity.

The advent of perforator f laps, comprising of skin and sub-cutaneous fat, was a significant leap forward in f lap based surgery.Vessels that supply blood to the f lap are isolated perforators that

pass from their source through or in between the deeper tissues ormuscle. The perforators pass from their source vessel origin throughor in between deeper structures. There are 2 main types of perforatorf laps. Myocutaneous flaps have blood vessels traverse through muscle,whereas septal or septocutaneous perforators traverse through septumto supply overlying skin.12

Several advantages exist with the use of perforator f laps overmuscle f laps. By preserving the underlying structures, donor-sitemorbidity is minimized. Fascia, muscles, and nerves are left in placeto continue performing their original function. Another advantage isthat like tissue is replaced with like. By using perforator f laps, freetissue transfers use only the elements that are required for wound cov-erage, namely, the skin and subcutaneous tissue. This allows for pre-cision in contour and color match.

Lower extremity reconstruction has benefited significantlywith the introduction of the perforator f lap. The advantages of per-forator skin f laps in the lower extremity are their relatively straight-forward design and sparing of the muscle. In addition, good contourwith thin, pliable tissue provides an excellent wound coverage option.The free ALT skin perforator has gained enormous popularity forthis reason. It has some of the best vascularity, a relatively easyperforator dissection, and a long pedicle.6,8,11,13,14 The donor sitehas minimal morbidity and can be closed primarily even with a skinpaddle width of 9 cm.15

Properly identifying the major perforator to be used for theanterolateral thigh f lap in the operating room can be challeng-ing. Like any successful surgery, preoperative planning is critical forsuccess. This can be divided into patient selection and flap selection.

Patient selection revolves around 2 primary issues: infectionsand obesity. Theoretical concerns exist in covering infected woundbeds with only skin and subcutaneous tissue. Some argue that thesef laps are not robust enough to help in eradicating high bacterialloads due to a paucity of blood supply. Recent studies have indica-ted that the ALT f lap in itself offers a rich blood supply that canovercome infected wound beds and contribute to the sterilizationand healing.16

TABLE 1. Flap Type Performed for Lower Extremity CoverageBased on the Years in Which It Was Performed

Flap Type 2007Y2009 2009Y2011 Total

Muscle 6 0 6

Fasciocutaneous 6 8 14

Total 12 8 20

FIGURE 1.

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Second, increased subcutaneous fat content from obesity cancompromise f lap dissection and increase recipient site complica-tions. The donor sites of these patients also have higher rates ofseromas and wound healing problems. Therefore, obesity is also arelative contraindication to performing the free ALT perforator f lap.In these cases, a muscle f lap with skin graft may still be the betterchoice for covering a complex lower extremity wound.

Flap selection techniques are equally important for success.Not a single perforator’s course, branches, or the relations with thesurrounding tissue is similar. As such, reliable imaging studies canbe quite helpful for estimating the length of intramuscular dissec-tion and the potential diameter of the pedicle before dissection. Inthis way, the surgeon can estimate whether the freestyle f lap canbe harvested as a free skin f lap for free tissue transfer. A number

FIGURE 2.

FIGURE 3.

Annals of Plastic Surgery & Volume 70, Number 4, April 2013 Free Tissue Transfer to the Lower Extremity

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of modalities, such as a handheld Doppler in the operating roomor computed tomographic angiography, have been used.17Y19 Colorduplex scan was the modality of choice in our experience and wasalways used before f lap elevation in the operating room. In this way,the size of the perforator and its intramuscular course can be identi-fied and interpreted.20,21 This provides an important road map fordissection as well as informs the surgeon which operative site maybe more desirable based on pedicle diameter, length, and course.A suprafascial dissection permitted the f lap to be harvested withless donor-site morbidity preserving fascia in its native location.

Finally, dissection techniques and surgeon comfort in micro-surgery are also critical for success. Surgical dissection of the per-forator and potential microvascular anastomosis of the pedicle vesselcan be challenging. Surgeons who plan to perform the free skin per-forator f lap may have a significant learning curve. With continuedrefinement of microsurgical skills and techniques, perforator f lap dis-section and the microvascular anastomosis can be performed safely.

The ALT flap can be based on a single musculocutaneousperforator although the f lap may be based on a septocutaneous per-forator in 15% of patients.12 The perforator should be larger than0.5 mm in diameter and should have a strong Doppler signal or visi-ble pulsation. The needed amount of intramuscular dissection of theperforator can vary. On average, intramuscular dissection of myo-cutaneous perforators is approximately 4 to 5 cm long, but longerintramuscular dissection can be quite tedious and more challenging.12

When performing intramuscular dissection of a myocutaneous per-forator, it is important to have good visualization of the perforatorat all times. This facilitates placing a proper amount of traction onthe pedicle to avoid excessive tension or twisting of the perforator.Antegrade dissection from the descending branch of the circumflexfemoral vessels toward the perforator may be used to speed up thepedicle dissection. Once an appropriate pedicle length is obtainedand the size is adequate for microvascular anastomosis, the pediclecan be divided, and flap dissection, completed. If the donor site is inthe thigh, the size of the skin island can be as large as 8 by 20 cm. Theaverage length of the pedicle is approximately 10 cm. However, thediameter of the pedicle can be quite small, and the surgeon shouldfeel comfortable performing microsurgery for a vessel between 1 and1.5 mm in diameter.

Although only based on a single surgeon’s experience at anacademic medical center in the United States, the data presented inthis study indicate that significantly more free ALT flaps have beenperformed for soft tissue coverage of a complex wound in the lowerextremity, especially in the last 2 years of the study. This represents aparadigm shift in f lap selection, at least in some centers in the UnitedStates. Likely, recently trained plastic surgery graduates armed with anew set of microsurgical skills likely feel much more comfortable toperform free ALT flaps than their more ‘‘senior’’ colleagues in thesame practice.

In nonobese patients, a free skin perforator f lap, such as anALT flap, can provide excellent reconstruction of a complex softtissue wound in the lower extremity. Good contour can be accom-plished without a need for further f lap debulking. Because the skinperforator f lap completely spares the muscle, donor-site morbiditycan be minimized, and any skin defect in the lower extremity can becovered by such a f lap.

CONCLUSIONSThere is a growing trend toward more free ALT flaps and less

free muscle f laps for lower extremity reconstruction in a tertiary

academic medical center. Although technically more challenging toperform, the free ALT flap has recently been used significantly morebecause of its minimal donor-site morbidity, reliable coverage, andimproved contour. This represents a paradigm shift in f lap section.However, in obese patients, free skin-grafted muscle f lap are still thesoft tissue of choice for coverage of complex lower extremity woundsbecause muscle f lap reconstruction is easier, with greater reliabilityand fewer complications.

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