Elastic properties of human skin: relation to age, sex, and anatomical region

Improvement of sensorimotor functions in old age by passive sensory stimulation

Sensorimotor functions decrease in old age. The well-documented loss of tactile acuity in elderly is accompanied by deterioration of haptic performance and fine manipulative movements. Physical training and exercise can maintain sensorimotor fitness into high age. However, regular schedules of training require discipline and physical fitness. We here present an alternative interventional paradigm to enhance tactile, haptic, and fine motor performance based on passive, sensory stimulation by means of tactile coactivation. This approach is based on patterned, synchronous tactile stimulation applied to the fingertips for 3 hours. The stimulation drives plastic reorganizational changes in somatosensory cortex that affect perception and behavior: We demonstrate that following 3 hours of coactivation tactile acuity as well as haptic object exploration and fine motor performance are improved for at least 96 hours. Because this kind of intervention does not require active participation or attention of the subjects, we anticipate that coactivation is a prime candidate for future therapeutic interventions in patients with impaired sensorimotor abilities. It can be assumed that the maintenance and restoration of sensorimotor functions can ensure and preserve independence of daily living. Further optimizing of the stimulation protocol can be assumed to strengthen both the range and durability of its efficacy.

Intraoperative acute tissue expansion for the closure of large myelomeningoceles

OBJECT

Skin closure has always been the main challenge in treating myelomeningoceles (MMCs). Most cutaneous defects can be treated with the simple undermining and primary suture of the wound edges. This is the ideal treatment, but it is not adequate in cases in which the lesions are greater than 5 cm in diameter. Numerous reconstructive procedures have been described and the results have been satisfactory. The need to mobilize large skin areas and the fact of excessive blood loss, however, are major problems in newborns. Moreover, the tissue undermining destroys most of the skin's vascularization and can harm the adaptation of the skin flaps. The authors describe a technique for primary closure of large MMC skin defects in which they use acute skin expansion during the surgical procedure.

METHODS

Skin expansion was achieved by traction of the wound edges with U-shaped sutures and without the need of skin flaps. Sixteen patients with MMCs greater than 5 cm in diameter were evaluated.

RESULTS

The MMC areas ranged from 30 to 64 cm2 (mean 45 cm2). Two suture systems were developed based on the quality of the skin edge and the size of the skin defect. Wound edge traction was performed in 10-minute periods. The edges were gradually approximated and this allowed the primary closure of the wound without undermining the tissue in all patients. In one patient skin necrosis developed, which was associated with compression of the malformed underlying vertebrae.

CONCLUSIONS

Simplicity, low cost, and satisfactory results were the main advantages of the method and an increase in operative time was a disadvantage. The goal of this technique is not to replace the other methods, but the technique constitutes an effective option in the treatment of large MMCs.

Estimates of percutaneous toxicity of sulfur mustard vapor suitable for use in protective equipment standards

An analysis was performed of historical human chamber data for exposure to sulfur mustard vapor, in order to correlate skin exposure dosages with effects in a manner specifically suitable for use in protective clothing standards. Data were reanalyzed to take into account (1) body region variability of skin responses to a single acute exposure to sulfur mustard vapor, (2) effect of hot/humid versus cooler exposure, and (3) influence of clothing. This approach permits deriving predicted skin responses pertinent to a protective clothing wearer, for a relatively short single acute exposure to vapor (up to a few hours) under the hot/humid conditions expected within a protective ensemble. Values for permissible dermal exposure to sulfur mustard vapor are proposed for protected emergency responders or military serving in combat theaters that may be used in standards intended to be employed in conjunction with evaluation of vapor protection provided by individual protective equipment for protection against chemical warfare agents by Man-in-Simulant vapor test methods.

In vivo measurements of the elastic mechanical properties of human skin by indentation tests

Knowledge about the human skin mechanical properties is essential in several domains, particularly for dermatology, cosmetic or to detect some cutaneous pathology. This study proposes a new method to determine the human skin mechanical properties in vivo using the indentation test. Usually, the skin mechanical parameters obtained with this method are influenced by the mechanical properties of the subcutaneous layers, like muscles. In this study, different mechanical models were used to evaluate the effect of the subcutaneous layers on the measurements and to extract the skin elastic properties from the global mechanical response. The obtained results demonstrate that it is necessary to take into account the effect of the subcutaneous layers to correctly estimate the skin Young's modulus. Moreover, the results illustrate that the variation of the measured Young's modulus at low penetration depth cannot be correctly described with usual one-layer mechanical models. Thus a two-layer elastic model was proposed, which highly improved the measurement of the skin mechanical properties.

Measurement of skin elasticity on the foot

BACKGROUND/PURPOSE

The Cutometer 580 MPA is a device that is designed to measure the viscoelastic properties of skin in response to the application of negative pressure. The aim of this study was to test the Cutometer 580 MPA for the repeatable, quantitative measurement of the specific indices of elasticity of pedal skin. The device was used to measure and compare these indices at weight-bearing and non-weight-bearing skin sites on the foot.

METHODS

The relationship between the pressure application and skin displacement was determined. The inter- and intra-tester repeatability was tested. These series of experiments were conducted on 20 individuals. Data were then collected from a group of 87 healthy people for the measurement of elasticity, viscoelasticity and plasticity on several sites on the foot. The possible influences of physiological variables such as age and sex on the indices of elasticity were analysed.

RESULTS

The Hookian elastic behaviour of the skin was confirmed. The pressure application did not remain constant during the collection of displacement data, resulting in an error in these readings of between 1.71% and 3.73%. Intra-tester and variability was minimal (CV<7%). The elasticity, viscoelasticity and plasticity indices were significantly greater (P<0.001) in dorsal skin compared with skin from medial longitudinal arch (MLA) and plantar aspect of the third metatarsophalangeal joint (PMA) sites. There was a negative correlation between age and elasticity on the dorsum and MLA skin sites (r=-0.216 and -0.261, respectively). Female skin exhibited greater plasticity than male skin on all three sites on the foot (P<0.05).

CONCLUSION

Under well-controlled conditions, the Cutometer 580 MPA has the ability to measure accurately the viscoelastic properties of pedal skin. Such non-invasive measurements may be useful for the evaluation of changes in the skin in response to therapeutic interventions and for monitoring the progression of dermatological conditions associated with the foot.

Ethnic differences regarding tactile and pain thresholds in the trigeminal region

The aim of the present study was to evaluate ethnic differences of the tactile detection threshold (TDT), the filament-prick pain detection threshold (FPT), the pressure pain detection threshold (PPT), and the pressure pain tolerance detection threshold (PTOL) in the orofacial region of symptom-free subjects. Twenty-two men and 22 women in Belgium and in Japan (age range from 20 to 31 years) participated. The TDT and the FPT were measured on the cheek skin (CS) overlying the masseter muscles (MM), on the maxillary gingiva (MG), and at the tip of the tongue (TT), using Semmes-Weinstein monofilaments. The PPT and PTOL were measured at the central part of the MM, using a pressure algometer. A general linear model was used in each case to capture ethnic and gender effects. Japanese women had the lowest TDT at CS, in contrast to Belgian men, who had the highest value; a significant ethnic and gender effect was found (P=.026 and P<.001, respectively). Similar results were found for FPT at CS with significant ethnic and gender effects (P<.001 for both). There was no significant ethnic effect regarding intra-oral TDT and FPT or regarding PPT and PTOL.

PERSPECTIVE

Our findings clearly indicate that future studies of tactile and pain measurements need to standardize and control for gender and ethnicity. Further, a comprehensive evaluation of results from various stimulation modalities may better clarify the pain mechanisms and gender/ethnic characteristics, as well as comparisons between normal subjects and patients.

Comparing the Vancouver Scar Scale With the Cutometer in the Assessment of Donor Site Wounds Treated With Various Dressings in a Randomized Trial

Cutaneous scarring observed in wounds is, to a significant degree, dependent upon the time it takes for the wounds to heal. Various topical dressings are proposed to influence healing time in donor sites. In this prospective randomized study, we examined the effect of Vaseline gauze (VD; Branolind, Paul Hartmann AG, Germany), Biobrane (BD; Bertek Pharmaceuticals, Inc., Morgantown, WV), an occlusive film dressing Barrier Flex (OD; Moelnlycke Health Care GmbH, Germany), and an equine collagen foil, Tissu Foil E (CD; Baxter, Heidelberg, Germany), on re-epithelialization and scarring in standardized donor site wounds. At 6 months after surgery, donor site scars and normal uninjured mirror sided skin were evaluated in 33 patients using both the Vancouver Scar Scale (VSS) and the cutometer SEM 575 (Courage and Khazaka). The median healing time for OD was 14 days, BD 16 days, CD 19 days, and VD 19 days. The single parameter pliability of the VSS was not significantly different from uninjured skin when all donor site scars were pooled. No difference was found between the four groups. Viscoelastic analysis of all pooled patient data showed a significant difference for Uf (total deformation), Ua (total recovery), Ur (immediate retraction), Ue (immediate distension), Ur/Ue, and Ur/Uf, indicating that donor sites significantly differed from normal uninjured skin. No significant correlation between objective viscoelastic measurements and the subjective pliability assessment of the VSS was found. Viscoelastic differences were greatest in the VD and BD groups. Viscolelastic differences did not significantly correlate with healing time. Various wound dressings had minimal yet significant influence on healing time and scarring. In contrast to the VSS, viscoelastic measurements of skin pliability can objectify scarring when few differences are anticipated.

Effect of dermal thickness, tissue composition, and body site on skin biomechanical properties

BACKGROUND/PURPOSE

Quantitative measurement of skin biomechanical properties has been used effectively in the investigation of physiological changes in tissue structure and function and to determine treatment efficacy. As the methods are applied to new questions, tissue characteristics that may influence the resultant biomechanical properties are important considerations in the research design. For certain applications, variables such as dermal thickness and subdermal tissue composition, as well as age and/or solar exposure, may influence the skin biomechanics.

METHODS

We determined the influence of dermal thickness, tissue composition, and age on the skin biomechanical properties at the shoulder, thigh, and calf among 30 healthy females. We compared two devices, the Biomechanical Tissue Characterization System and the Cutometer SEM 575 Skin Elasticity Meter , to determine the effect of tissue sampling size. Dermal thickness was measured with 20 MHz ultrasound (Dermascan C) and tissue composition was inferred from anthropomorphic data.

RESULTS

Skin thickness was significantly correlated with stiffness, energy absorption, and U(r)/U(f) for the shoulder. Body mass index (BMI) was significantly correlated with stiffness (negative correlation), energy absorption (positive), and skin thickness (negative) for the shoulder. Significant differences across body sites were observed. The calf was significantly different from the thigh and shoulders for all parameters (P<0.05, one-way anova). The calf had significantly lower laxity, laxity%, elastic deformation, energy absorption, elasticity, elasticity %, U(r), U(f), and U(r)/U(f) and significantly higher stiffness compared with the thighs and shoulders. sites. The thigh and shoulder sites were significantly different for all parameters except U(r)/U(f), elasticity %, laxity%, and stiffness. The dominant and non-dominant sides were significantly different. The dominant side (right for 90% of the subjects) had increased stiffness and decreased energy absorption (tissue softness, compliance) compared with the left side. A significant (P< or =0.02) negative relationship with age was seen for all biomechanical measures except stiffness at the shoulder. For the thigh and calf sites, significant negative correlations with age were found for elasticity %, U(r), and U(r)/U(f). Age and skin thickness were not correlated in this population. Skin thickness and age influenced the energy absorption at the shoulder site. The biological elasticity at the calf site could be predicted by age and BMI. The biological activity at the thigh site could be predicted by skin thickness and BMI.

CONCLUSIONS

Significant regional variations in biomechanical properties and dominant side effects were observed. The biomechanical properties were significantly influenced by age. Certain properties varied with dermal thickness and tissue composition. The parameters were well correlated between the two instruments. The Cutometer, with its smaller aperture, was found to be more sensitive to age relationships.

Effect of lipid-containing, positively charged nanoemulsions on skin hydration, elasticity and erythema--an in vivo study

Dry skin and other skin disorders such as atopic dermatitis are characterized by impaired stratum corneum (SC) barrier function and by an increase in transepidermal water loss (TEWL) leading to a decrease in skin hydration. The possibility that dermatological and cosmetic products containing SC lipids could play a part in the restoration of disturbed skin barrier function is of great interest in the field of dermatology and cosmetics. The aim of the present study was to evaluate the effect of positively charged oil/water nanoemulsions (PN) containing ceramide 3B and naturally found SC lipids (PNSC) such as ceramide 3, cholesterol, and palmitic acid on skin hydration, elasticity, and erythema. Creams of PNSC were compared to PN creams, to creams with negatively charged o/w nanoemulsion and SC lipids (NNSC) and to Physiogel cream, a SC lipid containing formulation, which is already on the market. The formulations (PN, PNSC, and NNSC) were prepared by high-pressure homogenization. After adding Carbopol 940 as thickener, particle size and stability of the creams were not significantly changed compared to the nanoemulsions. The studies were carried out on three groups, each with 14 healthy female test subjects between 25 and 50 years of age, using Corneometer 825, Cutometer SEM 575 and Mexameter 18 for measurements of skin hydration, elasticity, and erythema of the skin, respectively. The creams were applied regularly and well tolerated throughout the study. All formulations increased skin hydration and elasticity. There was no significant difference between PNSC and Physiogel. However, PNSC was significantly more effective in increasing skin hydration and elasticity than PN and NNSC indicating that phytosphingosine inducing the positive charge, SC lipids and ceramide 3B are crucial for the enhanced effect on skin hydration and viscoelasticity.

Tactile and pain thresholds in the intra- and extra-oral regions of symptom-free subjects

The aim of the present study was to evaluate the tactile detection threshold (TDT), the filament-prick pain detection threshold (FPT), the pressure pain threshold (PPT), and the pressure pain tolerance detection threshold (PTOL) at multiple measuring points in the orofacial region of normal subjects. Sixteen males and 16 females (age range from 20 to 41 years) participated. The TDT and the FPT were measured on the cheek skin overlying the central part of the masseter muscles (MM), on the maxillary gingiva, and at the tip of the tongue, using Semmes-Weinstein monofilaments. The PPT and PTOL were measured at the central part of the MM, using a pressure algometer. The pain intensity during the FPT, PPT and the PTOL measurements was assessed on a numeric rating scale (NRS). The tongue tip had the lowest value in TDT and FPT compared to the other sites. Females showed a significantly lower TDT and FPT at the cheek skin than males. Further, measurements of PPT and PTOL confirmed the previously reported higher thresholds in males. In contrast, while the intra-oral threshold measurements revealed no gender differences, a significantly higher pain perception as evaluated using NRS, was seen in the males. A strong correlation was found between the pain responses at the same measuring site (FPT, PPT, and PTOL over the MM). In addition, the TDT and the pain responses were also correlated positively.

Accuracy and reliability of a dynamic biomechanical skin measurement probe for the analysis of stiffness and viscoelasticity

A novel instrument has been devised for the in vivo examination of the dynamic biomechanical properties of skin. These properties include stiffness and viscoelasticity. The advantage of the device is its ability to examine the skin dynamically, thereby eliminating preconditioning effects. Furthermore, it is portable, hand-held and easy to operate in the clinical environment. The objective of this study was to determine the accuracy and reliability of the dynamic biomechanical skin measurement (DBSM) probe. The accuracy was determined by examining a series of silicone elastomer specimens. A comparison of the shear modulus (G*), obtained from a static indentation system, with stiffness, obtained from the DBSM probe, was performed. The reliability was determined by examining both silicone elastomers and forearm volar skin in vivo. In both cases assessment was by six different operators (inter-reliability) and also by an individual operator (intra-reliability). Statistical analysis was performed using Levene's test of homogeneity and analysis of variance to ascertain if there were significant differences between operators (inter-reliability) and with one individual operator (intra-reliability). It can be concluded, from this study, that the DBSM probe is accurate (R2 = 0.96, p = 0.01). It is also inter- and intra-reliable when assessing elastomer stiffness and skin stiffness. However, phase lag was not found to be a useful indicator of device reliability. It is anticipated that this device will be used to examine dermatological conditions and the benefits, or otherwise, of treatment. The DBSM probe promises to contribute to the objective measurement of physical properties of the skin in future investigative studies.

Quantitative Evaluation of Eyelid Elasticity Using the Cutometer SEM575 and Its Clinical Application in Assessing the Efficacy of Tacrolimus Ointment Treatment in Eyelid Atopic Dermatitis

PURPOSE

To study the clinical efficacy of a noninvasive suction device that measures eyelid skin elasticity in the treatment of eyelid atopic dermatitis using tacrolimus (FK-506) ointment.

METHODS

Ten patients with eyelid atopic dermatitis treated with tacrolimus ointment and 10 normal volunteers participated in this study. The cutometer SEM575 was used to quantitatively evaluate eyelid skin elasticity. Severity of the eyelid atopic dermatitis was scored, and comparisons were made before and after treatment.

RESULTS

Skin elasticity of patients with eyelid atopic dermatitis was significantly lower than that of normal volunteers (31.3 +/- 5.2% vs 40.2 +/- 7.8%, respectively). Skin elasticity of patients with eyelid atopic dermatitis improved significantly to 37.5 +/- 6.3% after treatment with tacrolimus ointment. The total severity score for eyelid atopic dermatitis also improved from 2.77 +/- 1.11 to 1.77 +/- 1.15.

CONCLUSION

Measurement of skin elasticity using the cutometer SEM575 is a useful and reliable method for objective and quantitative evaluation of eyelid skin condition in patients with eyelid atopic dermatitis. The efficacy of short-term tacrolimus ointment treatment in patients with eyelid atopic dermatitis was confirmed quantitatively using this apparatus.

Effects of aging and postmenopausal hypoestrogenism on skin elasticity and bone mineral density in Japanese women

Skin collagen content and bone mass decrease with aging. Loss of collagen from the skin might decrease its elasticity. We investigated associations between skin elasticity, bone mineral density (BMD), age, and menopausal hypoestrogenism. Thirty-eight healthy Japanese postmenopausal women were studied (mean age, 55.7 +/- 5.9 yr; range, 48 to 71). Skin elasticity was measured using a suction device applied to the dorsal right forearm. BMD values of L2 to 4 vertebral bodies were measured by dual-energy X-ray absorptiometry. Age showed significant negative correlations with both skin elasticity and BMD (r = -0.57, p<0.001 and r = -0.40, p<0.05, respectively). Years since menopause also showed significant negative correlations with both skin elasticity and BMD (r = -0.51, p<0.01 and r = -0.41, p<0.05, respectively). We also found a positive correlation between skin elasticity and BMD in these postmenopausal women (r = 0.44, p<0.01). In conclusion, we demonstrated declining skin elasticity and bone mass in postmenopausal women to possibly be age- and estrogen-related. Additionally, decreased skin elasticity might serve as a predictor of bone loss in postmenopausal women.

Relationship Between NMF (Lactate and Potassium) Content and the Physical Properties of the Stratum Corneum in Healthy Subjects

Natural moisturizing factor (NMF) of the stratum corneum (SC) has been established to play important roles in the physical properties of the SC. Few studies, however, have investigated the specific influences of NMF components other than the amino acids. In this study, therefore, we focus on the relationship between the ion content and physical properties of the SC in 40 healthy subjects. Changes in the physical properties of the SC induced by the extraction of NMF were equivalent to the changes that took place from summer to winter, demonstrating the important role of NMF in the physical properties of the SC in healthy subjects. The seasonal changes in the physical properties of the SC from summer to winter were accompanied by significant decreases in the levels of lactate, potassium, sodium, and chloride in the SC. Lactate and potassium were the only components found to correlate significantly with the state of hydration, stiffness, and pH in the SC. Interestingly, the levels of lactate and potassium in the SC were also significantly correlated. Moreover, potassium lactate restored the SC hydration state decreased by extraction of NMF. These results suggest that lactate and potassium may play roles in maintaining the physical properties of the SC in healthy subjects.

Skin elasticity meter or subjective evaluation in scars: a reliability assessment

Various methods are available for evaluating the elasticity of scars. However, the reliability and validity of these methods have been sparsely examined. The aim of this study was to examine the reliability of the subjective evaluation of scar pliability, while at the same time testing the reliability of the measurements of a non-invasive suction device (Cutometer Skin Elasticity Meter 575) on scars. Four observers assessed 49 scar areas of 20 patients with a subjective assessment of pliability. Subsequently, each observer measured the scar areas with the Cutometer. The intraclass correlation coefficients (ICC) of the elasticity (Ue) and extension (Uf) parameters of the Cutometer were acceptable (r = 0.76 and 0.74, respectively) when a single observer carried out the measurements. The subjective assessment of pliability needs to be completed by two or more observers to make the evaluation reliable (r = 0.79). The concurrent validities between the subjective pliability-assessment and each of the Cutometer parameters were statistically significant and ranged from r = 0.29-0.53. The correlations between each of the Cutometer parameters were high and statistically significant (r > or = 0.71).

CONCLUSION

A single observer can reliably use the Cutometer for the elasticity measurements of scars. Furthermore, either Ue or Uf, instead of all five elasticity values provided by the Cutometer, can be adequately used for the elasticity measurements of scars. The subjective assessment of pliability of scars can only be assessed reliably when completed by two or more observers. The concurrent validity showed that all Cutometer parameters, except for visco-elasticity (Uv), and the subjective assessment of pliability measured the same characteristic of a scar.

Skin tensile properties revisited during ageing. Where now, where next?

Skin and its subcutaneous layer represent a complex composite of tissues, whose mechanical characteristics depend upon the mutual interdependence of their constituent parts. The molecular and microanatomical structures of skin allow it to meet normal mechanical demands. They also determine the orientation both of Langer's lines and of relaxed skin tension lines. Ageing, photodamage, hormones, drugs, cosmetic products and dermatological interventions may modify the skin's overall tensile properties. In turn, any variation in mechanical stresses and strains imposed upon the skin's connective tissue influences the metabolic activity and phenotypic expression of fibroblasts and dermal dendrocytes. The viscoelastic functions of ageing skin can be tested by altering the orientation and magnitude of imposed stresses and strains over time. Assessment can be made of various biomechanical properties of skin: tensile, torsional, acoustic shear wave, indentation, impact and elevation. Such objective biomechanical assessments may be applied to dermocosmetic interventions, so providing opportunity for progress in cosmetic dermatological science.

Involvement of changes in stratum corneum keratin in wrinkle formation by chronic ultraviolet irradiation in hairless mice

Chronic exposure to ultraviolet (UV) radiation alters components of the skin. We previously reported that chronic low-dose UV irradiation induced wrinkle formation but did not significantly alter dermal components of hairless mice. In the present study, we examined whether the epidermal changes by UV irradiation could contribute to wrinkle formation. Hairless mice were irradiated with one-third the minimum erythema dose (MED) of UVB (20 mJ/cm2) and UVA (14 J/cm2) for 10 weeks, and followed up for another 24weeks without irradiation. Fine wrinkles were detected following irradiation, which existed even 24 weeks after cessation of irradiation. An increase in the viscoelastic proportion of the total distension (Uv/Ue) was recognized in irradiated mice, which may be related to wrinkle formation. In the epidermis, an increase in the amount of transepidermal water loss and a decrease in the water content of the stratum corneum were seen after 10 weeks of UV irradiation, neither of which recovered during the 24-week observation period. In addition, there was a significant increase in the amount of stratum corneum keratin after 10 weeks of irradiation, which persisted during the 24-week follow-up. The results of our study suggest that chronic low-dose UV irradiation primarily alters the epidermal rather than the dermal components of the skin. In addition, our results indicate that the increased keratin content of the stratum corneum may be involved in the alteration of the physical properties of the skin. This process could be one of the early events of wrinkle formation.

The influence of solid lipid nanoparticles on skin hydration and viscoelasticity--in vivo study

Effects on skin hydration and viscoelasticity are important criteria during the development of novel cosmetic formulations. This study focuses on the in vivo performance of a conventional o/w cream and of the same cream enriched with solid lipid nanoparticles (SLN). Influences on skin hydration and viscoelastic properties were investigated with validated devices (Corneometer and Cutometer). After an application period of 4 weeks, significant changes in skin hydration were detected for both formulations. The SLN-enriched cream was significantly more effective than the conventional cream (+24% for the cream and +31% for the SLN-cream). The viscoelastic parameters UF and UA/UF remained almost unchanged, which is attributed to the young age of the volunteers. At this stage, SLN represent a promising compound for hydrating new cosmetic formulations.

Mechanical properties of the skin: a comparison between two suction cup methods

BACKGROUND/AIMS

The objective measure of mechanical properties of the skin is relevant to the clinician as well as to the researcher concerned with skin physiology. The lack of standardization among methods used to obtain visco-elastic data from the skin is however, apparent and represents an obstacle to comparison of the results derived from the various studies concerning the subject.

METHODS

The mechanical properties of the ventral forearm were studied in 35 healthy volunteers. The Dermaflex and the DermaLab (Both Cortex Technology, Hadsund, Denmark) were compared. The results were analyzed with descriptive statistics and correlations using non-parametric methods. Measurement accuracy was assessed using coefficient of variation. Sub analysis was made in groups according to gender and age.

RESULTS

The overall correlations between the two methods were moderate (r = 0.383-0.437). A greater coefficient of variation was found in the DermaLab machine. Significant differences were found between all values of both methods when comparing the mechanical properties of the skin in 30-39 years olds versus the group of 40-58 years olds. No differences were found between the genders.

CONCLUSIONS

The results indicate that both methods are useful in the study of the mechanical aspects of the skin, especially for detecting age-related changes. The Dermaflex seems to produce more accurate for data. This is thought to be due to the conceptual design differences between the two methods. The methods measure related but not identical values of the mechanical properties of the skin, as reflected by the limited positive correlation between them.

Scar assessment tools: implications for current research

Scarring is considered a major medical problem that leads to cosmetic and functional sequelae. Scar tissue is clinically distinguished from normal skin by an aberrant color, rough surface texture, increased thickness (hypertrophy), occurrence of contraction, and firmness. Marked histologic differences are the change in dermal architecture and the presence of cells such as the myofibroblast. Many assessment tools are available for analysis of pathologic conditions of the skin; however, there is no general agreement as to the most appropriate tools for evaluation of scar tissue. This review critically discusses currently available objective measurement tools, subjective assessment tools, and potential devices that may be available in the future for scar assessment.

Risk Factors for Insufficient Fixation of Microkeratome During Laser in situ Keratomileusis

PURPOSE

To investigate the potential risk factors leading to insufficient fixation of a microkeratome during laser in situ keratomileusis (LASIK), especially in Asian eyes.

METHODS

We performed a retrospective analysis of 1809 eyes of 972 patients that underwent LASIK. Profiles of patients (age, sex, past medical history, width of palpebral fissure, corneal power, and postoperative clinical course) whose operations were discontinued due to insufficient fixation were compared to all LASIK patients.

RESULTS

Insufficient fixation was observed in 18 eyes of 16 patients. Those patients were significantly younger (26.1 +/- 5.5 yr) compared to all patients (32.3 +/- 8.6 yr). Mean keratometric power was 42.40 +/- 1.37 D in patients with insufficient fixation and 43.60 +/- 1.40 D in all patients (P < .001). Maximum width of palpebral fissure with eyes wide open was 0.96 +/- 0.20 mm in patients with insufficient fixation, and 1.10 +/- 0.19 mm in all patients (P = .0015). These patients subsequently underwent LASIK utilizing combinations of cooling, frequent corticosteroid instillation for several hours, and lateral canthotomy.

CONCLUSION

Narrow palpebral fissures commonly found in Asian populations might be a risk factor for insufficient fixation of a microkeratome in LASIK, especially in young patients with flat corneas.

Comparative effect of hormone replacement therapy on bone mass density and skin tensile properties

OBJECTIVES

connective tissues constitutive of skin and bones are affected during the climacteric. Hormone replacement therapy (HRT) can help mitigate their atrophy. The aim of this study was to compare the HRT effect on the skin tensile properties and bone mass density.

METHODS

a total of 120 postmenopausal women (60 untreated, 60 receiving HRT) were enrolled in the study. Skin tensile properties were assessed on the volar forearm using a computerized suction device. A 500 mbar suction was applied through a 4-mm diameter hollow probe. Two operating modes were applied using a steep and a progressive suction, respectively. BMD was measured on the hip, femoral neck and lumbar spine using dual X-ray absorptiometry.

RESULTS

in both groups of women skin elasticity was correlated with BMD. HRT significantly reduced the climacteric-associated decline in skin elasticity. A trend in better preserved BMD was also found in these women without, however, reaching significance.

CONCLUSIONS

it is concluded that measures of the skin tensile properties can be sensitive enough to disclose HRT efficacy upon connective tissue atrophy. Any decrease in skin elasticity during the climacteric should prompt to perform a BMD assessment.

Relationship between bone mass density and tensile strength of the skin in women

BACKGROUND

Skin and bone may be affected similarly during the climacteric and during long-term corticotherapy. Little is known about the correlation between the respective alterations in bone mass density (BMD) and tensile strength of the skin.

MATERIALS AND METHODS

A total of 100 women aged 19-88 years, receiving, or not, hormone replenishment therapy or systemic corticosteroids, were enrolled in the study. Tensile strength of the inner forearm skin was measured using the suction method operated in both the steep and progressive-force application modes. BMD was measured by dual X-ray absorptiometry at the hip, femoral neck and lumbar spine.

RESULTS

Being heterogeneous, the population of volunteers yielded a wide range of BMD and cutaneous tensile strength values. However, significant correlations were found between BMD and tensile skin parameters. In particular, a positive correlation was yielded between the biological elasticity of skin and the BMD of the hip and femoral neck.

CONCLUSION

An overall correlation is shown between skin elasticity on a relatively sun-protected area and cortico-trabecular BMD.

Outcome measures for evaluation of scar: a literature review

The number of interventions and the related costs of management of scar are increasing. Despite increasing emphasis on evidence-based practice, there is little comparative data on which to base treatment selection. The ability of a therapist to evaluate the natural progression of a scar or treatment efficacy may be hampered by the nature of the particular scar, the lack of conformity in descriptions of scar, and the lack of reliable standardized outcome measurements. This literature review seeks to clarify the constructs measured for scar and present the measures currently available for use.

A controlled evaluation of dermabrasion versus CO2 laser resurfacing for the treatment of perioral wrinkles

Facial skin treatments with laser resurfacing, dermabrasion, and chemical peels were responsible for a significant portion of the 2.7 million cosmetic procedures performed in 1998. Perioral wrinkles are a common problem for which plastic surgical consultation is obtained. The aim of this study was to compare and quantify the advantages and disadvantages of laser resurfacing versus dermabrasion in the treatment of perioral wrinkles. Twenty female patients provided informed consent and participated in the study. Half of the perioral area was treated with dermabrasion and half was treated with the UltraPulse CO2 laser. The two procedures were compared using high-quality photographs; a biophysical evaluation of skin color, hydration, and mechanical properties; and patient evaluation of outcomes. Photographs were evaluated by 10 board-certified plastic surgeons who were blinded to the treatment methods. The laser treatment had a significantly higher erythema score at 1 month and a small but significantly greater improvement in perioral wrinkles at 6 months. Thirteen subjects selected the laser treatment as producing the best result, despite the greater intraoperative pain for this procedure. Biomechanical measurements suggest that the laser treatment produced a skin state more similar to skin in younger patients, presumably with higher levels and/or greater organization of the collagen and elastin. Patient preference was inferred from the resurfacing method that they would recommend to a friend. Although the laser was selected as the best result in a majority of cases, patient preference was equally distributed between the two treatments. The authors think that by studying and quantifying the biophysical changes that occur as a result of CO2 laser resurfacing, greater improvements in restoring actinic damage (e.g., wrinkles) can be achieved. Patients consider more than the objective skin changes from a resurfacing technique when making a recommendation to a friend.

Late effects of dose fractionation on the mechanical properties of breast skin following post-lumpectomy radiotherapy

PURPOSE

Late radiation-induced skin effects were studied in a multicenter project using our new sensitive noninvasive viscoelasticity skin analyzer (VESA).

METHODS AND MATERIALS

Skin viscoelasticity and anisotropy were examined quantitatively in symmetric areas of both breasts in healthy women and in 110 breast cancer patients who underwent lumpectomy and radiotherapy. These parameters were evaluated by the VESA measurement of the speed of elastic wave propagation in the skin; higher VESA readings correspond to higher skin stiffness. Effect of radiation was estimated by comparison of the data recorded in the irradiated versus nonirradiated breast of the same patient.

RESULTS

Skin viscoelasticity and anisotropy were similar in contralateral areas of the breasts in healthy controls as well as in the nonirradiated breasts of the patients. With age, skin viscoelasticity decreased and anisotropy increased similarly in both breasts. Radiotherapy, by a total radiation dose in the range of 45-50 Gy given with 1.8 Gy/fraction (fx) resulted in a similar minor, but still statistically significant, increase of skin stiffness relative to control. The effect was more pronounced when a dose of 50 Gy was given in a higher dose/fraction of 2.5 Gy.

CONCLUSION

We found that the increase in dose of radiation per fraction had much more impact on the development of late skin effects than elevation in the total dose given.

Evaluation of skin viscoelasticity and anisotropy by measurement of speed of shear wave propagation with viscoelasticity skin analyzer

Skin viscoelasticity was evaluated by a fast, noninvasive assay based on the measurement of the speed of elastic shear wave propagation in the skin by a new portable and user-friendly viscoelasticity skin analyzer. The range of speed of elastic shear wave propagation measured by viscoelasticity skin analyzer allows the evaluation of the stiffness of a wide spectrum of artificial materials as well as the viscoelasticity of skin of laboratory animals and human subjects. The directional nature of the measurement enables to monitor the anisotropy of the materials tested. The speed of elastic shear wave propagation was shown to have a positive correlation with the stiffness of the material tested. In symmetric contralateral areas of intact skin in rabbit ears, similar viscoelasticity and anisotropy were observed. Twenty-four hours after the induction of local edema by croton oil, skin stiffness and anisotropy were significantly increased. In healthy human subjects of both sexes significant variations in skin stiffness and anisotropy were observed in three different skin areas along the forearms, but the speed of elastic shear wave propagation was similar in the symmetric contralateral areas. Age (17-65 y) seemed to have a limited effect on the viscoelasticity of the forearm skin. Hydrating creams decreased the stiffness of the forearm skin for only approximately 3 h. The stiffness and anisotropy of the skin of the breasts in female volunteers (20-86 y) increased with age, but the speed of elastic shear wave propagation was similar in symmetric contralateral areas in the same individuals. Based on these results, we propose the application of the viscoelasticity skin analyzer in experimental and clinical practice for quantitative evaluation of skin condition.

Quantification of skin elasticity changes associated with pulsed carbon dioxide laser skin resurfacing

BACKGROUND

While skin resurfacing using pulsed carbon dioxide lasers appears to have a skin-tightening effect clinically, the debate continues over its actual effects on dermal collagen.

OBJECTIVES

To provide quantitative measures of skin elasticity changes associated with pulsed carbon dioxide laser skin resurfacing and to introduce to the facial plastic surgery community the Cutometer SEM 575 skin elasticity meter, an instrument that is useful in the measurement of skin elasticity.

SETTING

University-based facial plastic surgery clinic and wound healing laboratory.

DESIGN

Intervention.

MAIN OUTCOME MEASURES

Measurements taken prior to and 6 months after procedure.

SUBJECTS AND INTERVENTION

Thirty-two patients undergoing pulsed carbon dioxide full-face laser skin resurfacing participated. There were 12 test sites measured in 6 aesthetic units per participant. The Cutometer SEM 575 skin elasticity meter was used to measure skin elasticity changes accompanying this procedure. This device measures skin deformation with an accuracy of 10 microns.

RESULTS

The change in elastic recovery (Ur/Ue) was determined. At all 6 of the facial sites, there was a statistically significant increase in skin elasticity (P < .001). Overall, there was an 18.2% improvement in skin elasticity. Site-specific changes ranged from 9% (forehead) to 22% (prejowl and periorbital).

CONCLUSIONS

Skin resurfacing with the pulsed carbon dioxide laser produces a true skin-tightening effect. The Cutometer is a valuable instrument that permits accurate quantification of skin elasticity and may be useful in the evaluation of other facial plastic procedure results.

Climacteric skin ageing of the face--a prospective longitudinal comparative trial on the effect of oral hormone replacement therapy

BACKGROUND

It is still a matter of debate whether HRT improves the physical quality of sun damaged skin.

OBJECTIVES

To compare in a prospective longitudinal study the effects of climacteric aging controlled or not by HRT upon the tensile properties of facial skin.

METHOD

A total of 140 women aged 40-52 years were enrolled in the study. The HRT group comprised 90 volunteers and a control group encompassed 50 non recipient volunteers. Yearly measurements of tensile functions of facial skin were performed for 5 years. A computerized suction device equipped with a 2-mm diameter hollow probe derived tensile variables quantifying skin distensibility, viscosity and elasticity.

RESULTS

Climacteric aging was characterized by increased skin distensibility (1.1% per year) and viscosity (1.3% per year) mirrored by a decrease in elasticity (1.5% per year). HRT helped mitigate such changes. However, the HRT efficacy was not similar in all volunteers. Groups of good and poor responders were clearly identified as far as benefit on skin elasticity was concerned.

CONCLUSION

The beneficial effect of HRT upon climacteric skin aging of the face is confirmed, at least in a subgroup of menopausal women.

[New prospects in the etiology of groin hernias]

AIM OF THE STUDY

To explore new etiological hypotheses of groin hernias, using a biomechanical and histochemical study of the transversalis fascia and of the rectus sheath.

PATIENTS AND METHODS

The samples were collected from 63 patients with uni- or bilateral hernias and from 30 control subjects without hernia. The biomechanical properties were assessed using a computerized-suction device (Cutometer). Sections were stained with hematoxylin and eosin, Masson-trichrome and double-stained with sirius red and orcein.

RESULTS

There was no major biomechanical and histological difference between the control and patient aponeuroses. The patient fasciae from the non-herniated sides presented an increased extensibility and elasticity, as compared with the control fasciae. Those fasciae also showed a collagen framework with disorganized areas and an increased number of isolated fibers.

CONCLUSION

The transversalis fascia from the nonherniated side appears to be a pathological fascia. Therefore, a connective tissue pathology seems to be involved in the genesis of groin hernias, with a preferential manifestation in the inguinal region which affects mainly the collagen fibers.

Cranio-caudal differences in granulation tissue formation: an experimental study in the rat

This study examined potential regional differences in the deposition of granulation tissue in cellulose sponges placed in the dorsum of rats. Four cellulose sponge implants, 10 x 10 x 5 mm in size, two in cranial and two in caudal positions, were used to induce granulation tissue formation in the back of the rat. A cranio-caudal difference in connective tissue formation was assessed from 1 to 24 weeks after implantation. Granulation tissue ingrowth, measured histomorphometrically, was enhanced at 2 weeks and the surrounding capsule was thinner from 1 to 3 weeks in implants located in the cranial part of the back. In the cranial position, the number of fibroblasts, assessed semiquantitatively, was higher and the ratio of inflammatory cells to fibroblasts lower at 2-3 weeks. Also, the ratio of hydroxyproline content to total nitrogen content was higher after the first week in cranial specimens. Thus, a distinct cranio-caudal difference in the proliferative phase was observed. These results show the obvious practical considerations underlying the need for randomization or comparison between implants from exactly corresponding cranio-caudal locations.