Int. J. Oral Maxillofac. Surg. 2000; 29: 272–276 Copyright C Munksgaard 2000Printed in Denmark . All rights reserved

ISSN 0901-5027

Oncology

Klaus-Dietrich Wolff, Thomas Plath,Bodo HoffmeisterPrimary thinning of theDepartment of Maxillofacial Plastic Surgery,Benjamin Franklin Medical Center, FreeUniversity of Berlin, Berlin, Germanymyocutaneous vastus lateralis

flapK.-D. Wolff, T. Plath, B. Hoffmeister: Primary thinning of the myocutaneousvastus lateralis flap. Int. J. Oral Maxillofac. Surg. 2000; 29: 272–276.C Munksgaard, 2000

Abstract. To expand the indicational spectrum of the myocutaneous vastuslateralis flap, which is often too voluminous for intraoral application, primarythinning of the fat and muscle component of this microsurgical transplant wasperformed in 14 patients. The surgical technique includes subfascial localizationof at least one myocutaneous perforating vessel of the lateral circumflex femoralartery and its dissection through the fascia, muscles and fatty tissue up to theskin. The epifascial fatty tissue is completely removed except for a 1–2 cm widecuff around the perforating vessel. The thinning technique was used for covering10 intraoral and 4 extraoral defects and enabled the raising of skin flaps with athickness of 4 mm even in obese patients. The vessel pedicle length of the thinnedflaps was between 12 and 16 cm; flap size varied between 4¿5 and 9¿15 cm andthe donor sites were directly closed. In one case, there was a partial necrosis

Key words: vastus lateralis flap; primary flap(20%), but the other flaps healed without complications. The described method thinning; microsurgical reconstruction.allows the raising of thick myocutaneous as well as thin skin flaps from the samedonor region. Accepted for publication 28 December 1999

Despite numerous established pro-cedures for microsurgical tissue trans-fer, the search continues for further im-provement of techniques for oral andmaxillofacial defect coverage, since nosingle method fulfils all requirements ofthe ‘‘perfect transplant’’. These can beformulated as follows: flap raising andtumor resection should be carried outsimultaneously, the vessel pedicleshould be long and of sufficient caliber,and the transplant should enable satis-factory aesthetic and functional resultswith a minimal donor site defect. Theapplication of a single flap as a ‘‘stan-dard transplant’’ is impossible due tothe great variation in size and volumeof defects. Thus, the surgeon must beable to cover different defects with suit-able transplants raised from various do-nor regions. With the aim of limitingthe number of donor sites for soft tissue

reconstruction, flap thinning can becarried out, so that thick myocutaneousas well as thin skin flaps can be raisedfrom the same donor region.

Radical removal of fatty tissue forthe creation of thin skin flaps was ini-tially carried out with local grafts andwith random pattern flaps, in whichonly the subdermal vascular plexus wasleft under the skin11,14–16. Althoughthese very thin flaps have shown mark-edly better survival than full thicknessskin grafts, frequent epidermolyses andpartial necroses have been seen due tothe nonaxial vessel supply. The thinningof axial pattern flaps enabled flap rais-ing with a larger rotation radius byclearly narrowing the flap basis; it alsoimproved the success rate, since the flapdesign was more appropriate for thecourse of the subdermal plexus sup-plied by the perforating vessels2,13,21,22.

Primary flap thinning was also appliedto microsurgical flaps including the lat-issimus dorsi10 and the extended rectusabdominis flap1,3,8, the groin flap9 andradial forearm flap7. The anterolateralthigh flap has proven to be especiallysuited for flap thinning, since its septo-cutaneous perforating vessel can be eas-ily isolated from the fatty tissue andthus reliably protected6.

To fulfil as many of the aforemen-tioned requirements for optimal micro-surgical transfer as possible, the prin-ciple of flap thinning was applied to thevastus lateralis flap, since this donor siteand vascular anatomy offer a good op-portunity for a two-team approach andthe flap has a long and high-caliber ves-sel pedicle17. Because of its large vol-ume, the main indications for this flap,which is raised from the middle or dis-tal segment of the descending branch of

Primary thinning of myocutaneous vastus lateralis flap 273

Fig. 1. a) Voluminous flap of an obese patient before thinning. b) Fig. 2. a) Primary fat removal of a raised myocutaneous vastus lat-Thinned flap for covering the floor of the orbit and the medial orbital eralis flap; the perforating vessel enters the flap proximally. b) A thinwall before the fabrication of an epithesis. c) Result of reconstruction and pliable flap was created by removal of the voluminous lobularafter 3 months without further thinning. subcutaneous fatty tissue; only a thin layer of fat directly under the

dermis was preserved. c) Application of the thinned transplant forvelum reconstruction. The patient’s speech and swallowing were un-impaired by the completely healed flap.

the lateral circumflex femoral artery,are extensive and deep defects of thetongue, cheek or neck18–20. Smaller andless extensive defects, as commonlyfound after tumor resection in the oralcavity, have thus far not been con-sidered as indications for this flap. In

contrast to the classical anterolateralthigh flap, which is supplied by a proxi-mal septocutaneous vessel12, the my-ocutaneous vastus lateralis flap is basedon more distal perforating vessels,which traverse the muscle primarily inits middle third; thus, the myocutane-

ous transplant can be considered to be adistal expansion of the septocutaneousanterolateral thigh flap. Anatomicalstudies17, as well as cases reported byK et al.8 and K et al.4,5,showed that less than half of these flapshad a septocutaneous perforating vessel

274 Wolff et al.

of the descending branch, so that in themajority of cases even the skin vessel ofthe anterolateral thigh flap perforatesthe vastus lateralis by at least a shortsegment. To be able to raise thick my-ocutaneous flaps as well as thin and pli-able skin flaps from the same donorregion, primary radical resection offatty and muscular tissue can be per-formed.

Material and methodsSurgical technique

The reliable identification of at least one my-ocutaneous perforating vessel in the middlesegment of the vastus lateralis muscle is im-portant for flap raising and thinning. This isfacilitated by preoperative localization usingvessel Doppler. The incision is made verti-cally in a craniocaudal direction over the rec-tus femoris muscle initially up to the fascialata. After incision, the perforating vessel canbe visualized above the vastus lateralis bysubfascial exposure. The incision is then con-tinued in a cranial direction to expose thevessel pedicle, which is located in the muscleseptum between the vastus lateralis, rectusfemoris and tensor fasciae latae. Using mag-nifying glasses, the 0.5–1.0 mm thick perfor-ating vessel is dissected through the muscleup to the descending branch and its few exitsto the muscle are clipped. Most of the vastuslateralis muscle can thus be preserved duringflap raising. Defatting of the flap is then per-formed according to the technique describedby K & S6 for the anterolateralthigh flap. By removing the subcutaneousfatty tissue close to the dermis, a flap thick-ness of 3–4 mm can be achieved without im-pairing perfusion. If a flap longer than 15 cmis needed, two perforating vessels should beintegrated into the flap. The donor site canbe closed directly with a flap width of up to8 cm.

Patients

Flap thinning was performed in 14 patients(10 men and 4 women aged 48–77 years).Extraoral defect coverage was carried out infour cases: twice after resection of part of themid-facial region including orbital exenter-ation, once after removing a carcinoma fromthe nose and cheek region, and once for de-fect coverage on the scalp. All four cases in-volved very obese patients, in whom the ap-plication of non-thinned flaps would have ledto an extreme volume surplus. The largest ofthese flaps was 9¿15 cm and was used on thescalp.

Intraoral flaps were applied in 10 patientswith squamous cell carcinomas of the oralmucosa: three on the anterior and four onthe lateral floor of the mouth, one in thecheek and two on the velum and lateral pha-ryngeal wall. All intraoral flaps were suppliedby one perforating vessel and were almost

completely thinned to 3–4 mm. Flap sizevaried between 4¿5 and 5¿8 cm; a segmentof the vastus lateralis muscle was raised inone case in order to cover a reconstructionplate.

Results

Although the majority of our 14 pa-tients were obese, which made the ex-posure of the myocutaneous perforatorvessel difficult, it could reliably belocated over the middle third of themuscle. For safe identification of thisvessel, preoperative Doppler localiz-ation proved to be helpful. The dur-ation of flap raising varied between 90and 180 minutes and increased with thelength of the perforating vessel runningthrough the muscle and the radicality ofthe thinning procedure. Using magnify-ing glasses, the muscle tissue around theperforating vessel could be almost com-pletely removed and the perforatorcould be followed up to the descendingbranch in all patients; this resulted in12–16 cm vessel pedicles which had suf-ficient caliber (arteries 2–2.5 mm, veins3–5 mm) for microsurgical anasto-mosis.

Fatty tissue was removed from theperiphery to the center, i.e. up to theentry site of the perforating vessel.While thinning was quickly performedwithout endangering flap perfusion inthe periphery, it became increasinglymore difficult toward the center, sinceinjury to the flap vessel had to beavoided here. Leaving an approximately1–2 cm wide fatty tissue cuff proved tobe sufficient in all 14 cases since alltransplants showed good perfusionafter thinning. All flap raisings were al-ready completed before tumor resectionso that the overall duration of surgerywas not increased. Pliable grafts couldbe created by flap thinning and theywere suited for intraoral coverage, evenif the defects were relatively flat. Aslight secondary excision of fatty tissuewas required in two cases of extraoralreconstruction since there was excessvolume around the entering vascularpedicle. Submandibular placement offatty tissue was carried out in all intra-oral reconstructions and did not causeany excess volume after neck dissection.All transplants healed completely ex-cept one, which developed a distal flapnecrosis (20%) after defect coverage onthe scalp.

Postoperative clinical evaluationshowed that flap thinning enabled good,

that is anatomically adequate, recon-structions and that secondary correc-tion was not required. Easily compre-hensible speech with preserved swal-lowing function and good mobility ofthe tongue was achieved in all cases byprimary reconstruction. Patients hadno or only minor short-term problemswith the directly closed donor sites andno functional impairments, for ex-ample, during running or climbingstairs. There was a slight concave mal-formation of the thigh at the donor sitein very obese patients.

Case reports

Case 1 (Fig. 1a–c)

After resection of an adenoid cystic car-cinoma, this 47-year-old patient had adefect of the floor and wall of the orbitwhich required closure before the appli-cation of an epithesis. The 6¿8 cm flapsupplied by a myocutaneous perforat-ing vessel was thinned to 3–4 mm andraised without the muscle componentafter exposure of the perforating vessel.The thin, flexible skin was well suitedfor reconstruction of the orbital walland the anastomosis between the facialartery and vein caused no problems.Wound healing was uneventful.

Case 2 (Fig. 2a–c)

After resection of a squamous cell carci-noma in the retromolar triangle, this68-year-old patient had a defect of theleft velum of the dorsolateral floor ofthe mouth and buccal plane. A myocut-aneous perforating vessel was locatedover the middle segment of the vastuslateralis muscle and excised. When out-lining the skin island, the perforatorwas positioned on the cranial flap poleso that only a small amount of fattytissue had to be left under the flap.Since a radical neck dissection was per-formed, a 14 cm vessel pedicle was ex-posed for anastomosis on the contra-lateral side of the neck. The flap healedprimarily, and speech and swallowingwere unimpaired.

Discussion

There have only been a few reports inthe literature on primary, radical thin-ning of microsurgical grafts, the mainindications being contractions afterburns in the neck region and the ex-tremities. For this purpose three typesof grafts have been used: the anterolat-

Primary thinning of myocutaneous vastus lateralis flap 275

eral thigh flap, the myocutaneous rectusabdominis flap and the groin flap6,8,9.While these authors suggested flap thin-ning to create extremely thin grafts forcovering large and flat skin defects, wemainly used flap thinning for coverageof intraoral, relatively small defects.Questions to be addressed include: 1. Isflap thinning a safe method and to whatextent can it be performed? 2. How re-liable is the method with the myocut-aneous vastus lateralis flap? 3. What re-constructive possibilities exist with thetransplant to be raised? 4. Are the re-quirements for an ‘‘optimal flap’’, i.e.long vessel pedicle, two-team approach,minimal donor site defect, fulfilled?

Previous experience with primarythinning of microsurgical grafts hasshown that radical removal of fattytissue does not impair flap perfusion, ifthe subdermal vascular plexus is pre-served and attention is paid to the vascu-lar territory of the corresponding flapvessels1,6–9. The literature generally re-ports very low complication rates. Allauthors agree, however, that flap thin-ning must be performed with a high de-gree of technical skill and exact knowl-edge of the vascular anatomy, which isespecially true for the groin flap sincecomplete flap loss has been reportedsince in 2 of 12 cases9. There is alsoagreement on the possible extent of flapthinning. A prerequisite for successfulthinning is the preservation of the sub-dermal vascular plexus, which meansthat flap thickness should not be lessthan 3–4 mm. While A et al.1 ini-tially limited the width to length ratio ofthe thinned flap portion to 1:2, mostauthors now assume that the size of thevascular territory of a thinned flap corre-sponds to conventional flaps6,8,9. The re-sults presented show that primary rad-ical removal of fatty tissue has no nega-tive influence on the survival rate of theflap and only one of 14 grafts showedpartial necrosis, which could be attri-buted to excessive thinning (less than 3–4 mm thickness).

K & S6 emphasize that thevessel anatomy of the anterolateral thighflap is especially suitable for flap thin-ning, since there is a single, visible cu-taneous vessel that perforates the fasciaafter branching off from the descendingbranch and courses directly to the skin.In contrast to the anterolateral thighflap, the vessel pedicle of which can beexposed up to a maximal length of about8 cm, a more distal, myocutaneous per-forating vessel over the vastus lateralis

muscle was selected here to serve as abasis for the thinning procedure. Theclinical applications for the use of thevastus lateralis flap have been publishedpreviously17–20. A great advantage is thepotential for a considerably longer vesselpedicle, which has proven to be espe-cially favorable for applications in thehead and neck area. Flap thinning nor-mally includes the exposure of the per-forating vessels and dissection throughthe muscles, which can only be achievedby using careful excision techniques andmagnifying glasses. It is, therefore, poss-ible to raise voluminous and large flapsas well as very thin and small flaps fromone and the same donor region. Thus,the potential use of this flap ranges fromtongue reconstruction with neuro-muscular flap reinnervation to defectcoverage of the velum with a thin skinflap. It must be mentioned, however, thatthe surgery is considerably more compli-cated as compared to a radial forearmflap and that the surgeon must be awareof possible variations in vascular ana-tomy. For example, K et al.4 de-scribed the absence of cutaneousbranches from the descending branch in5.4% of patients. This was true for onepatient from our population of 76 vastuslateralis flaps. It is also very important tobe aware of the branching pattern of skinvessels from the descending branch,which has been classified into 8 cate-gories4. However, these variations didnot impair the success of flap raising inany case. A low complication rate forflap thinning can only be achieved by asurgeon who is experienced with thismethod and has exact knowledge of ves-sel anatomy.

The method described makes possiblethe raising of very thin or voluminousflaps from the same donor site. The flapshave a long vascular pedicle with a suf-ficient caliber, and primary closure ofthe donor site is possible with a flapwidth of up to 8–10 cm. The techniquecan usefully be applied for a variety ofdefects in the oral and maxillofacial re-gion.

References

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Address:Prof. Dr. Dr. Klaus-Dietrich WolffDepartment of Oral and Maxillofacial

SurgeryKnappschafts-Krankenhaus

Bochum-LangendreerRuhr-University BochumIn der Schornau 23–2544892 BochumGermany