Antero-Lateral Thigh (ALT) Flap

These diagrams and illustrations have been designed to help you learn, memorise and recall key information.

INTRODUCTION

A versatile flap with a good donor site.        

It provides potentially thin pliable skin with a long pedicle.

It can be raised as a fascia-only flap if required.

 

CLASSIFICATION                 

“Perforator flap” based on myocutaneous or septocutaneous perforators.

 

COMPOSITION   

Fasciocutaneous Skin-fat-fascia.

 

PEDICLE                

Descending branch of lat. circumflex femoral art. (1-3 mm diameter)

Venae (slightly larger than artery at the origin).

>10cm pedicle length.

 

SKIN PADDLE

~25cm long (from 10cm inf to ASIS to 7cm sup. to patella).

~8 cm wide for direct closure (15cm if donor area is grafted).

 

INNERVATION   

Lateral femoral cutaneous nerve of the thigh.

Can be used to neurotize the flap.

 

COMMON USES

Workhorse flap for head and neck reconstruction and limb defects.

eg pharyngeal reconstruction as a tubed flap.

 

TECHNIQUE        

The patient must be consented, marked, prepped and draped for surgery.

I position the patient supine on the operating table.

Sometimes I use a sandbag under the hip to improve exposure.

 

PLANNING            

I draw a line from the ASIS to the lateral patella and mark the midpoint.

This corresponds to the septum between rectus femoris and vastus lateralis.

I then draw a 3cm radius circle at the mid-point of this line.

I identify the perforators in this region using a hand-held doppler.

Typically they lie in the inferolateral quadrant.

I then design my skin paddle to fit the defect, centred over the perforator.

I factor in where the flap will ultimately lie and where the anastamosis will be.

 

DISSECTION        

I dissect from the lateral side first.

I take the fascia with the flap.

Initially, I don’t extend too proximally so that the TFL perforator can still be included if need be.

I identify the perforators and then dissect more confidently around the flap.

I locate the mother vessel deep in the septum between rectus femoris and vastus lateralis.

I then dissect the perforators through the muscle (or take a cuff of muscle).

Generally only one perforator is required to perfuse the flap.

In 20% the perforators are septal.

In 80% they come through vastus lateralis.

The motor nerve to vastus lateralis lies lateral to the artery and should be preserved.

The lateral cutaneous n. of the thigh can be included to make the flap sensate. It lies superficial to the fascia at the superior incision. The pedicle is dissected proximally.

The donor site is closed directly or with a SSG.

 

ALT Flap Diagram
ALT Flap Diagram
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