Experimental Study And Clinical Observation Of Artificial Fractional Carbon Dioxide Laser In The Treatment Of Hypertrophic Scar

Aim:1.The purpose of the experimental study was to observe the effect and explore the possible mechanism of artificial fractional CO₂ laser on rabbit ear hypertrophic scar,which provided theoretical basis for the clinical treatment of hypertrophic scar.2.To observe the clinical effect of artificial fractional CO₂ laser on human hypertrophic scar and to explore the effectiveness and safety of this method.Methods:1.Hypertrophic scar model was established in 8 New Zealand white rabbits.The left ear was experimental group and the right ear was control group.Four weeks after establishing the model,the experimental group was treated with artificial fractional CO₂ laser,while the control group received no special treatment.The general appearance of the scar was observed after treatment.Two rabbits were randomly executed at immediately,1,4,and 8 weeks after laser treatment（denoted as 0w,1w,4w and 8w）.HE staining was used to observe the morphological changes and scar elevation index.Masson staining was used to observe the changes of collagen,and CD31 immunohistochemistry was used to detect the changes of microvessel density in the scar.2.Twenty-five patients with hypertrophic scar were treated with artificial fractional CO₂ laser under local anesthesia with 3-4 treatment sessions at 2-3 month interval.The hypertrophic scars were assessed at initial treatment and 6 months after the last treatment with VSS score and POSAS score.The effective rate and adverse effects incidence were calculated.Result:1.General appearance observation of rabbit ear scar:3 weeks after the model operation,all rabbit ear wounds were healed.The scar formation rate was87.5%.Hypertrophic scar had hard texture,red color and thicker shin than normal.There was a papillary bulge in the center of the scar.After laser treatment,hypertrophic scar in the experimental group gradually became be softer,flater,and lighter color.The scar thickness of the control group reached the peak at one week later,then the scar slowly became be flater,softer and the color was reduced.The changes in the experimental group were more obvious than those in the control group on the same time.In the experimental group,there were fewer fibroblasts and blood vessels and the collagen fibers arrangement became more regular after laser treatment.The scar elevation index（SEI）and microvascular density（MVD）in the experimental group was significantly lower than that in the control group at 1,4 and8w after laser treatment（p<0.05）.2.The VSS scores of before and after treatment were（8.67±2.39） and（5.08±2.15）（p<0.05）.PSAS scores of before and after treatment were（32.47±8.14）and （21.25±5.79）（p<0.05）.OSAS scores of before and after treatment were（35.38±9.32） and（24.17±7.46）（p<0.05）.The overall evaluation of the observers before and after treatment were（5.21±1.4） and（3.17±1.12）（p<0.05）.The overall evaluation of patients before and after treatment were（6.51±2.34） and（4.65±1.63）（p<0.05）.The effective rate of artificial fractional CO₂ laser treatment was 84%.Adverse reactions incidence was 12%.Conclusion:1.After the treatment of rabbit ear hypertrophic scar with artificial fractional CO₂ laser,collagen fibers arrangement was more regular,angiogenesis was reduced,and scar thickness was reduced.2.Artificial fractional CO₂ laser can effectively treat hypertrophic scar with few adverse reactions.