Treatment of Hypertrophic Scars Using Laser-Assisted Corticosteroid Versus Laser-Assisted 5-Fluorouracil Delivery

Efficacy of a multimodal approach of laser therapy for earlobe keloids management in dark population

BACKGROUND

Patients with keloids are often younger than 30 years old and have darker skin.

AIM

To evaluate the efficacy and safety of CO2 laser therapy in the management of earlobe and helix keloids in dark subjects.

METHODS

A total of 21 dark patients (five men and 16 women) presented with the earlobe and ear helix keloids, with a mean age of 30.5 (±6.7) years and with phototype between III-VI, were enrolled. In order to improve their earlobe and helix keloids, all patients underwent a single session of CO2 laser therapy immediately followed by a pulsed Dye laser procedure. A single well-experienced doctor performed all treatment sessions and the response to treatment. Patients were followed-up for 6 months after termination of therapy. Clinical images were examined and collected: all patients were examined clinically and with Dermoscopy.

RESULTS

The majority of the patients treated show complete remission of keloid lesions. Clinical photographs show a visible aesthetic improvement of several types of keloids in dark subjects.

CONCLUSIONS

Our data demonstrate that this combined laser therapeutic protocol appears to be effective and well tolerated for the management of earlobe and helix keloids in dark subjects, with no high recurrence rate and avoiding the adverse effects and lengthy recovery time.

Global research status of pathological scar reported over the period 2001-2021: A 20-year bibliometric analysis

Pathological scar is a classic problem in plastic and reconstructive surgery. Although the researches on pathological scar have been conducted for decades, the way to go to address this thorny problem still remains challenging. To the best of our knowledge, few bibliometric analysis concerning pathological scar have been reported. In this study, we set out to employ bibliometric and visual analysis to offer research status and trends of pathological scar over the period 2001-2021. All publications covering pathological scar during 2001-2021 were retrieved and extracted from the Web of Science database. We applied VOSviewer software to evaluate the keywords and research hotpots, and the online tool (http://bibliometric.com/) was used to carried out the publication trends analysis. A total of 2221 pathological scar-related articles were identified over the period 2001-2021. China is the country which had the largest volume of publications (819, 36.87%), followed by the United States (416, 18.73%), Japan (144, 6.48%), Korea (142, 6.39%), and England (118, 5.31%). Among the institutions and journals, Shanghai Jiao Tong University (167) and Wound Repair and Regeneration (85) accounted for the most papers related to pathological scar, respectively. Professor Bayat A, who had the most citation frequency (2303), made great contribution in pathological scar field. "Fibroblast", "expression", and "proliferation" were identified as the pathological scar research hotspot through analysis of the keywords. In terms of publication, China ranked first all over the world, but the numbers of publication are inconsistent with the citation frequency, ranking first and second, respectively. Shanghai Jiao Tong University and journal Wound Repair and Regeneration stand for the highest level of research in this field to a certain extent. In the early stage, the research focus was mainly on the prevention, treatment, and risk factors for recurrence of pathological scar from cases. In the later stage, the research focus was on the comprehensive management, in which the mechanism research was in-depth to the molecular and gene level.

Truncal Acne and Scarring: A Comprehensive Review of Current Medical and Cosmetic Approaches to Treatment and Patient Management

Acne vulgaris is one of the most common skin disorders worldwide. It typically affects skin areas with a high density of sebaceous glands such as the face, upper arms, chest, and/or back. Historically, the majority of research efforts have focused on facial acne vulgaris, even though approximately half of patients with facial lesions demonstrate truncal involvement. Truncal acne vulgaris is challenging to treat and poses a significant psychosocial burden on patients. Despite these characteristics, studies specifically examining truncal acne vulgaris are limited, with treatment guidelines largely derived from facial protocols. Therefore, truncal acne remains an understudied clinical problem. Here, we provide a clinically focused review on the epidemiology, evaluation, and available treatment options for truncal acne vulgaris. In doing so, we highlight knowledge gaps with the goal of spurring further investigation into the management of truncal acne vulgaris.

Hypertrophic Scars and Keloids: Advances in Treatment and Review of Established Therapies

Hypertrophic scars and keloids can have significant detrimental effects on patients both psychosocially and functionally. A careful identification of patient risk factors and a comprehensive management plan are necessary to optimize outcomes. Patients with a history of dystrophic scarring should avoid unnecessary procedures and enhance the wound-healing process using various preventive strategies. As there is no single, fully efficacious treatment modality, prevention remains the best approach in reducing aberrant scar formation. When prevention therapies fail, keloids have been shown to be respond to a variety of therapies including topical and injectable corticosteroids, 5-fluorouracil, radiotherapy, lasers, and surgical excision, all with varying efficacies. As such, management should be tailored to the individual patient's risk factors with the use of combination therapies to reduce recurrence rates. Still, keloid and hypertrophic scar therapies are widely diverse with novel treatment modalities providing alternatives for recurring lesions. Laser-assisted drug delivery, skin priming, and novel topical therapies may provide alternative options for the management of hypertrophic scars and keloids.

An Updated Review of Hypertrophic Scarring

Hypertrophic scarring (HTS) is an aberrant form of wound healing that is associated with excessive deposition of extracellular matrix and connective tissue at the site of injury. In this review article, we provide an overview of normal (acute) wound healing phases (hemostasis, inflammation, proliferation, and remodeling). We next discuss the dysregulated and/or impaired mechanisms in wound healing phases that are associated with HTS development. We next discuss the animal models of HTS and their limitations, and review the current and emerging treatments of HTS.

Laser-Assisted Drug Delivery: A Systematic Review of Safety and Adverse Events

Laser-assisted drug delivery (LADD) is an increasingly studied and applied methodology for drug delivery. It has been used in a wide variety of clinical applications. Given the relatively low barrier to entry for clinicians as well as ongoing research in this area, the authors aimed to review outcomes relating to safety in laser-assisted drug delivery. A systematic review was conducted, with the databases PubMed, Medline and Embase searched in September 2022. Included articles were those that mentioned laser-assisted drug delivery in human subjects that also reported adverse effects or safety outcomes. There were no language-based exclusions. Conference abstracts and literature reviews were excluded. The results were then tabulated and categorized according to the application of LADD. In total, 501 articles were obtained. Following deduplication, screening, and full text review 70 articles of various study designs were included. Common findings were erythema, oedema, pain, and crusting following LADD. Several notably more severe adverse effects such as generalized urticaria, infection, scarring and dyspigmentation were noted. However, these events were varied depending on the clinical use of LADD. Relevant negatives were also noted whereby no studies reported life-threatening adverse effects. Limitations included limited details regarding the adverse effects within the full texts, lack of follow-up, and risk of bias. In conclusion, there were multiple adverse effects that clinicians should consider prior to carrying out LADD, where treatment goals and patient tolerability should be considered. Further evidence is needed to quantitatively determine these risks.

Traditional Chinese medicine for hypertrophic scars—A review of the therapeutic methods and potential effects

Hypertrophic scar (HS) is a typical pathological response during skin injury, which can lead to pain, itching, and contracture in patients and even affect their physical and mental health. The complexity of the wound healing process leads to the formation of HS affected by many factors. Several treatments are available for HS, whereas some have more adverse reactions and can even cause new injuries with exacerbated scarring. Traditional Chinese Medicine (TCM) has a rich source, and most botanical drugs have few side effects, providing new ideas and methods for treating HS. This paper reviews the formation process of HS, the therapeutic strategy for HS, the research progress of TCM with its relevant mechanisms in the treatment of HS, and the related new drug delivery system of TCM, aiming to provide ideas for further research of botanical compounds in the treatment of HS, to promote the discovery of more efficient botanical candidates for the clinical treatment of HS, to accelerate the development of the new drug delivery system and the final clinical application, and at the same time, to promote the research on the anti-HS mechanism of multiherbal preparations (Fufang), to continuously improve the quality control and safety and effectiveness of anti-HS botanical drugs in clinical application.

Ablative fractional carbon dioxide laser improves quality of life in patients with extensive burn scars: A nested case-control study

BACKGROUND AND OBJECTIVES

Ablative fractional carbon dioxide laser (CO₂ -AFL) for small-area burn scar management shows encouraging outcomes. Few studies, however, focused on comprehensive outcomes following CO₂ -AFL treatment for extensive burn scars. This study evaluated whether CO₂ -AFL surgery improved the quality of life (QoL) for burn survivors with extensive hypertrophic scars.

METHODS

A retrospective nested case-control study was initiated to analyze the efficacy of CO₂ -AFL treatment for patients with large-area burn scars. Patients with extensive burn scars (≥30% total body surface area [TBSA]) were registered in our hospital from March 2016 to October 2018. Patients undergoing CO₂ -AFL surgery were divided into CO₂ -AFL group, and patients undergoing conventional surgery were matched in a 1:1 ratio as the conventional surgery group according to the burned area. The questionnaires were collected and followed up. The 36-Item Short Form Health Survey (SF-36) and Burns Specific Health Scale-Brief (BSHS-B) were the primary parameters. Secondary parameters included the Pittsburgh Sleep Quality Index (PSQI), University of North Carolina "4P" Scars Scale (UNC4P), Patient Scars Assessment Scale for Patient (POSAS-P), and Douleur Neuropathique 4 questions (DN4).

RESULTS

23 patients (55.96 ± 21.59% TBSA) were included in CO₂ -AFL group and 23 patients (57.87 ± 18.21% TBSA) in conventional surgery group. Both the BSHS-B total score (CO₂ -AFL vs. conventional surgery: 115.35 ± 29.24 vs. 85.43 ± 33.19, p = 0.002) and the SF-36 total score (CO₂ -AFL vs. conventional surgery: 427.79 ± 118.27 vs. 265.65 ± 81.66, p < 0.001) for the CO₂ -AFL group were higher than those for the conventional surgery group. Parameters for the CO₂ -AFL group were lower than those for the conventional surgery group in all of the following comparisons: PSQI total score (CO₂ -AFL vs. conventional surgery: 7.70 ± 3.74 vs. 12.26 ± 4.61, p = 0.001), POSAS-P total score (CO₂ -AFL vs. conventional surgery: 26.48 ± 6.60 vs. 33.04 ± 4.56, p < 0.001), UNC4P total score (CO₂ -AFL vs. conventional surgery: 5.57 ± 1.97 vs. 7.26 ± 1.81, p = 0.004), and DN4 score (CO₂ -AFL vs. conventional surgery: 3 [2-5] vs. 5 [4-8], p = 0.004).

CONCLUSIONS

Compared to conventional surgery, whole scar CO₂ -AFL surgery dramatically improved physical and mental health as well as QoL for people with extensive burn scars. Additionally, CO₂ -AFL enhanced the evaluation of scars including their appearance, pain, itching, and a host of other symptoms.

Efficacy of Fractional Carbon Dioxide Laser (FCO2) with Intralesional 5-Fluorouracil (5-FU) in the Treatment of Keloids

Context:

Managing keloids remains a challenge in clinical practice. Many therapeutic options are available, but none is universally accepted or without recurrence. Therefore, an effort is required to choose the treatment with maximal outcomes.

Aims:

To evaluate the effectiveness of combining fractional carbon dioxide (FCO₂) laser and intralesional 5-fluorouracil (5-FU) for the treatment of keloids.

Materials and Methods:

In this prospective open-label study, 24 patients received FCO₂ laser treatment, started at baseline, for a total of six sittings. The patients also received 1 mL/cm²/keloid of 5-FU (50 mg/mL) intralesionally, following irradiation, at identical time points. The primary outcome evaluated was the clinical response concerning height, pliability, vascularity, and pigmentation, using the Vancouver Score Scale (VSS). Adverse reactions and recurrences were recorded as secondary outcomes.

Results:

A significant reduction was observed in the VSS in terms of pliability and height after three treatment sessions. The mean VSS reduction was 65%, from 8.45 ± SD 0.93 at baseline to 3 ± SD 1.8 one month after the last treatment (P < 0.05). Most patients (79.1%; n = 19) showed a satisfactory response to treatment, with 57.8% (n = 11) achieving an excellent result. Adverse reactions included post-inflammatory hyperpigmentation in four patients and ulceration in two. Recurrences were reported in 21% of the patients who responded well.

Conclusions:

Combination therapy with FCO₂ laser and intralesional 5-FU showed a promising effect in the treatment of resistant keloids, with an acceptable safety profile and low recurrence rate.

Ablative fractional CO2 laser surgery improving sleep quality, pain and pruritus in adult hypertrophic scar patients: a prospective cohort study

Background

Poor sleep quality is associated with a decrease in quality of life in patients with major burn scars, combined with pruritus and pain. Few interventions have been reported to improve the sleep quality of patients with scars. In the current prospective cohort study, we investigated the efficacy of CO₂-ablative fractional laser (AFL) surgery vs conventional surgery in post-burn patients with hypertrophic scars with sleep quality as the primary study outcome.

Methods

In total 68 consecutive patients undergoing scar surgical treatment were recruited, including a CO₂-AFL surgery cohort (n = 35) and a conventional surgery cohort (n = 33). A subgroup from the AFL cohort was selected. Sleep quality, pain and pruritus were evaluated. Multiple linear regression analyses were performed to reveal the effect of CO₂-AFL surgery.

Results

The CO₂-AFL surgery cohort had significantly lower Pittsburgh sleep quality index (PSQI) global scores than the conventional surgery cohort after the last surgical treatment. In the subgroup of patients receiving hardware sleep monitoring, CO₂-AFL markedly increased deep sleep time, deep sleep efficiency and reduced initial sleep latency. Compared to the conventional surgery cohort, the CO₂-AFL cohort presented significantly lower pain and pruritus scores. Correlation analysis showed pain and pruritus were significantly associated with PSQI scores, and there were also significant correlations between pain and pruritus scores. Multiple linear regression analysis showed that surgery method was negatively linearly correlated with visual analog scale (VAS) pain score, brief pain inventory (BPI) total, VAS pruritus score, 5-D itch scale total, four-item itch questionnaire (FIIQ) total and PSQI total.

Conclusions

CO₂-AFL surgery significantly improved sleep quality and reduced pain and pruritus of hypertrophic scar patients. The alleviation of sleep disorder was associated with improvement of deep sleep quality including deep sleep time and deep sleep deficiency.

Trial registration

The Chinese Clinical Trial Registry (ChiCTR200035268) approved retrospectively registration on 5 Aug 2020.

A six-herb Chinese medicine composition ointment as a promising candidate for treatment of hypertrophic scars

Objective

To study the anti-hypertrophic scar effect of the six-herb Chinese medicine composition (SCMC) ointment on the rabbit ear hypertrophic scar models.

Methods

The optimal formulation of SCMC ointment matrix was screened by the orthogonal designs and a series of evaluation tests. The SCMC ointment was prepared through emulsifying method. The rabbit ear hypertrophic scar models were established and used to investigate the anti-hypertrophic scar effect of SCMC ointment.

Results

Our results demonstrated that all the quality control indications of the SCMC ointment met the requirements. Anti-hypertrophic scar activity results showed that all the rabbit ear scar tissues appeared different degrees of shrink and fading, and took an unobvious but palpable shift from hard to soft texture with the low, middle and high concentration SCMC ointments treatments in vivo. Additionally, on 21st day the scar area and thickness in different concentrations of SCMC ointment groups were significantly reduced than control group, in a concentration-dependent manner. The immunohistochemical results also indicated that the SCMC ointment had good anti-hypertrophic scar properties and could inhibit hypertrophic scar formation.

Conclusion

The SCMC ointment could improve the blood circulation condition of hypertrophic scar tissues. Our research has demonstrated the Chinese medicine composition ointment with good anti-hypertrophic scar properties that could be used to treat hypertrophic scars. Meanwhile, it provides a theoretical basis for further clinical application.

Pulse-Dye Laser Followed by Betamethasone-Calcipotriol and Fractional Ablative CO2-Laser-Assisted Delivery for Nail Psoriasis

BACKGROUND

Nail psoriasis is a common and potentially debilitating condition for which no effective and safe nonsystemic therapy is currently available. Recently, laser-assisted drug delivery (LADD) is being increasingly used to facilitate transcutaneous penetration of topical treatments.

OBJECTIVES

We set to assess the efficacy and safety of combined pulse-dye laser and fractional CO2 laser-assisted betamethasonecalcipotriol gel delivery for the treatment of nail psoriasis.

MATERIAL AND METHODS

We conducted a prospective, intrapatient comparative study in a series of 22 patients with bilateral fingernail psoriasis. Nails on the randomized hand were treated with 3 monthly sessions of pulse-dye laser to the proximal and lateral nail folds followed by fractional ablative CO2 laser to the nail plate. Between treatments and one month following the last treatment, the participants applied betamethasone propionate-calcipotriol gel once daily to the nail plate. Clinical outcome was ascertained using nails photography, the Nail Psoriasis Severity Index (NAPSI) and patient satisfaction.

RESULTS

Seventeen completed the study. Three participants withdrew from the study because of treatment-associated pain. Treatment was associated with a statistically significant improvement of the NAPSI scale (p < .002). Patient satisfaction was high.

CONCLUSION

Combined PDL and fractional ablative CO2-LADD of betamethasone-calcipotriol gel should be considered for the treatment of nail psoriasis.

5-Fluorouracil Management of Oculofacial Scars: A Systematic Literature Review

PURPOSE

To review the literature for the safety and efficacy of intralesional 5-fluorouracil (5-FU) in the management of oculofacial scars.

METHODS

A literature search was performed in July 2019 in the PubMed database to identify reports of the use of 5-FU injections for modulating oculofacial cutaneous scars. The search yielded 152 articles, of which 15 met criteria outlined for assessment. Data were abstracted from these 15 relevant articles.

RESULTS

While there were no high-level prospective randomized controlled trials, 8 were lower-quality randomized controlled trial, 3 were retrospective cohort studies, and 4 were case series. Most studies pooled results of facial and nonfacial cutaneous applications. Three studies focused solely on oculofacial applications, and these were all lower-level evidence studies. The study outcomes included scar dimension reduction, erythema, patient satisfaction score, observer assessment of scar improvement, and recurrence rates. 5-Fluorouracil was administered as monotherapy or as part of multimodality treatment with other agents (usually corticosteroids) or with CO2 laser, radiotherapy, or pulsed dye laser. 5-Fluorouracil was usually given as an intralesional injection, but in some studies, it was applied topically after micropuncture of the skin. The number and timing of treatments varied between studies. Overall, the level of safety of 5-FU was high. Pain with injection was the most common reported side effect. Other common adverse side effects included pruritus, telangiectasias, changes in pigmentation, and purpura, and 2 studies noted more serious events, such as ulceration, superficial necrosis, and local infection. There were no severe side effects such as anaphylaxis, immune suppression, secondary malignancy, systemic infection, blindness, or death. In all studies, 5-FU was associated with prophylaxis of oculofacial scars or improvement of keloids or hypertrophic scars in terms of reducing size, erythema, and pruritus. 5-Fluorouracil application was associated with favorable patient satisfaction and observer assessment scores especially compared with corticosteroid injections alone.

CONCLUSIONS

High-quality randomized controlled trials are currently lacking, and the existing literature is predominately not specific to use of 5-FU on the face. These studies, however, suggest that intralesional 5-FU is safe and probably more effective than other options in the management of cutaneous scars in the oculofacial region. The delivery methods, timing, dosing, and concomitant therapies were highly variable. Further high-quality controlled studies specific to oculofacial scars may be indicated to assess the efficacy of 5-FU and to establish the best protocols for administering this medication.

Effect of Artesunate Combined With Fractional CO2 Laser on the Hypertrophic Scar in a Rabbit Model

BACKGROUND AND OBJECTIVES

Hypertrophic scar (HS), a common complication in wound healing, is characterized by the disarrangement of collagen, fibers, and extracellular matrix. Artesunate (ART) can inhibit the abnormal formation of fibroblasts and collagens. Fractional CO2 laser (FCO2 L) can facilitate tissue remodeling and the absorption of drugs into ablative microthermal columns in HS. So far, no research has investigated the efficacy of ART combined with an FCO2 L in treating HS. To investigate the theoretical basis and clinical significance of this combination, we established a rabbit model of HS to observe the change in the expression of transforming growth factor β1 (TGF-β1) and proliferating cell nuclear antigen (PCNA).

STUDY DESIGN/MATERIALS AND METHODS

Forty New Zealand white rabbits were randomly divided into four groups: control group, ART group, FCO2 L group, and ART + FCO2 L (combination) group. Four wounds were surgically established in the ear of each rabbit and allowed to develop into HS. ART (20 μL/cm2 ) was injected in ART and combination groups, and FCO2 L (combo mode, deep energy:10m J, super energy: 50 mJ) in FCO2 L and combination groups on the 28th day after HS occurred. Three rounds of treatment were applied (once every 14 days). HS samples were measured by hematoxylin and eosin staining, Van Gieson staining, immunohistochemistry, and Western blot analysis on the 70th day.

RESULTS

The morphological and histopathological changes in HS were significant. HSs were smoother and smaller and the collagen fibers were thinner and less disordered in the combination group than those in ART and FCO2 L groups. Meanwhile, the hypertrophic index (HI), fiber density (NA), and collagen fiber content (AA) were lower in the combination group (1.54 ± 0.15, 3.30 ± 0.22, 30.37 ± 1.41%) than in the ART group (2.51 ± 0.22, 4.69 ± 0.16, 44.68 ± 2.30%) and FCO2 L group (1.99 ± 0.14, 4.13 ± 0.12, 37.74 ± 1.38%) (P < 0.01). Additionally, the expressions of TGF-β1 and PCNA protein were suppressed in the ART group (0.30 ± 0.03, 0.25 ± 0.03) and FCO2 L group (0.35 ± 0.03, 0.32 ± 0.05), and the suppression was more significant in the combination group(0.07 ± 0.02, 0.07 ± 0.02) (P < 0.01).

CONCLUSIONS

The combination of ART and FCO2 L can effectively reduce HS in the rabbit model. This is the first report about this combination in the treatment of HS. A novel treatment is expected to be based on our findings. Lasers Surg. Med. © 2021 Wiley Periodicals LLC.

Lessons Learned from the First Decade of Laser-Assisted Drug Delivery

Laser-assisted drug delivery augments the distribution and penetration of topically applied treatments, leading to enhanced delivery and bioavailability. We discuss the therapeutic application of laser-assisted drug delivery in clinical practice in cases of non-melanoma skin cancer, vitiligo, melasma, scarring, and alopecia (female pattern hair loss, male pattern hair loss, alopecia areata) as well as for vaccination, local anaesthesia, analgesia, viral warts, infantile haemangiomas and cosmetic uses, and we review clinical studies that have used this technique over the last decade. Our review shows that the application of laser-assisted drug delivery enhances topical agent efficacy, potentially reducing the agent concentration and duration of topical treatment required. Future research into the use of laser-assisted drug delivery before topical therapies is needed to establish the optimal techniques to enhance drug delivery and thus improve patient outcomes.

Combination therapy of refractory keloid with ultrapulse fractional carbon dioxide (CO2 ) laser and topical triamcinolone in Asians-long-term prevention of keloid recurrence

Keloid often recur after treatment, and recent studies in keloid management favor the combination therapy of laser-assisted drug delivery over monotherapy. Unfortunately, the previous researches lack long-term follow-up. In this prospective study, 41 individuals with refractory keloids underwent eight treatment sessions at 4 weeks intervals consisting of ultrapulse fractional carbon dioxide laser (UFCL), followed by postoperative application topical triamcinolone acetonide (40 mg/ml). Four follow-up moments were chosen, with follow-up of 24 months. The effects of combination therapy on scar pliability, thickness, relief, vascularization, surface area, pain, and itchiness were examined by means of the Patient and Observer Scar Assessment Scale (POSAS). 38 patients completed the full 24 months of follow-up after the whole treatment. The results reveal a fast and abiding improvement of keloid scars after the combination therapy. The mean keloid POSAS scores showed a decreasing trend in subsequent times. All POSAS components improved significantly between baseline and 24 months after start of therapy (P < .05). Long-term follow-up results demonstrate that combination keloid therapy using UFCL and tropical triamcinolone has overall significant improvement and low recurrence rate with a long-term stable results.

Laser management of hypertrophic burn scars: a comprehensive review

Hypertrophic scars often develop following burn-related injuries. These scars can be cosmetically unappealing, but associated symptoms of pruritus, pain and restricted range of motion can impair a person’s quality of life. Laser and light therapies offer a minimally invasive, low-risk approach to treatment, with a short postoperative recovery period. As laser technology developed, studies have shown decreased scar thickness, neuropathic pain and need for surgical excision, as well as improved scar pigmentation, erythema, pliability, texture, height and pruritus. In this review, we present the evolution of laser therapy for hypertrophic burn scars, how different types of lasers work, indications, perioperative considerations and guidelines for practice management.

Fractional CO2 laser ablation of porcine burn scars after grafting: Is deeper better?

INTRODUCTION

Fractional CO₂ lasers have been used in clinical settings to improve scarring following burn injury. Though used with increasing frequency, the appropriate laser settings are not well defined and overall efficacy of this therapy has not been definitively established. As it has been proposed that for thick hypertrophic scars proportionally greater fluence and thus deeper ablation into the scar tissue would be most effective, the goal of this study was to examine the role of ablation depth on scar outcomes in a highly-controlled porcine model for burn scars-after grafting.

METHODS

Properties of laser ablated wells were quantified on ex vivo pig skin as a function of laser energy (20, 70 or 150mJ). Full-thickness burn wounds were created on the dorsum of red Duroc pigs with the eschar excised and grafted with a split-thickness autograft meshed and expanded 1.5:1. After four weeks of healing, sites were treated with either 20, 70, or 150mJ pulse energy from a fractional CO₂ laser at 5% density or left untreated as a control. Sites were treated every four weeks with three total sessions. Scar area, pigmentation, erythema, roughness, histology, and biomechanics were evaluated prior to each laser treatment at day 28, 56, and 83, as well as four weeks after the final laser treatment, day 112. Additional biopsies were collected at day 112 for gene expression analysis.

RESULTS

The depth of the laser ablated wells increased with increasing pulse energy while the width of the wells was smaller in the 20mJ group and not significantly different in the 70 and 150mJ groups. Scar properties (area, color, biomechanics) were not significantly altered by laser therapy at any of the laser energies tested versus controls. Average scar roughness was improved by laser therapy in a dose dependent manner with scars treated with 150mJ of energy having the smoothest surface; however, these changes were not statistically significant. Assessment of matrix metalloproteinase 9 gene expression showed a slight upregulation in scars treated with 70 or 150mJ versus control scars and scars treated with 20mJ pulse energy.

CONCLUSION

The current study demonstrated that the properties of the ablative well (depth and width) are not linearly correlated with laser pulse energy, with only a small increase in well depth at energies between 70 and 150mJ. Overall, the study suggests that there is little difference in outcomes as a function of laser energy. Fractional CO₂ laser therapy did not result in any statistically significant benefit to scar properties assessed by quantitative, objective measures, thus highlighting the need for additional clinical investigation of laser therapy efficacy with non-treated controls and objective measures of outcome.