Efficacy and safety of a dual-scan protocol for carbon dioxide laser in the treatment of split-thickness skin graft contraction in a red Duroc pig model

Background:Fractional CO_(2) laser plays an important role in scar management post split-thickness skin graft by loosening the graft contracture and restoring the smoothness of the surface.However,the optimal treatment protocol remains unknown.This study applied a dual-scan protocol to achieve both releasing and ablation of contracted skin graft.We comprehensively describe this treatment method and compare the efficacy and safety between this dual-scan method and the conventional mono-scan mode.Methods:A hypercontracted scar model after split-thickness skin grafting in red Duroc pigs was established.All scars meeting the inclusion criteria were randomly divided into four groups:high fluence–low density(HF–LD),low fluence–high density(LF–HD),combined group and control group.The energy per unit areawas similar in the HF–LD and LF–HD groups.Two laser interventions were performed at a 6-week interval.The efficacy of the treatment was evaluated by objective measures of scar area,release rate,elasticity,thickness and flatness,while the safetywas evaluated based on adverse reactions and melanin index.Collagen structurewas observed histologically.The animals were followed up for a maximum of 126 days after modeling.Results:A total of 28 contracted scars were included,7 in each group.At 18 weeks postoperatively,the HF–LD and the combined groups showed significantly increased scar release rate(p=0.000)and elasticity(p=0.036)and decreased type I/III collagen ratio(p=0.002)compared with the control and LF–HD groups.In terms of flatness,the combined group was significantly better than the HF–LD group for elevations<1mm(p=0.019).No significant skin side effects,pigmentation or scar thickness changes were observed at 18 weeks.Conclusions:Dual-scan protocol could achieve superficial ablation and deep release of contracted split-thickness skin graft in a single treatment,with similar contraction release and texture improvement compared to a single deep scan.Its main advantage is to restore a smoother scar appearance.Adequate laser penetration was necessary for the release of contracted scars.