Components separation technique of the abdominal wall: Which muscle release produces the greatest reduction in tension on the mideline?

Background The components separation technique (CS) is used for the reconstruction of complex abdominal wall defects. Release and undermining of the rectus abdominis muscle (RAM) and external oblique muscle (EOM) decrease tension on the abdominal midline, reducing recurrence of ventral hernia, but causes major changes in the physiology of abdominal wall. The purpose of the study was to determine which muscle release and undermining produces the lowest tension on the midline. Methods Twenty fresh cadavers were dissected and the anterior and posterior layers of the rectus sheath were isolated in the midline. The forces necessary to advance the layers of the rectus sheath to the mid abdomen were measured bilaterally at two points located 3 cm above and 2 cm below the umbilicus, and at 3 different stages: before any muscle release; after release and undermining of the right RAM and left EOM; and after release and undermining of the left RAM and right EOM. Comparisons of tensile forces were conducted separately for the different muscles involved, layers of the rectus sheath, measurement points, and stages of separation. Results Tension on the abdominal midline after the release and undermining of both the RAM and EOM was reduced by 56% (p <0.05), 42% after the release and undermining of the EOM alone (p <0.05), and 35% after release and undermining of the RAM alone (p <0.05). Conclusion Release and undermining of the EOM by CS led to lower tension on the abdominal midline compared to that associated with the release of the RAM alone.