[The impact of silicone spray on scar formation. A single-center placebo-controlled double-blind trial]

Silicone gel sheeting for treating hypertrophic scars

BACKGROUND

Each year, in high-income countries alone, approximately 100 million people develop scars. Excessive scarring can cause pruritus, pain, contractures, and cosmetic disfigurement, and can dramatically affect people's quality of life, both physically and psychologically. Hypertrophic scars are visible and elevated scars that do not spread into surrounding tissues and that often regress spontaneously. Silicone gel sheeting (SGS) is made from medical-grade silicone reinforced with a silicone membrane backing and is one of the most commonly used treatments for hypertrophic scars.

OBJECTIVES

To assess the effects of silicone gel sheeting for the treatment of hypertrophic scars in any care setting.

SEARCH METHODS

In April 2021 we searched the Cochrane Wounds Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE (including In-Process & Other Non-Indexed Citations); Ovid Embase and EBSCO CINAHL Plus. We also searched clinical trials registries for ongoing and unpublished studies, and scanned reference lists of relevant included studies as well as reviews, meta-analyses and health technology reports to identify additional studies. There were no restrictions with respect to language, date of publication or study setting.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that enrolled people with any hypertrophic scars and assessed the use of SGS.

DATA COLLECTION AND ANALYSIS

Two review authors independently performed study selection, 'Risk of bias' assessment, data extraction and GRADE assessment of the certainty of evidence. We resolved initial disagreements by discussion, or by consulting a third review author when necessary.

MAIN RESULTS

Thirteen studies met the inclusion criteria. Study sample sizes ranged from 10 to 60 participants. The trials were clinically heterogeneous with differences in duration of follow-up, and scar site. We report 10 comparisons, SGS compared with no SGS treatment and SGS compared with the following treatments: pressure garments; silicone gel; topical onion extract; polyurethane; propylene glycol and hydroxyethyl cellulose sheeting; Kenalog injection; flashlamp-pumped pulsed-dye laser; intense pulsed light  and Gecko Nanoplast (a silicone gel bandage). Six trials had a split-site design and three trials had an unclear design (resulting in a mix of paired and clustered data). Included studies reported limited outcome data for the primary review outcomes of severity of scarring measured by health professionals and adverse events (limited data reported by some included studies, but further analyses of these data was not possible) and no data were reported for severity of scarring reported by patients. For secondary outcomes some pain data were reported, but health-related quality of life and cost effectiveness were not reported. Many trials had poorly-reported methodology, meaning the risk of bias was unclear. We rated all evidence as being either of low or very low certainty, often because of imprecision resulting from few participants, low event rates, or both, all in single studies. SGS compared with no SGS Seven studies with 177 participants compared SGS with no SGS for hypertrophic scars. Two studies with 31 participants (32 scars) reported severity of scarring assessed by health professionals, and it is uncertain whether there is a difference in severity of scarring between the two groups (mean difference (MD) -1.83, 95% confidence interval (CI) -3.77 to 0.12; very low-certainty evidence, downgraded once for risk of bias, and twice for serious imprecision). One study with 34 participants suggests SGS may result in a slight reduction in pain level compared with no SGS treatment (MD -1.26, 95% CI -2.26 to -0.26; low-certainty evidence, downgraded once for risk of bias and once for imprecision). SGS compared with pressure garments One study with 54 participants was included in this comparison. The study reported that SGS may reduce pain levels compared with pressure garments (MD -1.90, 95% CI -2.99 to -0.81;  low-certainty evidence, downgraded once for risk of bias and once for imprecision). SGS compared with silicone gel One study with 32 participants was included in this comparison. It is unclear if SGS impacts on severity of scarring assessed by health professionals compared with silicone gel (MD 0.40, 95% CI -0.88 to 1.68; very low-certainty evidence, downgraded once for risk of bias, twice for imprecision). SGS compared with topical onion extract One trial (32 participants) was included in this comparison. SGS may slightly reduce severity of scarring compared with topical onion extract (MD -1.30, 95% CI -2.58 to -0.02; low-certainty evidence, downgraded once for risk of bias, and once for imprecision). SGS compared with polyurethane One study with 60 participants was included in this comparison. It is unclear if SGS impacts on the severity of scarring assessed by health professionals compared with polyurethane (MD 0.50, 95% CI -2.96 to 3.96; very low-certainty evidence, downgraded once for risk of bias, and twice for imprecision). SGS compared with self-adhesive propylene glycol and hydroxyethyl cellulose sheeting One study with 38 participants was included in this comparison. It is uncertain if SGS reduces pain compared with self-adhesive propylene glycol and hydroxyethyl cellulose sheeting (MD -0.12, 95% CI -0.18 to -0.06). This is very low-certainty evidence, downgraded once for risk of bias, once for imprecision and once for indirectness. SGS compared with Gecko Nanoplast One study with 60 participants was included in this comparison. It is unclear if SGS impacts on pain compared with Gecko Nanoplast (MD 0.70, 95% CI  -0.28 to 1.68; very low-certainty evidence, downgraded once for risk of bias and twice for imprecision. There was a lack of reportable data from the other three comparisons of SGS with Kenalog injection, flashlamp-pumped pulsed-dye laser or intense pulsed light.

AUTHORS' CONCLUSIONS

There is currently limited rigorous RCT evidence available about the clinical effectiveness of SGS in the treatment of hypertrophic scars. None of the included studies provided evidence on severity of scarring validated by participants, health-related quality of life, or cost effectiveness. Reporting was poor, to the extent that we are not confident that most trials are free from risk of bias. The limitations in current RCT evidence suggest that further trials are required to reduce uncertainty around decision-making in the use of SGS to treat hypertrophic scars.

New insights on keloids, hypertrophic scars, and striae

This article presents an overview of the literature regarding treatments for keloid disease, hypertrophic scars, and striae distensae in dark pigmented skin. Striae, keloid, and hypertrophic scarring present a challenging problem for both the clinician and patient. No single therapy is advocated for hypertrophic scars, keloid scars, or striae distensae. New therapies have shown promise in the treatment of hypertrophic and keloid scars, and in patients with dark pigmented skin. This article provides guidance on the assessment and determination of patients' suitability for certain treatment options, as well as advice on the follow-up of patients affected with problematic scarring and striae.

Silicone gel sheeting for preventing and treating hypertrophic and keloid scars

BACKGROUND

Keloid and hypertrophic scars are common and are caused by a proliferation of dermal tissue following skin injury. They cause functional and psychological problems for patients, and their management can be difficult. The use of silicone gel sheeting to prevent and treat hypertrophic scarring is still relatively new and started in 1981 with treatment of burn scars.

OBJECTIVES

To determine the effectiveness of silicone gel sheeting for:(1) prevention of hypertrophic or keloid scarring in people with newly healed wounds (e.g. post surgery);(2) treatment of established scarring in people with existing keloid or hypertrophic scars.

SEARCH METHODS

In May 2013 we searched the Cochrane Wounds Group Specialised Register; the Cochrane Central Register of Controlled Trials (CENTRAL); Ovid MEDLINE; Ovid MEDLINE (In-Process & Other Non-Indexed Citations); Ovid EMBASE; and EBSCO CINAHL for this second update.

SELECTION CRITERIA

Any randomised or quasi-randomised controlled trials, or controlled clinical trials, comparing silicone gel sheeting for prevention or treatment of hypertrophic or keloid scars with any other non surgical treatment, no treatment or placebo.

DATA COLLECTION AND ANALYSIS

We assessed all relevant trials for methodological quality. Three review authors extracted data independently using a standardised form and cross-checked the results. We assessed all trials meeting the selection criteria for methodological quality.

MAIN RESULTS

We included 20 trials involving 873 people, ranging in age from 1.5 to 81 years. The trials compared adhesive silicone gel sheeting with no treatment; non silicone dressing; other silicone products; laser therapy; triamcinolone acetonide injection; topical onion extract and pressure therapy. In the prevention studies, when compared with a no treatment option, whilst silicone gel sheeting reduced the incidence of hypertrophic scarring in people prone to scarring (risk ratio (RR) 0.46, 95% confidence interval (CI) 0.21 to 0.98) these studies were highly susceptible to bias. In treatment studies, silicone gel sheeting produced a statistically significant reduction in scar thickness (mean difference (MD) -2.00, 95% CI -2.14 to -1.85) and colour amelioration (RR 3.49, 95% CI 1.97 to 6.15) but again these studies were highly susceptible to bias.

AUTHORS' CONCLUSIONS

There is weak evidence of a benefit of silicone gel sheeting as a prevention for abnormal scarring in high-risk individuals but the poor quality of research means a great deal of uncertainty prevails. Trials evaluating silicone gel sheeting as a treatment for hypertrophic and keloid scarring showed improvements in scar thickness and scar colour but are of poor quality and highly susceptible to bias.

Management of keloids and hypertrophic scars: current and emerging options

In the context of growing aesthetic awareness, a rising number of patients feel disappointed with their scars and are frequently seeking help for functional and aesthetic improvement. However, excessive scarring following surgery or trauma remains difficult to improve despite a plethora of advocated treatment strategies as frequently observed in daily clinical routine. It is thus still preferable to prevent scarring by minimizing risk factors as much as possible. Hence, it remains crucial for the physician to be aware of basic knowledge of healing mechanisms and skin anatomy, as well as an appreciation of suture material and wound closure techniques to minimize the risk of postoperative scarring. Next to existing, well known prophylactic and therapeutic strategies for the improvement of excessive scarring, this article discusses emerging techniques such as intralesional cryotherapy, intralesional 5-fluorouracil, interferon, and bleomycin. Some of them have been successfully tested in well-designed trials and already have extended or may extend the current spectrum of excessive scar treatment in the near future. Innovative options such as imiquimod 5% cream, photodynamic therapy, or botulinum toxin A may also be of certain importance; however, the data currently available is too contradictory for definite recommendations.