Complications Following Tissue Expander-Based Reconstruction in Pediatric Burn Injuries: A Retrospective Analysis.

BACKGROUND: Tissue expansion has been widely used to reconstruct soft tissue defects following burn injuries in pediatric patients, allowing for satisfactory cosmetic and functional outcomes. Factors impacting the success of tissue expander (TE)-based reconstruction in these patients are poorly understood. Herein, we aim to determine the risk factors for postoperative complications following TE-based reconstruction in pediatric burn patients. METHODS: A retrospective review of pediatric patients who underwent TE placement for burn reconstruction from 2006 to 2019 was performed. Primary outcomes were major complications (TE explantation, extrusion, replacement, flap necrosis, unplanned reoperation, readmission) and wound complications (surgical site infection and wound dehiscence). Descriptive statistics were calculated. The association between primary outcomes, patient demographics, burn characteristics, and TE characteristics was assessed using the chi-squared, Fisher's exact, and Mann-Whitney U tests. RESULTS: Of 28 patients included in the study, the median [interquartile range (IQR)] age was 6.5 (3.3-11.8) years, with a follow-up of 12 (7-32) months. The majority were males [n = 20 (71%)], Black patients [n = 11 (39%)], and experienced burns due to flames [n = 78 (29%)]. Eleven (39%) patients experienced major complications, most commonly TE premature explantation [n = 6 (21%)]. Patients who experienced major complications, compared to those who did not, had a significantly greater median (IQR) % total body surface area (TBSA) [38 (27-52), 10 (5-19), P = 0.002] and number of TEs inserted [2 (2-3), 1 (1-2), P = 0.01]. Ten (36%) patients experienced wound complications, most commonly surgical site infection following TE placement [n = 6 (21%)]. Patients who experienced wound complications, compared to those who did not, had a significantly greater median (IQR) %TBSA [35 (18-45), 19 (13-24), P = 0.02]. CONCLUSION: Pediatric burn injuries involving greater than 30% TBSA and necessitating an increasing number of TEs were associated with worse postoperative complications following TE-based reconstruction.

Total Face Reconstruction with Flap Prefabrication and Soft-Tissue Expansion Techniques.

SUMMARY: Total facial deformities always lead to psychological and functional consequences, making plastic and reconstructive surgery a great challenge. The skin of the anterior chest area is matched in thickness, texture, and color to the head and face. The purpose of this article was to discuss and evaluate reconstructive surgeons' experiences with obtaining a monoblock flap from the anterior thoracic area for entire face reconstruction using flap prefabrication, soft-tissue expansion, and facial plastic surgery following skin flap transplantation. Two patients underwent prefabricated expanded anterior thoracic flap reconstructions for total facial deformities; data collection included face defect size, flap type, the shape of the expander, expansion time, and complications. All the face flaps that were transplanted survived without major complications. It is concluded that using a prefabricated expanded flap to reconstruct an entire facial soft-tissue defect can provide a high degree of matching, a wide enough covering area, and a thin enough skin thickness to cover the face. Autologous flap grafting is easy to implement and has a high application value.

Towards developing a matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) compatible tissue expansion protocol.

Mass spectrometry imaging (MSI) visualizes spatial distribution of molecules in a biological tissue. However, compared with traditional microscopy-based imaging, conventional MSI is limited to its spatial resolution, resulting in difficulties in identifying detailed tissue morphological characters, such as lesion boundary or nanoscale structures. On the other hand, expansion microscopy, a tissue expansion method widely used in optical imaging to improve morphological details, has great potential to solve insufficient spatial resolution in mass spectrometry imaging (MSI). However, expansion microscopy was not originally designed for MSI, resulting in problems while combining expansion microscopy and MSI such as expanded sample fragility, vacuum stability and molecule loss during sample preparation. In this research we developed a MALDI MSI compatible expansion protocol by adjusting sample preparation methods during tissue expansion, successfully combining expansion microscopy with MSI. After tissue expansion the expanded sample can be readily applied to MALDI MSI sample preparation and further data acquisition. The MALDI MSI compatible expansion protocol has great potential to be widely applied in MALDI MSI sample preparation to facilitate improvement of MSI spatial resolution.

Machine learning analysis of online patient questions regarding breast reconstruction.

BACKGROUND: Social media has become a dominant educational resource for breast reconstruction patients. Rather than passively consuming information, patients interact directly with other users and healthcare professionals. While online information for breast reconstruction has been analyzed previously, a robust analysis of patient questions on online forums has not been conducted. In this study, the authors used a machine learning approach to analyze and categorize online patient questions regarding breast reconstruction. METHODS: Realself.com was accessed and questions pertaining to breast reconstruction were extracted. Data collected included the date of question, poster's location, question header, question text, and available tags. Questions were analyzed and categorized by two independent reviewers. RESULTS: 522 preoperative questions were analyzed. Geographic analysis is displayed in Figure 1. Questions were often asked in the pre-mastectomy period (38.3%); however, patients with tissue expanders currently in place made up 28.5%. Questions were often related to reconstructive methods (23.2%), implant selection (19.5%), and tissue expander concerns (16.7%). Questions asked in the post-lumpectomy period were significantly more likely to be related to insurance/cost and reconstructive candidacy (p < 0.01). The "Top 6″ patient questions were determined by machine learning analysis, and the most common of which was "Can I get good results going direct to implant after mastectomy?" CONCLUSIONS: Analysis of online questions provides valuable insights and may help inform our educational approach toward our breast reconstruction patients. Our findings suggest that questions are common throughout the reconstructive process and do not end after the initial consultation. Patients most often want more information on the reconstructive options, implant selection, and the tissue expansion process.

Prediction model for haematoma after tissue expander placement: A retrospective cohort study of 7080 cases over 20 years.

Haematoma is an early complication of tissue expander placement and can lead to infection, capsule contracture and various complications, hindering successful reconstruction. However, no scientific models can accurately predict the risk of haematoma following tissue expansion. Therefore, this study aimed to develop and validate a prediction model for haematoma following tissue expander placement. The medical records of patients who underwent expander placement between 2001 and 2021 were obtained from the clinical database of the Department of Plastic Surgery at the Xijing Hospital. A total of 4579 consecutive patients with 7080 expanders and 179 expanded pocket haematomas were analysed. Multivariate logistic regression analysis identified adult age (P = 0.006), male sex (P < 0.001), scar reconstruction (P = 0.019), perioperative hypertension (P < 0.001), face and neck location (P = 0.002) and activated partial thromboplastin time above the normal range (P < 0.001) as risk factors for haematoma. Therefore, these were included in the prediction model, and a nomogram was constructed. The discrimination of the nomogram was robust (area under the curve: 0.78; 95% confidence interval: 0.72-0.83). Further, the prediction model had a strong fit (Hosmer-Lemeshow test, P = 0.066) and maintained similar discrimination after considering performance optimism (bootstrapped area under the curve: 0.79; 95% confidence interval: 0.73-0.84). This clinical prediction model was created using a generalisable dataset and can be utilised to obtain valid haematoma predictions after expander placement, assisting surgeons in implementing preventive measures or interventions to reduce the occurrence of haematoma.

The Dynamic Changes in Skin Thickness of Forehead during Tissue Expansion.

In addition to providing extra flap size, the tissue expansion process also brings changes in flap thickness. This study aims to identify the changes in the forehead flap thickness during the tissue expansion period. Patients undergoing forehead expander embedment from September 2021 to September 2022 were included. The thickness of the forehead skin and subcutaneous tissue were measured with ultrasound before and 1, 2, 3, and 4 months after expansion. Twelve patients were included. The average expansion period was 4.6 months, and the mean expansion volume was 657.1 mL. The thickness of skin and subcutaneous tissue in the central forehead changed from 1.09 ± 0.06 to 0.63 ± 0.05 mm and from 2.53 ± 0.25 to 0.71 ± 0.09 mm, respectively. In the left frontotemporal region, skin and subcutaneous tissue thickness changed from 1.03 ± 0.05 to 0.52 ± 0.05 mm and 2.02 ± 0.21 to 0.62 ± 0.08 mm. On the right side, skin and subcutaneous tissue thickness changed from 1.01 ± 0.05 to 0.50 ± 0.04 mm and 2.06 ± 0.21 to 0.50 ± 0.05 mm. This study measured the dynamic changes in the thickness of the forehead flap during expansion. The thickness of the forehead flap decreased the fastest in the first 2 months of expansion, and the changes in skin and subcutaneous thickness slowed down in the third and fourth months and tended to a minimum value. Additionally, the thickness of subcutaneous tissue decreased greater in magnitude than the dermal tissue.

Resurfacing of Sleeve-Like Circumferential Giant Congenital Melanocytic Nevi on the Upper Extremity With Pre-Expanded Pedicled Flap.

As the relative shortage of healthy tissue obviates the option of local soft tissue coverage, reconstruction of circumferential giant congenital melanocytic nevi (GCMN) on the upper extremity remains particularly challenging. Here the authors report a 3-stage procedure involving pre-expanded pedicled flap from the torso for the reconstruction of upper extremity after circumferential GCMN excision in pediatric patients. The giant nevus was completely removed and the size of the excised nevus was 31 × 14.5 cm. The donor site was primarily closed. No major complication was encountered. Reconstruction with expanded pedicled flap achieved satisfactory results, both functionally and cosmetically.

The current use of tissue expanders in breast reconstruction: device design, features, and technical considerations.

INTRODUCTION: The use of tissue expanders (TE) in post-mastectomy breast reconstruction is a widely accepted practice, especially in patients desiring implant-based breast reconstruction. It has become the standard of care to perform a two-staged breast reconstruction using tissue expanders for the past 50 years due to its reliability, safety, cost-effectiveness, and versatility. Due to its popularity, there are numerous types and features of breast tissue expanders and various surgical approaches available for plastic surgeons. AREAS COVERED: In this article, we will review the role of tissue expanders in breast reconstruction, the types and features of breast tissue expanders, and technical considerations. EXPERT OPINION: The use of tissue expanders in breast reconstruction offers significant advantages of preserving the breast skin envelope and reestablishing the breast mound. With evolving approaches to breast reconstruction, tissue expander design, and application underwent several refinements and modifications. Due to these advances, studies on its long-term efficacy and safety profile typically fall behind and more studies with higher levels of evidence are needed to better evaluate the efficacy and safety profile of tissue expanders. With increased understanding, reconstructive surgeons can minimize complications and maximize reconstructive, aesthetic outcomes with high patient satisfaction.

Lower Extremity Pediatric Tissue Expansion: A Single Surgeon's 16-Year Experience.

BACKGROUND: Tissue expansion is a well-established approach to soft tissue reconstruction in the pediatric population for lower extremity pathologies. Unfortunately, complication rates range from 19% to 40% in literature, including infection and implant extrusion, leading to delays in reconstruction. These challenges have prompted investigation toward categorizing risk factors for lower extremity tissue expander placement. METHODS: A retrospective study of pediatric patients who underwent lower extremity tissue expander placement by the senior author (R.J.R.) was performed over a 16-year period. Patient charts were reviewed to categorize baseline and operative characteristics. Primary outcome variables were surgical-site infection, expander extrusion, and expander deflation. Univariate and multivariate logistic regressions were performed ( α < 0.05). RESULTS: There were 59 tissue expanders in our cohort. The overall complication rate was 27.1% with a 77.2% successful reconstruction rate. Greater number of expanders placed during 1 operation is associated with 2.5 increased odds of having any complication and is associated with 0.4 decreased odds of having a successful reconstruction. Incisions made in scar tissue for expander placement appear to be associated with a greater than 7 times increased odds of readmission. CONCLUSIONS: Reconstruction of soft tissue pathologies using lower extremity tissue expanders in the pediatric population is an effective yet challenging technique. This study identified that the number of expanders inserted during 1 operation, incisions made over scar tissue, and expanders placed in the anterior thigh were correlated with having a negative impact on reconstructive outcomes. Extra care should be taken with patients who require multiple expanders during 1 operation and with choosing the location and incision of expander placement.

Impact of Initial Filling Medium on Outcomes of Subpectoral, Two-Stage, Implant-Based Breast Reconstruction: Air versus Saline.

BACKGROUND: In two-stage expander-based breast reconstruction, the use of air as the initial filling medium has been suggested to confer clinical advantages over conventional saline, but this has not been demonstrated in a large series. This study aimed to evaluate the association between material type (air versus saline) for initial expander filling and postoperative outcomes. METHODS: This retrospective study included patients who underwent immediate, subpectoral, tissue expander-based breast reconstruction between January of 2018 and March of 2021. The participants were categorized into two groups according to the material used for initial filling: saline-inflated expanders, which were used during the first 22 months consecutively, and air-inflated expanders, which were used during the latter 17 months consecutively. Complications including mastectomy flap necrosis and postoperative expansion profiles were compared. Multivariable analyses were performed to identify independent predictors of postoperative complications. RESULTS: A total of 443 breasts (400 patients), including 161 air-filled and 282 saline-filled breasts, were analyzed. The two groups had similar baseline characteristics. The air-filled group showed a significantly lower rate of mastectomy flap necrosis; this difference remained significant after adjustment for other variables in the multivariable analysis. The rates of other complications did not differ between the two groups. The air-filled group had fewer office visits and a shorter period to complete expansion. CONCLUSIONS: The use of air for initial expander filling could provide safe and reliable outcomes with reduced patient discomfort during postoperative expansion; thus, air-filled expanders might be an effective alternative to saline-filled expanders. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Tracing the Change and Contribution of Subcutaneous Adipose to Skin Expansion Using a Luciferase-Transgenic Fat Transplantation Model.

BACKGROUND: During skin expansion, subcutaneous adipose tissue undergoes the greatest change. The adipose layer appears to gradually thin or even disappear in long-term expansion. The response and contribution of adipose tissue to skin expansion remain to be elucidated. METHODS: The authors established a novel expansion model by transplanting luciferase-transgenic adipose tissue into the rat dorsum, followed by integrated expansion, to trace the dynamic changes in subcutaneous adipose tissue during expansion and the migration of adipose tissue-derived cells. In vivo luminescent imaging was performed to continuously track the adipose tissue changes. Histologic analysis and immunohistochemical staining evaluated the regeneration and vascularization of the expanded skin. Growth factor expression in expanded skin with or without adipose tissue was determined to evaluate the paracrine effect of adipose tissue. Adipose tissue-derived cells were traced in vitro by anti-luciferase staining, and their fate was determined by costaining for PDGFRα, DLK1, and CD31. RESULTS: In vivo bioimaging showed that cells in adipose tissue were alive during expansion. After expansion, the adipose tissue exhibited fibrotic-like structures, with more DLK1 + preadipocytes. Skin expanded with adipose tissue was significantly thicker than that without adipose tissue, with more blood vessels and cell proliferation. Vascular endothelial growth factor, epidermal growth factor, and basic fibroblast growth factor expression was higher in adipose tissue than in skin, indicating paracrine support from adipose tissue. Luciferase-positive adipose tissue-derived cells were observed in expanded skin, indicating direct participation in skin regeneration. CONCLUSION: Adipose tissue transplantation can effectively promote long-term skin expansion by contributing to vascularization and cell proliferation by means of various mechanisms. CLINICAL RELEVANCE STATEMENT: The authors' findings suggest that it would be better if the expander pocket is dissected over the superficial fascia to preserve a layer of adipose tissue with skin. In addition, their findings support the treatment of fat grafting when expanded skin presents with thinning.

Outcomes after tissue expander exchange to implant in two-stage prepectoral breast reconstruction with and without acellular dermal matrix: A retrospective cohort study.

As prepectoral implant placement becomes widely adopted, recent studies investigating the use of acellular dermal matrix (ADM) during tissue expander placement have demonstrated no major benefit with regard to postoperative outcomes. We sought to evaluate second-stage outcomes 1 year after tissue expander exchange to implant with and without ADM. Consecutive patients who underwent prepectoral tissue expander-based breast reconstruction with and without ADM were identified. Patients were followed up for 1 year after tissue expander exchange to implant. Second-stage outcomes of interest including implant rippling, capsular contracture, implant explantation, additional revision surgeries, and patient-reported outcomes were collected and compared. Sixty-eight breasts in the ADM cohort and sixty-one breasts in the no ADM cohort underwent tissue expander exchange to implant. Second-stage outcomes of interest were similar between the ADM and no ADM cohorts with no statistically significant differences identified regarding incidences of implant rippling (24.6% vs. 12.1%, p = 0.08), capsular contracture (4.5% vs. 3.3%, p = 1.00), and explantation (6.6% vs. 1.7%, p = 0.67) between the two cohorts. BREAST-Q scores were similar between the two cohorts with the exception of physical wellbeing and satisfaction in terms of implant rippling, as can be seen, which improved in the no ADM cohort (p = 0.04). Our study reports no major benefit for the inclusion of ADM with respect to implant rippling, capsular contracture, explantation, need for additional revision surgeries, and patient-reported satisfaction in prepectoral second-stage implant-based breast reconstruction.

Platelet-rich gel versus external tissue expansion technique in treating scalp defects: A retrospective study.

Reconstruction of scalp defects is a complicated and challenging procedure for reconstructive surgeons. This retrospective observational study assessed the effectiveness of using platelet-rich gel (PRG) versus the external tissue expansion technique (TET) in reconstructing scalp defects. The clinical data of 24 patients with scalp defects treated with PRG or external TET were collected from September 2018 to March 2022. Data on the wound characteristics, wound healing time, cost of treatment, visual analog scale, and observed wound healing status were collected. The mean wound healing times in the PRG and TET groups were 25.00 ± 5.77 and 13.58 ± 9.68 days, respectively (P < .05). The PRG group was significantly more cost-effective than the TET group (P < .05). TET treatment significantly increased patients' postoperative pain, which decreased over time (P < .05), while PRG treatment caused no significant change in pain (P > .05). The 2 groups showed no tissue depression or color change after wound healing at follow-up, but the hair growth in the TET group was significantly better than that in the PRG group (P < .05). Compared with TET treatment of scalp defects, PRG is not only simple and painless but also has a low treatment cost and, more importantly, does not involve the risk of surgery and anesthesia. However, using TET to treat scalp defects requires the careful selection of appropriate cases.

Surgical delay increases the survival of expanded random-pattern flap in pediatric patients.

Despite the aid of tissue expansion, the ideal design of random pattern flap is not always available in patients with extensive skin lesions. We investigated the effectiveness of surgical delay on expanded flaps in pediatric patients. Retrospective cohort study was performed on patients who underwent tissue expansion surgery for extensive skin lesions at Seoul National University Children's Hospital. The surgical delay technique was employed for patients with unfavorable flap conditions related to location or transposition angles. The dimensions of skin lesions and flaps were measured based on medical photographs. Fifty patients underwent a total of 66 tissue expansion procedures (49 conventional procedures among 41 patients, 17 surgical delay procedures among 15 patients) from January 2016 to September 2019. Although flaps in the surgical delay group were more narrow-based (p < 0.001), the partial flap loss rate and excised area-to-inflation amount ratio was comparable between the two groups (p = 0.093 and p = 0.194, respectively). Viable flaps, excluding postoperative necrosis, in the surgical delay group were significantly more narrow-based in terms of the length-to-base width ratio and the area-to-base width ratio compared to conventional group (p < 0.01, p < 0.01). Surgical delay can result in outcomes comparable to well-designed random flaps, even in disadvantageous conditions. Patients with large skin lesions but limited areas for expansion may benefit from surgical delay.

Customization of Soft Tissue Expanders: Improving Safety, Accuracy, and Efficiency for Treatment of Large and Complicated Skin Lesions.

BACKGROUND: Soft tissue expansion is a common technique for restoring large skin defects. Fixed-type expanders may be inappropriate for the following reasons: (1) the shapes and sizes of the defects vary in different patients; and (2) the bulged base of the fixed-type expander does not fit the curve of the human body, which may induce complications such as concave deformities or nerve palsy from continuous mechanical compression. The customized expander adjusts better to the shape and the topography of the expansion site compared with the fixed-type expander. It improves expansion efficiency and reduces complications caused by compression. METHODS: Between 2016 and 2022, customized soft tissue expansion was performed in 38 patients with skin lesions, including giant congenital melanocytic nevi and postburn scars. This series of patients included patients with a specific donor site shape that is unsuitable for fixed-type expanders. An expander was customized according to the shape of the donor site and then implanted in the subcutaneous pocket. After the expander reached a sufficient volume, the expander was removed, and the extra expanded skin flap was transferred to resurface the skin lesion. In the follow-up, the outcome and the complications were recorded. RESULTS: All the customized expanders fit not only the dimension but also the topography of the donor site. During expansion, 2 patients experienced leakage of the expander, and 3 patients suffered a skin rupture. In the remaining 33 patients, the expansion was successfully completed, and the expanded flaps restored the skin lesions as designed. The color and texture of the skin flaps remained satisfactory after long-term follow-up. CONCLUSIONS: Unlike fixed-type expanders, our customized expanders make it possible for "accurate" expansion, irrespective of the dimension and topography of the donor area. Customization of the expander helps increase efficiency and reduce complications caused by undue compression.

[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.

Hydrogel based soft tissue expanders for orodental reconstruction.

Tension-free flap closure to prevent soft tissue dehiscence is a prerequisite for successful bone augmentation in orodental reconstructive surgery. Since soft tissue contour follows the underlying jaw bony architecture, resorption of alveolar (jaw) bone limits the availability of soft tissue for wound closure following major bone reconstruction, required to facilitate oral rehabilitation with endosseous dental implants following tooth loss. Although there are several clinical procedures to increase soft tissue volume, these techniques are complicated and technically demanding. Soft tissue expansion, an established technique in reconstructive surgery, is an ideal alternative to generate surplus soft tissue prior to bone augmentation and dental implant placement. Increase in tissue volume can be achieved by using soft tissue expanders (STEs). Contemporary STEs have evolved from silicone balloons to osmotically inflating hydrogel-based systems. Here, we provide an overview of STEs in clinical oral surgery, outline the current research in STEs, and an update on recent clinical trials as well as the associated complications. Also, the mechanism governing soft tissue expansion and the critical factors that control the expansion process are covered. Design considerations for STEs for intraoral applications are given particular attention. Finally, we present our perspectives on utilization of minimally invasive methods to administer STEs for orodental applications. STATEMENT OF SIGNIFICANCE: Soft tissue expansion is required for a range of reconstructive applications and more notably in regenerative dentistry for vertical bone augmentation. This review describes the commercially available soft tissue expanders along with the latest systems being currently developed. This review insightfully discusses the biological and physical mechanisms leading to soft tissue expansion and critically assesses the design criteria of soft tissue expanders. A particular focus is given on the development of a new generation of hydrogel-based soft tissue expanders; their chemistry and required physical properties for tissue expansion is described and the obstacles towards clinical translations are identified. Finally, the review elaborates on promising minimally invasive injectable hydrogel-based tissue expanders and highlights the beneficial features of these systems.

Extensive Defect Reconstruction With Pre-expanded Anterolateral Thigh Flap: Tissue Expansion of the "Outskirts".

BACKGROUND: Previously reported pre-expansion techniques of the anterolateral thigh flap are mainly perforator-based. The expansion will interfere with the flap harvest if the requisite perforator is found unsuitable as a pedicle. Expansion of the peripheral territories of the flap donor site can minimize the interference from the expansion. METHODS: Forty-eight peripheral pre-expansions of the anterolateral thigh flap were retrospectively reviewed in 38 patients from 2012 to 2021. The reconstructive outcomes, including flap success, increase in flap size, donor-site closure, and complications, were assessed. In addition, subgroup analysis was performed based on the expanded territories. RESULTS: Rate of successful flap elevation of 100% and flap survival rate of 97.9% were achieved. One patient had total flap necrosis, which was salvaged with skin grafting. Peripheral expansion attained a mean 55.5% ± 19.6% increase in flap width. Primary donor-site closure was accomplished in 95.8% of flaps and fascial restoration in 97.9% of the donor sites. Three patients developed major expansion-related complications, which required surgical intervention. One patient had wound dehiscence in the donor site, which healed by secondary intention. Compared with other subgroups, the lateral-and-medial-side expansion provided a larger flap for reconstruction (P = 0.001). CONCLUSIONS: If time is not of the essence, peripheral pre-expansion permits direct donor-site closure with size augment of the anterolateral thigh flap. In addition, it preserves the reliability and versatility of the anterolateral thigh flap.