ALT Flap

ALT FLAPDr sumer singhPlastic and reconstructive deptt

History 1984 - 1st introduced by Song et al 1986 - for head & neck reconstruction 1st described by Koshima et al 1992 1st microvascular transfer of VL muscle flap Wolff1995 for lower extremity defect1996 ultrathin flap (3-4 mm) preserving subdermal plexus Kimura et alVery popular reconstructive flap in AsiaLimited use in West vascular anatomy variations difficult dissection thick thigh fat

Indications Head & neck reconstructionsBuccal mucosa defectBuccal through & through defectPharyngo-oesophageal reconstructionLower lipTongueLateral & anterior skull baseScalpCombined with free fibula flap Extremity reconstruction

ContraindicationsPrevious surgeries Injury to upper thighMorbid obesity too thick flap Difficult intramuscular dissectionSevere peripheral disease

Types

Free flapPedicled flap Distally based (on distal minor pedicle) for knee defect Proximally based Trochanteric bed soreLower abdominal defectsPerineal reconstructionGluteal defect

Types Type B/C Fasciocutaneous flap (type B - septocutaneous perforator) or ( type C - musculocutaneous perforator )Musculocutaneous flapFascial flapAdipo fascial flap for Romberg diseaseSensate flap(include lateral femoral cutaneous nv.)Osteo fascio cutaneous flapChimeric flap ( 2 or more separate defect)2 small independent flapsMuscle only flapFlow through flap (to salvage extremity, where proximal & distal ends of pedicle anastomosed to recipient vessel)

Pre-Op preparationExclude previous trauma/surgery to thighDoppler study over lateral intermuscular septum 2-3 cm lateral to lateral intermuscular septum(over medial part of VL)Angiography - not helpfulCheck for popliteal pulsationConsent for - failure/risk/alternate (RFFF)Donor site morbidity, knee instability / limping gaitNo IV line in flap leg

LandmarksLine drawn between ASIS & supero-lateral border of patellaCorresponds to the septum between RF & VL.Skin perforators mapped by Doppler Accuracy of Doppler decreases as BMI increases.

Flap dimensionsMaximum length 30 cmMaximum width 15 cmFor direct closure maximum width 8 - 10 cm or < 16% of thigh circumference

Muscles of antero lateral thigh

Vascular system of Anterolateral thigh & standard skin paddle

Standard flap design

Flap harvestingInitial skin incision on medial flap aspect over RF , 2-3 cm medial to lateral inter-muscular septum.Proximal incision between TFL & RFSub-fascial incision through deep fascia with lateral dissection until perforators identified Supra-fascial - for thin flap carried laterally until perforators identified

Flap harvestingSkin incision completed after perforator identificationRetrograde dissection of pedicle to descending branchMay involve dissection of VL. A cuff of muscle may be left to protect perforating branches.Advantage of taking a part of VL easy harvest no intramuscular dissection pedicle twisting will be lessLateral femoral cutaneous nerve sensate flapThinning performed in deep fat layer to avoid pedicle injury.

Pedicle

1 Artery, 2 Venae commitantes, motor branch of femoral nerve to VL Based on perforators from descending branch of lateral circumflex femoral artery (90%). From transverse branch of LCFA (4%).From profunda femoris (4%) pierces through RF. Descending branchCan be safely dissected proximally to its major branch to RF, which should be preserved Runs in inter-muscular space b/w RF & VL.Terminates by anastomosing with superior lateral genicular artery.

Dimensions of vascular pedicleAverage length of pedicle 12 cmDiameter ( DLCFA ) Artery - 1.5 2.5 mm ( Avg - 2.1 mm )Veins 1.8 3.3 mm ( Avg - 2.3 mm )

Cutaneous perforator origin

Perforators Mapping A (most proximal),B, C (most distal)Musculocutaneous perforator (80-90%) - traverse VL (close to medial edge) & deep fascia to supply skinSeptocutaneous perforator (10-20%) runs in-between RF & VLpierces the fascia lata to supply skin

Perforator classificationType 1 (50 %) Perpendicularly to subdermal plexus.Type 2 (35%) Branch in adipose & extends into subdermal plexus.Type 3 (15%) Extends along deep fascia & gradually into adipose .

Sensory innervations Lateral femoral cutaneous nerve(L2-L3)Direct branch of lumbar plexusEnters thigh deep to IL near ASIS.Follows path of deep circumflex iliac artery & veinLies along line connecting ASIS to lateral patella.Pierces fascia lata 10 cm distal to IL.Travels in deep subcutaneous layer immediately superficial to deep fascia.

ALT Flap Markings

Medial flap incision & septum identification

Opening of septum

Septum dissection distal to proximal

Medial retraction of RF & Identification of pedicle

Dissection of perforator & preservation of motor branches of femoral nerve

Final skin paddle & Readjustment

Medial retraction of RF & Identification of DLCFA

Skin incision

Incision of fascia

Exposure of vascular pedicle

Detachment of inter-muscular septum

Separation of pedicle components

Identification of perforator & distal ligation of pedicle

Circumcision of skin paddle

Fixation of skin paddle to muscle

Dissection of vascular pedicle

Cross section anatomy of flap

Flap ready for microvascular transfer

Myo-cutaneous flap containing 2 perforator

Advantages Minimal long term donor site morbidityLong,reliable,larger pedicleLarge skin paddleCan cover complex woundGood pliabilityNo major artery is sacrificedAbility to tailor the thickness of flap.

Disadvantages Bulky flapHair bearing flap in malePrimary closure of donor site is not possible in most cases.

Post operative care

Removal of drain - output < 30 ml/day, with sero sanguinous discharge.Encourage to walk on 3rd post op day.

Post op complications Recipient site

Flap necrosis

Fistula (head & neck reconstruction )

Haemorrhage

Arterial occlusionLocal abscess

Exposed bone/plate Donor site

STSG lossWound infectionDog earsPain & weakness in thigh- injury to nerve to VL.Seroma/haematomaPartial necrosis of foot & calf in a case of DLCFA act as a critical collateral for an obstructed superficial femoral artery.

Outcome & prognosisMinimal long term donor site complicationsAllowed to walk after 3 daysNo significant decrease in strength or range of motion

ALT vs Radial forearm free flap ALTIncreased learning curvePrimary closureMorbidity related to vastus lateralis damagePotential dysfunction Quadriceps Pain Disto-lateral thigh anaesthesia /paraesthesia Radial forearm free flapPotential tendon exposureSacrifice of dominant distal blood supplyClosure with STSGPotential dysfunctions - Hand stiffness Pain Anaesthesia / paraesthesia

Anatomical VariationsAbsence of cutaneous perforator in 5.4 % Absence of descending branch in 22.6 % replaced by medial descending branch ( inominate branch )Ascending branch can supply a perforator to upper part of ALT, which can be used when normal ALT perforators are inadequateOther leg can be used

ALT Failure EtiologyInadvertent perforator divison at fascial plane

Inadvertent perforator injury during intramuscular dissection

Pedicle twisting during inset

Follow up recipient area Aesthetic Sagging of flapHair growth on flapContour defectFlap bulkiness need of debulking ( shoe wearing)

Follow up recipient area. Functional

Speech problemsOral incompetenceEating problemsFacial painNasal obstruction

Follow up Donor area Aesthetic Hypertrophic scarHypo/hyper pigmentationKeloidContour defect

Follow up donor site. Functional

Slightly limping gaitSensory disturbancesCold intolerance

Controversies Anatomy unpredictableDissection difficultDoppler identification of perforator is difficult.

Future Emerged as new workhouse flap for soft tissue head & neck reconstruction.

Thank u