Tissue expansion using osmotically active hydrogel systems for direct closure of the donor defect of the radial forearm flap

Radially Pedicled In-Situ Split-Thickness Skin Grafts, an Alternative to Distal Split-Thickness Skin Grafts

OBJECTIVE

This study aimed to introduce a novel radially pedicled in-situ split-thickness skin graft (STSG). The morbidity, esthetic, and functional outcomes of the radially pedicled in-situ STSG were in comparison with those of the distal STSG.

STUDY DESIGN

Retrospective analysis.

SETTING

A single-institution review.

METHODS

Seventy patients with oral cancer who underwent radical surgical resection and simultaneous radial forearm free flap (RFFF) reconstruction from July 2021 to March 2022 were included. De-epithelialized RFFFs and traditional RFFFs were used to repair oral defects of 35 patients in Group A and Group B, respectively, while radially pedicled in-situ STSGs and distal STSGs taken from abdomens were used to repair donor site defects in the above groups, respectively. Patient demographics, wound healing complications, and esthetic and functional outcomes of the forearms were compared between the 2 groups.

RESULTS

No significant difference between Group A and Group B was observed in terms of donor site and recipient site complications. The esthetic outcome was superior in Group A compared to Group B (P = .011). The extension range, sensation, and pinch strength of operated forearms were significantly reduced in both groups after surgery (P < .05), however, intergroup differences were not observed.

CONCLUSION

Taken together, our results suggest that radially pedicled in-situ STSG is an applicable technique for direct closure and better esthetic outcomes in the forearm donor site.

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.

Soft tissue expansion using self-inflating osmotic hydrogel expanders prior to bone augmentation: healing and complications. Evidence-based review

AIM

This review aims to assess complication rates, soft tissue gain, and bone gain associated with the use of self-inflating osmotic hydrogel tissue expanders (SOHTEs) for soft tissue expansion (STE).

METHODS

A comprehensive search on Pubmed and Google Scholar databases was conducted to identify human studies using SOHTEs for STE; last searched in March 2023. Expansion phase details and expander variables were documented. Complication rates, soft tissue gain, and bone gain reported in each study were also recorded. The inclusion criteria encompassed human studies ranging from evidence levels II-IV (Oxford Centre for Evidence-Based Medicine Levels of Evidence), without specific date limits. For assessing bias in randomized controlled trials (RCTs), a Risk of Bias tool was employed. The synthesised results were presented through tables, sunburst plots, and bar charts.

RESULTS

A total of 13 studies were identified, comprising 4 RCTs, 1 cohort study, and 8 case-series. Employment of SOHTEs yielded an overall complication rate of 17% (24/140 sites), with expander perforation accounting for 9.3% (13/140) of the sites. Specific complication rates included dehiscence (1.4%, 2/140 sites), paraesthesia (1.4%, 2/140 sites), and infection (1.4%, 2/140 sites). All randomized controlled trials (RCTs) were categorised at Level II. The remaining investigations primarily consisted of Level IV case-series lacking controls. All studies demonstrated some concerns towards bias.

CONCLUSION

STE studies using SOHTEs exhibit a reduction in complications associated with bone augmentation in scenarios of inadequate soft tissue coverage. Preliminary evidence suggests potential benefits even in cases with sufficient soft tissue. Adherence to procedural precautions may reduce the risk of expander perforations, further diminishing complications. Subsequent studies should incorporate individual patient and expander variables in their reports to explore the impact of expansion phases on complication rates, as well as bone and soft tissue augmentation.

An Overview of Scaffolds and Biomaterials for Skin Expansion and Soft Tissue Regeneration: Insights on Zinc and Magnesium as New Potential Key Elements

The utilization of materials in medical implants, serving as substitutes for non-functional biological structures, supporting damaged tissues, or reinforcing active organs, holds significant importance in modern healthcare, positively impacting the quality of life for millions of individuals worldwide. However, certain implants may only be required temporarily to aid in the healing process of diseased or injured tissues and tissue expansion. Biodegradable metals, including zinc (Zn), magnesium (Mg), iron, and others, present a new paradigm in the realm of implant materials. Ongoing research focuses on developing optimized materials that meet medical standards, encompassing controllable corrosion rates, sustained mechanical stability, and favorable biocompatibility. Achieving these objectives involves refining alloy compositions and tailoring processing techniques to carefully control microstructures and mechanical properties. Among the materials under investigation, Mg- and Zn-based biodegradable materials and their alloys demonstrate the ability to provide necessary support during tissue regeneration while gradually degrading over time. Furthermore, as essential elements in the human body, Mg and Zn offer additional benefits, including promoting wound healing, facilitating cell growth, and participating in gene generation while interacting with various vital biological functions. This review provides an overview of the physiological function and significance for human health of Mg and Zn and their usage as implants in tissue regeneration using tissue scaffolds. The scaffold qualities, such as biodegradation, mechanical characteristics, and biocompatibility, are also discussed.

Self-swelling tissue expander for soft tissue reconstruction in the craniofacial region: An in vitro and in vivo evaluation

BACKGROUND

Craniofacial soft-tissue defects mostly have an impact on the treatment of various oral diseases. Tissue expander is an important technique for tissue reconstruction, especially for soft tissues in reconstructive surgery.

OBJECTIVE

This research aimed to develop a new self-swelling tissue expander, namely hydrogel, for soft tissue reconstruction in craniofacial region.

METHODS

In vitro, the chemical and physical characteristics of hydrogel were evaluated by SEM, swelling rate, mechanical testing, EDS, and FT-IR. In vivo, the craniofacial implant model of SD rats were divided into group A as control, group B with hydrogels for 1 week expansion, group C for 2 weeks and group D for 4 weeks (n = 5), and the effects were analyzed by HE staining, histological and radiographic evaluation.

RESULTS

The in vitro results suggested that dry hydrogel possessed a uniform surface with micropores, the surface of post-swelling hydrogel formed three-dimensional meshwork. Within 24 hours, hydrogels expanded markedly, then slowed down. The mechanical property of hydrogels with longer expansion was better, whose main elements were carbon and oxygen. FT-IR also verified its molecular structure. In vivo, the wounds of rats recovered well, hydrogels could be removed as one whole piece with original shape and examined by radiographic evaluation, besides, the expanded skin and developed fibrous capsule formed surrounding hydrogels.

CONCLUSION

The new expander was designed successfully with good chemical and physical characteristics, and could be applied in an animal model to help tissue reconstruction.

A Novel Design of V-shaped Radial Forearm Free Flap Facilitates the Direct Closure of Donor Site Wound

ABSTRACT

The radial forearm free flap (RFFF) is one of the commonly used flaps in the repair of head and neck soft tissue defects, especially small and medium-sized defects. The free skin grafts from abdomen are usually used to repair the RFFF donor site wound. This study aims to design a novel V-shaped RFFF, hoping that it might facilitate the direct closure of the forearm donor site wound. From August to December in 2019, 20 patients with oral cancers received radical surgeries, and V-shaped RFFFs were designed to repair the soft defects and the forearm donor site wound was directly closed. The patients were followed up for 6 months to assess the final outcome of repair. The results showed that the pre-designed V-shaped RFFF met the needs of soft tissue defect repair, with the size ranging from 24 cm2 to 30 cm2. Fifteen patients with tongue cancers and four with buccal cancers had satisfactory repair results, and only one patient with buccal cancer had mild limitation of mouth opening. There were 3 patients with a small area of ischemia. The mean postoperative hospital stay was 13.85 ± 1.09 days. In 5 patients, wrist tilt motility decreased compared with that before surgery. The postoperative influence score of wrist exercise on daily life was 2.75 ± 0.44 points. In conclusion, the V-shaped RFFF can meet the needs of small and medium-sized defect repair. This novel design can directly close the forearm donor site wound, which avoids surgical trauma to secondary donor site, and significantly reduces related complications.

Shape-modified radial forearm free tissue transfer in oral cavity reconstruction: Technique and a prospective comparison with the conventional technique

BACKGROUND

Donor site morbidity is a significant drawback of the radial forearm flap. The purpose of this study is to describe a new shape-modified technique. The donor site morbidity was compared to that of the conventional technique, in terms of the esthetic, functional outcomes, and quality of life (QOL).

METHODS

This is a prospective study of 30 patients with oral cancer who underwent reconstruction using radial forearm flaps, in two groups.

RESULTS

Regarding the donor site characteristics, the differences in the time for healing (P = .006), the scar score (P < .0001), and the QOL score (P < .0001) were significant. The number of patients with sensory deficit was 11 in the conventional group and 3 in the shape-modified group (P = .009).

CONCLUSIONS

The functional and esthetic outcomes of the donor site were better for the shape-modified technique. It is best suited for small defects. Compromise of the pedicle length is a limitation.

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.

Skin Extension by Multiple Incisions (SEMI)

BACKGROUND/AIM

There is a need for a simple and atraumatic technique for wound closure in soft tissue defects. The aim of this study was to evaluate the technique of skin extension by multiple incisions in the healing of soft tissue defects following trauma.

PATIENTS AND METHODS

This is a retrospective clinical study on soft tissue defects after trauma. The dimensions of the defects were measured intra-operatively. Exclusion criteria were combined techniques of skin extension by multiple incisions with local flaps or free skin grafts, preoperative numbness, and incomplete data. Complications until wound healing were documented.

RESULTS

One hundred soft tissue defects were evaluated. Uneventful healing occurred in 81. Minor complications were found in 15, and revision was performed in 4. Sensitivity to touch was normal in all.

CONCLUSION

Skin extension by multiple incisions is very easy to learn and can be performed without special instruments. The survival rate of the extended skin is high. Sensitivity to touch and mobility of the skin can be preserved, which results in a very durable nearly normal skin.

Tissue expanders with a focus on extremity reconstruction

INTRODUCTION

Acute traumatic or surgical wounds that cannot be primarily closed often cause substantial morbidity and mortality. This often leads to increased costs from higher material expenses, more involved nursing care, and longer hospital stays. Advancements in soft tissue expansion has made it a popular alternative to facilitate early closure without the need for more complicated plastic surgical procedures.

AREAS COVERED

In this review, we briefly elaborate on the history and biomechanics of tissue expansion and provide comprehensive descriptions of traditional internal tissue expanders and a variety of contemporary external tissue expanders. We describe their uses, advantages, disadvantages, and clinical outcomes. The majority of articles reviewed include case series with level IV evidence. Outcome data was collected for studies after 1990 using PubMed database.

EXPERT COMMENTARY

An overall reduction in cost, time-to-wound closure, hospital length-of-stay, and infection rate may be expected with most tissue expanders. However, further studies comparing outcomes and cost-effectiveness of various expanders may be beneficial. Surgeons should be aware of the wide array of tissue expanders that are commercially available to individualize treatment based on thorough understanding of their advantages and disadvantages to optimize outcomes. We predict the use of external expanders to increase in the future and the need for more invasive procedures such as flaps to decrease.

Reshapable polymeric hydrogel for controlled soft-tissue expansion: In vitro and in vivo evaluation

Tissue expansion is the process by which extra skin is generated using a device that applies pressure from underneath the skin. Over the course of weeks to months, stretching by this pressure creates a flap of extra tissue that can be used to cover a defect area or enclose a permanent implant. Conventional tissue expanders require a silicone shell inflated either by external injections of saline solution or air, or by internal osmotic pressure generated by a hydrophilic polymer. In this study, a shell-free tissue expander comprised only of a chemically cross-linked biocompatible polymeric hydrogel is developed. The cross-linked network of hydrophilic polymer provides for intrinsically controlled swelling in the absence of an external membrane. The new type of hydrogel expanders were characterized in vitro as well as in vivo using a rat-skin animal model. It was found that increasing the hydrophobic polyester content in the hydrogel reduced the swelling velocity to a rate and volume that eliminate the danger of premature swelling rupturing the sutured area. Additionally, increasing the crosslinking density resulted in enough mechanical strength of the hydrogel to allow for complete post-swelling removal, without the hydrogel cracking or crumbling. No systemic toxicity was noted with the expanders and histology showed the material to be highly biocompatible. These expanders have an advantage of tissue expansion without requiring an external silicone membrane, and thus, they can be cut or reshaped at the time of implantation for applications in small or physically constrained regions of the body.

Mucosal Perfusion Preservation by a Novel Shapeable Tissue Expander for Oral Reconstruction

Background:

There are few methods for expanding oral mucosa, and these often cause complications such as tissue necrosis and expander eruption. This study examines mucosal blood perfusion following insertion of a novel shapeable hydrogel tissue expander (HTE). The canine model used subgingival insertion of HTE following tooth extraction and alveolar bone reduction. The primary goal of this study was to gain understanding of epithelial perfusion and reparative responses of gingival mucosa during HTE expansion.

Methods:

Nine Beagle dogs underwent bilateral premolar maxillary and mandibular tooth extraction. Three to four months later, HTE-contoured inserts were implanted submucosally under the buccal surface of the alveolar ridge. After removal and following a 6- to 7-month period of healing, new HTE implants were inserted at the same sites. The area was assessed weekly for tissue perfusion and volume of expansion. Biopsies for histological analysis were performed at the time of expander removal.

Results:

Within 2 weeks following the second insertion, blood flow returned to baseline (defined as the values of perfusion measurements at the presurgery assessment) and remained normal until hydrogel full expansion and removal. Volume expansion analysis revealed that the hydrogel doubled in volume. Histological assessment showed no macrophage or inflammatory infiltration of the mucosa. No superficial fibrosis, decreased vascularity, or mucosal change was seen.

Conclusion:

Maintenance of adequate tissue perfusion is a clinically important aspect of tissue expander performance to reduce risk of device loss or injury to the patient, particularly for areas with a history of previous surgeries.

Pre-augmentation soft tissue expansion: an overview

OBJECTIVES

The aim of this study was to explore the development of soft tissue expanders, their different types and their potential applications prior to bone augmentation and implant placement.

MATERIAL AND METHODS

A review of pertinent literature was performed using PubMed to comprehend the dynamics of soft tissue expanders and determine the current position of their pre-augmentation applications.

RESULTS

There is promising, albeit preliminary information regarding the benefits of pre-augmentation soft tissue expansion. Findings cannot be generalised due to relatively small sample size.

CONCLUSIONS

Further clinical trials with larger sample sizes and long-term follow-up are needed before soft tissue expanders can be confidently applied in everyday clinical practice.

Two-Stage Cranioplasty: Tissue Expansion Directly over the Craniectomy Defect Prior to Cranioplasty

Performing a skull reconstruction for a long-term existing large cranium defect usually needs either skin enhancement or skin flaps and cranioplasty. This procedure can be accompanied with aesthetic and functional complications. The presented case describes a 27-year-old man in need of a cranial reconstruction following decompressive craniectomy as treatment for severe traumatic brain injury. Autologous cranioplasty after decompressive craniectomy failed due to bone flap infection. Because of cognitive behavioral problems, a protective helmet needed to be worn in awaiting cranioplasty. The final titanium cranioplasty was placed subsequent to scalp expansion. The expansion was realized by placing a temporary and custom-made polymethylmethacrylate (PMMA) plate over the defect with a tissue expander on top of it, using the existing scar and skull defect. Our reported technique avoids additional skin flap creation and accompanied complications such as additional scalp and bone damage. In cognitive damaged patients who need to wear a helmet constantly, this simple method provides, concurrently, protection of the brain and tissue expansion. We demonstrate a successful novel technical manner to provide scalp enhancement by positioning a temporary PMMA graft over the skull defect and placing the tissue expander on top of it.

Soft tissue expansion before vertical ridge augmentation: Inflatable silicone balloons or self-filling osmotic tissue expanders?

Recent advances in periodontal plastic surgical procedures allow the clinician to reconstruct deficient alveolar ridges in more predictable ways than previously possible. Placement of implant/s in resorbed ridges poses numerous challenges to the clinician for successful esthetic and functional rehabilitation. The reconstruction frequently utilizes one or combination of periodontal plastic surgical procedures in conjunction with autogenous bone grafting, allogenic bone block grafting, ridge split techniques, distraction osteogenesis, or guided bone regeneration (GBR) for most predictable outcomes. Current surgical modalities used in reconstruction of alveolar ridge (horizontal and/or vertical component) often involve the need of flap transfer. Moreover, there is compromise in tissue integrity and color match owing to different surgical site and the tissue utilized is insufficient in quantity leading to post surgical graft exposition and/or loss of grafted bone. Soft tissue expansion (STE) by implantation of inflatable silicone balloon or self filling osmotic tissue expanders before reconstructive surgery can overcome these disadvantages and certainly holds a promise for effective method for generation of soft tissue thereby achieving predictable augmentation of deficient alveolar ridges for the implant success. This article focuses and compares these distinct tissue expanders for their clinical efficacy of achieving excess tissue that predominantly seems to be prerequisite for ridge augmentation which can be reasonably followed by successful placement of endosseous fixtures.

Submucosal implantation of soft tissue expanders does not affect microcirculation

AIM

To investigate the effect of submucosal implantation of self-filling osmotic tissue expanders on mucosal microcirculation.

MATERIAL AND METHODS

In ten beagle dogs, all premolars were extracted on both sides of the mandible. Tooth-supporting bone and excess soft tissue were removed to mimic a severely resorbed edentulous ridge. Six weeks later, tissue expanders with 0.7 ml final volume were implanted into a submucosal pouch at randomly selected test sites, while contralateral sites served as untreated controls. Microcirculation was assessed in perfusion units (PU) before surgery, after local anaesthesia, directly after surgery, and after 1 and 3 days, using Laser Doppler flowmetry.

RESULTS

Local anaesthesia caused a significant decrease of blood flow from baseline (zero) to -6.4 PU (median; Q1 -10.5; Q3 -0.9; P = 0.006); however, no additional significant decrease was recorded after completion of surgery. Blood flow showed significant increases to -3.6 PU (median; Q1 -11.3, Q3 2.1; P = 0.02) and -4.0 PU (median; Q1 -9.2, Q3 1.1; P = 0.013) after 1 and 3 days, respectively, when compared to the measurements obtained after application of local anaesthesia and completion of surgery. Blood flow had returned to unimpaired baseline levels 1 day after surgery (P > 0.05).

CONCLUSIONS

Submucosal implantation of self-filling osmotic tissue expanders results in only momentary disturbance of microcirculation. The minor impairment of perfusion may explain the consistently good outcomes of submucosal implantation of these tissue expanders.

Reconstruction of a large scalp defect by the sequential use of dermal substitute, self-filling osmotic tissue expander and rotational flap

Large scalp defects pose a challenge for the surgeon. Here, we present a 31-year-old male patient with a soft tissue defect on the temple with exposed bone. To allow reconstruction, we placed a self-filling osmotic expander in the subgaleal pocket for 12 weeks. The final volume of the tissue expander was 300 mL. In the last step, a rotational flap was created after removal of the tissue expander from its pocket. Thereby, a tension-free suturing was possible. The post-surgical healing was uncomplicated. Osmotic tissue expanders are a valuable tool for the closure of large tissue defects without the necessity of repeated filling procedures.

Synthesis and properties of a novel anisotropic self-inflating hydrogel tissue expander

The advent of self-inflating hydrogel tissue expanders heralded a significant advance in the reconstructive techniques available for the surgical restoration of a wide variety of soft tissue defects. However, their use in specific applications such as cleft palate surgery is limited on account of their isotropic expansion. An anisotropic self-inflating hydrogel tissue expander has been developed which markedly increases the potential indications for which this restorative tool may be employed. These include complex pediatric soft tissue reconstructions of the palate, nose, ear and digits. Anisotropic expansion in a hydrogel polymer network composed of methyl methacrylate and vinylpyrrolidone has been achieved by annealing the xerogel under a compressive load for a specified time period. By controlling the anisotropic processing conditions and composition we have been able to accurately tailor the ultimate expansion ratio up to 1500%. The expansion rate of the xerogel has also been significantly reduced by encapsulating the polymer within a semi-permeable silicone membrane. The structure and properties of the novel anisotropic hydrogel were characterized by attenuated total reflectance infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis and small-angle neutron scattering.

Expanding soft tissue with Osmed tissue expanders in the goat maxilla

OBJECTIVES

soft tissue limitations are encountered in implant dentistry, due to the loss of alveolar bone. The aim of this study is to compare the outcome of soft tissue preparation using Osmed self-inflating soft tissue expanders with different in situ times in two implantation techniques.

MATERIAL AND METHODS

Osmed self-inflating soft tissue expanders were implanted in goats using a tunnel approach and a flap approach. The animals were sacrificed after 1h (controls) and 40 days (treated). A tattoo technique for stereographic measurements was used to look for soft tissue surface gain. Histological and histomorphometric analyses were performed to quantify and compare the changes in soft tissue volume and bone volume after 1h and 40 days of implantation.

RESULTS

after 40 days, the expansion was visible and none of the goats had shown any inflammation. The space between the soft tissue and the bone was filled by the completely expanded expander and surrounding connective tissue. Between the test groups and the control groups, there was no histological difference in the structure of the soft tissue.

CONCLUSIONS

all the tissue expanders expanded to their maximum size (2.8 times) and were a reliable product for creating a space between soft tissue and bone. The overlying soft tissue remained in excellent shape. There was no difference in the soft tissue volume and the bone volume between the tunnel and the flap approach after 40 days.

Micro-computed tomography and histologic evaluation of the interface of hydrogel expander and underlying bone: influence of pressure distributors on bone resorption

PURPOSE

Tissue expanders lead to changes in the underlying bone and can cause bone resorption. We investigated whether the insertion of mechanical devices that distribute the load on the bone can influence these effects.

MATERIALS AND METHODS

A total of 28 Lewis rats were assigned to 1 of 4 groups. Hydrogel expanders were placed subcutaneously either directly on the calvaria, on titanium mesh, or on a titanium plate. The fourth group of rats served as the controls. The bone quality and thickness were assessed beneath, and at the periphery of, the expanders using micro-computed tomography and histologic examination.

RESULTS

Micro-computed tomography images were obtained before and 21 days after insertion. The images revealed a significant decrease in hydroxyapatite density beneath the expanders in the group with only expanders. This decrease was reduced with the use of titanium mesh and completely prevented with the use of titanium plates. Histologic examination revealed a significant decrease in bone density and marked lacunae beneath the hydrogel expanders in the group with only expanders. In contrast, the titanium mesh decreased the size of the lacunae, and the titanium plates completely prevented both the formation of lacunae and the decrease in bone thickness.

CONCLUSION

The bone resorption caused by hydrogel expanders can be diminished using titanium mesh and completely prevented by the insertion of a titanium plate.

[Investigation of surgical applicability of acryl-based tissue expanders]

INTRODUCTION

Hydrogels made of acrylamide (AAm), acrylic acid (AAc) and N-isopropylacrylamide (NIPAAm) display outstanding ability of swelling in vitro and this property can be influenced by the composition of the polymers. Our objective was to study the in vivo behavior of hydrogels made of acrylics and their potential role in surgery.

MATERIALS AND METHODS

Cylinder-shaped hydrogels were implanted under the skin of rats in the dorsal region. In group 1 AAm, in group 2 AAc while in group 3 NIPAAm expanders were applied. The observation period lasted 18 days, during this time the length and the diameter of the hydrogels were measured daily. After removal of the polymers the moisture mass and the rheological parameters were determined. Furthermore, biopsies were taken from adjacent tissues.

RESULTS

Expanders achieved the peak of swelling in two weeks. During the observation period their mass significantly increased. NIPAAm polymers demonstrated the highest tendency to retain their preformed shape. Histological analysis revealed that implantation of AAc devices was associated with serious tissue damage while healthy skin was harvested with the other two polymers.

CONCLUSION

In conclusion, NIPAAm hydrogel seems to be the most promising candidate for surgical utilization.

Review of the radial free flap: is it still evolving, or is it facing extinction? Part one: soft-tissue radial flap

The versatile fasciocutaneous radial flap is robust and reliable, straightforward to harvest, and often produces a satisfactory reconstruction with relatively little long-term morbidity at the donor site. Many surgeons prefer to use a limited number of trusted flaps, and these qualities will ensure that in the intermediate future most surgical trainees will continue to be shown the fasciocutaneous radial flap as both the basic training flap and the established option for reconstruction. Evidence from observational clinical studies and one randomised clinical trial indicates that there is increasing support for the use of the evolutionary technique of suprafascial dissection to minimise morbidity at the donor site. The suprafascial donor site may be repaired with either a meshed or unmeshed partial-thickness skin graft, or a fenestrated full-thickness skin graft, with good rates of successful healing. The application of a negative pressure dressing to the wound seems to facilitate the healing of all types of skin graft. The subfascial donor site, however, remains more prone to complications. It may be helpful to position the donor site of the flap more proximally, but this has not been proven. These refinements probably produce the best outcomes that can currently be achieved, given the inherent flaws of the radial donor site.

Postburn scalp reconstruction using a self-filling osmotic tissue expander

Tissue expanders have been used in the past few decades for various reconstructive procedures. The conventional expander requires serial filling injections in repeated visits over a few months period, and carries a substantial complication rate. An osmotic self-filling expander was invented ten years ago, but has still not gained a wide spread use. We describe here our first experience with this expander in reconstruction of a post-burn scalp scar in a young patient, and discuss its advantages: no filling injections are needed, thus lowering the possibility of infection and significantly reducing the number of required visits to the outpatient clinic; the swelling is much more gradual and subtle and there is no pain that usually follows the filling injection; the small initial volume of the expander requires a relatively small pocket and can be performed under local anesthesia and results in a relatively short scar.

Closure of radial forearm free flap donor site defect with a local meshed full-thickness skin graft: a retrospective study of an original technique

INTRODUCTION

Closure of the radial free flap donor site remains a problem. Donor site morbidity is related to poor skin graft taking, inaesthetic appearance and hand sensory dysfunction.

PATIENTS AND METHODS

From January 1998 to December 2002, 41 radial free flaps were harvested. The donor site closure technique consisted of a combination of: flexor tendons coverage, purse string and local meshed full-thickness skin graft.

RESULTS

The mean time of wound healing of the donor site was 4.68 weeks. Four patients (16%) developed a partial necrosis of the skin graft. Nine patients (36%) showed a definitive hypoaesthesia in the dorsal region of the thumb. Neither total necrosis of the skin graft nor exposure of flexor carpi radialis tendon was noted. The average visual analogue scale of the aesthetics was 6 (patients), 4.18 (students) and 7.2 (first author) out of 10.

CONCLUSION

This technique for closing a small-to-medium sized radial donor site defect is recommended.

Investigation of the Expansion Properties of Osmotic Expanders with and without Silicone Shell in Animals

BACKGROUND

Particularly in clinical studies, it has been found that rapid swelling of tissue expanders leads to high-pressure peaks that can cause hypoxia in the tissue and thus also skin damage. For this reason, the present study in animals investigated whether an osmotic expander with silicone shell is capable of expanding in tissue and bringing about useful tissue expansion without complications. It was also examined whether and what quantitative and qualitative differences there are between conventional osmotic expanders and the new expanders with silicone shell.

METHODS

The expansion of osmotic expanders with silicone shell was compared with that of osmotic expanders without silicone shell in four mini pigs. The expander type used was an M1 rectangle with an initial volume of 6 ml. Five expanders were implanted in each pig, meaning that 20 expanders were measured. The volume of the expanders was measured directly after explantation. Indirect volume determination was performed by producing plaster casts for subsequent laser optical measurement.

RESULTS

Comparison of the two curve profiles showed a much flatter profile for the expanders with silicone shell. The absolute values for the volumes of the expanders with silicone shell were likewise substantially lower.

CONCLUSIONS

Controlled skin expansion is a technique of providing localized donor tissue for reconstructive surgery. The new expanders could be in a position to lower the rate of complications in tissue expansion.

The Transverse Radial Artery Forearm Flap

BACKGROUND

In an attempt to improve the versatility of the radial forearm flap, a new design was developed: the transverse radial artery forearm flap.

METHODS

The transverse radial artery forearm flap is designed elliptically in the distal palmar forearm with the long axis oriented transversely parallel to the wrist. The donor defect is closed by a V-shaped flap, which is elevated as a fasciocutaneous flap based on the ulnar artery by V-Y advancement. This second flap allows defect coverage without the need for a skin graft. From March of 1994 to February of 2005, the authors treated 39 patients with this flap. Free flaps were used in 36 patients and three patients were operated on with reverse pedicled flaps.

RESULTS

Twenty-five patients had head and neck defects, 11 patients had defects of the distal foot or great toe, and three patients had hand defects. In 13 cases, an osteocutaneous flap was elevated, and three flaps were transferred as sensate flaps. Maximum flap dimensions were 10 x 6 cm. The longest vascular pedicle in this series was 20 cm. All flaps survived. Except for two cases of delayed healing, no complications occurred at the donor site.

CONCLUSIONS

The transverse radial artery forearm flap is more versatile than the conventional radial flap, with the additional advantage of a long vascular pedicle. Its design allows for harvest of a piece of radial bone, which is pedicled on a completely different portion of the radial artery than the skin paddle. Thus, the setting of the bony portion can be chosen liberally. Donor-site morbidity is reduced, and the result is aesthetically pleasing.

Cleft palate repair with the use of osmotic expanders: a preliminary report

A new method of cleft palate repair by expansion of tissue by means of osmotic expanders implanted in the first stage of treatment is described. Self-expanding expanders manufactured by OSMED (Ilmenau, Germany) were implanted under the mucoperiosteal layer of the hard palate, on purpose to generate more tissue and provide facility for palate repair performed 24-48h later. Nineteen children aged from 2 to 3 years were operated from January 2004 to 15 April 2005. In clefts<10mm, tissue repair was possible without relaxing incisions. In 11 patients with clefts>10mm, cleft palate repair was more difficult and the outcomes were less favourable. Despite more generous dissection of the neurovascular bundles and other adjunctive measures such as mucosal V-Y plasty [Bardach J, Salyer K. Surgical techniques in cleft lip and palate. Chicago, London: Year Book Medical Publishers, Inc.; 1987.] and suturing of the mucosal grafts at the border of the hard and soft palate, seven 2-4mm fistulae were noted, however. Concluding, in spite of some shortcomings and unacceptable rate of fistula in wide clefts, the above-presented method seems to be an attractive concept. Despite some technical problems related mostly to still tested optimal filling phase, tissue expansion makes palate repair easier, probably without relaxing incisions and bone denudation. Consequently, some adverse effects on facial growth may be reduced. So far, there is no evidence for it, however, and since this is a preliminary report, there is a need for longer observations and larger material.

Donor site morbidity of the fasciocutaneous radial forearm flap: what does the patient really bother?

The objective of this study was the evaluation of donor site morbidity in head and neck cancer patients after reconstruction using a free vascularized radial forearm flap with emphasis on subjective complaints. Fifty patients who underwent at least 6 months before a reconstruction using a free vascularized radial forearm flap were asked to fill out two questionnaires regarding cosmetics and sensibility and forearm disabilities. Furthermore, a function test including movement extensions (flexion-extension, ulnar-radial deviation and pronation-supination), strength (pinch and grip) and temperature (digiti I and V) of the donor and non-donor site were measured and compared. Thirty-five percent of the patients reported no complaints regarding cosmetics and sensibility and 75% mentioned no forearm disabilities. There was no difference in movement extensions, temperature and grip strength between donor and non-donor sites. The difference in pinch strength appeared to be significant (p < 0.001). The total score of the questionnaire on forearm disabilities correlated significantly with extension, pronation and grip strength of the donor arm. Donor site morbidity of the radial forearm flap measured by objective functional tests was limited but subjective self-ratings revealed complaints regarding cosmestics and sensibility and to a lesser extent regarding forearm disability. The present data may be used for solid patient counselling.

Sustainability of mechanically lengthened bowel in rats

INTRODUCTION

It has been shown that the length of an intestinal segment may be doubled by applying gradual mechanical stretching. This study evaluated whether the lengthened intestinal segment retained the structure and function after the stretching device was removed.

METHODS

A 1.5-cm jejunal segment was separated from intestinal continuity in 20 rats. After advancing a screw into the isolated jejunal segment by 5 mm 3 times a week until it was stretched by 3 cm, the screw was removed. Three weeks later, the jejunal segments were retrieved for analyses. Comparisons were made between the lengthened jejunal segments.

RESULTS

The jejunal segment doubled its length after gradual stretching and retained this length 3 weeks after the screw removal (3.1 +/- 0.8 vs 3.2 +/- 0.4 cm, P > .05). The villous height, the muscular thickness, and the total alkaline phosphatase and lactase activities of the stretched jejunal segments were also unchanged 3 weeks after the screw removal.

CONCLUSIONS

Mechanical force induced the sustained lengthening of isolated jejunal segments in rats. The histologic and enzymatic alterations also persisted 3 weeks after the mechanical force was removed. This phenomenon may provide a novel method for the treatment of short bowel syndrome.

Proximal Forearm Flap Based on a Septocutaneous Vessel from the Radial Artery

BACKGROUND

The radial forearm flap has been a workhorse flap for soft-tissue or coverage reconstruction in the head and neck area. Although it has several major advantages, it requires sacrifice of the radial artery. In this article, the authors present their modification of harvesting a forearm flap based on a large septocutaneous branch of the radial artery in the proximal forearm with or without sacrificing the main radial artery. They name it the proximal radial forearm flap.

METHODS

From September of 2003 to March of 2004, a total of 14 free proximal radial forearm flaps were used for head and neck reconstruction in 12 patients. There was one female patient and 11 male patients. Their ages ranged from 32 to 85 years. The skin flap size ranged from 2.0 x 6.0 cm to 4.5 x 18 cm.

RESULTS

All free proximal radial forearm flap reconstructions had immediate success. There were one delayed flap loss caused by wound infection and one death attributable to advanced medical disease. Six flaps were harvested with preservation of the radial artery trunk. Six of the eight radial arteries that were killed during flap harvest were repaired with a short segment (3 to 4 cm) of vein graft. The average diameter and length of the septocutaneous vessel of the proximal radial forearm flap was 0.73 mm and 3.3 cm, respectively. Two flaps were harvested in conjunction with the conventional free radial forearm flaps. Nine donor sites were closed primarily and five donor sites required skin grafts.

CONCLUSIONS

The proximal radial forearm flap can be used successfully in head and neck reconstruction with the advantages of moving the donor site to the proximal forearm for better scar concealment and possible preservation of the radial artery trunk. The disadvantages of this flap are short pedicle length and small pedicle diameter when the radial artery is to be preserved.

Comparison of the Radial Forearm Flap and the Thinned Anterolateral Thigh Cutaneous Flap for Reconstruction of Tongue Defects: An Evaluation of Donor-Site Morbidity

The radial forearm flap is commonly used for reconstruction of tongue defects following tumor extirpation. This flap is easy to harvest and offers thin tissue with large-caliber vessels. However, its use leaves behind a conspicuous aesthetic deformity in the forearm and requires the sacrifice of a major artery of that limb, the radial artery. The anterolateral thigh cutaneous flap has found clinical applications in the reconstruction of soft-tissue defects requiring thin tissue. More recently, in a thinned form, the anterolateral thigh flap has been used for reconstructing defects of the tongue with functional results equivalent to that of the radial forearm flap. For the reconstruction of tongue defects, these two flaps could provide similar soft-tissue coverage, but they seem to result in different donor-site appearances. The donor site is closed primarily, leaving only a linear scar that is inconspicuous with normal clothing, and no functional deficit is left behind in the thigh. Thus, for the supply of flaps for tongue defects, a comparison between the radial forearm flap and the anterolateral thigh flap donor sites is provided in this study. Between December of 2000 and August of 2002, 41 patients who underwent reconstruction of defects of the tongue using either a radial forearm flap or an anterolateral thigh flap were evaluated. The focus was on the evaluation of the functional and aesthetic outcome of the donor site after harvesting these flaps for the purpose of reconstructing either total or partial tongue defects. Finally, a comparison was performed between the donor sites of the two flaps. The disadvantages of the radial forearm flap include the conspicuous unattractive scar in the forearm region, pain, numbness, and the sacrifice of a major artery of the limb. In some patients, the donor-site scar of the forearm acted as a social stigma, preventing these patients from leading a normal life. In contrast, the anterolateral thigh cutaneous flap, after thinning, achieved the same results in reconstructing defects of the tongue without the associated donor-site morbidity. Most importantly, the donor site in the thigh could be closed primarily in almost all patients without any functional deficit. The thinned anterolateral thigh cutaneous flap is a viable substitute for the radial forearm flap when reconstructing defects of the tongue. The results achieved are similar to those of the radial forearm flap, and the donor-site morbidity is significantly decreased.

Use of self-expanding, hydrophilic osmotic expanders (hydrogel) in the reconstruction of congenital clinical anophthalmos

PURPOSE OF REVIEW

Rehabilitation of the congenitally anophthalmic orbit is frustrating to both the parents and physician. Traditional methods involve using progressively enlarging static acrylic conformers to expand the conjunctival socket, followed by placement of conventional static spherical orbital implants, dermis-fat grafts, or inflatable balloon expanders for orbital enlargement. Limitations of these methods typically result in less-than-optimal cosmetic outcomes, with retardation of bony orbital and overlying soft tissue growth adversely affecting midfacial growth and symmetry. Recent advances in tissue expansion technology may offer additional, novel alternatives to conventional therapies.

RECENT FINDINGS

Hydrogel tissue expanders were recently adapted for use in congenital anophthalmia. The expanders are placed in their dry, contracted states, and expand gradually to their full size via osmosis of surrounding tissue fluid, with up to a 10-fold increase in volume. Offering the benefit of predictable and controllable self-expansion, hydrogel expanders may offer yet another alternative or adjunctive therapy to the early rehabilitation of the contracted socket. Separate appliances are used for conjunctival and orbital reconstruction. Initial results appear promising. Tempering the enthusiasm for their use, however-particularly in terms of implanted orbital expanders-is the recent spate of long-term complications reported from previous uses of hydrogels as scleral buckling material.

SUMMARY

Self-expanding hydrogel tissue expanders appear to offer an intriguing reconstructive alternative to the frustrating condition of congenital anophthalmia. Long-term safety of the material as an orbital implant has not yet been demonstrated, but early results are promising.

Primary Closure of Radial Forearm Flap Donor Defects with a Bilobed Flap Based on the Fasciocutaneous Perforator of the Ulnar Artery

To primarily repair a series of radial forearm flap donor defects, a total of 10 bilobed flaps based on the fasciocutaneous perforator of the ulnar artery were designed at the Chang Gung Memorial Hospital in Kaohsiung in the period from January of 2002 to January of 2003. All patients were male, with ages ranging from 36 to 67 years. The forearm donor defects ranged in size from 5 x 6 cm to 8 x 8 cm, with the average defect being 47 cm. One to three sizable perforators from the ulnar artery were consistently observed in the distal forearm and were most frequently located 8 cm proximal to the pisiform, which could be used as a pivot point for the bilobed flap. The bilobed flap consisted of two lobes, one large lobe and one small lobe. With elevation and rotation of the bilobed flap, the large lobe of the flap was used to repair the radial forearm donor defect and the small lobe was used to close the resultant defect from the large lobe. All bilobed flaps survived completely, without major complications, and no skin grafting was necessary. Compared with conventional methods for reconstruction of radial forearm donor defects, such as split-thickness skin grafting, the major advantage of this technique is its ability to reconstruct the donor defect with adjacent tissue in a one-stage operation. Forearm donor-site morbidity can be minimized with earlier hand motion, and better cosmetic results can be obtained. Furthermore, because a skin graft is not used, no additional donor area is necessary. However, this flap is suitable for closure of only small or medium-size donor defects. A lengthy postoperative scar is its major disadvantage.