Soft Tissue Expansion Research Articles

Advances in methods and mechanisms for skin soft tissue expansion

Skin soft tissue expansion is one of the most commonly used treatments in plastic surgery and has great clinical application value. For a long time, clinicians and researchers hope to take into account both quality and speed of expansion and get extra skin well and quickly. This article outlines the mechanism of dilated skin regeneration and reviews the recent advances in methods and mechanisms for skin soft tissue expansion. Key words: Skin soft tissue expansion; Methods; Mechanisms; Recent advances

Evaluation of self-inflating soft tissue expanders prior to vertical ridge augmentation in atrophic posterior mandible

Aim: To evaluate the self-inflating tissue expander prior to vertical ridge augmentation of atrophic posterior mandible.Materials and methods: Eight patients with atrophic posterior mandible were included in the study. Self-inflating tissue expander was inserted in a submucosal pouch and removed after 60 days. Vertical ridge augmentation was performed using sandwiched graft technique with allogenic bone blocks.Results: No signs of inflammation or thinning of the mucosa was observed. None of the patients were presented with any dehiscence or graft exposure during different follow up periods. The height of the bone blocks used was measured with a periodontal probe for all the patients after insertion in the surgical site with a mean vertical height gain of 8.36 ± 1.63 mm. The mean soft tissue volume gain according to the measurements obtained from the optical analysis was 834.4 ± 59 mm3Conclusion: Self-inflating tissue expanders combined with sandwiched vertical ridge augmentation procedure in posterior atrophic mandibles showed excellent results regarding healing, absence of inflammation, adequate soft tissue and hard tissue gain with absence of any signs of dehiscence or graft exposure.

Hydrogel Tissue Expanders for Stomatology. Part II. Poly(styrene-maleic anhydride) Hydrogels.

Self-inflating soft tissue expanders represent a valuable modality in reconstructive surgery. For this purpose, particularly synthetic hydrogels that increase their volume by swelling in aqueous environment are used. The current challenge in the field is to deliver a material with a suitable protracted swelling response, ideally with an induction period (for sutured wound healing) followed by a linear increase in volume lasting several days for required tissue reconstruction. Here, we report on synthesis, swelling, thermal, mechanical and biological properties of novel hydrogel tissue expanders based on poly(styrene-alt-maleic anhydride) copolymers covalently crosslinked with p-divinylbenzene. The hydrogels exerted hydrolysis-driven swelling response with induction period over the first two days with minimal volume change and gradual volume growth within 30 days in buffered saline solution. Their final swollen volume reached more than 14 times the dry volume with little dependence on the crosslinker content. The mechanical coherence of samples during swelling and in their fully swollen state was excellent, the compression modulus of elasticity being between 750 and 850 kPa. In vitro cell culture experiments and in vivo evaluation in mice models showed excellent biocompatibility and suitable swelling responses meeting thus the application requirements as soft tissue expanders.

Expanded flaps with vascular anastomosis for the treatment of scar contracture deformities of extensively burned patients

Objective: To explore the effect of expanded flaps with vascular anastomosis in the treatment of scar contracture deformities of extensively burned patients. Methods: From April 2016 to February 2018, 9 patients with severe scar contracture deformities caused by extensive burns were hospitalized in our unit, including 7 males and 2 females, aged 23-54 years. There were 14 sites of scar contracture deformities and dysfunction, including 8 in face and neck, 2 in elbow, and 4 in wrist and hand. The expander was inserted into the chest or abdomen and was expanded by 2 to 3 times of its rated volume with injection of normal saline. After satisfied expansion, the expanded flap was harvested and transplanted with arteriovenous anastomosis onto the recipient site, where the scar was removed, the deformity was corrected, and the contracture was released. The number of expanders, the volume of normal saline injected, the period of expansion, the complications of skin and soft tissue expansion, the number, size, thickness, transplantation modes, and survival of flaps, and the repair method of donor site were observed and recorded. The reconstruction effect of scar contracture deformity was followed up. The patients' satisfaction with the therapeutic effect of various surgical sites during follow-up was investigated with a 5-point Likert Scale. The Burn Specific Health Scale-Brief was used to evaluate the quality of life of the patients pretreatment and during follow-up. Data were processed with paired sample t test or Wilcoxon signed-rank sum test. Results: A total of 16 expanders were inserted in this group of patients, including 6 in the chest and 10 in the abdomen. The volume of normal saline injected at the end of expansion was (1 421±348) mL. The expansion time was (8.1±2.6) months. One case of expander leakage and one case of injection port turnover resulted in failure of water injection occurred during expansion. Totally 17 flaps were resected from 16 expanded areas. The size of flaps ranged from 15 cm×13 cm to 30 cm×25 cm. The thickness was (0.49±0.06) cm in 6 chest flaps and (0.76±0.15) cm in 11 abdomen flaps. Free transplantation with vascular anastomosis was performed in 14 flaps, and pedicled transplantation supercharged with distal vascular anastomosis was performed in 3 flaps, one of which the vascular pedicle was divided and re-anastomosed to the other side of the recipient area 2 weeks later. Except for one donor site of abdomen flap which was transplanted with thin split-thickness scalp, the other donor sites were sutured directly. After operation, 2 flaps were slightly necrotic at the distal end and healed after dressing change and thin split-thickness scalp transplantation respectively, while the remaining 15 flaps all survived. During the follow-up of 6-24 months, the texture of the flaps was soft. The abdomen flap transplanted to the palm of hand in one patient was slightly hypertrophic, which was thinned 3 months after operation, while the other flaps were good in thickness. At the last follow-up, the appearance and function of the sites repaired by flaps of all patients were obviously improved compared with those before operation, the satisfaction score of the patients with the therapeutic effect of the surgical site was (4.4±0.6) points, the total score of quality of life and the scores of heat sensitivity, treatment antipathy, body image, and affect of patients were significantly higher than those before treatment (t=3.232, 2.683, 3.969, 2.884, 2.588, P<0.05), while the scores of hand function, sexuality, interpersonal relationship, simple function abilities, perception in returning to work of patients were close to those before treatment (t=0.778, 1.000, 1.664, Z=1.826, 1.633, P>0.05). Conclusions: Expanded flaps with vascular anastomosis are suitable for the treatment of scar contracture deformities of extensively burned patients. The flaps are large in size and suitable in thickness. The donor sites are easy to be closed directly. The treatment can obviously improve the appearance, function, and the quality of life of the patients, with a high satisfaction of patients.

Atraumatic Calf Swelling In Recreational Cyclist

HISTORY: 51 year-old male presented with intermittent left calf pain and swelling for the past 2 months. The pain and swelling became constant the week preceding his presentation. He had no known injury but first noticed the pain after a spin class 2 months ago. The pain was worse with cycling, jogging, and swimming and at the end of the day. He had no knee pain, ankle pain, or hip pain. He denied lower extremity weakness or numbness. The pain did not radiate. PHYSICAL EXAMINATION: There was a soft tissue enlargement in posterior medial aspect of left calf that was mildly tender to palpation, soft, and non-mobile. Transillumination of the area was positive. No overlying erythema or skin changes were noted. Calf musculature and strength were normal. There was no tenderness along the rest of the gastrocnemius or Achilles tendon and no pretibial edema was present. Neurovascular examination was unremarkable. DIFFERENTIAL DIAGNOSIS: 1. Deep Vein Thrombosis 2. Synovial Cyst 3. Abscess 4. Morel-Lavallée lesion 5. Lipoma 6. Hematoma TESTS AND RESULTS: - Knee x-rays: Grossly normal; generally preserved joint space, with osteophyte formation and mild patellofemoral arthritis - Bedside ultrasound of calf: Large, hypoechoic, cystic appearance; connected with a small stalk to the posterior knee joint capsule (popliteal); no vascularity seen on Color Flow Doppler - Fluid analysis: Yellow, hazy; no crystals seen; minimal nucleated cells FINAL/WORKING DIAGNOSIS: Synovial cyst connected to the popliteal aspect of the knee joint TREATMENT AND OUTCOMES: 1. Bedside ultrasound evaluation 2. Aspiration of popliteal cyst, 85cc of straw-colored fluid, sent for analysis 3. ACE wrap recommended in attempt to prevent re-accumulation of fluid 4. Orthopedic evaluation due to re-accumulation of fluid, recommended continued monitoring given asymptomatic nature 5. Could consider surgical excision if becomes symptomatic

Introduction of a novel guided bone regeneration memory shape based device.

Bone regeneration by periosteal distraction has been reported in numerous animal studies; however, the main disadvantages of this technique are poor bone quality and soft tissue invasion in the distracted space. The purpose of this study was to evaluate a novel shape memory-based device to promote bone regeneration in a large, secluded growth space in a rabbit model. Twenty rabbits were divided into two groups. In the first group (n = 10), a device composed of silicone sheets and nitinol strips was inserted subperiosteally in the calvarial area. In the second group (n = 10), only silicone sheets were inserted in the calvarial area. Each group was further divided in half: five animals were sacrificed at 8 weeks postoperatively, and the other five were sacrificed at 16 weeks postoperatively. In the study group, the new device vertically expanded the overlying soft tissue 4 mm above the original bone and created a secluded space; the newly generated bone maximum height median ranged between 2.7 mm in 8 weeks group and 2.6 mm in 16 weeks group. In the control group, a very thin rim of bone was generated below the flat silicone sheets on top of the original bone. Maximum bone heights median ranged from 0.37 mm in 8 weeks group to 0.32 mm in 16 weeks group. The device was proven to be effective at vertically augmenting bone by applying the guided bone regeneration and soft tissue expansion procedures simultaneously. This device may pave the way for a new generation of smart guided bone regeneration membranes that can remember the original dimensions of resorbed bone areas.

Effect of skin soft tissue expansion on repair of large area of scars on extremities

Objective: To investigate the effect of skin soft tissue expansion on repair of large area of scars on extremities. Methods: Twenty-five patients with large area of scars on extremities were admitted to our department from June 2007 to October 2014. There were 14 males and 11 females, aged 4 to 36 years. Operations were performed under local infiltration anesthesia or general anesthesia. In the first stage, 1 to 5 cylindrical expanders with capacities of 250 to 600 mL were placed at left or right sides or at upper or lower parts of the scars. In the second stage, scars of 21 patients were repaired with expanded transverse propulsive and lateral flaps, and scars of 4 patients were repaired with expanded perforator flaps whose pedicles were perforators of brachial artery, superior ulnar collateral artery, or posterior interosseous artery according to areas and shapes of the scars. The secondary wound areas ranged from 13 cm×7 cm to 34 cm×18 cm after dissolution or excision of scars. The areas of flaps ranged from 13 cm×7 cm to 20 cm×12 cm. The donor sites were sutured directly. The flaps after operation and follow-up of patients were observed and recorded. Results: All expanded flaps survived after operation. And the superficial distal part of flap whose pedicle was perforator of posterior interosseous artery in one patient was with necrosis, and other flaps survived well. During follow-up of 3 to 15 months after operation of the second stage, color and texture of flaps were similar to surrounding skin, while extremities of donor sites were thinner and auxiliary incisional scars formed after expansion. Conclusions: Expanded flap is a good way to repair large area of scar on extremities. Bilateral skin of scar is the first choice of donor site of expanded flap. If there isn't enough skin for expanding on bilateral sides, expanded perforator flap designed at upper or lower part of the scar is another choice to repair the scar.

Successful treatment of pathologic femoral shaft fracture associated with large arteriovenous malformations using a 3-dimensional external fixator and teriparatide: a case report

BackgroundArteriovenous malformations (AVMs) are rare congenital vascular lesions associated with early quiescence, late expansion, and, ultimately, infiltration and destruction of local soft tissue and bone. The extremities are a common location. Incidence of bony involvement by AVM has been reported as high as 31%. However, there are few reports on management of pathologic fracture associated with AVM. Teriparatide is a recombinant parathyroid hormone (PTH) analogue consisting of the 1–34 fragment of PTH. Recently, some reports have shown the ability of teriparatide to improve fracture healing. Here, we present a case of pathologic femoral shaft fracture associated with large AVMs that was treated successfully by external fixation and teriparatide.Case presentationA 68-year-old Japanese woman, previously diagnosed as having large AVMs, sustained a right femoral shaft fracture due to a fall. At the time of admission, she presented with massive swelling and venous varicosities of the right thigh. Plain radiography of the right thigh revealed femoral shaft fracture with bony erosion and calcification of soft tissue. We planned closed reduction and intramedullary nailing with a unilateral external fixator following embolization of the feeding artery. However, closed reduction using the fracture table was difficult. When we attempted open reduction, massive bleeding (1000 mL) after incision of subcutaneous tissue occurred. Finally, we carefully applied a Taylor Spatial Frame. Fracture displacement was corrected successfully and bony union was obtained with administration of teriparatide 15 months after the initial surgery. The patient is able to walk using 1 cane.ConclusionWe present the first report of pathologic fracture associated with large AVMs that achieved bony union using a 3-dimensional external fixator and teriparatide.

The Preparation of the Recipient Site in Fat Grafting: A Comprehensive Review of the Preclinical Evidence.

Several methods to prepare the recipient site in fat grafting have been proposed in recent decades. However, to date, these procedures have never been reviewed exhaustively. The purpose of the present study is to provide a comprehensive overview of the different techniques to prepare the recipient site for fat grafting as they were investigated in preclinical studies, with resulting outcomes and underlying mechanisms of action. The PubMed/MEDLINE database was queried to search for preclinical investigations on the preparation of the recipient site in fat grafting using the following algorithm: ((recipient site) AND (fat grafting) OR (lipofilling) OR (lipograft)). A priori criteria were applied to review the resulting articles. Thirteen animal studies met inclusion criteria. Overall, five techniques were identified: external volume expansion, implantation of alloplastic material (silicone sheets), administration of cell-proliferation factors (i.e., vascular endothelial growth factor, adipose tissue-derived stromal vascular fraction, and interleukin-8), ischemia, and microneedling. A positive effect on cellular activity (cell proliferation and angiogenesis) was demonstrated by all studies and achieved with all techniques. Seven of the eight authors who examined this aspect reported enhancement of fat graft survival. Improvement of fat grafting surgical outcomes is documented preclinically using different recipient-site preparation techniques, particularly through enhancement of vascularization and soft-tissue expansion. This understanding will lead to further clinical research, especially for those cases where improvement of the recipient site is recommended, such as contracted scars or preirradiated tissues.

Characterization of pigment epithelium-derived factor expression in mechanically expanding skin

Objective To characterize the pigment epithelium-derived factor (PEDF) expression in the mechanically expanding skin tissues. Methods The rat PEDF expression was identified by immunofluorescence staining on skin tissue sections and by quantitative characterization using Western blotting on tissue lysates originated from the mechanically expanding skin samples. To further elucidate the effects of expansion-relevant tissue microenvironment stimuli on the cellular PEDF expression, the PEDF gene transcription levels were determined respectively on epidermal cells that were incubated in vitro under either hypoxia or mechanical stretching conditions. Results For normal oxygen group, epidermal cell line HaCaT cells were cultured and collected at 1, 3, 6 and 9 h, and the PEDF mRNA espression levels were 0.392±0.174, 0.385±0.207, 0.491±0.134, 0.122±0.040 respectively at 1, 3, 6 and 9 h. For hypoxia group, PEDF mRNA expression levels were markedly upregulated correspondingly [2.271±0.781 (P<0.05), 3.419±0.774 (P<0.05), 2.886±0.019 (P<0.05), and 2.673±0.219 (P<0.05) respectively at 1, 3, 6 and 9 h]. For stretch group, HaCaT cells were applied to mechanical stretch for the same period under the normal oxygen. It was found that the PEDF mRNA expression levels were also upregulated correspondingly [1.535±0.199, 1.078±0.167, 1.295±0.012 and 1.500±0.104 respectively at 1, 3, 6 and 9 h]. However, the difference in the mRNA expression levels between stretch group and normal oxygen group was just significant at 1 h after the onset of mechanical stretching. Conclusion The microenvironmental hypoxia and mechanical strain significantly upregulate epidermal cellular PEDF expression respectively. Key words: Pigment epithelium-derived factor; Soft tissue expansion; HaCaT cells

Transplantation of Adipose-Derived Stem Cells Before Flap Expansion and After Expanded Flap Elevation Result in Different Effects.

Studies of using mesenchymal stem cells to assist skin and soft tissue expansion have shown that stem cells can improve expansion efficiency through promoting tissue regeneration. However, the issue that whether the flap viability is also improved is unknown. Sixteen pigs were equally divided into 2 groups. A pair of 150 mL expanders was symmetrically inserted into each pig's dorsum. Group 1 received adipose-derived stem cells (ADSCs) injection before expansion, and group 2 received ADSCs grafting after flap elevation. After 4 weeks' expansion, a random flap measuring 2 cm × 16 cm was elevated along the long axis of each expanded flap on the pigs' back. Flap viability was measured at postoperative day 7. Histological analysis and cell tracking were performed. The expression of vascular endothelial growth factor was determined. The flap viability of the ADSCs-grafted expanded flap (75.5 ± 6.6%) was similar to the control (69.4 ± 8.4%) in group 1 (transplantation before expansion). However, in group 2 (transplantation after flap elevation), the ADSCs-grafted expanded flap had a higher flap viability (92.6 ± 5.7%) compared with control (66.2 ± 7.4%). Moreover, the ADSCs-grafted expanded flap in group 1 showed increased skin thickness, collagen content, cells proliferation, vascularization, and vascular endothelial growth factor expression. Cell tracking showed that the positively stained cell differentiating into an endotheliocyte could be seen in group 2. Transplantation of ADSCs before tissue expansion does not improve flap viability but can promote tissue regeneration. Injection of ADSCs after flap elevation can increase the surviving rate of the expanded flap.

Clinical Study of Squamous Cell Carcinoma as a Result of a Fissured Epulis in Upper Total Edentulous Patient: A Case Report

Introduction: The fissured epulis is a reactive tissue growth that develops underneath a dental prosthesis. Its etiology is related to removable of partial or total dentures and other irritative or traumatic factors. Oral cancer (CAB) is a malignant neoplasm of aggressive behavior, and it has become one of the most serious health problems worldwide. Currently, squamous cell carcinoma is considered a disease with a high mortality rate. This article aims to describe the clinical management of a squamous cell carcinoma, as a result of a fissured epulis in upper total edentulous patient. Case Report: A female patient, 58 years of age, with no systemic or family history, went for a lower removable prosthesis. The clinical examination in the maxilla presented an enlargement of soft tissue in the bottom of the vestibule on the left side, asymptomatic, compatible with a fissured epulis. Two surgical procedures were performed to remove the pathology and a sample was taken to perform a biopsy, which resulted in a squamous cell carcinoma. The patient was referred to a center specialized in cancer treatments (Society for the Fight Against Cancer) where she currently is receiving the attention of the case. Conclusions: The lack of knowledge of this injury on the part of the patient, and the lack of symptomatology, absence of periodic controls, maladjustment, and incorrect prosthetic design were the risk factors that triggered the injury.

Use of Tissue Expander for Contracted Scarred Saddle Deformity Rhinoplasty.

The main purpose of this article is to present an alternative technique for the reconstruction of saddle nose deformity in patients with severely scarred or contracted soft tissue envelopes. In this single surgeon case series, the authors present a two-staged reconstruction performed on four adult patients with saddle nose deformities and contracted soft tissue envelope stemming from a variety of etiologic factors including vasculitis, sarcoidosis, and trauma. Stage one involved placement of a 1 × 4 cm tissue expander along the nasal dorsum through anterior scalp and endonasal incisions. The tissue expander port was positioned under the anterior scalp and injected with saline over 3 weeks in-office. Stage two involved removal of the tissue expander and rhinoplasty using osteocartilaginous rib grafts. All four patients had successful expansion of the contracted soft tissue envelope, creating adequate space for the newly reconstructed nasal framework. One patient developed exposure of the tissue expander through the endonasal incision, which did not lead to any adverse outcome. All patients in this series tolerated expansion well, without complaints of pain or external skin breakdown. The use of soft tissue expanders along the nasal dorsum can successfully expand contracted and scarred soft tissue envelopes prior to reconstructive rhinoplasty. This technique may be an effective alternative to the use of interpolated flaps in treating these patients.

Prostaglandin analogue drops for the treatment of soft tissue expansion and exophthalmos in patients with inactive thyroid eye disease

Thyroid eye disease (TED) is characterized by an inflammatory response leading to soft tissue expansion within the bony orbit, which may cause exophthalmos. Studies of glaucoma patients reported periorbital fat atrophy after treatment with prostaglandin analogue drops. We hypothesize that owing to this side effect, prostaglandin analogue drops may benefit patients with TED-induced exophthalmos. Interventional prospective pilot study. Five adults with inactive TED and exophthalmos treated with a single daily drop of bimatoprost to both eyes for 6 months. The effect of treatment was evaluated by clinical examinations, Hertel exophthalmometry, marginal reflex distance (MRD), and comparison of digital photographs from before and after treatment by 3 masked oculoplastic surgeons. Patients' subjective satisfaction was recorded as well. Hertel exophthalmometry showed an improvement in exophthalmos after treatment in 3 patients and no change in 2. Both MRD1 and MRD2 increased (for MRD2 p = 0.007). Two observers correctly identified the photograph taken after treatment in 4 patients, and the third observer correctly identified 2 patients and was indecisive about the others. Four patients reported an improvement in their appearance, although additional eyelid retraction was observed. Adverse effects were minimal. Topical prostaglandin analogue treatment of TED-associated exophthalmos appears safe. Although this pilot study was statistically underpowered to show positive results, our findings suggest a treatment-related reduction in periorbital fat volume in most cases and a subjective improvement in appearance. These findings have potential implications for the treatment of exophthalmos in the clinical setting, but more research is required.

Assisting Rapid Soft-Tissue Expansion with Adipose-Derived Stem Cells: An Experimental Study in a Pig Model.

Rapid tissue expansion has been attempted, aiming at shortening the period of conventional expansion. However, it has scarcely been clinically applied because of its drawbacks such as low expansion efficiency and tissue destruction. Adipose-derived stem cell transplantation is a promising therapeutic method in regenerative medicine. However, its effects on rapid expansion remain poorly understood. Twenty-four expanders were implanted in the dorsum of 12 pigs. Rapid expansion persisted for 1 week with 20 ml of saline daily. The increased area of the expanded skin was measured. Histologic and ultrastructural analysis and cell tracking were performed. The expression of vascular endothelial growth factor, fibroblast growth factor-2, and epidermal growth factor was also determined. The increased area of adipose-derived stem cell-grafted expanded skin (0.91 ± 0.06 cm) was significantly more than the non-adipose-derived stem cell-treated control (0.51 ± 0.05 cm) (p < 0.01). Enhanced tissue regeneration in the adipose-derived stem cell-grafted expanded skin was evidenced by increased skin thickness, proliferating cells, extracellular matrix, and vascularization (113 ± 19/mm versus control 59 ± 14/mm) (all p < 0.05). Higher expression of vascular endothelial growth factor and epidermal growth factor was observed in the adipose-derived stem cell-transplanted expanded skin (p < 0.01 and p < 0.05, respectively), whereas the expression of fibroblast growth factor-2 was higher in the non-adipose-derived stem cell-treated control (p < 0.05). Transmission electron microscopy showed that a high density of collagen fibers could be seen in the adipose-derived stem cell-treated expanded skin. Cell tracking showed that the positively stained cells could be seen. For rapid tissue expansion, adipose-derived stem cell transplantation may limit tissue destruction and improve the expansion efficiency by promoting tissue regeneration.

Biocompatibility of injectable hydrogel from decellularized human adipose tissue in vitro and in vivo.

Adipose tissue engineering is considered as a promising treatment for repairing soft tissue defects. The decellularized extracellular matrix (ECM) is becoming the research focus in tissue engineering for its tissue specificity. In this study, the human adipose tissue liposucted from healthy people were decellularized by a series of mechanical, chemical, and enzymatic methods. The components of cell and lipid were effectively removed, whereas the collagens and other ingredients in adipose tissue were retained in the human decellularized adipose tissue (hDAT). Then the extracted hDAT was further fabricated into injectable hydrogel, which could be self-assembled to form gel under certain condition. The hDAT hydrogel was nontoxic to human adipose-derived stem cells (ADSCs) and could spontaneously induce adipogenic differentiation in vitro. It was highly biocompatible and could not cause inflammation and rejection after being implanted subcutaneously. The hDAT hydrogel developed in this study will be one of the available choices for soft tissue enlargement and cosmetic fillers because of its noninvasive in collection and implantation process. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1684-1694, 2019.

Bioinspired 3D structures with programmable morphologies and motions

Living organisms use spatially controlled expansion and contraction of soft tissues to achieve complex three-dimensional (3D) morphologies and movements and thereby functions. However, replicating such features in man-made materials remains a challenge. Here we report an approach that encodes 2D hydrogels with spatially and temporally controlled growth (expansion and contraction) to create 3D structures with programmed morphologies and motions. This approach uses temperature-responsive hydrogels with locally programmable degrees and rates of swelling and shrinking. This method simultaneously prints multiple 3D structures with custom design from a single precursor in a one-step process within 60 s. We suggest simple yet versatile design rules for creating complex 3D structures and a theoretical model for predicting their motions. We reveal that the spatially nonuniform rates of swelling and shrinking of growth-induced 3D structures determine their dynamic shape changes. We demonstrate shape-morphing 3D structures with diverse morphologies, including bioinspired structures with programmed sequential motions.

Acromegaly: a challenging condition to diagnose.

Acromegaly is an uncommon, chronic disease, characterized by hypersecretion of a pituitary growth hormone by somatotroph adenomas, along with increased levels of insulin-like growth factor-1. Although acromegaly presents a wide array of clinical manifestations, the salient symptoms include acral and soft tissue enlargement, joint pain, heart and respiratory failure, diabetes mellitus, and hypertension, leading to increased morbidity and mortality. Hence, early diagnosis of the disease is critical to enhance life expectancy and quality of life. New approaches are being developed for diagnosis and surveillance (both screening and follow-up), including sensitive biochemical assays and the use of MRI to visualize extremely small tumors, and are helpful in the early diagnosis of acromegaly, subsequent treatment, and disease control. This mini-review summarizes the most common and effective tools used in the diagnosis of acromegaly.

Baseline Biomechanical Properties of Epithelia prior to Tissue Expansion in Dogs.

Background:Soft-tissue deficiencies pose a challenge in a variety of disease processes when the end result is exposure of underlying tissue. Although multiple surgical techniques exist, the transposition of tissue from one location to another can cause donor-site morbidity, long incisions prone to dehiscence, and poor patient outcomes as a result. Use of tissue expansion prior to grafting procedures has been shown to have success in increasing available soft tissue to aid in repairing wounds. However, the current tissue expanders have biomechanical limits to the extent and rate of expansion that usually exceeds the tissue capacity, leading to incisional dehiscence or expander extrusion. Understanding the baseline biomechanical properties of the tissue to be expanded would provide useful information regarding surgical protocol employed for a given anatomical location. Therefore, the aim of this study was to test and compare the baseline (preexpansion) biomechanical properties of different common expansion sites in dogs.Methods:Four samples measuring approximately 20 × 15 × 1 mm were harvested from 8 dogs. The samples were collected from the hard palate, alveolar mucosa, scalp, and chest of the animal and analyzed for stress, strain, maximum tangential stiffness, maximum tangential modulus, and tensile strength using a Texture Technologies TA.XT texture analyzer with corresponding biomechanical measurement software. Samples were compared as to their baseline biomechanical properties prior to any soft-tissue expansion. Histological sections of the samples were analyzed using hematoxylin eosin in an attempt to correlate the histological description to the biomechanical properties seen during testing. Summary statistics (mean, standard deviation, standard error, range) are reported for stress, strain, maximum tangential stiffness, maximum tangential modulus, and tensile strength and for the histological parameters by intraoral site. Analysis of variance was used to compare the biomechanical and histological parameters among the 4 locations while accounting for multiple measurements from each dog.Results:The scalp had significantly higher maximum stress (σmax) than chest, mucosa, and palate (P < 0.0001), with no differences among the other 3 locations (P > 0.63). Scalp site also had significantly higher maximum tangential modulus (ε) than chest, mucosa, and palate (P < 0.006), with no differences among the other 3 locations (P > 0.17). The locations did not have significantly different maximum tangential stiffness (k; P = 0.72). Histologically, 2 separate patterns of collagen disruption were evident.Conclusion:Although different results were obtained than theorized, this study showed that the scalp had the greatest resiliency to expand prior to tearing, and the highest tangential modulus, with all sites having statistically similar modulus of elasticity. Based on this study, the scalp could be expanded more aggressively compared with the other sites.

Application of soft tissue expander in plastic reconstruction of head

Objective To explore the timing of surgical operation and surgical incision for the treatment of head of electrical injury and scarred alopecia with soft tissue expander. Methods Twenty-three patients with high tension electrical injury and scarred alopecia were collected, the soft tissue expander was used to repair the wound and scar area.Selected the expander to embed the incision: patients with scarred alopecia were selected to be near the hair area in the scar; high tension electrical injury in patients with incision location selection based on the time of injury and wound repair requirements vary; within 5 days after injury, surgery incision can be selected from the wound about 2-3cm; more than 5 days after injury, the patients chose to stay away from the wound incision, incision about 4-5cm. Results Of 23 patients, postoperative scalp expansion flap good blood supply, a period to solve the high tension electrical injury caused by skull necrosis and scarred alopecia problems.The patients according to the wound debridement and repair requirements using different surgical incision for dilator implantation, wound and flap infection, dilated flap poor blood supply, necrosis, dilator exposed and other issues did not occur after surgery. Conclusion Flexible use of expander embedded surgical incision can be more effectively adapted to the wound repair requirements, timely reduction of implantation expander surgery when the difficulty of stripping, shorten the operation time, the maximum possible protection of healthy scalp tissue, and eventually get a satisfactory clinical cosmetic repair effect. Key words: Tissue expansion device; Electric injuries; Alopecia; Reconstructive surgical procedures