Abdominal symmetry index after reconstruction of traumatic lumbar hernia with dual polypropylene mesh: a comparative CT-based study

PURPOSE: Traumatic lumbar hernia (TLH) is a rare and challenging abdominal wall defect. In these patients, treatment success is usually assessed by recurrence, although persistent postoperative bulging or asymmetry may remain clinically relevant even without true failure of repair. This study evaluated the abdominal symmetry index (ASI), defined as a CT-based side-to-side ratio of lateral abdominal wall distance, as an objective morphologic parameter after TLH reconstruction with dual polypropylene mesh. METHODS: A single-center retrospective comparative study was performed at a tertiary academic referral center from 2006 to 2025. The study included 25 consecutive eligible patients with TLH who underwent elective open abdominal wall reconstruction with dual polypropylene mesh and 25 controls without abdominal wall disease. In the TLH group, ASI was assessed on CT before and after surgery; controls underwent a single CT-based assessment. The operative repair consisted of deep preperitoneal/retroperitoneal reinforcement whenever feasible, muscle reapproximation when possible, and preaponeurotic/onlay reinforcement. RESULTS: Sex distribution did not differ significantly between groups. Mean age was 42 +/- 13 years in the hernia group and 37 +/- 13 years in controls, while mean body mass index was 31 +/- 4 and 28 +/- 5 kg/m2, respectively (p = 0.023). Hernia volume was estimated using the ellipsoid formula and had a median value of 443 cm3 (range, 244-1013 cm3). Clinical follow-up was 62 +/- 47 months, and the interval between surgical repair and the latest postoperative CT scan was 687.3 +/- 712.6 days. No recurrence was observed. Before surgery, the measurement on the hernia side was significantly greater than on the contralateral side (185 +/- 24 mm vs. 144 +/- 12 mm; p < 0.0001). After reconstruction, this difference was no longer statistically significant (154 +/- 15 mm vs. 149 +/- 13 mm; p = 0.1022). Mean ASI was 1.29 +/- 0.18 preoperatively, 1.03 +/- 0.07 postoperatively, and 0.99 +/- 0.03 in controls (overall p < 0.0001). Holm-Sidak adjusted pairwise comparisons showed significant differences between preoperative TLH and controls (p = 1.14 × 10^-13) and between preoperative and postoperative TLH (p = 1.64 × 10^-11), whereas postoperative TLH did not differ significantly from controls (p = 0.2142). CONCLUSION: ASI was feasible as an exploratory CT-based morphologic index for postoperative evaluation of TLH repair. Reconstruction with dual polypropylene mesh was associated with substantial improvement in abdominal wall symmetry, with postoperative values approaching those of controls. Further validation, including interobserver reproducibility and correlation with patient-reported outcomes, is required before broader adoption.