Theoretical basis for optimal surgical incision planning to reduce hypertrophic scar formation.

BACKGROUND: After approximately 24 weeks of gestation, human cutaneous wounds and incisions heal by scar formation. Continued or unregulated stimulation of tissue fibroblasts is thought to lead to an activated state with ongoing collagen deposition resulting in a visible hypertrophic scar. There is evidence that mechanical forces as sensed by fibroblasts lead to downstream events such as excessive extracellular matrix deposition. Mechanical forces acting on the wound fibroblast are exerted by underlying muscles as well as intrinsic forces found in the dermal component of the surrounding skin. Under static conditions, collagen is oriented parallel to the direction of strain. In an effort to minimize resultant scar formation various and often contradictory lines of non-extension, lines of least tension, have been described for planning optimal surgical incisions. HYPOTHESIS: We hypothesize that it is possible to avoid longitudinal stretch on incisions and thereby minimize resultant pathologic scars if defined anatomical considerations are respected. We hypothesize that placement of skin incisions parallel to lines of minimal longitudinal stretch, non-invasively measured by orientation of collagen orientation would in turn result in minimal scar formation. EVIDENCE: Historical recommendations often derived from human post mortem studies and animal experiments have shed some light on cutaneously observed lines of non-extension. Theoretical considerations of non-extension lines have suggested possible directions of surgical incisions. Post surgical analysis of dermatological interventions have similarly added to our understanding of possible non-extension lines. Measuring anisotropy in the skin can determine collagen orientation in the skin and may therefore allow one to objectively place incisions parallel to non-extension lines. To date no randomized clinical study in humans has addressed whether such an approach would lead to less scarring. A study involving volunteers examining many body areas seems ethically challenged. CONCLUSION: The hypothesis, although not proven, is supported by available evidence. If our hypothesis that measurable cutaneous collagen orientation guided incisions improved scar formation then surgical incision planning would deservedly require more clinical attention. Preoperative measurement or at least pre-closure assessment of anisotropy prior to surgical incision placement or closure would notably reduce the incidence of hypertrophic scars.

Dehydrated human amnion/chorion membrane for the treatment of severe skin and tissue loss in an preterm infant: a case report.

Extreme prematurity complicated with severe congenital cutaneous candidiasis (CCC) is rare and clinically challenging. We present the case of a 615g dizygotic twin delivered at 24 weeks gestation with congenital candidiasis, who developed severe skin and tissue loss, successfully treated with dehydrated human amnion/chorion membrane (dHACM). The infant had a complicated medical course, including treatment for patent ductus arteriosus (PDA), necrotising enterocolitis (NEC), and neonatal abstinence syndrome (NAS). In the operating room after debridement, dHACM was placed over all abdominal and back areas of skin loss and covered with a non-occlusive, non-adherent silver dressing. This dressing regimen was chosen in an effort to provide not only topical antimicrobial coverage, but also to maintain a non-shear, moist wound healing environment, which was so important in the dry incubator environment of the neonatal intensive care centre. Over the next four weeks, the baby was medically managed, and the wounds healed on their own with only weekly bedside dressing changes. This case report provides the first example of successful complex management of extensive life-threatening wounds in a premature infant using dHACM.

Is UV radiation beneficial in postburn wound healing?

Currently strict ultraviolet (UV) light avoidance strategies and utilizing sunblock containing products are generally advocated during the reepithelialization process as well as after wound closure. These recommendations are guided by a common appreciation of UV radiation as a predominant cause of skin cancer development. It is possible however that the currently accepted practice of near continuous UV protection abrogates the normal cutaneous response to injury, with melanocyte redistribution and pigmentation creating hypopigmented scars. We hypothesize that judicious UV exposure might in fact be beneficial for wound healing and skin homeostasis. UV light should be investigated as a potential modulator of keratinocyte-melanocyte cross-talk in wound healing. In vitro studies will have to prove whether UV radiation induced melanocyte activation might have a stimulatory paracrine effect on keratinocyte proliferation which could beneficially affect wound healing. We further hypothesize that UV exposure to wounds might stimulate and restore normal melanocyte distribution and melanin content in reepithelialized wounds preventing hypopigmentation. Furthermore, exposure of reepithelialized wounds to UV light might exert a photo protective effect in the skin by the production of melanin. This in turn may protect the epidermis from UV-induced damage and carcinogenesis. It is therefore proposed that moderate UV exposure should be commenced early in the healing process of cutaneous wounds. At present, current practice and literature do not support the notion that UV-sun block is necessary in postburn scar management. Burn scars do not seem to exert an enhanced risk for melanomagenesis, the occurrence of which has only very rarely been reported in burn scars. Different mutations in susceptibility genes or in genes involved in the control of the cell cycle or maintenance of cellular integrity which are UV radiation independent are involved in the initiation and promotion steps of skin cancer.

Cutaneous microcirculatory assessment of the burn wound is associated with depth of injury and predicts healing time.

RATIONALE: Current trends for the treatment of deep partial thickness and full-thickness burns include early excision and skin grafting. In this study we retrospectively evaluated the ability of Laser Doppler Flowmetry (LDF), taken within 24h of the burn to predict: (1) burn wound depth and (2) wounds which would heal in less than 21 days. METHOD: The Laser Doppler Flowmeter (O2C, LEA Medizintechnik, Germany) was employed to non-invasively measure the cutaneous microcirculation of 173 selected areas on 28 patients who suffered burns. RESULTS: A distinct association between initial flow (<24h after burn injury) and the clinical assessment of depth of burn wounds was observed. Wounds demonstrating an initial blood flow of >100 AU were, in 93.1% of cases, correctly (positively) predicted for spontaneous healing within 21 days. A blood flow of <100 AU (negatively) predicted in 88.2%, those wounds which would not go on to heal within 21 days. Sequential measurement analysis (<24h, 3 days after injury and 6 days after injury) revealed no significant decrease in skin perfusion velocity or flow rate. CONCLUSION: LDF can provide immediate results for early determination of burn wound depth and is useful in selecting patients for conservative treatment of their burn wounds.

Treatment of deep partial thickness and indeterminate depth facial burn wounds with water-jet debridement and a biosynthetic dressing.

BACKGROUND: Debriding deep thermal injury to face and neck can be particularly challenging with cold knife techniques. Timely healing, a precondition for minimal scarring, is dependant upon optimal wound bed preparation. OBJECTIVE: A new water-jet surgical tool (Versajet) (Smith & Nephew, Hull, UK) has been designed for wound debridement. Ex vivo histologic analysis of depth of debridement on human skin confirmed that predictable and controlled depth of debridement could be obtained by adjusting apparatus settings. METHODS & MATERIALS: We prospectively studied the versatility of this instrument for the treatment of deep and indeterminate depth face and neck burns. Wounds were then covered with either a biosynthetic (Biobrane) (Bertek Pharmaceuticals Inc) or cultured biosynthetic dressing (TransCyte). RESULTS: Patient follow-up demonstrated no adverse effects. Placement of biosynthetic dressings was compatible with water-jet debridement. Median healing time for wounds covered with biosynthetic dressings was 14 days, and 12 days for those which received the cultured biosynthetic dressing. CONCLUSION: We have found the water-jet system to be a versatile instrument for surgical burn debridement with particular advantage in addressing the challenging and delicate contoured regions found in the face and neck. Accurate control of debridement depth facilitates wound bed preparation for simultaneous treatment with growth promoting biosynthetic dressings.

Self-reported skin sensitivity in a general adult population in France: data of the SU.VI.MAX cohort.

OBJECTIVE: This study aimed to examine the frequency of self-assessed facial skin sensitivity and its different patterns, and the relationship with gender and sun sensitivity in a general adult population. METHODS: A standardized 11-item questionnaire investigating reactions experienced during the past year was developed. The questions explored different patterns of skin sensitivity: pattern I (blushing related to vascular reactivity), pattern II (skin reactions to certain environmental conditions), pattern III (skin reactions after substance contact), and for women pattern IV ('breakout of spots' related to menstrual cycle). Additional items were addressed for women and men, including sun sensitivity. The questionnaire was administered to a large middle-aged population involved in the 'Supplément en Vitamines et Minéraux Antioxydants' (SU.VI.MAX) cohort. RESULTS: Sensitive facial skin was reported by 61% of the women (n = 5074) and 32% of the men (n = 3448), and the frequency decreased with age. The frequency of patterns I, II and III was greater for women (78, 72 and 58%, respectively) than for men (56, 48 and 28%) of comparable classes of age. The frequency of pattern IV was reported by 49% of premenopausal women, and skin reactions after shaving by 41% of the men. Sun sensitivity was found to be a major component of skin sensitivity. Factor analysis showed that individuals with fair phototype frequently evoked reactions associated with pattern I, and skin redness and burning sensations were related to certain environmental conditions (pattern II). CONCLUSION: Skin sensitivity is a common concern that declines with age and is relevant for men as well as for women.

Daily variations in skin surface properties using mixed model methodology.

In order to explore the variations over the course of a day in certain skin biophysical properties, a study was conducted on 8 female volunteers. An assessment of several skin biophysical properties was carried out on the face and the volar forearm every 4 h over a period of 48 h. The biophysical parameters were assessed on the face for sebum secretion, skin surface pH, skin colour, transepidermal water loss, capacitance and skin surface temperature. The same parameters were measured on the volar forearm (excepted for sebum secretion). A statistical analysis based on mixed effect models was conducted. Four models, with different covariance structures, were successively tested. The analysis allowed us to identify a structure that repeated itself over time in the same way over each 24-hour period for capacitance on the forearm and for sebum secretion, skin surface pH and skin colour (L* and a* parameters) on the face. Mixed effect methodology is a powerful tool to analyse longitudinal data involving correlations among repeated measurements made on the same subject.

Assessment of sun reactive skin type with multiple correspondence analysis, hierarchical and tree-structured classification methods.

The sun reactive skin type classification is based on sunburn susceptibility, tanning ability and phenotypic information. As subjects rarely match all features of a given skin type, the attribution to a class is partially subjective. The aims of the study, were to analyse the contribution of each characteristic to the classification made by the expert, and to establish a classification based on a statistical approach conducted on 212 women living in the Ile-de-France area. Multiple regression was used to construct a formula for each phototype. The coefficients obtained demonstrated that the importance of each characteristic was extremely variable from one phototype to another, suggesting that the phototype determination could be facilitated by adding a weight for every characteristic in the decision. Then, multiple correspondence analysis and clustering analysis methods showed that one phototype could be divided into two more homogenous classes.

Using lower eyelid fascial slings for recalcitrant burn ectropion.

Burns of the lower eyelid represent a difficult management problem. Even with skin grafting, scarring and contraction can result in ectropion. This condition creates a marked aesthetic deformity, poses a risk of corneal exposure, and jeopardizes the patient's vision. Historically, full-thickness skin grafts and tarsorrhaphies have been described to manage recurrent ectropion. The lower eyelid fascial sling (LEFS) uses a temporalis fascial strip to create a suspension sling for the lower eyelid. In a series of 7 patients, the LEFS procedure resolved the symptoms permanently in all patients. Because the LEFS procedure counteracts the natural scar contraction forces of lower eyelid burns, it can resolve recalcitrant ectropion successfully while preserving the function and aesthetics of the lower eyelid.

Global classification of human facial healthy skin using PLS discriminant analysis and clustering analysis.

Today's classifications of healthy skin are predominantly based on a very limited number of skin characteristics, such as skin oiliness or susceptibility to sun exposure. The aim of the present analysis was to set up a global classification of healthy facial skin, using mathematical models. This classification is based on clinical, biophysical skin characteristics and self-reported information related to the skin, as well as the results of a theoretical skin classification assessed separately for the frontal and the malar zones of the face. In order to maximize the predictive power of the models with a minimum of variables, the Partial Least Square (PLS) discriminant analysis method was used. The resulting PLS components were subjected to clustering analyses to identify the plausible number of clusters and to group the individuals according to their proximities. Using this approach, four PLS components could be constructed and six clusters were found relevant. So, from the 36 hypothetical combinations of the theoretical skin types classification, we tended to a strengthened six classes proposal. Our data suggest that the association of the PLS discriminant analysis and the clustering methods leads to a valid and simple way to classify healthy human skin and represents a potentially useful tool for cosmetic and dermatological research.

Use of multiple correspondence analysis and cluster analysis to study dietary behaviour: food consumption questionnaire in the SU.VI.MAX. cohort.

Although the effects of individual foods or nutrients on the development of diseases and their risk factors have been investigated in many studies, little attention has been given to the effect of overall dietary patterns. The main objectives of this study were to identify dietary patterns and groups of subjects with similar food consumption habits, i.e. 'dietary profiles', using multiple correspondence analysis and cluster analysis. A food frequency questionnaire was sent to a large population-based sample (2923 women and 2,180 men), recruited among the 'SUpplementation en VItamines et Minéraux AntioXydants' (SU.VI.MAX.) cohort participants in France. The food items were dichotomised in order to focus the study on the highest levels of consumption. Multiple correspondence analysis allows the construction of principal components, which optimally summarise the data, and enables the construction of graphical displays. An interesting property of these graphical displays is that associations between food items can be observed on various projection planes, each category of each food item being located at the centre of gravity of the subjects corresponding to this category. An ascending hierarchical classification was unsuccessfully tried in order to determine clusters from these principal components. Therefore, a 'dissection' of the cloud of points was performed according to the orientation of the axes, providing a readily interpretable eight-dietary profiles typology for each sex. This statistical approach allows identification of particular dietary patterns and dietary profiles, which might be more appropriate in studies of diet-disease associations than the single food or nutrient approach that has dominated past epidemiological research.

[Statistical analysis in the evaluation of controlled diffusion of iodine in the water in developing countries]. / Contribution statistique à l'évaluation de la diffusion contrôlée d'iode dans l'eau dans les pays en développement.

This report describes the methodology and findings of a novel statistical technique for evaluation of the efficacy of the Rhodifuse Iode system in prevention of endemic goiter in Mali. The system involves continuous release of iodine in ground water used for drinking. Study was carried out in four villages for one year. The iodine release system was used in three villages. The fourth village served as the control. The incidence of goiter graded using the criteria of the WHO was assessed in each village according to sex. Statistical analysis consisted of correlating goiter grade with four predictors, i.e., village, sex, iodine release, and time. Since goiter grade is a dependent variable, its law of probability was modeled in function of the predictors. The Cat Mot procedure included in the SAS software package allowed both definition of the law of probability of grade of goiter and its transformation in function of predictor. The generalized linear model was obtained by either the generalized least square method or greatest likelihood method. The Proc Catmod procedure was then used to generalize analysis of variance in case of a nominal or ordinal, binary or polytomic response. The results of this novel statistical technique suggested that the Rhodifuse Iode system was effective.

Repairing the cleft lip nasal deformity.

OBJECTIVE: The repair of the cleft lip nose and nasal deformity remains a challenging endeavor for reconstructive surgeons. Psychosocially, this complex, multifaceted deformity significantly stigmatizes the patient. Numerous techniques have been advocated by multiple authors for the treatment and reconstruction of these deformities, usually requiring serial staged reconstructions. METHOD: Described is our technique for early primary repair of the cleft lip nasal deformity. The use of multiple suspension sutures to repair the nasal defect facilitates the repair of even very wide cleft lips. CONCLUSIONS: These maneuvers provide an aesthetic and functional repair of the nasal defect in conjunction with the lip repair. Long-term results have minimized the need for surgical revision.

Epidemiologic determinants of skin photoaging: baseline data of the SU.VI.MAX. cohort.

BACKGROUND: Although skin disorders associated with long-term sun exposure account for high morbidity, only few data on sun-related preclinical skin changes are available in the general population. OBJECTIVE: In the present study we determined reference values for markers of photoaging in French adults, and we evaluated the relationship between photoaging, phototype, and both behavioral and environmental factors. METHODS: The SU.VI.MAX trial is a multicenter, national intervention trial on 12,735 adults living in France. A transverse analysis was performed on the inclusion data of the sample of volunteers between 45 and 60 years of age who underwent skin evaluation in 1995: 3057 women and 3606 men. Skin was evaluated by means of the Larnier skin photoaging photographic scale and a sun reactive skin type classification derived from those proposed by Fitzpatrick in 1976 and Césarini in 1977. RESULTS: The prevalence of skin photoaging, assessed as a dichotomous variable (from moderate/severe to very severe), was comparable in men and women in same age groups: in women, age group 45-49 years = 22%, 50-54 years = 36%, and 55-60 years = 42%; in men, age group 45-49 years = 17%, 50-54 years = 38%, and 55-60 years = 45%. After adjusting for body mass index, exposure to tobacco, and sunlight exposure, the only variables found to be related to skin photoaging in women were age (55-60 years age group: adjusted odds ratio [AOR] = 6.0, 95% confidence interval [CI] = 4.4-8.2), phototype IIIa, IIIb, and IV (AOR = 0.2, 95% CI = 0.1-0.4; AOR = 0.3, 95% CI = 0.2-0.6; and AOR = 0.4, 95% CI = 0.3-0.8; respectively), menopausal status (AOR = 1.4, 95% CI = 1.1-1.9), and geographic location (Southern France: AOR = 0. 7, 95% CI = 0.6-0.9), with a more pronounced effect in lighter phototypes I-II and a protective impact related to southern locations. No relationship was found between the use of oral contraceptives and skin photoaging. The age effect was also found in men (55-60 years age group: AOR = 10.4, 95% CI = 8.3-13.1) and geographic location (Southern France: AOR = 0.8, 95% CI = 0.6-0.9), with a most pronounced effect in darker phototypes (phototypes > IV: AOR = 2.8, 95% CI = 1.4-5.6). CONCLUSION: Our results suggest that the prevalence of skin photoaging in the adult French population is determined by age, sex, geographic location, and phototype. The continuation of this longitudinal study will allow for the investigation of the relationship between skin photoaging and the risk of the development of skin diseases.

A comparison of the outgrowth potentials of split-thickness skin grafts sectioned by scalpel, mechanical mesher, and CO2 laser.

Mechanical meshers that press blades through immobilized skin are routinely used to expand split-thickness skin grafts, and scanned incisional lasers are currently under investigation for the same purpose. However, in contrast to the atraumatic wound edge that is created on these grafts by a sliding scalpel blade, the skin "crushing" and skin coagulation that can occur with the use of mechanical meshers and lasers are thought to reduce the outgrowth potential of the epidermis. With the use of an in vitro explant outgrowth system, epithelialization derived from wound edges that were created by a scalpel, a mechanical mesher, and a CO2 laser at various settings was studied. The area of epithelialization around skin explants was not significantly different for skin bridges produced by scalpel cuts and those produced by the skin mesher, and histologic sections demonstrated similar epiboly-growth under these explants. In contrast, wounds created with the CO2 laser showed impaired epithelialization. Incisions were made at several power settings, ranging from 11 passes at 4 mW to 1 pass at 24 mW. Only minor differences were demonstrated, with the lower laser power yielding slightly better results. Recruitment of keratinocytes into the proliferative state, as assessed by bromodeoxyuridine incorporation, was equivalent for scalpel and mesh cut skin. This data does not support concerns about decreased graft viability resulting from the crushing blade action used by mechanical meshers. The possibility of cutting and meshing skin grafts with lasers of the far-infrared and mid-infrared light spectrum are discussed.

Harvesting iliac bone graft: decreasing the morbidity.

OBJECTIVE: This is a review of modifications made to the classic technique for harvesting bone graft from the iliac crest. Prior techniques for harvesting iliac bone often resulted in significant postoperative pain, disability, and a cosmetically unacceptable scar and contour deformity. DESIGN: A retrospective review of patients who underwent bone graft harvest over a 7-year period was done. INTERVENTIONS: The modifications described use a skin incision medial to the anterior superior iliac crest. The medial aspect of the iliac crest is elevated along the midsagittal axis of the crest. The medial cap is reflected outward, exposing cancellous bone. RESULTS: A review of 51 patients demonstrated only two minor self-limiting complications. CONCLUSIONS: This procedure provides an abundant supply of both cortical and cancellous bone, an aesthetically acceptable scar, and decreased patient discomfort.

Use of the repeated cross-over design in assessing bioequivalence: (within and between subjects variability - Schuirmann Confidence Intervals estimation).

In 1992, the Division of Bioequivalence in the Office of Generic Drugs published a guide to Statistical procedures for bioequivalence studies using a standard two-treatments cross-over design (1). This paper describes the application of the guidelines to a practical protocol and the recent Proc MIXED (SAS) will be shown to be much more convenient than the traditional Proc GLM for theoretical and practical reasons (correct estimation of residuals, analysis of the within-subjects variation, direct calculation of the Schuirmann 90% Confidence Intervals). This new procedure was applied to a study protocol on riluzole (Rilutek) including a replicate design with the within-subject and between-subject variances being estimated on Cmax and AUC biopharmaceutic parameters.

A simplified technique of otoplasty: the temporary Kaye suture.

The prominent or lop ear is often characterized by the absence of the antihelical fold. Various methods have been described to correct the deformity. Many involve placement of permanent sutures to reform the cartilage into the proper shape to correct the deformity. Marking the antihelical fold on the cartilage can be difficult and time-consuming when performing an otoplasty. By placing several percutaneous stay sutures from the anterior we are able to adjust the level of fold finely on the antihelix. We describe a technique that is simple, quick, and precise.