Skin Expansion Research Articles

Complications of Skin Expansion in the Pediatric Population: A 10-year Retrospective Study

Complications of Skin Expansion in the Pediatric Population: A 10-year Retrospective Study

Reveal mechanical and optical properties changes during prolonged skin stretching via in vivo continuous investigation

Skin expansion is a well-established technique in plastic surgery, and recent studies have highlighted its potential in promoting hair regeneration. This study aimed to explore how the mechanical and optical properties of skin change during a prolonged stretching process. A hybrid method was developed to assess, in vivo, the effects of an 8-day skin stretching protocol—previously used in hair regeneration research—on the dorsal skin of mice. This method combined mechanical and optical measurement systems. Tensile stress–strain curves were generated using a spring-based setup, while optical properties such as scattering and birefringence were analyzed with a polarimetry imaging system that incorporated the Mueller matrix (MM) and Mueller matrix polar decomposition (MMPD) methods. The results showed that Young's modulus increased from approximately 5 kPa on day 1 to 60–100 kPa by days 6–8, indicating collagen fiber straightening and increased stiffness. Optical analysis revealed greater anisotropy in both scattering and birefringence, as reflected by changes in MM elements and MMPD results. These changes suggest skin adaptation and regeneration, particularly within the first 24 h of stretching. Interestingly, alterations in optical properties closely mirrored changes in mechanical properties, pointing to a coordinated process of structural remodeling and functional adaptation in the skin. These findings offer valuable insights into skin remodeling and adaptation, which could guide future tissue engineering strategies.

Total Ankle Arthroplasty Incision Management: What Matters? A Systematic Review

Modern advancements in total ankle arthroplasty techniques and implants have increased the popularity of this treatment for ankle osteoarthritis. The preeminent approach for ankle replacement involves an anterior incision, however, wound complications with this approach provide a persistent challenge to surgeons. The present study was conducted to synthesize current data on ankle replacement wound complications via an anterior approach. A systematic review was completed including studies published from 1993 to present that employed an anterior approach and had precise criteria for wound healing and revisions. Twenty-nine studies, with level 3 to 4 evidence and moderate to serious bias, were included for a total of 6,986 ankle arthroplasties. The rate of wound healing without any complication was 90.38%. Minor dehiscence occurred in 6.00% of cases, while major wounds or infections occurred in 3.62%. Across 2,966 implants, the rate of major wounds or infections decreased from 7.03% before 2013 to 4.75% after 2013 (p = 0.034). Limited comparisons involving simple suture closure to various adjunct wound management techniques including negative pressure wound therapy, 2-octyl cyanoacrylate, platelet-rich plasma, dehydrated human amniotic membrane allograft, non-invasive skin expansion strips, compression wound dressings, tranexamic acid, surgical helmets, tourniquets, ankle arthrodesis, and lateral approach ankle arthroplasty, yielded non-significant differences (p > 0.18). Therefore, contemporary techniques, patient selection, and current implants may be leading to better soft tissue healing. As ankle replacement continues to surge in popularity, further research is needed to evaluate causative factors in successful anterior incision healing. Level of Clinical Evidence3

Mechanical force regulates the paracrine functions of ADSCs to assist skin expansion in rats

BackgroundIn the repair of massive tissue defects using expanded large skin flaps, the incidence of complications increases with the size of the expanded area. Currently, stem cell therapy has limitations to solve this problem. We hypothesized that conditioned medium of adipose-derived stem cells (ADSC-CM) collected following mechanical pretreatment can assist skin expansion.MethodsRat aortic endothelial cells and fibroblasts were cultured with ADSC-CM collected under 0%, 10%, 12%, and 15% stretching force. Ten-milliliter cylindrical soft tissue expanders were subcutaneously implanted into the backs of 36 Sprague-Dawley rats. The 0% and 10% stretch groups were injected with ADSC-CM collected under 0% and 10% stretching force, respectively, while the control group was not injected. After 3, 7, 14, and 30 days of expansion, expanded skin tissue was harvested for staining and qPCR analyses.ResultsEndothelial cells had the best lumen formation and highest migration rate, and fibroblasts secreted the most collagen upon culture with ADSC-CM collected under 10% stretching force. The skin expansion rate was significantly increased in the 10% stretch group. After 7 days of expansion, the number of blood vessels in the expanded area, expression of the angiogenesis-associated proteins vascular endothelial growth factor, basic fibroblast growth factor, and hepatocyte growth factor, and collagen deposition were significantly increased in the 10% stretch group.ConclusionsThe optimal mechanical force upregulates specific paracrine proteins in ADSCs to increase angiogenesis and collagen secretion, and thereby promote skin regeneration and expansion. This study provides a new auxiliary method to expand large skin flaps.

A machine learning approach to predict in vivo skin growth

Since their invention, tissue expanders, which are designed to trigger additional skin growth, have revolutionised many reconstructive surgeries. Currently, however, the sole quantitative method to assess skin growth requires skin excision. Thus, in the context of patient outcomes, a machine learning method which uses non-invasive measurements to predict in vivo skin growth and other skin properties, holds significant value. In this study, the finite element method was used to simulate a typical skin expansion protocol and to perform various simulated wave propagation experiments during the first few days of expansion on 1,000 individual virtual subjects. An artificial neural network trained on this dataset was shown to be capable of predicting the future skin growth at 7 days (avg. R2=0.9353\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R^2 = 0.9353$$\\end{document}) as well as the subject-specific shear modulus (R2=0.9801\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R^2 = 0.9801$$\\end{document}), growth rate (R2=0.8649\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R^2 = 0.8649$$\\end{document}), and natural pre-stretch (R2=0.9783\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$R^2 = 0.9783$$\\end{document}) with a very high degree of accuracy. The method presented here has implications for the real-time prediction of patient-specific skin expansion outcomes and could facilitate the development of patient-specific protocols.

Concentrated growth factor intradermal injection assisted super-thin flap expansion for repairing skin defects: A randomized, single blinded, split-site study.

The super-thin skin flap formed by skin and soft tissue expansion has large area and good ductility, so it can be used to repair skin defects. However, because the flap is thin, the blood flow in the dermis of the super-thin expanded flap is weakened, and flap rupture and necrosis after secondary flap transfer may occur. To compare the skin thickness difference between the expanded ultrathin flaps injected with concentrated growth factor (CGF) and the blank group or saline group. From June 2021 to December 2023, 10 patients (44 sites) with large-area scars or skin tumors were treated, and a single center half randomized controlled trial was conducted. The test site of expander implantation was divided into three groups: intradermal injection of CGF group, normal saline group and blank group. The same amount of expansion was performed every 1-2 weeks, and CGF or normal saline was injected into the dermis every 4 weeks, a total of three times. After 2-3 months of expansion, color Doppler ultrasound was used to measure the skin thickness of each group. Compared with the blank group, the skin thickness of CGF group was 1.75 ± 0.08 mm, and that of BLA blank group was 1.42 ± 0.07 mm, with statistically significant difference (p < 0.0001); In the other group, compared with the saline group, the skin thickness of the CGF group was 1.54 ± 0.08 mm, and the average skin thickness of the saline group was 1.40 ± 0.08 mm, with significant difference between the two groups (p = 0.0067). CGF intradermal injection can increase the skin thickness of super-thin skin flap in the process of soft tissue expansion, which is a safe and effective auxiliary method of skin expansion.

Comparing Energy-Based Devices for Striae Improvement: A Systematic Review and Network Meta-Analysis of Randomized Controlled Trials.

Striae distensae (SD) are cutaneous lesions that are caused by hormones or mechanical stress leading to rapid expansion of skin. Therefore, SD are now a cosmetic concern. However, improving SD is notoriously difficult. Among different treatments, energy-based devices (EBDs) are much more effective and controllable. The aim of this review was to determine the most effective type of EBD for improving the appearance of striae. The study was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The population comprised patients suffering from striae. Different types of EBDs used to improve striae were compared. The primary outcome of the reduction in the width of striae was evaluated. A random-effects model was performed. The means and standard deviations were extracted. Eighteen randomized controlled trials were included. The network meta-analysis revealed that after a comparison among the 4 types of EBDs, no significant differences were observed in the reduction of striae width. Radiofrequency, ablative lasers, nonablative lasers, and intense pulsed light are all effective treatments for reducing the striae width. None of them was superior to the others. However, radiofrequency and ablative lasers may have the highest chance of improving the appearance of striae.

A Case Report of Arrhythmia Caused by Skin Expander Implantation

A 51-year-old female patient suffered facial burns during her youth. Following the healing of the wound, a skin expander was implanted on 7 December 2021 to address scar contracture. The preoperative electrocardiogram (ECG) indicated sinus rhythm within the normal range. Color Doppler ultrasound revealed no abnormalities. The patient had no history of hypertension, heart disease, diabetes, arrhythmia, or other cardiovascular and cerebrovascular conditions. On 16 June 2022, the skin expander was removed, and facial scar resection was performed. The routine ECG showed ventricular premature beats. During the operation, when the surgeon pulled and compressed the neck dilator, significant arrhythmia was observed, with the heart rate dropping below 50 beats per minute and frequent ventricular premature beats occurring. The surgeon promptly halted the procedure, resulting in immediate relief of the patient's pain. Subsequently, the ventricular premature beats ceased, and normal sinus rhythm was restored. Once the heart rate exceeded 60 beats per minute, the surgeon resumed the operation, but ventricular premature beats persisted. After removing the dilator, the heart rate gradually returned to normal, and no further arrhythmia occurred. The patient recovered smoothly post-operation, with stable vital signs and no reported discomfort. She safely returned to the ward. It was determined that the patient's arrhythmia was caused by the compression of the carotid sinus due to the stretching of the neck dilator.

The impact of national health insurance on the cost of auricular reconstruction with skin expansion for microtia in China: A single-center retrospective study based on 1290 surgeries

BackgroundCongenital microtia presents challenges that encompass physical disabilities and psychosocial distress. It is reported that people with low income have a higher possibility of giving birth to babies with congenital malformations. At the end of June 2023, auricular reconstruction was partially incorporated into national health insurance in our hospital. MethodsBriefly, 1290 surgeries, including stage-I and stage-II auricular reconstruction with tissue expansion were performed in 2023, involving 779 patients. Patient data, including age, sex, length of stay, residence, and costs, were retrieved from the electronic medical record system. The final cost before and after health insurance coverage, as well as the medical insurance reimbursement ratio in each province and municipality were statistically analyzed. ResultsFollowing insurance coverage, a significant increase in the number of surgeries was observed (514 [39.84%] vs. 776 [60.16%], χ2 = 45.99, p = 0.000), with notable reductions in out-of-pocket costs for unilateral and bilateral stage-I and -II auricular reconstructions ($3915.01 vs. $6645.28, p < 0.05; $11546.80 vs. $5198.08, p < 0.05). Disparities in reimbursement rates across regions were evident, but showed no correlation to the local GDP per capita. There was a positive correlation between the length of stay and inpatient cost. Patient’s age was not related to the inpatient cost, but to the length of stay. ConclusionThe health insurance coverage for microtia treatment significantly alleviated financial burdens on the patients’ family and increased the number of auricular reconstruction surgeries. These findings underscore the critical role of insurance coverage in enhancing healthcare accessibility and affordability for patients with congenital microtia.

Abstract PO3-22-12: Clinical feasibility of nipple sparing mastectomy (NSM) followed by immediate reconstruction based on direct-to-implant technique

Abstract [Background] The development of NSM approach combined with immediate implant-based breast reconstruction (IBBR) for patients with earlystage breast cancer (BC) preserve the natural skin envelope including nipple-areolar complex (NAC) to able to immediately reconstruct the breast with a permanent implant and simultaneously omit the skin expansion with a tissue expander. We retrospectively analyzed the clinical results of NSM+IBBR and compared the complication rate, outcome of patients who underwent immediate (one-stage) or delayed (two-stage) IBBR followed by standard TM or NSM. [Patients and Results] A total of 108 patients who underwent a TM that included SSM or NSM followed by one- or two-stage IBBR between January 2013 and April 2022. 53 patients underwent a total mastectomy (TM) and 32 patients underwent an NSM followed by two-stage IBBR, and 24 patients underwent an NSM followed by one-stage IBBR. The operation times were 236, 247.2, and 321 min, and the mean surgical bleeding was 60.4, 88.8, and 138 ml, respectively. The complications in the three groups included infection (2.7%, 11.1%, and 6.3%), seroma/hematoma (0%, 5.6%, and 6.3%), flap necrosis (2.7%, 11.1%, and 12.5%), and loss of tissue expander or implant (2.7%, 5.6%, and 6.3%), respectively. At the median 62-month follow-up after the NSM + IBBR, one patient was diagnosed with distant lymph node metastases at the 24-month follow-up and one patient had new primary breast cancer within the reconstructed breast at the 38-month follow-up. But no loco-regional recurrence at the NAC or other distant recurrence were detected in the patients undergone regardless TM or NSM + one-stage or two-stage IBBR. [Summary] Our results suggested that the use of one-stage IBRR tended to increase the operating time and the amount of bleeding compared to two-stage IBRR and the complication rate might be higher in cases in which an NSM is followed by IBBR. Oncological outcome was consistent with the studies showing that loco-regional recurrence is less likely at the NAC regardless of whether the patients underwent one-stage or two-stage IBBR following an NSM. Citation Format: Uhi Toh, Yuko Takao, Yuriko Katagiri, Rie Sugihara, Hidetaka Watanabe. Clinical feasibility of nipple sparing mastectomy (NSM) followed by immediate reconstruction based on direct-to-implant technique [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-22-12.

CERVICAL SCAR CONTRACTURES: EXPERIENCE OF THE PLASTIC SURGERY DEPARTMENT IN MARRAKECH

Deep cervical burns can lead to disabling sequelae, especially in cases of delayed, incorrect, or inadequate initial burn management. The aim of this study is to report the various epidemiological aspects of cervical contractures, analyze therapeutic modalities, and emphasize the importance of prevention. Our work is a retrospective study spanning a period of 10 years from July 2013 to July 2023, which includes 107 cases of cervical contractures followed at the Plastic and Reconstructive Surgery Department and Burn Unit of the Mohammed VI University Hospital Center in Marrakech. The average age of our patients is 20 years, ranging from 1 to 55 years. 68% of the studied population is female, with a sex ratio of 2.14. They mostly come from a low socioeconomic background. The most frequently found circumstances of the initial burn were domestic accidents, accounting for 80% of all accidents. The etiology of the initial burn is thermal in all patients in our series, 100%. In our study, the majority of cases were initially managed in non-specialized health centers or even at home through traditional practices. Initial treatment involved conventional treatment in 45.5% of cases, early excision with grafting in 22.7% of cases, and physiotherapy (compression therapy, massage) in 22.7% of cases. The topographic distribution of sequelae showed a predominance of anterior neck involvement in 96% of cases. Facial burn sequelae are most frequently associated (70%) with cervical contractures, followed by trunk sequelae (50%). The majority of patients (80.5%) present with deformation of the cervico-mental angle, as well as limitation of cervical extension. Severe cervical contractures (according to Achauers classification) are the most frequent, representing 44.6% of cases. Surgical treatment of these sequelae involves various methods, including skin grafts used in 50.6% of cases, local flaps used in 38.4% of cases, flaps used in 5.5% of cases, and skin expansion used in 5.5% of cases. Functional and aesthetic improvement is achieved in 85.9% of cases, while surgical revision was necessary in 5 patients. Cervical burn sequelae pose a major therapeutic challenge, despite the diversity of surgical procedures, hence the importance of prevention.

Dynamic alterations in M2 macrophage subtypes enhance flap expansion efficiency and tissue regeneration.

Dilatation of soft skin tissue is a common surgical procedure in plastic surgery. M2 macrophages play a critical role in reducing inflammation, promoting epithelial and vascular endothelial cell proliferation, enhancing collagen synthesis in fibroblasts, and orchestrating extracellular matrix remodelling by promoting angiogenesis, epithelialisation, and fibrosis. Macrophages improve flap survival by promoting microangiogenesis and collagen remodelling. However, the role of macrophages in flap expansion has not yet been investigated. Improving the expansion efficiency of dilatation flaps and promoting flap vascularisation are the pressing problems in the fields of plastic and reconstruction surgery. In the present study, we used a mouse model to assess the effects of macrophage activation on skin expansion, thickness, ultrastructure, intradermal angiogenesis, and collagen and cytokine levels. Our findings revealed dynamic changes in the macrophage content and subtypes within the expansion flaps. The enrichment of M2 macrophages significantly enhanced the efficiency of flap expansion, vascularisation, and collagen synthesis. Our findings underline the pivotal role of M2 macrophages in tissue regeneration at the molecular and biochemical levels. These findings provide a basis for improving flap expansion efficiency using M2 macrophages.

Sustained Physiological Stretch Induces Abdominal Skin Growth in Pregnancy.

Supraphysiological stretches are exploited in skin expanders to induce tissue growth for autologous implants. As pregnancy is associated with large levels of sustained stretch, we investigated whether skin growth occurs in pregnancy. Therefore, we combined a mechanical model of skin and the observations from suction experiments on several body locations of five pregnant women at different gestational ages. The measurements show a continuous increase in stiffness, with the largest change observed during the last trimester. A comparison with numerical simulations indicates that the measured increase in skin stiffness is far below the level expected for the corresponding deformation of abdominal skin. A new set of simulations accounting for growth could rationalize all observations. The predicted amount of tissue growth corresponds to approximately 40% area increase before delivery. The results of the simulations also offered the opportunity to investigate the biophysical cues present in abdominal skin along gestation and to compare them with those arising in skin expanders. Alterations of the skin mechanome were quantified, including tissue stiffness, hydrostatic and osmotic pressure of the interstitial fluid, its flow velocity and electrical potential. The comparison between pregnancy and skin expansion highlights similarities as well as differences possibly influencing growth and remodeling.

Skin Expander for Scalp Reconstruction: Reappraisal of a Reconstructive Procedure for Aplasia Cutis Congenita.

Aplasia cutis congenita (ACC) is a heterogeneous group of congenital disorders characterized by the absence of epidermis, dermis, appendages, subcutaneous tissue, and bone. The aim of the study is to describe a clinical report of ACC of the scalp treated with skin expanders. In October 2019, a 16-year-old female patient underwent scalp expansion with 2 rectangular devices (150 and 250cm3; Radovan Mentor-Johnson&Johnson). The inflation started 30 days after surgery and continued once every 7 to 10 days to gain 10% of overexpansion. After 3 months, the patient underwent the second surgical step with the expanded scalp transposed to close the defect. Clinical examination 6 months after surgery revealed an acceptable cosmetic result with a hidden surgical scar and hair growth in the previous area of frontoparietal alopecia. Skin expander for the reconstruction of extensive ACC defects of the scalp is a valid procedure.

Continuous External Tissue Expansion for Closure of Forehead Flap Donor Site.

Continuous external tissue expansion has been shown to be effective in the management of craniofacial wounds resulting from tumor resection, trauma, and wound dehiscence. Forehead flap donor sites are typically managed with secondary intention healing. However, this can create esthetic problems in pigmented skin because of the tendency to form thick scars. Here, the authors describe the use of continuous external tissue expansion for the management of a paramedian forehead flap donor site. A Dermaclose device was used at the time of forehead flap elevation and removed at the pedicle division and inset. Sufficient skin expansion was achieved for primary closure. The final scar was esthetically pleasing. External tissue expansion is ideal for forehead flap donor sites as the second stage of the operation provides an opportunity for expander removal and wound closure.

Use of the modified meek technique for the coverage of extensive burn wounds

IntroductionAutologous split thickness skin grafting using meshing technique remains the preferred option for the management of deep dermal and full thickness burns. The limited donor site availability seen in patients with extensive burns, however, restricts use of the mesh grafting technique for skin expansion. Meek micrografting was developed to allow for greater expansion, and, therefore, more reliable treatment of extensive burns. This study aimed to present our outcomes using the Meek micrografting technique and identify risk factors for graft failure. MethodsA retrospective review of patients admitted to our large academic hospital who were treated with the Meek micrografting technique from 2013 to 2022 was conducted. Patient demographics, surgical characteristics and outcomes were reported. Regression analyses were performed to identify factors that influence graft take and reoperation rate. ResultsA total of 73 patients with a mean age of 45.7 ± 19.9 years and mean burn size of 60.0 ± 17.8%TBSA, with 45.3 ± 14.9% TBSA being third degree burns, received Meek transplantation. The mean graft take after removal of the pre-folded polyamide gauze at the tenth post-operative day was 75.8 ± 14.7%. Pre-treatment with use of an allograft, longer waiting time between admission and Meek grafting and transplantation over a dermal matrix were identified as positive predictors for graft take, while age was established as a negative predictor. ConclusionBy examining the outcomes of the Meek micrografting technique in extensive burn wounds we identified that preconditioning of the wound bed, through allograft or negative pressure wound therapy application, positively correlates with improved outcomes, including higher graft take. At the same time, older age was seen to negatively correlate with graft take. Overall, Meek transplantation displays a favorable safety profile with promising outcomes. Future prospective studies and clinical trials can optimize the procedure and help establish it as the golden standard for extensive and complex burns.

Activating autophagy promotes skin regeneration induced by mechanical stretch during tissue expansion.

Tissue expansion, a technique in which skin regeneration is induced by mechanical stretch stimuli, is commonly used for tissue repair and reconstruction. In this study, we aimed to monitor the autophagy levels of expanded skin after the application of expansion stimuli and explore the effect of autophagy modulation on skin regeneration. A rat scalp expansion model was established to provide a stable expanded skin response to mechanical stretch. Autophagy levels at different time points (6, 12, 24, 48 and 72h after the last expansion) were detected via western blotting. The effect of autophagy regulation on skin regeneration during tissue expansion was evaluated via skin expansion efficiency assessment, western blotting, immunofluorescence staining, TUNEL staining and laser Doppler blood flow imaging. The autophagic flux reached its highest level 48h after tissue expansion. Activating autophagy by rapamycin increased the area of expanded skin as well as the thicknesses of epidermis and dermis. Furthermore, activating autophagy accelerated skin regeneration during tissue expansion by enhancing the proliferation of cells and the number of epidermal basal and hair follicle stem cells, reducing apoptosis, improving angiogenesis, and promoting collagen synthesis and growth factor secretion. Conversely, the regenerative effects were reversed when autophagy was blocked. Autophagy modulation may be a promising therapeutic strategy for improving the efficiency of tissue expansion and preventing the incidence of the complication of skin necrosis.

Coexpression analysis of angiogenesis, proliferation, apoptosis, autophagy and SHH pathway genes involved in skin expansion

Skin and soft tissue expansion is a widely used technique in plastic surgery. However, the regulatory mechanisms associated with cellular processes involved in skin expansion are not well elucidated. In the present study, we aimed at exploring the transcriptome changes associated with skin expansion and profiling the difference in gene expression between the skin tissue in the top of the dilator and the skin tissue in the side of the dilator. A mouse model of skin expansion was established and RNA sequencing (RNA-Seq) was performed on samples collected at different time points. Differential expression analysis was performed using the DESeq2 package while STEM was used for time series clustering profiling. The regulatory networks were established and the functions of sets of genes were analyzed. The mRNA expression levels of candidate genes were validated by the quantitative RT-PCR. Among the skin tissue in the top of the dilator and normal samples at days 1, 3, 7, 14 and 28, 53 commonly upregulated and 7 commonly downregulated genes were identified while among the skin tissue in the side of the dilator and normal samples, 98 downregulated and 255 upregulated genes were identified. Genes differentially expressed among the skin tissue in the top of the dilator and normal samples were involved in coagulation and proliferation-associated pathways while those among the skin tissue in the side of the dilator and normal samples were involved in the inflammation, immune response, and defense response. Among the skin tissue in the top of the dilator and the skin tissue in the side of the dilator samples, 161 were constantly upregulated while 27 were constantly downregulated; these genes were enriched in the biological processes of cell adhesion and regulation of cell proliferation (n = 11). Furthermore, we identified that SHH signaling genes formed a coexpression regulatory network with cellular proliferation, apoptosis, autophagy and angiogenesis-related genes in the expanded skin. In conclusion, our findings can promote research and understanding of the mechanism of skin expansion and will find application in plastic surgery.

Dynamics of cutaneous atmospheric oxygen uptake in response to mechanical stretch revealed by optical fiber microsensor.

Skin expands and regenerates in response to mechanical stretch. This important homeostasis process is critical for skin biology and can be exploited to generate extra skin for reconstructive surgery. Atmospheric oxygen uptake is important in skin homeostasis. However, whether and how cutaneous atmospheric oxygen uptake changes during mechanical stretch remains unclear, and relevant research tools to quantify oxygen flux are limited. Herein, we used the scanning micro-optrode technique (SMOT), a non-invasive self-referencing optical fibermicrosensor, to achieve real-time measurement of cutaneous oxygen uptake from the atmosphere. An invivo mechanical stretch-induced skin expansion model was established, and an invitro Flexcell Tension system was used to stretch epidermal cells. We found that oxygen influx of skin increased dramatically after stretching for 1 to 3 days and decreased to the non-stretched level after 7 days. The enhanced oxygen influx of stretched skin was associated with increased epidermal basal cell proliferation and impaired epidermal barrier. In conclusion, mechanical stretch increases cutaneous oxygen uptake with spatial-temporal characteristics, correlating with cell proliferation and barrier changes, suggesting a fundamental mechanistic role of oxygen uptake in the skin in response to mechanical stretch. Optical fiber microsensor-based oxygen uptake detection provides a non-invasive approach to understand skin homeostasis.

Clinical application of retrosigmoid approach for BONEBRIDGE implantation after auricle reconstruction using expanded postauricular flap

Objective: To explore the safety and reliability of retrosigmoid approach BONEBRIDGE implantation in patients with auricle reconstruction using skin expansion flap. Methods: A retrospective analysis was conducted on 43 congenital aural atresia cases (43 ears) who underwent BONEBRIDGE implantation from September 2019 to January 2023 in Beijing Tongren Hospital. 30 males and 13 females were included in this work. The implantation age was 9-36 years old (median age=10 y/o). All cases underwent auricle reconstruction surgery using the posterior ear flap expansion method, with 36 cases using the single expanded postauricular flap method and 7 cases using two-flap method. BONEBRIDGE implant surgery was performed during the third stage of auricle reconstruction or after all stages. The hearing improvements were evaluated by comparing the changes in pure tone hearing threshold and speech recognition rate of patients before and after BONEBRIDGE implantation. Routine follow-up was conducted to observe the hearing results and complications. SPSS 14.0 software was applied for data statistical analysis. Results: All 43 patients healed well and had no surgical complications when discharge. The average bone conduction hearing threshold after surgery was (8.2±6.6) dBHL, and there was no statistically significant difference compared to the preoperative [(8.1±5.7) dBHL] (P=0.95). After surgery, the threshold of hearing assistance with power on was significantly lower than that without hearing assistance [(32.8±4.6) dBHL vs (60.5±5.5) dBHL], and the difference was statistically significant (P<0.001). The speech recognition rate of monosyllable words, disyllabic words and short sentences in quiet environment increased to 72%, 84%, and 98% respectively. The differences were statistically significant (P<0.001). The speech recognition rate of monosyllabic words, disyllabic words, and short sentences in noise environment was significantly increased by 70%, 80%, and 92% respectively (P<0.001). After a follow-up of 4 to 47 months (median=24 months), the hearing results were stable and the aesthetic outcomes were satisfying. One patient had delayed hematoma around coil of the implant. After aspiration and compressed dressing for one week, hematoma was not recurrent. Conclusion: For patients after auricle reconstruction using expanded postauricular flap, the preference of retrosigmoid approach is a good choice in terms of safety and reliability of operation, as well as aesthetic appearance.