A Retrospective Analysis of the Effectiveness of Fractional CO₂ Laser Therapy in Treating Linear Scars: Investigating the Ideal Timing for Intervention

Linear scars, resulting from surgical incisions or traumatic injuries, can pose both aesthetic and functional dilemmas. Ablative fractional CO₂ laser (AFCL) therapy has been recognized for its ability to enhance the appearance and flexibility of scars; however, the ideal timing for such treatments remains a subject of debate. This study retrospectively evaluates the effectiveness of AFCL in treating linear atrophic and hypertrophic scars, with a focus on identifying the optimal timing to achieve the best possible outcomes. Patients who underwent treatment for linear scars using AFCL at our hospital between January 2022 and July 2024 were included in the study. Participants were categorized into two groups: those with atrophic scars and those with hypertrophic scars. Hypertrophic scars were assessed using the Vancouver Scar Scale (VSS), whereas atrophic scars were evaluated with the Scar Cosmesis Assessment and Rating (SCAR) scale. Furthermore, considering the timing of scar formation-with a six-month period as the threshold-two subgroups were categorized as early treatment and late treatment. The disparities in scar improvement rates were then computed and subjected to analysis. Among 55 patients, 31 had atrophic scars and 24 had hypertrophic scars. AFCL treatment significantly improved clinical scores in both groups. The SCAR score for atrophic scars decreased from 6.50 (SD 1.31) to 4.92 (SD 1.71) (p < 0.001), and the VSS score for hypertrophic scars decreased from 6.02 (SD 0.46) to 2.73 (SD 0.39) (p < 0.001). The early-treatment subgroup showed a 35.38% (SD 24.54%) improvement in atrophic scars, significantly higher than the 12.53% (SD 25.65%) in the late-treatment subgroup (p = 0.018). No significant timing effect was found for hypertrophic scars (p = 0.764). AFCL is an effective treatment for linear scars. Early intervention, specifically within the first 6 months, leads to superior outcomes for atrophic scars. In contrast, the timing of treatment is less critical for hypertrophic scars. Chinese clinical trial registry: Registration no. ChiCTR2400092038.