Abdominal component separation is used commonly for closure of midline abdominal wounds. The value of each step in reducing tension has not been studied. Our aim was to test whether component separation decreases tension in the midline closure and to quantify the value of each procedural step.

Tension required to bring the rectus muscle to midline was measured using tensiometry after subcutaneous dissection (step 1), external oblique muscle release (step 2), separation of the internal and external oblique muscles (step 3), and internal oblique muscle release (step 4). Measurements were taken in the upper, middle, and lower thirds of the abdominal midline. Distance to midline was also measured after each surgical step. Tension (measured as percent change) and distance were analyzed using Student's t-test with significance set at p < 0.05.

In 41 hemi-abdominal defects, tension decreased in middle, upper, and lower thirds of the abdomen by 22.5%, 24.3%, and 34.8% after step 1; 33.4%, 31.8%, and 39.8% after step 2; 26.5%, 22.2%, and 27.4% after step 3; and 33.2%, 28.2%, and 23.5% after step 4. Mean distance change was 0.97 cm, 1.97 cm, 2.22 cm, and 2.59 cm after steps 1 to 4, respectively.

This study shows through a quantitative measure of tension that all steps of the component separation procedure decrease wound tension to variable degrees, with the release of the external and internal oblique muscles being the more effective steps. An internal oblique release is a useful and simple adjunct to the classical component separation procedure.