What is the component separation technique (CST) used for in abdominal wall reconstruction, particularly for patients with significant abdominal wall defects or recurrent hernias?

Component Separation Technique for Abdominal Wall Reconstruction

Primary Indication and Recommendation

The component separation technique (CST) is a useful and low-cost option for repair of large midline abdominal wall hernias, but should always be performed with mesh reinforcement and reserved exclusively for definitive closure—never for temporary closure. 1

What is Component Separation?

CST is a surgical technique that enlarges the abdominal wall surface by translating muscular layers without damaging muscle innervation and blood supply. 1 The technique creates innervated and vascularized muscle flaps that provide dynamic support for the reconstructed abdominal wall. 2

Critical Technical Principles

When to Use CST

• Use CST only for definitive closure of large abdominal wall defects, not for temporary fascial closure. 1, 3
• CST is particularly valuable when primary fascial closure cannot be achieved due to defect size (typically >10 cm). 4, 5
• The technique is especially advantageous in contaminated fields where synthetic mesh is contraindicated. 4

Mesh Reinforcement is Mandatory

• CST without mesh should no longer be performed due to unacceptably high recurrence rates (up to 38.7%). 1, 6
• When mesh is used with CST, recurrence rates drop significantly to approximately 4.1%. 7

Technical Approaches: Anterior vs Posterior CST

Anterior Component Separation (External Oblique Release)

• Involves external oblique release with posterior rectus sheath release. 7
• Anterior CST has higher wound complication rates (42.9%) compared to posterior approaches (31.2%). 7
• Anterior CST also demonstrates higher recurrence rates (7.0% vs 2.7% for posterior CST). 7
• If anterior CST is performed, use endoscopic and perforator-sparing techniques to reduce wound complications from 42.9% to 19.6%. 7, 6

Posterior Component Separation (Transversus Abdominis Release/TAR)

• Posterior CST with transversus abdominis release produces superior results compared to open anterior CST. 6
• Lower wound complication rates and recurrence rates make this the preferred approach when feasible. 7, 6
• Robot-assisted posterior CST with TAR represents the latest, most promising development. 6

Mesh Selection Algorithm

Clean/Clean-Contaminated Fields

• Use synthetic mesh for reinforcement in clean surgical fields. 3, 8
• Synthetic mesh provides optimal long-term durability when infection risk is low. 1

Contaminated Fields

• Non-cross-linked biologic meshes are preferred in sublay position when the linea alba can be reconstructed. 1, 3
• Cross-linked biologic meshes in fascial-bridge position (without linea alba closure) reduce ventral hernia recurrence in contaminated settings. 1, 3
• Never use synthetic mesh as a fascial bridge in contaminated fields—this causes adhesions, erosions, and fistula formation. 1, 3

Expected Outcomes and Complications

Wound Complications

• Overall wound complication rate is approximately 35.1% across all CST techniques. 7
• Prehabilitation and perforator-sparing techniques significantly reduce complications. 7
• Common complications include seroma, hematoma, wound infection, and skin necrosis. 4

Recurrence Rates

• With mesh reinforcement, recurrence rates are 4.1% at mean 23-month follow-up. 7
• Complete fascial closure and absence of wound complications significantly improve outcomes. 7
• Without mesh, recurrence rates reach 32-38.7%, making mesh-free CST obsolete. 1, 4

Critical Pitfalls to Avoid

• Never use CST for temporary closure—it is a definitive reconstruction technique only. 1, 3
• Never perform CST without mesh reinforcement due to prohibitive recurrence rates. 6
• Avoid open anterior CST when endoscopic or posterior approaches are available. 6
• Do not place synthetic mesh directly on bowel or use as a bridge in contaminated fields. 1, 3

Alternative When CST Fails

• When definitive fascial closure cannot be achieved even with CST, skin-only closure remains viable with subsequent eventration repair using delayed abdominal closure and synthetic mesh at a later stage. 1
• Planned ventral hernia is acceptable for complicated open abdomen scenarios where no other alternatives exist. 1, 3