In the face and neck, keloid scar distribution is related to skin thickness and stiffness changes associated with movement.

Keloid scars tend to occur in high-tension sites due to mechanical stimuli that are involved in their development. To date, a detailed analysis of keloid distribution focused specifically on facial and neck areas has not been reported, and limited literature exists as to the related mechanical factors. To rectify this deficiency of knowledge, we first quantified the facial and neck keloid distribution observed clinically in 113 patients. Subsequently, we performed a rigorous investigation into the mechanical factors and their associated changes at these anatomic sites in healthy volunteers without a history of pathologic scarring. The association between keloid-predilection sites and sebaceous gland-dense and acne-prone sites was also examined. To assess skin stretch, thickness and stiffness, VECTRA, ultrasound and indentometer were utilised. Baseline skin stiffness and thickness were measured, as well as the magnitude of change in these values associated with facial expression and postural changes. Within the face and neck, keloids were most common near the mandibular angle (41.3%) and lateral submental (20.0%) regions. These areas of increased keloid incidence were not associated with areas more dense in sebaceous glands, nor linked consistently with acne-susceptible regions. Binomial logistic regression revealed that changes in skin stiffness and thickness related to postural changes significantly predicted keloid distribution. Skin stiffness and thickness changes related to prolonged mechanical forces (postural changes) are most pronounced at sites of high keloid predilection. This finding further elucidates the means by which skin stretch and tension are related to keloid development. As a more detailed analysis of mechanical forces on facial and neck skin, this study evaluates the nuances of multiple skin-mechanical properties, and their changes in a three-dimensional framework. Such factors may be critical to better understanding keloid progression and development in the face and neck.

Reassessing the normal toe-brachial index in young healthy adults.

OBJECTIVE: The purpose of this study was to measure the toe-brachial index (TBI) in healthy young adults and to compare it with the accepted reference range. METHODS: Medical students from the undergraduate classes at the University of British Columbia were prospectively recruited. Participants were surveyed on physical parameters (height, weight), lifestyle factors (physical activity and type, smoking status, alcohol consumption), and medical history (current medications, medical conditions, family history). Bilateral brachial, ankle (using both dorsalis pedis and posterior tibial arteries), and toe blood pressures were measured by stethoscope, Doppler device, and photoplethysmograph, respectively. Ankle-brachial index (ABI) and TBI were calculated and assessed against published reference ranges. TBI was calculated as the mean great toe blood pressure divided by the average of the higher arm systolic blood pressures. RESULTS: Seventy-three medical students with a mean age of 24.3 ± 2.0 years without any comorbidity were studied. Participants maintained relatively healthy lifestyles (hours of activity per week, 4.6 ± 2.7; body mass index, 21.9 ± 2.4). Caffeine and alcohol consumption was modest (8.2 ± 8.0 and 1.7 ± 2.6 servings/week, respectively). There were no current or past smokers. No significant differences in lifestyle factors were observed between men and women. Mean brachial blood pressure was 116 ± 10 mm Hg (left) and 120 ± 11 mm Hg (right). Mean TBI was 0.98 ± 0.12 (left) and 0.97 ± 0.12 (right) for men and 0.95 ± 0.21 (left) and 0.94 ± 0.21 (right) for women. The overall ABI was 1.10 ± 0.07 when averaged by gender and side. Whereas men had significantly higher blood pressures in the arm, toe, and ankle compared with women, these differences disappeared when the indices were determined. There were no significant differences in TBI or ABI between men and women. CONCLUSIONS: In comparison to published reference values, the TBI in young, healthy individuals is significantly higher. Whereas no gender difference existed, greater variability of the TBI was observed in women. Further studies are recommended to determine if the threshold for diagnosis of peripheral arterial disease based on TBI should be raised.