Steps of ALT flap harvest

1. Position and prepare
   • Patient supine, with the whole thigh accessible.
   • Prepare the recipient site concurrently where possible.
   • Assess donor-site width for primary closure versus split-thickness skin graft.
2. Mark landmarks and perforators
   • Draw a line from the anterior superior iliac spine (ASIS) to the superolateral patella. This approximates the septum between rectus femoris and vastus lateralis.
   • Identify perforators with handheld Doppler, usually around the midpoint of this line, often slightly lateral and distal.
   • Design the skin paddle centered on a reliable perforator. A common design places roughly one-third of the flap medial and two-thirds lateral to the line. The vascular basis is usually the descending branch of the lateral circumflex femoral artery (LCFA). Campbell's Operative Orthopaedics, p. 3922.
3. Make the medial incision first
   • Incise the medial edge of the planned paddle through skin, subcutaneous tissue, and deep fascia.
   • Elevate the flap in a subfascial plane toward the intermuscular septum.
   • Identify the yellow fat stripe between rectus femoris and vastus lateralis.
4. Identify suitable perforator(s)
   • Look first for a septocutaneous perforator in the septum.
   • If absent, continue laterally to identify a musculocutaneous perforator traversing the anterior vastus lateralis.
   • Select one or more dominant pulsatile perforators with satisfactory caliber. Most ALT perforators are musculocutaneous. AO harvest technique
5. Perform retrograde perforator dissection
   • Trace the selected perforator from the fascia back to the descending LCFA branch.
   • For a musculocutaneous perforator, carefully split vastus lateralis fibers in the direction of the fibers, controlling small muscular branches as needed.
   • Preserve motor nerve branches to vastus lateralis whenever feasible.
   • Avoid traction, thermal injury, twisting, or skeletonizing the perforator excessively.
6. Dissect and lengthen the pedicle
   • Retract rectus femoris medially to expose the descending LCFA branch and its venae comitantes.
   • Dissect the pedicle proximally to obtain the required length and vessel caliber.
   • Preserve the rectus femoris branch and its venous drainage. Do not extend dissection proximally in a way that compromises rectus femoris perfusion. Campbell's Operative Orthopaedics, p. 3922.
7. Complete flap elevation
   • Once perforator perfusion is confirmed, make the lateral, distal, and posterior incisions.
   • Elevate the flap completely while maintaining the selected perforator(s) and pedicle.
   • If a sensate ALT is planned, include the lateral femoral cutaneous nerve as appropriate.
   • For a chimeric or myocutaneous flap, include the needed cuff/segment of vastus lateralis while protecting the perforator supply.
8. Release tourniquet and assess flap
   • Confirm dermal bleeding, flap color, capillary refill, perforator pulsatility, and venous outflow.
   • Ensure the pedicle is not under tension, kinked, or compressed.
9. Divide pedicle only when recipient vessels are ready
   • Systemic anticoagulation, pedicle division, ischemia-time recording, transfer, and microvascular anastomosis follow local protocol.
   • The pedicle typically provides one artery and one or two venae comitantes; reported usable pedicle length is commonly about 8-16 cm. NCBI technique overview
10. Donor-site closure

• Achieve meticulous hemostasis.
• Insert a suction drain.
• Close primarily if tension-free; otherwise use skin grafting.
• Monitor for hematoma, seroma, wound dehiscence, sensory change, and quadriceps dysfunction.

Practical intraoperative points

• Medial-first elevation lets the surgeon identify perforators before committing to the remainder of the flap.
• In the absence of a septocutaneous vessel, do not abandon the flap prematurely: a musculocutaneous perforator through vastus lateralis is common.
• Final skin-paddle dimensions and flap choice should be adjusted after direct visualization of perforator anatomy.
• Do not divide the pedicle until recipient vessels are prepared and the flap is confirmed viable.

1. Surface marking and flap design

2. Perforator identification and intramuscular dissection

3. Anatomy to recognize during harvest