Imbrication versus excision for fascial healing

BACKGROUND: The purpose of this study was to determine whether imbrication of native fascia versus excision and closure of new raw fascia forms a stronger union. METHODS: We utilized the anterior rectus sheath fascia of Sprague-Dawley rats as the model. Sixty rats underwent fascial tightening procedures. Each rat had the anterior rectus sheath shortened by 1 cm, 30 by imbrication and 30 by excision and closure. Ten of each group were harvested at 7 days' healing, 10 at 14 days, and 10 of each group at 28 days' healing. The anterior rectus sheath was removed, a 'dumbbell' shape constructed, and the cross sectional area at the point of interest determined. The fascia was placed on an instron tensiometer to determine the breaking strength. Tensile strength was calculated and the data analyzed by ANOVA and the Kruskall-Wallis test. Tissue samples of the closures were histologically analyzed for fibroblast counts, degree of inflammation, and presence of dense fibrous connective tissue. Tissue samples were also analyzed for enzymatic collagen crosslinking. RESULTS: There was a statistically significant difference in tensile strength between the two groups at 7, 14, and 28 days. Results show that at 7 days the mean tensile strength of excision was 0.133 kg/mm² ± 0.056 and the mean tensile strength of imbrication was 0.083 kg/mm² ± .048 (P <0.05); at 14 days the mean tensile strength of excision was 0.105 kg/mm² ± 0.033 and the mean tensile strength of imbrication was 0.057 kg/mm² ± 0.014 (P <0.002), and at 28 days the mean tensile strength of excision was 0.279 kg/mm² ± 0.143 and the mean tensile strength of imbrication was 0.145 kg/mm² ± 0.061 (P <0.03). Histologic findings showed no statistical significance between the two closure methods when comparing degree of inflammation or the number of fibroblasts present. However, at 7 and 14 days there is a significantly greater presence of dense fibrous connective tissue in the excision group (P<0.03 at 7 days and P <0.044 at 14 days by ANOVA). Collagen crosslink analysis showed that by day 28 there is a significantly greater amount (P <0.05 by ANOVA) of the difunctional crosslink dihydroxylysinonorleucine (DHLNL) and a greater ratio between DHLNL and the difunctional crosslink hydroxylysinonorleucine (HLNL) in the excision and closure group. CONCLUSION: We conclude that at 7, 14, and 28 days healing, excision provides a significantly stronger closure than imbrication. According to the crosslinking analysis, it is likely that this strength advantage may continue to increase over time. These findings suggest that excision and closure may be the preferred method for fascial tightening procedures.