What are the indications and considerations for using an anterolateral thigh (ALT) flap in patients with significant soft tissue defects?

Anterolateral Thigh (ALT) Flap: Indications and Clinical Considerations

Primary Indications

The anterolateral thigh flap is indicated for reconstruction of significant soft tissue defects in head and neck cancer, extremity trauma, abdominal wall defects, and complex composite tissue loss requiring vascularized coverage. 1, 2

Head and Neck Reconstruction

• For advanced oral cavity cancers (T3/T4) requiring wide surgical excision, the ALT flap is a preferred option when mandibular continuity remains intact 1
• The radial forearm and ALT flaps are specifically recommended for oral cavity reconstruction following oncologic resection 1
• For osteoradionecrosis with extensive tissue loss requiring complex reconstruction, the ALT fascia lata rescue flap can arrest mandibular ORN progression 1
• The flap provides adequate bulk and pliable tissue for oral cavity defects while maintaining acceptable donor site morbidity 3

Complex Extremity Defects

• Use the ALT flap for extensive lower extremity soft tissue defects, particularly those involving exposed bone, joints, or requiring tendon reconstruction 4, 5
• For defects requiring both cutaneous and deep tissue coverage, the ALT/vastus lateralis chimeric flap allows reconstruction of extensive defects with joint involvement using a single vascular pedicle 5
• The vascularized fascia lata component can replace tendon structures, fascial sheaths, and aponeuroses in single-stage reconstruction 2, 4

Abdominal Wall and Trunk Reconstruction

• For abdominal wall fascial defects, the ALT flap with vascularized fascia lata provides structural support for single-stage reconstruction 2
• The flap is suitable for internal pelvis, groin, and genitoperineal defects when used as a pedicled flap 6

Technical Considerations

Flap Design and Harvest

• The ALT flap can be harvested as either a perforator flap or myocutaneous flap depending on defect requirements 6
• Flap dimensions range from 5×8 cm to 15×15 cm, with larger flaps potentially requiring skin grafting of the donor site 6
• The long vascular pedicle (descending branch of lateral femoral circumflex) provides excellent reach without restriction to arc of rotation 6, 3
• Mark the septum between vastus lateralis and rectus femoris to facilitate harvest 3

Composite Flap Options

• For complex defects requiring multiple tissue types, harvest the ALT with vascularized fascia lata on a common pedicle with individually dissected branches 2, 4
• The fascia lata component can reconstruct:
  • Abdominal wall and fascial defects 2
  • Tendon structures (hand, forearm, Achilles) 4
  • Synovial membranes and plantar aponeurosis 4
  • Dural defects 4

Pedicled vs. Free Flap Application

• Use pedicled ALT flaps for regional reconstruction of internal pelvis, lateral thigh, groin, and genitoperineal defects 6
• Free tissue transfer is required for head and neck, distal extremity, and distant trunk defects 3
• The flap provides reliable vessel diameter and pedicle length for microvascular anastomoses 3

Clinical Outcomes and Success Rates

• Overall flap survival rates of 97% have been reported in large series 2
• All pedicled flaps in regional reconstruction survived without vascular compromise 6
• Partial flap necrosis occurs in approximately 13% of cases and can be managed with minimal debridement 4
• Donor site morbidity is minimal, with only mild quadriceps deficiency reported and no difficulties in daily ambulation 2

Critical Pitfalls to Avoid

Surgical Technique

• Confirm flap dimensions prior to final harvest and ensure no mechanical obstruction to the pedicle during inset 3
• Allow for anticipated postoperative edema in flap positioning 3
• Identify and prepare suitable recipient vessels before final flap harvest 3
• For vascularized fascia components, recognize that fascia lata lacks muscle-synchronized excursion properties despite mimicking fascial sheaths 2

Postoperative Management

• Implement rigorous postoperative monitoring to identify vascular compromise early and maximize successful outcomes 3
• Primary closure of donor sites is achievable for flaps up to 15×15 cm in most cases 6
• Functional outcomes at donor sites remain excellent with minimal long-term morbidity 2, 5