Background: The long-term implications of components separation for the lateral oblique and rectus muscles remain unknown. The authors hypothesized that recreation of the tendinous insertion of the linea alba through components separation results in expansion of the rectus muscle with potential atrophy of the external obliques. Methods: The authors conducted a retrospective study analyzing preoperative and long-term postoperative computed tomographic scans for consecutive patients undergoing bilateral components separation at a single institution over a 5-year period. Standardized measurements (area, width, and thickness) were recorded for the rectus abdominis, external oblique, internal oblique, and transversus abdominis at the L3-L4 level on axial imaging. Results: Twenty-eight patients with a mean time to follow-up computed tomographic scan of 17.4 ± 1.6 months were reviewed. After reconstruction of the linea alba, the right and left rectus muscles significantly increased in area (right, 38.8 ± 6.3 percent; left, 35.7 ± 6.6 percent; p < 0.0001) and width (right, 51.8 ± 9.9 percent; left, 39.9 ± 7.4 percent; p < 0.0001) while decreasing in thickness (right, -17.8 ± 7.8 percent; left, -12.8 ± 5.0 percent; p ≤ 0.02). The right and left external oblique muscles significantly decreased in area (right, -10.7 ± 4.7 percent; left, -8.92 ± 4.01 percent; p ≤ 0.03). In contrast, the internal oblique (right, 21.6 ± 4.9 percent; left, 16.4 ± 4.5 percent; p ≤ 0.001) and transversus abdominis (right, 23.0 ± 4.7 percent; left, 24.2 ± 6.2 percent; p < 0.0001) muscles increased significantly in area following surgery. Conclusions: Reestablishing the midline with components separation results in expansion of the rectus muscle, atrophy of the external oblique muscle, and presumed compensatory hypertrophy of the internal oblique and transversus abdominis muscles. Future studies are needed to determine the functional implications of these changes. Clinical Question/Level of Evidence: Therapeutic, IV.
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