Assessment of myofascial medialization following posterior component separation via transversus abdominis muscle release in a cadaveric model

Purpose: Posterior component separation (PCS) via the transversus abdominis release (TAR) procedure continues to gain popularity. However, neither the physiologic basis nor the extent of myofascial medialization after TAR is established. We aimed to assess both anterior and posterior rectus fascia (AF and PF) medialization following each step of the TAR procedure. Methods: Ten fresh cadavers underwent PCS via TAR. Steps included midline laparotomy (MLL), retrorectus dissection (RRD), incision of the posterior rectus sheath (IPL), transversus abdominis muscle division (TAD), and retromuscular dissection (RMD). Medial advancement of AF and PF was measured following application of 2.5, 5.0 lb, and maximal tension to the fascial edge. Values are represented as mean advancement past midline in centimeters. Results: MLL allowed advancement of 2.5, 3.7, and 4.9 cm. RRD provided advancement of 4.1, 5.9, and 7.6 cm for AF and 4.4, 6.2, and 7.5 cm for PF. IPL provided advancement of 4.2, 6.1, and 8.0 cm for AF and 4.6, 6.6, and 8.3 cm for PF. TAD provided advancement of 4.5, 6.6, and 8.6 cm for AF and 5.3, 7.5, and 9.5 cm for PF. RMD provided advancement of 5.5, 7.9, and 9.9 cm for AF and 6.9, 9.6, and 11.2 cm for PF. Overall, the complete TAR procedure provided AF advancement of 102% and PF advancement of 129%, over baseline. Conclusions: The TAR procedure provides for substantial medial advancement of both anterior and posterior myofascial components of the abdominal wall. Retromuscular dissection deep to the divided transversus abdominis muscle appears to be the key step of the procedure, allowing for effective reconstruction of very wide (≈ 20 cm) defects.