Martijn B. A. van der Wal

Biological background of dermal substitutes

Dermal substitutes are of major importance in treating full thickness skin defects, both in acute and chronic wounds. In this review we will outline specific requirements of three classes of dermal substitutes: Biological and clinical requirements will be translated to composition, physical structure, immunological properties and cell-matrix interactions of the various materials. Important properties like pore size, cell adhesion sites (e.g. RGD sequences), crosslinking, degradability and the presence of a basement membrane will be discussed for each of the different classes of materials.

Rasch analysis of the Patient and Observer Scar Assessment Scale (POSAS) in burn scars

PurposeThe Patient and Observer Scar Assessment Scale (POSAS) is a questionnaire that was developed to assess scar quality. It consists of two separate six-item scales (Observer Scale and Patient Scale), both of which are scored on a 10-point rating scale. After many years of experience with this scale in burn scar assessment, it is appropriate to examine its psychometric properties using Rasch analysis.MethodsCross-sectional data collection from seven clinical trials resulted in a data set of 1,629 observer scores and 1,427 patient scores of burn scars. We examined the person–item map, item fit statistics, reliability, response category ordering, and dimensionality of the POSAS.ResultsThe POSAS showed an adequate fit to the Rasch model, except for the item surface area. Person reliability of the Observer Scale and Patient Scale was 0.82 and 0.77, respectively. Dimensionality analysis revealed that the unexplained variance by the first contrast of both scales was 1.7 units. Spearman correlation between the Observer Scale Rasch measure and the overall opinion of the clinician was 0.75.ConclusionThe Rasch model demonstrated that the POSAS is a reliable and valid scale that measures the single-construct scar quality.

An objective device for measuring surface roughness of skin and scars

BACKGROUND Scar formation remains a major clinical problem; therefore, various therapies have been developed to improve scar quality. To evaluate the effectiveness of these therapies, objective measurement tools are necessary. An appropriate, objective measuring instrument for assessment of surface roughness is not yet available in a clinical setting. The Phaseshift Rapid In Vivo Measurement of the Skin (PRIMOS) (GFMesstechnik GmbH, Teltow, Germany) could be such an instrument. This device noninvasively produces a 3-dimensional image of the skin microtopography and measures surface roughness. OBJECTIVE The aim of this study was to investigate the reliability and validity of the PRIMOS for objective and quantitative measurement of surface roughness of skin and scars. METHODS Three observers assessed skin and burn scars in 60 patients using the PRIMOS and a subjective scale, the Patient and Observer Scar Assessment Scale. Reliability was tested using the intraclass correlation of intraobserver and interobserver measurements. An intraclass correlation coefficient of 0.7 or greater was required for reliable results. To test validity, scores of the PRIMOS were compared with scores of the subjective scale (Pearson correlation). A Pearson correlation coefficient greater than 0.6 was considered a strong positive correlation. RESULTS All 3 surface roughness parameters of the PRIMOS showed good intraobserver and interobserver reliability for skin and scars (intraclass correlation coefficient arithmetic mean of surface roughness > 0.85, mean of 5 highest peaks and 5 deepest valleys from entire measuring field > 0.88, peak count > 0.86). The parameter arithmetic mean of surface roughness showed a strong correlation with the subjective score (Pearson arithmetic mean of surface roughness 0.70; mean of 5 highest peaks and 5 deepest valleys from entire measuring field 0.53; peak count 0.54). LIMITATIONS The reliability and validity of the PRIMOS were only tested on skin and burn scars, not in other dermatologic diseases. CONCLUSIONS The PRIMOS is a valid and reliable tool for objective noninvasive evaluation of surface roughness of both skin and burn scars.

Outcome after burns: an observational study on burn scar maturation and predictors for severe scarring.

Long‐term outcome of burn scars as well as the relation with clinically relevant parameters has not been studied quantitatively. Therefore, we conducted a detailed analysis on the clinical changes of burn scars in a longitudinal setup. In addition, we focused on the differences in scar quality in relation to the depth, etiology of the burn wound and age of the patient. Burn scars of 474 patients were subjected to a scar assessment protocol 3, 6, and 12 months postburn. Three different age groups were defined (≤5, 5–18, and ≥18 years). The observer part of the Patient and Observer Scar Assessment Scale revealed a significant (p < 0.001) improvement in scar quality at 12 months compared with the 3‐ and 6‐month data. Predictors for severe scarring are depth of the wound (p < 0.001) and total body surface area burned (p < 0.001). Etiology (p = 0.753) and age (p > 0.230) have no significant influence on scar quality when corrected for sex, total body surface area burned, time, and age or etiology, respectively.

Topical silicone gel versus placebo in promoting the maturation of burn scars: a randomized controlled trial

Background: Silicone sheets are widely used in the treatment of hypertrophic scars, although application around joints may cause limited adherence and reduced movement. To approach these problems, a topical silicone gel was developed that can be applied easily in a thin layer, and that is nonrestrictive and less apparent. The objective of this study was to investigate the effectiveness of topical silicone gel in promoting the maturation of burn scars. Methods: Forty-six scars on 23 patients were included in a randomized, placebo-controlled, within-subject comparative, double-blinded, clinical trial and followed for 1 year. The mean age of the scars at inclusion was 4 months. Effectiveness on scar quality was evaluated using the Patient and Observer Scar Assessment Scale and the DermaSpectrometer. Significance was tested using repeated measures analyses and Wilcoxon paired-sample signed rank tests. Results: Over all visits, the benefit on surface roughness was statistically significant (p = 0.012). At individual time points, the surface of the topical silicone gel–treated scars showed significantly less roughness (p = 0.014) at 3 months after start of the treatment, and the topical silicone gel–treated scars were significantly less itchy (p = 0.018 and p = 0.013, respectively) at 3 and 6 months. Conclusion: Topical silicone gel significantly improves the surface roughness of burn scars, and patients experience significantly less itching in the first half year after application.

Objective Scar Assessment Tools: A Clinimetric Appraisal

Background: Scars may lead to an array of cosmetic, psychological, and functional problems. Different scar features can be distinguished (i.e., color, thickness, relief, pliability, and surface area) that are clinically relevant and contribute to the quality and judgment of a scar. Today, objective evaluation of these scar features is indispensable for practicing evidence-based medicine (e.g., to evaluate the outcome of clinical trials). In this review, an overview and update are given on the most relevant noninvasive objective measurement tools for scar evaluation. Methods: A PubMed literature search was performed. Articles evaluating the clinimetric properties of noninvasive scar assessment tools were included. The selected objective measurement tools were then critically reviewed with respect to the clinimetric properties of reliability, validity, and feasibility. Results: In total, 75 articles were selected and 23 different noninvasive measurement methods were evaluated. Conclusion: Based on the scar features color, thickness, relief, pliability, and surface area, the best measurement tools that are currently available were recommended.

Clinical effectiveness of dermal substitution in burns by topical negative pressure: A multicenter randomized controlled trial

Previous research has shown clinical effectiveness of dermal substitution; however, in burn wounds, only limited effect has been shown. A problem in burn wounds is the reduced take of the autograft, when the substitute and graft are applied in one procedure. Recently, application of topical negative pressure (TNP) was shown to improve graft take. The aim of this study was to investigate if application of a dermal substitute in combination with TNP improves scar quality after burns. In a four‐armed multicenter randomized controlled trial, a split‐skin graft with or without a dermal substitute and with or without TNP was compared in patients with deep dermal or full‐thickness burns requiring skin transplantation. Graft take and rate of wound epithelialization were evaluated. Three and 12 months postoperatively, scar parameters were measured. The results of 86 patients showed that graft take and epithelialization did not reveal significant differences. Significantly fewer wounds in the TNP group showed postoperative contamination, compared to other groups. Highest elasticity was measured in scars treated with the substitute and TNP, which was significantly better compared to scars treated with the substitute alone. Concluding, this randomized controlled trial shows the effectiveness of dermal substitution combined with TNP in burns, based on extensive wound and scar measurements.

Objective color measurements: clinimetric performance of three devices on normal skin and scar tissue.

Color measurements are an essential part of scar evaluation. Thus, vascularization (erythema) and pigmentation (melanin) are common outcome parameters in scar research. The aim of this study was to investigate the clinimetric properties and clinical feasibility of the Mexameter, Colorimeter, and the DSM II ColorMeter for objective measurements on skin and scars. Fifty scars with a mean age of 6 years (2 months to 53 years) were included. Reliability was tested using the single-measure interobserver intraclass correlation coefficient. Validity was determined by measuring the Pearson correlation with the Fitzpatrick skin type classification (for skin) and the Patient and Observer Scar Assessment Scale (for scar tissue). All three instruments provided reliable readings (intraclass correlation coefficient ≥ 0.83; confidence interval: 0.71–0.90) on normal skin and scar tissue. Parameters with the highest correlations with the Fitzpatrick classification were melanin (Mexameter), 0.72; ITA (Colorimeter), −0.74; and melanin (DSM II), 0.70. On scars, the highest correlations with the Patient and Observer Scar Assessment Scale vascularization scores were the following: erythema (Mexameter), 0.59; LAB2 (Colorimeter), 0.69; and erythema (DSM II), 0.66. For hyperpigmentation, the highest correlations were melanin (Mexameter), 0.75; ITA (Colorimeter), −0.80; and melanin (DSM II), 0.83. This study shows that all three instruments can provide reliable color data on skin and scars with a single measurement. The authors also demonstrated that they can assist in objective skin type classification. For scar assessment, the most valid parameters in each instrument were identified.

The hand held Doppler device for the detection of perforators in reconstructive surgery: What you hear is not always what you get

BACKGROUND Perforator-based flaps have become indispensable in the treatment of burn scars. Pre-operative perforator mapping is often performed by use of the hand held Doppler device, partly due to its convenience and the low costs. We expected to find sufficient evidence in literature to support the use of the device, however available literature showed a distinct lack of clinimetric studies that adequately tested the reliability. METHODS To assess reliability, perforator locations were mapped independently by two clinicians using an 8MHz Doppler device. In healthy volunteers the elbow region or the peri-umbilical region were randomly chosen to be the measurement areas of predefined squares (7cm×7cm). Subsequently, the perforators within the area were mapped with Duplex to establish the validity by means of the positive predictive value. RESULTS 20 volunteers were included. The hand held Doppler technique showed moderate reliability with a mean Dice coefficient of 0.56. Also, poor validity was found expressed by a mean positive predictive value of 55%. CONCLUSIONS Surprisingly, this study has shown that performance of the hand held Doppler device was moderate. The Doppler should not be used alone for the detection of perforators.

In a clinimetric analysis, 3D stereophotogrammetry was found to be reliable and valid for measuring scar volume in clinical research

OBJECTIVES Volume is an important feature in the evaluation of hypertrophic scars and keloids. Three-dimensional (3D) stereophotogrammetry is a noninvasive technique for the measurement of scar volume. This study evaluated the reliability and validity of 3D stereophotogrammetry for measuring scar volume. STUDY DESIGN AND SETTING To evaluate reliability, 51 scars were photographed by two observers. Interobserver reliability was assessed by the intraclass correlation coefficient (ICC), and the measurement error was expressed as limits of agreement (LoA). To assess validity, 60 simulated (clay) scars were measured by 3D stereophotogrammetry and subsequently weighed (gold standard). The correlation of volumes obtained by both measures was calculated by a concordance correlation coefficient (CCC), and the measurement error was expressed as a 95% prediction interval. RESULTS The ICC was 0.99, corresponding to a high correlation of measurements between two observers, although the LoA were relatively wide. The correlation between 3D stereophotogrammetry and the gold standard was also high, with a CCC of 0.97. Again, the plot of the differences and LoA showed moderate agreement for the validity. CONCLUSION Three-dimensional stereophotogrammetry is suitable for the use in clinical research but not for the follow-up of the individual patient.