P.D.H.M. Verhaegen

Differences in collagen architecture between keloid, hypertrophic scar, normotrophic scar, and normal skin: An objective histopathological analysis

Normotrophic, hypertrophic, and keloidal scars are different types of scar formation, which all need a different approach in treatment. Therefore, it is important to differentiate between these types of scar, not only clinically but also histopathologically. Differences were explored for collagen orientation and bundle thickness in 25 normal skin, 57 normotrophic scar, 56 hypertrophic scar, and 56 keloid biopsies, which were selected on clinical diagnosis. Image analysis was performed by fast fourier transformation. The calculated collagen orientation index ranged from 0 (random orientation) to 1 (parallel orientation). The bundle distance was calculated by the average distance between the centers of the collagen bundles. The results showed that compared with all three types of scars, the collagen orientation index was significantly lower in normal skin, which indicates that scars are organized in a more parallel manner. No differences were found between the different scars. Secondly, compared with normal skin, normotrophic scar, and hypertrophic scar, the bundle distance was significantly larger in keloidal scar, which suggests that thicker collagen bundles are present in keloidal scar. This first extensive histological study showed objective differences between normal skin, normotrophic, hypertrophic, and keloidal scar.

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.

A Clinimetric Overview of Scar Assessment Scales

Standardized validated evaluation instruments are mandatory to increase the level of evidence in scar management. Scar assessment scales are potentially suitable for this purpose, but the most appropriate scale still needs to be determined. This review will elaborate on several clinically relevant scar features and critically discuss the currently available scar scales in terms of basic clinimetric requirements. Many current scales can produce reliable measurements but seem to require multiple observers to obtain these results reliably, which limits their feasibility in clinical practice. The validation process of scar scales is hindered by the lack of a “gold standard” in subjective scar assessment or other reliable objective instruments which are necessary for a good comparison. The authors conclude that there are scar scales available that can reliably measure scar quality. However, further research may lead to improvement of their clinimetric properties and enhance the level of evidence in scar research worldwide.

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.

Adaptation of the dermal collagen structure of human skin and scar tissue in response to stretch: An experimental study

Surgeons are often faced with large defects that are difficult to close. Stretching adjacent skin can facilitate wound closure. In clinical practice, intraoperative stretching is performed in a cyclical or continuous fashion. However, exact mechanisms of tissue adaptation to stretch remain unclear. Therefore, we investigated collagen and elastin orientation and morphology of stretched and nonstretched healthy skin and scars. Tissue samples were stretched, fixed in stretched‐out position, and processed for histology. Objective methods were used to quantify the collagen orientation index (COI), bundle thickness, and bundle spacing. Also sections were analyzed for elastin orientation and quantity. Significantly more parallel aligned collagen bundles were found after cyclical (COI = 0.57) and continuous stretch (COI = 0.57) compared with nonstretched skin (COI = 0.40). Similarly, more parallel aligned elastin was found after stretch. Also, significantly thicker collagen bundles and more bundle spacing were found after stretch. For stretched scars, significantly more parallel aligned collagen was found (COI = 0.61) compared with nonstretched scars (COI = 0.49). In conclusion, both elastin and collagen realign in a parallel fashion in response to stretch. For healthy skin, thicker bundles and more space between the bundles were found. Rapid changes in extension, alignment, and collagen morphology appear to be the underlying mechanisms of adaptation to stretching.

A reliable, non‐invasive measurement tool for anisotropy in normal skin and scar tissue

Background: Anisotropy of the skin varies depending on different locations and pathological conditions. Currently, no reliable non‐invasive measurement tool is available for tissue anisotropy. The Reviscometer® is an anisotropy measurement tool that measures the resonance running time (RRT) of a shock wave. This study was initiated to establish the reliability of the Reviscometer® on normal skin and scars, and to provide basic information on tissue alignment in normal skin and scars.

Collagen bundle morphometry in skin and scar tissue: a novel distance mapping method provides superior measurements compared to Fourier analysis

Histopathological evaluations of fibrotic processes require the characterization of collagen morphology in terms of geometrical features such as bundle orientation thickness and spacing. However, there are currently no reliable and valid techniques of measuring bundle thickness and spacing. Hence, two objective methods quantifying the collagen bundle thickness and spacing were tested for their reliability and validity: Fourier first‐order maximum analysis and Distance Mapping, with the latter constituting a newly developed morphometric technique. Histological slides were constructed and imaged from 50 scar and 50 healthy human skin biopsies and subsequently analyzed by two observers to determine the interobserver reliability via the intraclass correlation coefficient. An intraclass correlation coefficient larger than 0.7 is considered as representing good reliability. The interobserver reliability for the Fourier first‐order maximum and for the Distance Mapping algorithms, respectively, showed an intraclass correlation coefficient above 0.72 and 0.89. Additionally, we performed an assessment of validity in the form of responsiveness, in particular, demonstrating medium to excellent results via a calculation of the effect size, highlighting that both methods are sensitive enough to measure a treatment effect in clinical practice. In summary, two reliable and valid measurement methods were demonstrated for collagen bundle morphometry for the first time. Due to its superior reliability and more useful measures (bundle thickness and bundle spacing), Distance Mapping emerges as the preferred and more practical method. Nevertheless, in the future, both methods can be used for reliable and valid collagen morphometry of skin and scars, whereas further applications evaluating the quantitative microscopy of other fibrotic processes are anticipated.