Background Fractional CO2 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 area was 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 safety was evaluated based on adverse reactions and melanin index. Collagen structure was 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 <1 mm (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.

中文翻译：

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二氧化碳激光双扫描方案治疗红杜洛克猪模型皮层移植收缩的疗效和安全性

背景 CO2 点阵激光通过松动移植物的挛缩和恢复表面的光滑度，在劈层皮肤移植后的疤痕管理中发挥着重要作用。然而，最佳治疗方案仍然未知。本研究应用双扫描方案来实现收缩皮肤移植物的释放和消融。我们全面描述了这种治疗方法，并比较了这种双扫描方法与传统单扫描模式的疗效和安全性。方法 建立红杜洛克猪厚层植皮后超收缩瘢痕模型。所有符合纳入标准的瘢痕随机分为四组：高通量-低密度（HF-LD）、低通量-高密度（LF-HD）、联合组和对照组。HF-LD 和 LF-HD 组的单位面积能量相似。以 6 周的间隔进行两次激光干预。疗效通过瘢痕面积、释放率、弹性、厚度和平整度等客观指标评价，安全性则根据不良反应和黑色素指数进行评价。组织学观察胶原结构。在建模后对动物进行最长随访 126 天。结果共纳入28处收缩性瘢痕，每组7处。术后 18 周，与对照组和 LF 相比，HF-LD 组和联合组的瘢痕释放率 (p = 0.000) 和弹性 (p = 0.036) 显着增加，I/III 型胶原比率降低 (p = 0.002) –高清组。在平坦度方面，联合组明显优于 HF-LD 组，海拔 <1 mm (p = 0.019)。在 18 周时未观察到明显的皮肤副作用、色素沉着或疤痕厚度变化。结论 双扫描方案可以在一次治疗中实现收缩的厚层皮肤移植物的表面消融和深度释放，与单次深度扫描相比具有相似的收缩释放和纹理改善。它的主要优点是恢复更光滑的疤痕外观。充分的激光穿透对于释放收缩的疤痕是必要的。