Total reconstruction of the auricle: our experiences on indications and recent techniques

Cost-effective 3D scanning and printing technologies for outer ear reconstruction: current status

Current 3D scanning and printing technologies offer not only state-of-the-art developments in the field of medical imaging and bio-engineering, but also cost and time effective solutions for surgical reconstruction procedures. Besides tissue engineering, where living cells are used, bio-compatible polymers or synthetic resin can be applied. The combination of 3D handheld scanning devices or volumetric imaging, (open-source) image processing packages, and 3D printers form a complete workflow chain that is capable of effective rapid prototyping of outer ear replicas. This paper reviews current possibilities and latest use cases for 3D-scanning, data processing and printing of outer ear replicas with a focus on low-cost solutions for rehabilitation engineering.

Auricular Protrusion After the Postauricular Approach: A Review of the Current Literature

The postauricular approach is a widely adopted surgical technique for the ear due to its unique access to the middle ear, mastoid, and other internal structures, while adeptly concealing the surgical incision for aesthetic superiority. Despite its advantages, concerns have emerged regarding the potential for auricular protrusion following the procedure. While the exact mechanisms underlying this phenomenon remain under debate, it is worth noting that comprehensive literature on this topic is scant. Nevertheless, available studies predominantly indicate no association between the postauricular approach and lasting auricular protrusion. In the few reports that do note its occurrence, the protrusion appears transient, resolving over time. These findings suggest that surgeons should continue using the postauricular approach without concerns regarding auricular protrusion. Nonetheless, it is recommended to take all precautionary measures, including appropriate patient selection, engagement of an experienced surgeon, and meticulous postoperative dressing.

Characterization of Auricular Growth within the Pediatric Population Using Computed Tomography Scan Measurements

Background

In patients with microtia, auricular reconstruction is ideally performed promptly to prevent impaired socialization during formative childhood years. The earliest viable age for reconstruction is widely accepted from 7-10 years of age, as full auricular size is achieved around age 8, with some variability dependent on sex. This retrospective study aims to provide an auricular growth curve that accounts for age and sex, enhancing the individualized approach to ear reconstruction.

Methods

A total of 319 images of unaffected patients who underwent computed tomography angiography of the head and neck were reviewed, with bilateral cartilage height and width measured according to a consensus-standardized image measurement protocol. Means and SDs of cartilage height and width were calculated for both sexes, and analysis of ear growth was performed through plotting the mean cartilage height, width, and width:height ratio over time.

Results

Cartilage height and width differed significantly between male and female groups. Maximum cartilage height was reached at age 11 for female and at age 12 for male patients, whereas maximum cartilage width was reached at ages 10 and 8, respectively. On average, the width:height ratio for female group was 0.58. For male group, the average width:height ratio was 0.59.

Conclusions

An auricular growth map was designed using computed tomography measurements demonstrating maximum auricular size at age 11 and 12 respectively for female and male patients, with both sexes having a width:height ratio maintained at approximately 0.6 throughout growth.

Efficient engineering of human auricular cartilage through mesenchymal stem cell chaperoning

A major challenge to the clinical translation of tissue-engineered ear scaffolds for ear reconstruction is the limited auricular chondrocyte (hAuC) yield available from patients. Starting with a relatively small number of chondrocytes in culture results in dedifferentiation and loss of phenotype with subsequent expansion. To significantly decrease the number of chondrocytes required for human elastic cartilage engineering, we co-cultured human mesenchymal stem cells (hMSCs) with HAuCs to promote healthy elastic cartilage formation. HAuCs along with human bone marrow-derived hMSCs were encapsulated into 1% Type I collagen at 25 million/mL total cell density with different ratios (HAuCs/hMSCs: 10/90, 25/75, 50/50) and then injected into customized 3D-printed polylactic acid (PLA) ridged external scaffolds, which simulate the shape of the auricular helical rim, and implanted subcutaneously in nude rats for 1, 3 and 6 months. The explanted constructs demonstrated near complete volume preservation and topography maintenance of the ridged "helical" feature after 6 months with all ratios. Cartilaginous appearing tissue formed within scaffolds by 3 months, verified by histologic analysis demonstrating mature elastic cartilage within the constructs with chondrocytes seen in lacunae within a Type II collagen and proteoglycan-enriched matrix, and surrounded by a neoperichondrial external layer. Compressive mechanical properties comparable to human elastic cartilage were achieved after 6 months. Co-implantation of hAuCs and hMSCs in collagen within an external scaffold efficiently produced shaped human elastic cartilage without volume loss even when hAuC comprised only 10% of the implanted cell population, marking a crucial step toward the clinical translation of auricular tissue engineering.

The cutting edge of customized surgery: 3D-printed models for patient-specific interventions in otology and auricular management-a systematic review

PURPOSE

3D-printing (three-dimensional printing) is an emerging technology with promising applications for patient-specific interventions. Nonetheless, knowledge on the clinical applicability of 3D-printing in otology and research on its use remains scattered. Understanding these new treatment options is a prerequisite for clinical implementation, which could improve patient outcomes. This review aims to explore current applications of 3D-printed patient-specific otologic interventions, including state of the evidence, strengths, limitations, and future possibilities.

METHODS

Following the PRISMA statement, relevant studies were identified through Pubmed, EMBASE, the Cochrane Library, and Web of Science. Data on the manufacturing process and interventions were extracted by two reviewers. Study quality was assessed using Joanna Briggs Institute's critical appraisal tools.

RESULTS

Screening yielded 590 studies; 63 were found eligible and included for analysis. 3D-printed models were used as guides, templates, implants, and devices. Outer ear interventions comprised 73% of the studies. Overall, optimistic sentiments on 3D-printed models were reported, including increased surgical precision/confidence, faster manufacturing/operation time, and reduced costs/complications. Nevertheless, study quality was low as most studies failed to use relevant objective outcomes, compare new interventions with conventional treatment, and sufficiently describe manufacturing.

CONCLUSION

Several clinical interventions using patient-specific 3D-printing in otology are considered promising. However, it remains unclear whether these interventions actually improve patient outcomes due to lack of comparison with conventional methods and low levels of evidence. Further, the reproducibility of the 3D-printed interventions is compromised by insufficient reporting. Future efforts should focus on objective, comparative outcomes evaluated in large-scale studies.

Tissue engineering of human ear pinna

Auricular deformities (Microtia) can cause physical, social as well as psychological impacts on a patient's wellbeing. Biofabrication of a complex structure such as ear pinna is not precise with currently available techniques. These limitations can be overcome with the help of tissue engineering. In this article, the authors presented molding and three dimensional (3D) printing to generate a flexible, human size ear pinna. The decellularization of goat ear cartilage protocol and bioink alkaline digestion protocol was followed to yield complete removal of all cellular components without changing the properties of the Extra Cellular Matrix (ECM). Decellularized scaffold used in molding technology and 3D printing technology Computer-Aided Design /Stereolithography (CAD/STL) uses bioink to construct the patient-specific ear. In vivo biocompatibility of the both ear pinnae showed demonstrable recellularization. Histology and scanning electron microscopy analysis revealed the recellularization of cartilage-specific cells and the development of ECM in molded and 3D printed ear pinna after transplantation. Both the techniques provided ideal results for mechanical properties such as elasticity. Vascular Associated Protein expression revealed specific vasculogenic pattern (angiogenesis) in transplanted molded pinna. Chondrocyte specific progenitor cells express CD⁹⁰⁺ which highlighted newly developed chondrocytes in both the grafts which indicated that the xenograft was accepted by the rat. Transplantation of molded as well as 3D ear pinna was successful in an animal model and can be available for clinical treatments as a medical object to cure auricular deformities.

Novel method for high-density porous polyethylene ear reconstruction stent remodeling to achieve high satisfactory outcomes

OBJECTIVE

We aimed to explore a novel method for ear reconstruction stent remodeling to achieve high patient satisfactory outcomes.

METHODS

This study is a retrospective review of patients with congenital or acquired ear defects who were prepared for one-stage ear reconstruction with high-density porous polyethylene stent between May 2020 and May 2021. A standardized data collection template was used to collect related variables. In this study, the detailed reconstruction surgery process is carefully described, and the postoperative healing process of the ear reconstruction was closely observed.

RESULTS

A total of 26 patients for one-stage ear reconstruction with high-density porous polyethylene stent or autogenous costal cartilage scaffolds were admitted to the department of plastic surgery in our hospital between May 2020 and May 2021. All patients were followed until their ear flaps were alive and details of the ear shape were revealed. The patients with new remolding method were no severe complications and only a patient had stent exposure, and were highly satisfied with both appearance and function.

CONCLUSIONS

The application of novel remodeling method is a promising way for ear reconstruction stent shaping with little postoperative complication and excellent postoperative patient satisfaction.

Three-Dimensional-Printed External Scaffolds Mitigate Loss of Volume and Topography in Engineered Elastic Cartilage Constructs

OBJECTIVE

A major obstacle in the clinical translation of engineered auricular scaffolds is the significant contraction and loss of topography that occur during maturation of the soft collagen-chondrocyte matrix into elastic cartilage. We hypothesized that 3-dimensional-printed, biocompatible scaffolds would "protect" maturing hydrogel constructs from contraction and loss of topography.

DESIGN

External disc-shaped and "ridged" scaffolds were designed and 3D-printed using polylactic acid (PLA). Acellular type I collagen constructs were cultured in vitro for up to 3 months. Collagen constructs seeded with bovine auricular chondrocytes (BAuCs) were prepared in 3 groups and implanted subcutaneously in vivo for 3 months: preformed discs with ("Scaffolded/S") or without ("Naked/N") an external scaffold and discs that were formed within an external scaffold via injection molding ("Injection Molded/SInj").

RESULTS

The presence of an external scaffold or use of injection molding methodology did not affect the acellular construct volume or base area loss. In vivo, the presence of an external scaffold significantly improved preservation of volume and base area at 3 months compared to the naked group (P < 0.05). Construct contraction was mitigated even further in the injection molded group, and topography of the ridged constructs was maintained with greater fidelity (P < 0.05). Histology verified the development of mature auricular cartilage in the constructs within external scaffolds after 3 months.

CONCLUSION

Custom-designed, 3D-printed, biocompatible external scaffolds significantly mitigate BAuC-seeded construct contraction and maintain complex topography. Further refinement and scaling of this approach in conjunction with construct fabrication utilizing injection molding may aid in the development of full-scale auricular scaffolds.

The Application of Cartilage Tissue Engineering with Cell-Laden Hydrogel in Plastic Surgery: A Systematic Review

BACKGROUND

As a contour-supporting material, the cartilage has a significant application value in plastic surgery. Since the development of hydrogel scaffolds with sufficient biomechanical strength and high biocompatibility, cell-laden hydrogels have been widely studied for application in cartilage bioengineering. This systematic review summarizes the latest research on engineered cartilage constructed using cell-laden hydrogel scaffolds in plastic surgery.

METHODS

A systematic review was performed by searching the PubMed and Web of Science databases using selected keywords and Medical Subject Headings search terms.

RESULTS

Forty-two studies were identified based on the search criteria. After full-text screening for inclusion and exclusion criteria, 18 studies were included. Data collected from each study included culturing form, seed cell types and sources, concentration of cells and gels, scaffold materials and bio-printing structures, and biomechanical properties of cartilage constructs. These cell-laden hydrogel scaffolds were reported to show some feasibility of cartilage engineering, including better cell proliferation, enhanced deposition of glycosaminoglycans and collagen type II in the extracellular matrix, and better biomechanical properties close to the natural state.

CONCLUSION

Cell-laden hydrogels have been widely used in cartilage bioengineering research. Through 3-dimensional (3D) printing, the cell-laden hydrogel can form a bionic contour structure. Extracellular matrix expression was observed in vivo and in vitro, and the elastic modulus was reported to be similar to that of natural cartilage. The future direction of cartilage tissue engineering in plastic surgery involves the use of novel hydrogel materials and more advanced 3D printing technology combined with biochemistry and biomechanical stimulation.

Tissue Engineering the Pinna: Comparison and Characterization of Human Decellularized Auricular Biological Scaffolds

Decellularization is one of the promising techniques in tissue engineering used to create a biological scaffold for subsequent repopulation with the patient's own cells. This study aims to compare two different decellularization protocols to optimize the process of auricle decellularization by assessing and characterizing the decellularization effects on human auricular cartilage. Herein, 12 pairs (8 females, 4 males) of freshly frozen adult human cadaveric auricles were de-epithelialized and defatted leaving only the cartilaginous framework. An auricle from each pair was randomly assigned to either protocol A (latrunculin B-based decellularization) or protocol B (trypsin-based decellularization). Gross examination of the generated scaffolds demonstrated preservation of the auricles' contours and a change in color from pinkish-white to yellowish-white. Hematoxylin and eosin staining demonstrated empty cartilaginous lacunae in both study groups, which confirms the depletion of cells. However, there was greater preservation of the extracellular matrix in auricles decellularized with protocol A as compared to protocol B. Comparing protocol A to protocol B, Masson's trichrome and Safranin-O stains also demonstrated noticeable preservation of collagen and proteoglycans, respectively. Additionally, scanning electron micrographs demonstrated preservation of the cartilaginous microtopography in both study groups. Biomechanical testing demonstrated a substantial decrease in Young's modulus after decellularization using protocol B (1.3 MPa), albeit not significant (P-value > 0.05) when compared to Young's modulus prior to decellularization (2.6 MPa) or after decellularization with protocol A (2.7 MPa). A DNA quantification assay demonstrated a significant drop (P-value < 0.05) in the DNA content after decellularization with protocol A (111.0 ng/mg) and protocol B (127.6 ng/mg) in comparison to before decellularization (865.3 ng/mg). Overall, this study demonstrated effective decellularization of human auricular cartilage, and it is concluded that protocol A provided greater preservation of the extracellular matrix and biomechanical characteristics. These findings warrant proceeding with the assessment of inflammation and cell migration in a decellularized scaffold using an animal model.

3D printing of human ear pinna using cartilage specific ink

Biofabrication of a complex structure such as ear pinna is not precise with currently available techniques. Auricular deformities (e.g. microtia) can cause physical, social as well as psychological impacts on a patient's wellbeing. Currently available surgical techniques and transplantation methods have many limitations that can be overcome with the help of 3D bioprinting technology. Printable bioink enriched with cartilage-specific extracellular matrix (ECM) synthesis was done by digesting goat ear pinna cartilage and polymerized by adding polyvinyl alcohol and gelatine. Rheological analysis and Fourier-transform infrared spectroscopy were used for the characterization of bioink to get desired viscosity and polymerization. Human ear pinna was printed using extrusion method and computer-aided design, stereolithography software which facilitated the automated printing in relatively less time without continuous monitoring. Thermal degradation of pinna was checked by thermal gravimetric analysis. Biodegradability and swelling of ear pinna were observed for understanding the nature of pinna and the impact of external factors. Reconstructed pinna's biocompatibility was proved byin ovoandin vivostudies. The occurrence of angiogenesis in the grafted ear manifested the capacity of proliferation and engraftment of cartilage cells. Histology and SEM analysis revealed the recellularization and the synthesis of ECM components such as glycosaminoglycan and collagen in transplanted 3D printed ear pinna. The expression of CD90+ which indicated newly synthesized cartilage in the transplanted 3D printed ear pinna. The absence expression of CD14+ also indicated acceptance of xenogenic transplanted 3D printed ear pinna. Transplantation of 3D ear pinna was successful in an animal model and can be utilized as tissue engineered ear bank.

The Utility of Smartphone 3D Scanning, Open-Sourced Computer-aided Design, and Desktop 3D Printing in the Surgical Planning of Microtia Reconstruction: a Step by Step Guide and Concept Assessment

Introduction

Microtia, a congenital anomaly of the auricle with a wide spectrum of presentation with challenging reconstruction. Management depends on its severity with variable reconstructive options. Preoperative planning is crucial to achieve better results and decrease operative time. In this article, we aim to show the utility of an affordable technology with the use of a smartphone, an open-source computer-aided design (CAD) software, and a desktop 3D printer in planning future ear location for unilateral microtia reconstruction in step-by-step fashion.

Methodology

Facial 3D scanning was done using a smartphone that has a three-dimensional capture system. The scan was then used in an open-sourced CAD software. A mirror image mask was created by reflecting normal side anatomic features to the abnormal side. The mask constitutes the desired area for reconstruction given the ear anthropometrics. Finally, the model was 3D printed and fitted to the patient in which incision marking and framework location was planned.

Discussion

Ear reconstruction requires careful assessment and specific technicality in its anthropometric measures. One important aspect in surgical planning resides in future ear location that varies between person to person. This variability makes the reconstructive option more customized based on the patient's needs. The utility of CAD software in the measurement and planning can help predict and optimize postoperative results as possible; however, it has major technical demands and added surgical fees.

Conclusion

Herein, we demonstrate the efficacy of an easy-to-use system beneficial for preoperative planning that is affordable, time-saving, and cost effective.

Systematic Review of Tissue Expansion: Utilization in Non-breast Applications

Background

Tissue expansion is a versatile reconstructive technique providing well-vascularized local tissue. The current literature focuses largely on tissue expansion for breast reconstruction and in the context of burn and pediatric skin/soft tissue replacement; however, less traditional applications are also prevalent. The aim of this study was to systematically review the utilization of tissue expansion in such less well-characterized circumstances.

Methods

The authors conducted a systematic review of all publications describing non-breast applications of tissue expansion. Variables regarding expander specifications, expansion process, and complications were collected and further analyzed.

Results

A total of 565 publications were identified. Of these, 166 publications described tissue expansion for "less traditional" indications, which fell into 5 categories: ear reconstruction, cranioplasty, abdominal wall reconstruction, orthopedic procedures, and genital (penile/scrotal and vaginal/vulva) reconstruction. While lower extremity expansion is known to have high complication rates, tissue expander failure, infection, and exposure rates were in fact highest for penile/scrotal (failure: 18.5%; infection: 15.5%; exposure: 12.5%) and vaginal/vulva (failure: 20.6%; infection: 10.3%; exposure: 6.9%) reconstruction.

Conclusions

Tissue expansion enables index operations by providing additional skin before definitive reconstruction. Tissue expanders are a valuable option along the reconstructive ladder because they obviate the need for free tissue transfer. Although tissue expansion comes with inherent risk, aggregate outcome failures of the final reconstruction are similar to published rates of complications without pre-expansion. Thus, although tissue expansion requires a staged approach, it remains a valuable option in facilitating a variety of reconstructive procedures.

Using 3D Printing Technology to Teach Cartilage Framework Carving for Ear Reconstruction

Objective: The aim of this study was to determine the validity of using a carvable 3D printed rib model in combination with a 3D printed auricular framework to facilitate the teaching, training and planning of auricular reconstruction. Design: 3D printed costal cartilages from ribs 6-9 were produced using a FormLabs Form3 Printer and used to make negative molds. 2:1 silicone-cornstarch mixture was added to each mold to make 12 simulated 6-9th costal cartilages suitable for carving. 3D printed auricular frameworks were produced in polylactic acid using an Ultimaker 3 3D printer to demonstrate the component parts and constructed framework of an auricular reconstruction. Participants: Twelve plastic surgery trainees attended a workshop in which they each attempted auricular reconstruction using the carvable models and 3D printed plastic models as a guide. All candidates completed a pre- and post-training questionnaire to assess confidence and comprehension of auricular reconstruction, and the suitability of the models for facilitating this teaching. Results: Only 42% of trainees (n = 5) had observed an ear reconstruction in theater prior to the training course. Statistically significant improvements in the appreciation of the different components that make an auricular framework (p < 0.0001) and confidence in carving and handling costal cartilage (p < 0.0001) were noted following completion of the training. Highly significant improvements in comprehension of the approach to ear reconstruction (p = 0.006) and locating the subunits of a reconstructed ear from costal cartilage (p = 0.003) were also noted. 100% of participants felt the 3D printed teaching aids directly enhanced their learning. Conclusions: Ear reconstruction is a complex, time consuming multi-stage operation demanding significant amounts of experience, planning and an appreciation of the 3D chondrocutaneous structure. In this study we have demonstrated the value of 3D printing in producing a suitable simulated costal cartilage model and as an adjunct to comprehending and planning a framework for auricular reconstruction.

First Pediatric Experience With a Novel, Adhesive Adapter Retained, Bone Conduction Hearing Aid System

OBJECTIVES

To assess the audiological outcomes, practicalities, and impact on quality of life of a new, nonimplantable, adhesive retained bone conduction hearing aid in children.

STUDY DESIGN

A prospective, single-subject repeat measure, cohort study.

SETTING

Community and in pediatric assessment center.

PATIENTS

Twenty-one children aged between 5 and 15 years with a conductive hearing loss of >/=25 dB HL in the better hearing ear.

INTERVENTION

Audiological comparisons were made using pure-tone thresholds; unaided, with a softband aid, and with the new adhesive retained bone conducting system.

MAIN OUTCOME MEASURES

Comparison of hearing threshold levels. Data analysis via paired t-testing, significance set at p value <0.01. Quality of life was assessed via the Glasgow Children's Benefit Inventory and a 10 cm linear analogue scale. A hearing aid review questionnaire provided insight into practical use.

RESULTS

Statistically significant improvement in thresholds of 7.3 dB HL (p=0.0001) was demonstrated with the adhesive system as compared with softband aids. After 4 weeks of usage, the mean hearing thresholds for the adhesive hearing system improved from 55 dB HL ± 2.4 to 31 dB HL± 7.9 in unaided and aided conditions.Improvements in QOL were demonstrated with LAS and GCBI. Four children reported mild skin reactions. Eighty-six percent reported improved self-confidence.

CONCLUSION

The adhesive aid produces comparable audiological results to the commercial softband hearing aids. It provides an excellent alternative in the treatment of conductive hearing loss without the possible complications and costs of a surgical intervention. Furthermore, it preserves skin envelope over the mastoid for those who wish to proceed with an autologous pinna reconstruction in the future.

Alloplastic Auricular Reconstruction: Review of Implant Types, Adverse Events, and Aesthetic Outcomes

IMPORTANCE

Alloplastic implants have been applied successfully in reconstruction of the external ear, either for congenital microtia or traumatic injury.

OBJECTIVE

The objective of this study was to conduct a comprehensive systematic review of alloplastic implant materials utilized in the reconstruction of the external ear stratified by indication, specific implant type, postoperative complications, and aesthetic outcomes.

EVIDENCE REVIEW

A comprehensive systematic review of published literature on alloplastic external ear reconstruction data was conducted utilizing Medline/PubMed database without timeframe limitations in June 2019. Articles were stratified by (1) indication (microtia versus trauma reconstruction) and (2) implant material type. All postoperative complications were recorded and comparatively analyzed between implant types. Aesthetic outcomes were also identified and compared between implant types.

FINDINGS

A total of 755 patients (14 case series; follow-up range = 3 months--10 years) met the criteria for this study. Overall complication rate was 12.05% across all indications and materials used. The most frequent complications reported were graft exposure (7.8%), graft explantation (1.72%), and wound dehiscence (0.8%). Of the patients requiring graft explantation (n = 13), 7 (53.85%) received Medpor implants, and the other 6 (46.15%) were identified in silicone implants. Infection was only reported in Medpor implants. The overall rate of an acceptable aesthetic outcome was 99.34%.

CONCLUSIONS AND RELEVANCE

Alloplastic implants are a reliable means of achieving an acceptable complication profile in external ear reconstruction. While there was an overall high rate of acceptable aesthetic outcomes, the studies evaluated in this systematic review differed in their criteria for final evaluation of aesthetic outcomes.

Addition of decellularized extracellular matrix of porcine nasal cartilage improves cartilage regenerative capacities of PCL-based scaffolds in vitro

Composite scaffolds can improve regenerative capacities of scaffolds in various tissue-engineering approaches. In order to generate a 3D printable scaffold that is capable of cartilage regeneration, decellularized extracellular matrix (DECM) of porcine nasal cartilage was added to 3D printed polycaprolactone (PCL) scaffolds. Subsequently, scaffolds (PCL, PCL/DECM and DECM) were seeded with human primary nasoseptal chondrocytes and differentiated with cartilage inductive medium for up to 42 days in vitro. Afterwards samples were analyzed with scanning electron microscopy, histology, biochemical assays and gene expression analysis. In short, results showed cell attachment and proliferation on all scaffolds. There was a trend towards ossification on pure PCL scaffolds, whereas we found evidence for cartilage tissue formation on DECM scaffolds as well as on PCL/DECM scaffolds. Moreover, biochemical analysis indicated an enhanced differentiation on novel PCL/DECM scaffolds. In conclusion, the addition of DECM to 3D printable PCL scaffolds may yield a new composite material for regenerative approaches in cartilage for facial reconstructive surgery. Further research will be necessary to evaluate these findings in vivo.

Comparison of three-dimensional and two-dimensional templates on auricle reconstruction in patients with unilateral microtia

To confirm the advantage of 3D template over the traditional 2D template in auricle reconstruction. Two hundred patients with Marx III unilateral microtia treated in our hospital during the last four years were included in this retrospective study. They were divided into two groups according to the surgery which was assisted by 2D or 3D template. The outcome was evaluated 6 months after the surgery in the following aspects: the mean surgical time, the similarity rate for ear size, nasal-tip to tragus length and auriculocephalic angle, the patient's satisfaction and the quality of life after surgery. The surgical time for the 3D group was 3.2 ± 1.9 hours, significantly shorter than that for the 2D group (4.1 ± 3.7 hours; P < 0.05). The similarity rates between both sides were 91.24 ± 1.71%, 96.46 ± 2.51%, and 88.15 ± 10.20% respectively for ear size, nasal tip-tragus length, and auriculocephalic angle in the 3D group. While the corresponding values in the 2D group were smaller and were 87.47 ± 3.66%, 90.16 ± 3.27%, and 78.25 ± 1.26% respectively. The difference was significant in nasal tip-tragus length and auriculocephalic angle (P < 0.05), but not for ear size (P > 0.05). The patients' satisfaction was better in the 3D group. The averaged GCBI score was 65.6 ± 13.2 in the 3D group, which was significantly higher than the value of 55.3 ± 16.8 in the 2D group (P < 0.05). The use of 3D template resulted in a better outcome in the auricle reconstruction surgery.

The in vivo chondrogenesis of cartilage stem/progenitor cells from auricular cartilage and the perichondrium

Bone marrow-derived stem cells are commonly studied for cartilage tissue engineering and regeneration medicine applications, but their ossification tendency and their limited capacity for chondrogenic differentiation depending on the donor age limit their clinical application. Cartilage stem/progenitor cells are ideal seeding cells, as cartilage stem/progenitor cells from auricular cartilage and the perichondrium have the inherent advantages of chondrogenesis capacity and an easy and nontraumatic harvesting process, displaying promise for applications. The identification and comparison of cartilage stem/progenitor cells from auricular cartilage and the perichondrium in vitro were explored in our previous study, but the in vivo chondrogenesis of these cells has not been fully examined. In the current study, we explored the ectopic chondrogenesis of cartilage stem progenitor/cells from auricular cartilage and the perichondrium after chondrogenic induction in vitro. Our results suggest that stem/progenitor cells from auricular cartilage exhibit significantly better chondrogenesis than those from the perichondrium in vivo, with upregulated chondrogenic genes and a stable cartilage phenotype, as well as good mechanical properties, indicating that stem/progenitor cells from auricular cartilage could be one type of ideal seeding cells for cartilage tissue engineering.

Design and fabrication of a hybrid alginate hydrogel/poly(ε-caprolactone) mold for auricular cartilage reconstruction

The aim of this study was to design and manufacture an easily assembled cartilage implant model for auricular reconstruction. First, the printing accuracy and mechanical properties of 3D-printed poly-ε-caprolactone (PCL) scaffolds with varying porosities were determined to assess overall material properties. Next, the applicability of alginate as cell carrier for the cartilage implant model was determined. Using the optimal outcomes of both experiments (in terms of (bio)mechanical properties, cell survival, neocartilage formation, and printing accuracy), a hybrid auricular implant model was developed. PCL scaffolds with 600 μm distances between strands exhibited the best mechanical properties and most optimal printing quality for further exploration. In alginate, chondrocytes displayed high cell survival (~83% after 21 days) and produced cartilage-like matrix in vitro. Alginate beads cultured in proliferation medium exhibited slightly higher compressive moduli (6 kPa) compared to beads cultured in chondrogenic medium (3.5 kPa, p > .05). The final auricular mold could be printed with 300 μm pores and high fidelity, and the injected chondrocytes survived the culture period of 21 days. The presented hybrid auricular mold appears to be an adequate model for cartilage tissue engineering and may provide a novel approach to auricular cartilage regeneration for facial reconstruction. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1711-1721, 2019.

Ear Prosthesis for Postburn Deformity

Prosthodontics is not just confined to replacement of missing teeth but beyond one's scope. The fabrication of any extraoral maxillofacial prosthesis presents the prosthodontist with several phenomenal challenges. Psychologically, these patients are severely affected either by congenital absence or loss of ear due to trauma or burns. Replacement or reconstruction can be done by surgical or prosthetic approach. However, not all situations are favourable to surgical reconstruction. This article emphasises on the steps in fabrication of ear prosthesis for burn deformity.

The Use of Temporoparietal Fascia Flap for Surgical Treatment of Traumatic Auricle Defects

Background

Auricular reconstruction is 1 of the biggest challenges of facial plastic surgery. The aim of this study was to evaluate the efficacy of 1-stage reconstruction of an auricle using a temporoparietal fascia flap (TPFF).

Methods

In this nonrandomized study, autologous auricle bodies with emergency condition and cartilaginous graft from projection of a costal arch from the VI-VII ribs were used. Temporal fascia sample with vascular pedicle (a temporal artery with the accompanying veins) by the Z-shaped incision of skin in temporal area for auricular reconstruction was extracted. Skin grafts were taken from the supraclavicular area or from the left or right flank. Grafts of partial auricle bodies (n = 8) along with cartilaginous framework from a costal arch (n = 21) were used for auricle reconstruction. The follow-up period studied after 6 months in 29 operated patients.

Results

The graft of partial auricle bodies or the graft of a cartilaginous framework from a costal arch presented a perfect auricular reconstruction. By avoiding a difficult microsurgery and its possible complications, the use of TPFF led to beneficial results in 75% and 90.4% of cases, respectively. Overall, no major complication (alopecia, hematoma, or necrosis) occurred, and further surgery was not required.

Conclusion

TPFF is a technique of choice for surgical treatment of traumatic auricle defects.

[Application progress of digital technology in auricle reconstruction]

Objective

To review the application progress of digital technology in auricle reconstruction.

Methods

The recently published literature concerning the application of digital technology in auricle reconstruction was extensively consulted, the main technology and its specific application areas were reviewed.

Results

Application of digital technology represented by three-dimensional (3D) data acquisition, 3D reconstruction, and 3D printing is an important developing trend of auricle reconstruction. It can precisely guide auricle reconstruction through fabricating digital ear model, auricular guide plate, and costal cartilage imaging.

Conclusion

Digital technology can improve effectiveness and decrease surgical trauma in auricle reconstruction. 3D bioprinting of ear cartilage future has bright prospect and needs to be further researched.

Total Ear Reconstruction Using Porous Polyethylene

Total ear reconstruction has been approached by several techniques involving autologous graft, prosthetic implant, and alloplastic implant options. Recent studies have shown the superiority of porous polyethylene (Medpor, Porex Surgical) reconstruction over autologous reconstruction based on improved aesthetic results, earlier age of intervention, shorter surgery times, fewer number of required procedures, and a simpler postoperative recovery process. A durable and permanent option for total ear reconstruction, like Medpor, can help alleviate the cosmetic concerns that patients with auricular deformities may be burdened with on a daily basis. In this article, the authors discuss the advantages of Medpor-based ear reconstruction and discuss recent advances in the surgical techniques involved, such as harvesting a temporoparietal fascia flap and full-thickness skin graft to adequately cover the Medpor framework and decrease extrusion rates.

Cartilage engineering in reconstructive surgery: auricular, nasal and tracheal engineering from a surgical perspective

This review provides an update on cartilage tissue engineering with particular focus on the head and neck. It is aimed at scientists and clinicians who are interested in tissue engineering and its clinical applicability. Principal tissue engineering strategies are summarized in the first part of this review. In the second part, current clinical approaches to auricular, nasal and tracheal reconstruction are discussed from a surgical perspective. By this approach, the requirements for clinical applicability are outlined and new insight into relevant aims of research is given to accelerate the transfer from bench to bedside.

Fabrication of postsurgical auricle separator stent in reconstruction of the ear

A natural appearing ear with appropriate projection from the head remains a great challenge in the reconstruction of the ear. Surgical and prosthetic means have been addressed in the management of patients with microtia, with each carrying its own merits and demerits. Lack of adequate projection of the ear and adhesion of tissues are some common complications of reconstructive surgery that can adversely affect the treatment outcome. This article describes a technique for the fabrication of a postsurgical stent to prevent adhesion of the surgically reconstructed ear to the underlying tissues. This also enhances the projection of the ear from the head.

Reconstructive Surgery of Auricular Defects: An Overview

Context:

Despite the ongoing advances in surgical procedures and promising progress in bioengineering techniques, auricular reconstruction remains a significant challenge in plastic surgery. There are different causes for acquired auricular defects, including trauma, tumor ablation and burns. The management options for upper, middle and lower third auricular defects are briefly reviewed in the current paper.

Evidence Acquisition:

Original research papers investigating the plastic surgeons, otolaryngologists and maxillofacial surgeons in approaching the complicated issue of auricular reconstruction published from January 1995 to December 2014 were aggregated and used in the current study.

Results:

Utilizing autologous stem cell populations to treat craniofacial defects is a promising field of ongoing investigations. Studies show that cartilage stem/progenitor cells (CSPCs) are highly chondrogenic and can produce elastic reconstructive material with long-term tissue restoration.

Conclusions:

Auricular reconstruction surgery is a challenging plastic procedure that requires great expertise and expert knowledge of the various techniques available. Novel techniques in the fields of reconstructive bioengineering and regenerative medicine are promising but further research is required before widespread clinical application.

Auricular reconstruction using biofabrication-based tissue engineering strategies

Auricular malformations, which impose a significant social and psychological burden, are currently treated using ear prostheses, synthetic implants or autologous implants derived from rib cartilage. Advances in the field of regenerative medicine and biofabrication provide the possibility to engineer functional cartilage with intricate architectures and complex shapes using patient-derived or donor cells. However, the development of a successful auricular cartilage implant still faces a number of challenges. These challenges include the generation of a functional biochemical matrix, the fabrication of a customized anatomical shape, and maintenance of that shape. Biofabrication technologies may have the potential to overcome these challenges due to their ability to reproducibly deposit multiple materials in complex geometries in a highly controllable manner. This topical review summarizes this potential of biofabrication technologies for the generation of implants for auricular reconstruction. In particular, it aims to discuss how biofabrication technologies, although still in pre-clinical phase, could overcome the challenges of generating and maintaining the desired auricular shapes. Finally, remaining bottlenecks and future directions are discussed.

Magnetic resonance imaging of the ear for patient-specific reconstructive surgery

Introduction

Like a fingerprint, ear shape is a unique personal feature that should be reconstructed with a high fidelity during reconstructive surgery. Ear cartilage tissue engineering (TE) advantageously offers the possibility to use novel 3D manufacturing techniques to reconstruct the ear, thus allowing for a detailed auricular shape. However it also requires detailed patient-specific images of the 3D cartilage structures of the patient’s intact contralateral ear (if available). Therefore the aim of this study was to develop and evaluate an imaging strategy for acquiring patient-specific ear cartilage shape, with sufficient precision and accuracy for use in a clinical setting.

Methods and Materials

Magnetic resonance imaging (MRI) was performed on 14 volunteer and six cadaveric auricles and manually segmented. Reproducibility of cartilage volume (Cg.V), surface (Cg.S) and thickness (Cg.Th) was assessed, to determine whether raters could repeatedly define the same volume of interest. Additionally, six cadaveric auricles were harvested, scanned and segmented using the same procedure, then dissected and scanned using high resolution micro-CT. Correlation between MR and micro-CT measurements was assessed to determine accuracy.

Results

Good inter- and intra-rater reproducibility was observed (precision errors <4% for Cg.S and <9% for Cg.V and Cg.Th). Intraclass correlations were good for Cg.V and Cg.S (>0.82), but low for Cg.Th (<0.23) due to similar average Cg.Th between patients. However Pearson’s coefficients showed that the ability to detect local cartilage shape variations is unaffected. Good correlation between clinical MRI and micro-CT (r>0.95) demonstrated high accuracy.

Discussion and Conclusion

This study demonstrated that precision and accuracy of the proposed method was high enough to detect patient-specific variation in ear cartilage geometry. The present study provides a clinical strategy to access the necessary information required for the production of 3D ear scaffolds for TE purposes, including detailed patient-specific shape. Furthermore, the protocol is applicable in daily clinical practice with existing infrastructure.