What is acellular dermal matrix (ADM) and how is it used in surgical procedures?

What is Acellular Dermal Matrix (ADM)?

Acellular dermal matrix (ADM) is a biological collagen scaffold derived from human, porcine, or bovine dermis that has undergone a decellularization process to remove all cellular components while preserving the intact extracellular matrix structure. 1, 2

Composition and Structure

• ADM consists of preserved collagen-based extracellular matrix that maintains the native dermal architecture after cells have been removed through decellularization 1, 2
• The material retains low antigenicity, making it immunologically inert and well-tolerated without causing significant immune rejection 3
• The preserved matrix structure serves as a scaffold that provides physiological cues mimicking native tissue microenvironment 2

Classification of ADM

ADM products are categorized based on several characteristics 1:

• Species of origin: Allogenic (human) or xenogenic (porcine/bovine)
• Tissue source: Dermis, pericardium, or intestinal submucosa
• Cross-linking status:
  • Cross-linked (partially remodeling) - resist mechanical stress better and longer 1
  • Non-cross-linked (completely remodeling) - allow more complete host tissue integration 1
• Storage requirements: Temperature-dependent preservation needs
• Preparation: Rehydration requirements before use 1

How ADM Works After Implantation

Upon implantation, ADM becomes recolonized by host fibroblasts and myofibroblasts, undergoes revascularization, and is gradually remodeled into autologous tissue. 1, 2

Biological Integration Process

• Cellular infiltration: The scaffold becomes populated by host fibroblasts, myofibroblasts, lymphocytes, macrophages, multinucleated giant cells, granulocytes, and mast cells within weeks to months 2
• Angiogenesis: Blood vessel ingrowth occurs relatively rapidly after implantation 2
• Lymphangiogenesis: Lymphatic vessel formation is a slower process, detected approximately 9 months post-implantation 2
• Collagen deposition: Host fibroblasts deposit new collagen, gradually replacing the scaffold with native tissue 1

Clinical Applications and Surgical Technique

Abdominal Wall Reconstruction

For contaminated or dirty surgical fields in hernia repair, ADM offers advantages over synthetic mesh by being less susceptible to infection, though long-term durability remains uncertain. 1

• ADM is particularly useful in emergency ventral hernia repair with contaminated fields (38%), potentially contaminated fields (26.7%), and dirty fields (35.2%) 1
• In emergency incarcerated hernia repair with human ADM, infection rates were very low (1.6%) with recurrence rates of 15.9% at 43-month follow-up 1
• Critical risk factors for recurrence: BMI (P=0.008), defect size (P=0.016), and number of ADM sheets used (P=0.027) 1
• Optimal placement technique: Sublay extra-peritoneal positioning (OR=0.45, P=0.009) with anterior fascia closure (OR=0.33, P=0.04) reduces wound complications 1

Important caveat: Systematic reviews show pooled hernia recurrence rates of 27.2% with biological meshes versus only 3.2% with synthetic non-absorbable meshes in contaminated fields, though wound infection rates were similar 1

Breast Reconstruction

ADM is highly effective for revision breast reconstruction, with 95.5% success rates and only 5% overall complication rates. 4

• Primary indications 4:

  • Inferior fold malposition (37% of cases)
  • Inferior pole support (25.9%)
  • Capsular contracture (27.2%)
  • Rippling (6.4%)
  • Symmastia (3.2%)

• Surgical technique: ADM provides lower pole coverage, controls implant positioning in the inframammary fold, and prevents contractile pseudocapsule formation around breast implants 2

• Complication profile: Most common complication is capsular contracture (3.2%), with infection occurring in only 0.6% of cases 4

Critical warning: Seromas between ADM and implants significantly increase infection risk (RR 2.47,95% CI 1.71-3.57); remove drains when output <30 mL/day, not exceeding 7-14 days 5

Soft Tissue Augmentation

For gingival recession coverage requiring thickness augmentation, ADM serves as a scaffold for growth factors like rhPDGF-BB, though autogenous connective tissue graft remains the gold standard. 1, 6

• ADM eliminates donor site morbidity compared to autogenous grafts 6
• The decellularization process significantly impacts ADM structure and its ability to promote cell migration and proliferation, which may limit synergistic effects with growth factors 1
• Target gingival thickness of ≥1.46 mm is required for long-term gingival margin stability 1, 6

Diabetic Foot Ulcers

Do not use ADM for diabetic foot ulcers in preference to standard care, as evidence does not support routine use. 1

• Small, poor-quality studies have reported ADM use in diabetic wounds, but provided no good data to justify routine clinical application 1
• The IWGDF (International Working Group on the Diabetic Foot) recommends against selecting agents that alter wound biology, including ADM, over accepted standards of care (strong recommendation; low-quality evidence) 1

Key Clinical Considerations and Pitfalls

Factors Associated with Complications

In abdominal wall reconstruction, large implant size (≥100 cm²), prolonged surgical time (≥300 minutes), and use of ≥3 ADM sheets significantly increase infection and recurrence risk. 7

• Direct approximation of ADM to fascial edge (P=0.02), rather than overlay technique, increases recurrence rates 7
• Postoperative wound infections occur in 35% of cases and are significantly associated with subsequent recurrence (P=0.02) 7
• Despite high infection rates, ADM removal is rarely required 7

Tissue Sampling for Infected ADM

When infection is suspected in ADM-containing reconstructions 5:

• Obtain minimum 3, optimally 5-6 separate tissue specimens (not swabs) from different sites using separate sterile instruments
• Submit at least 1 mL fluid or 0.5 g tissue per specimen
• Request anaerobic cultures, as Propionibacterium acnes and other anaerobes are common
• Withhold antibiotics for ≥2 weeks prior to culture collection when medically safe
• Two or more cultures yielding identical organisms confirms prosthetic infection

Material Properties

• ADM is biocompatible with human fibroblasts, showing similar proliferation and viability to control conditions 6
• The material does not cause significant resorption, contracture, or encapsulation due to low antigenicity 3
• Adequate knowledge of biomaterial properties and careful compliance with specific recommendations are mandatory to optimize outcomes 3