Autogenous and Prosthetic Reconstruction of the Ear

An automated parametric ear model to improve frugal 3D scanning methods for the advanced manufacturing of high-quality prosthetic ears

Ear prostheses are commonly used for restoring aesthetics to those suffering missing or malformed external ears. Traditional fabrication of these prostheses is labour intensive and requires expert skill from a prosthetist. Advanced manufacturing including 3D scanning, modelling and 3D printing has the potential to improve this process, although more work is required before it is ready for routine clinical use. In this paper, we introduce a parametric modelling technique capable of producing high quality 3D models of the human ear from low-fidelity, frugal, patient scans; significantly reducing time, complexity and cost. Our ear model can be tuned to fit the frugal low-fidelity 3D scan through; (a) manual tuning, or (b) our automated particle filter approach. This potentially enables low-cost smartphone photogrammetry-based 3D scanning for high quality personalised 3D printed ear prosthesis. In comparison to standard photogrammetry, our parametric model improves completeness, from (81 ± 5)% to (87 ± 4)%, with only a modest reduction in accuracy, with root mean square error (RMSE) increasing from (1.0 ± 0.2) mm to (1.5 ± 0.2) mm (relative to metrology rated reference 3D scans, n = 14). Despite this reduction in the RMS accuracy, our parametric model improves the overall quality, realism, and smoothness. Our automated particle filter method differs only modestly compared to manual adjustments. Overall, our parametric ear model can significantly improve quality, smoothness and completeness of 3D models produced from 30-photograph photogrammetry. This enables frugal high-quality 3D ear models to be produced for use in the advanced manufacturing of ear prostheses.

[Options for reconstruction after injuries in the head and neck region]

Reconstruction of lesions in the head and neck region must be both functionally and esthetically adequate, as the exposed anatomic position can easily lead to social stigmatization after injury. Distortion of symmetry, e.g., by a crooked nose, enophthalmos, or a (partial) amputation of the outer ear, is easily visible. On the other hand, limitations to nasal breathing and olfaction or diplopia may significantly reduce quality of life, and restoration of form and function continues to be challenging. This review discusses the treatment options for trauma of the external nose and the lateral midface, including the orbital floor and the auricle.

Auricular reconstruction via 3D bioprinting strategies: An update

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Capturing patient anatomy for designing and manufacturing personalized prostheses

Prostheses play a critical role in healthcare provision for many patients and encompass aesthetic facial prostheses, prosthetic limbs and prosthetic joints, bones, and other implantable medical devices in musculoskeletal surgery. An increasingly important component in cutting-edge healthcare treatments is the ability to accurately capture patient anatomy in order to guide the manufacture of personalized prostheses. This article examines methods for capturing patient anatomy and discusses the degrees of personalization in medical manufacturing alongside a summary of current trends in scanning technology with a focus on identifying workflows for incorporating personalization into patient-specific products. Over the next decade, with increased harmonization of both personalization and automated prosthetic manufacturing will be the realization of improved patient compliance, satisfaction, and clinical outcomes.

An advanced prosthetic manufacturing framework for economic personalised ear prostheses

Craniofacial prostheses are commonly used to restore aesthetics for those suffering from malformed, damaged, or missing tissue. Traditional fabrication is costly, uncomfortable for the patient, and laborious; involving several hours of hand-crafting by a prosthetist, with the results highly dependent on their skill level. In this paper, we present an advanced manufacturing framework employing three-dimensional scanning, computer-aided design, and computer-aided manufacturing to efficiently fabricate patient-specific ear prostheses. Three-dimensional scans were taken of ears of six participants using a structured light scanner. These were processed using software to model the prostheses and 3-part negative moulds, which were fabricated on a low-cost desktop 3D printer, and cast with silicone to produce ear prostheses. The average cost was approximately $3 for consumables and $116 for 2 h of labour. An injection method with smoothed 3D printed ABS moulds was also developed at a cost of approximately $155 for consumables and labour. This contrasts with traditional hand-crafted prostheses which range from $2,000 to $7,000 and take around 14 to 15 h of labour. This advanced manufacturing framework provides potential for non-invasive, low cost, and high-accuracy alternative to current techniques, is easily translatable to other prostheses, and has potential for further cost reduction.

Coating Medpor® Implant with Tissue-Engineered Elastic Cartilage

Inert biomaterials used for auricular reconstruction, which is one of the most challenging and diverse tasks in craniofacial or head and neck surgery, often cause problems such as capsule formation, infection, and skin extrusion. To solve these problems, scaffold consisting of inert biomaterial, high-density polyethylene (Medpor^®) encapsulated with neocartilage, biodegradable poly(DL-lactic-co-glycolic acid) (PLGA) was created using a tissue engineering strategy. PLGA scaffold without Medpor^® was created to serve as the control. Scaffolds were vacuum-seeded with rabbit chondrocytes, freshly isolated from the ear by enzymatic digestion. Then, cell-seeded scaffolds were implanted subcutaneously in the dorsal pockets of nude mice. After 12 weeks, explants were analyzed by histological, biochemical, and mechanical evaluations. Although the PLGA group resulted in neocartilage formation, the PLGA-Medpor^® group demonstrated improved outcome with the formation of well-surrounded cartilage around the implants with higher mechanical strength than the PLGA group, indicating that Medpor^® has an influence on the structural strength of engineered cartilage. The presence of collagen and elastin fibers was evident in the histological section in both groups. These results demonstrated a novel method of coating implant material with engineered cartilage to overcome the limitations of using biodegradable scaffold in cartilage tissue regeneration. By utilizing the patient's own chondrocytes, our proposed method may broaden the choice of implant materials while minimizing side effects and immune reaction for the future medical application.

Using Osseointegrated Implants Concomitant With Onlay Bone Grafting for Auricular Reconstruction

Conventional dental implants have been reported for nasal and orbital regions but due to limited thickness of calvarium they are not used in mastoid region. Onlay bone grafting in skull concomitant with implants is a predictable method and experimental animal studies confirm it. Parietal bone and lateral mandibular ramus are suggested source of bone grafts and dental implants with 7 mm length can be used safely. Increased fixture length may lead to increase survival in long term.

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

INTRODUCTION

Auricular reconstruction is a great challenge in facial plastic surgery. With the advances in surgical techniques and biotechnology, different options are available for consideration. The aim of this paper is to review the knowledge about the various techniques for total auricular reconstruction based on the literature and our experience.

METHODS

Approximately 179 articles published from 1980 to 2013 were identified, and 59 articles were included. We have focused on the current status of total auricular reconstruction based on our personal experience and on papers of particular interest, published within the period of review. We have also included a prospective view on the tissue engineering of cartilage.

RESULTS

Most surgeons still practice total auricular reconstruction by employing techniques developed by Brent, Nagata, and Firmin with autologous rib cartilage. Within the last years, alloplastic frameworks for reconstruction have become well established. Choosing the reconstruction techniques depends mainly on the surgeon's preference and experience. Prosthetic reconstruction is still reserved for special conditions, even though the material is constantly improving. Tissue engineering has a growing potential for clinical applicability.

CONCLUSION

Auricular reconstruction still receives attention of plastic/maxillofacial surgeons and otolaryngologists. Even though clinical applicability lags behind initial expectations, the development of tissue-engineered constructs continues its potential development.