What are the indications and considerations for using a Pmmc (Pectoralis Major Myocutaneous) flap in head and neck reconstruction?

Pectoralis Major Myocutaneous (PMMC) Flap in Head and Neck Reconstruction

Primary Recommendation

Free flaps should be prioritized over PMMC flaps for head and neck reconstruction when microsurgical resources and patient medical status permit, as they offer superior versatility and outcomes with 92% success rates; however, PMMC flaps remain a reliable alternative with 96-99% survival rates in specific clinical scenarios. 1, 2

Specific Indications for PMMC Flap Use

Primary Indications

• Patients with compromised medical status who cannot tolerate prolonged microsurgical procedures 1
• Institutions lacking microsurgical resources or free flap capabilities 1
• Salvage procedures after free flap failure, pharyngocutaneous fistula, or osteoradionecrosis 1, 2, 3
• Coverage of exposed hardware such as mandibular reconstruction plates in segmental defects 1
• Immediate reconstruction when vessel access for microvascular anastomosis is compromised 1

Anatomic Sites with Good Outcomes

• Pharyngeal and hypopharyngeal defects - excellent reach and bulk for closure 2, 3
• Neck and facial defects including carotid exposure 1, 2
• Oral cavity defects - though associated with higher complication rates (see caveats below) 2, 3
• Temporal bone and cheek reconstruction 2

Technical Considerations and Success Rates

Flap Survival

• Overall flap survival: 96-99.2% across multiple large series 2, 3
• Total flap loss: only 1-3.6% in experienced hands 1, 2, 3
• Provides definitive closure in 100% of cases when appropriately selected 2

Reconstruction Strategy for Segmental Mandibular Defects

When free flap reconstruction is not feasible, use a spanning reconstruction plate across the segmental defect covered by PMMC flap - though metal fatigue and fracture can occur with prolonged function 1

Critical Caveats and Complications

Aesthetic and Functional Limitations

• Larger pedicle flaps like PMMC may result in facial asymmetry and malocclusion - a significant consideration for anterior defects 1
• Excessive bulk compared to fasciocutaneous free flaps, particularly problematic in oral cavity reconstruction 4
• Intraoral hair growth from skin paddle requires ongoing management 5

Complication Rates and Risk Factors

• Overall complication rate: 13-35% depending on series and patient selection 2, 4, 3
• Prior radiation therapy significantly increases complication rates - particularly wound dehiscence and infection 2
• Salvage procedures have higher complication rates than primary reconstruction 4, 3
• Oral cavity reconstructions have higher complication rates than pharyngeal or neck defects 4, 3
• Multiple comorbidities and heavy smoking history (>92% of patients in one series) increase complications 2, 3

Common Complications

• Wound dehiscence and infection (most common) 2, 4, 3
• Partial skin paddle necrosis (5-10% of cases) 6, 7
• Hematoma and seroma formation 4, 3
• Fistula formation 4, 3
• Donor site morbidity including decreased shoulder function 4, 7

Evolving Role in Modern Practice

The role of PMMC flap has shifted from primary reconstruction to salvage procedures in centers with microsurgical capabilities - in one series, salvage procedures increased from 8% (1998-2003) to 29% (2003-2008) of PMMC flap usage 6

When PMMC Remains First-Line

• Developing countries or resource-limited settings where microsurgical expertise is unavailable 7
• Emergency situations requiring rapid, reliable soft tissue coverage 2
• Elderly patients with limited life expectancy where operative time must be minimized 1

Maxillary Reconstruction Specific Considerations

For maxillectomy defects extending into the sinus (full thickness), myocutaneous flaps like PMMC can be used for reconstruction, though osteomyocutaneous free flaps are preferred when dental implantation is desired 1, 8, 9

Obturation with prosthetic appliance may be considered for patients who are poor candidates for any flap surgery 1, 9

Practical Algorithm for Decision-Making

1. Assess patient medical status: If ASA ≥4 or life expectancy <1 year → consider PMMC over free flap 1
2. Evaluate institutional resources: If microsurgical capability absent → PMMC is appropriate choice 1
3. Determine defect characteristics:
   • Pharyngeal/neck defects → PMMC excellent option
   • Anterior oral cavity/aesthetic units → strongly favor free flap if possible 1
4. Consider radiation history: If prior RT >50 Gy → expect higher complication rates with PMMC but still viable 1, 2
5. Salvage scenario: PMMC remains reliable option after free flap failure 2, 3, 6