Autologous Ear Reconstruction for Microtia Does Not Result in Loss of Cutaneous Sensitivity

Bioengineered human tissue regeneration and repair using endogenous stem cells

We describe a general approach to produce bone and cartilaginous structures utilizing the self-regenerative capacity of the intercostal rib space to treat a deformed metacarpophalangeal joint and microtia. Anatomically precise 3D molds were positioned on the perichondro-periosteal or perichondral flap of the intercostal rib without any other exogenous elements. We find anatomically precise metacarpal head and auricle constructs within the implanted molds after 6 months. The regenerated metacarpal head was used successfully to surgically repair the deformed metacarpophalangeal joint. Auricle reconstructive surgery in five unilateral microtia patients yielded good aesthetic and functional results. Long-term follow-up revealed the auricle constructs were safe and stable. Single-cell RNA sequencing analysis reveal early infiltration of a cell population consistent with mesenchymal stem cells, followed by IL-8-stimulated differentiation into chondrocytes. Our results demonstrate the repair and regeneration of tissues using only endogenous factors and a viable treatment strategy for bone and tissue structural defects.

Ear Reconstruction: Empirical Data of 406 Cases of Carving the Convex Structures of the Framework

OBJECTIVE

In auricular reconstruction, the convex structures of the framework determine the esthetics, and young doctors often need sufficient training to determine the best carving techniques. This study aimed to recommend optimal carving methods and provide measured data of convex structures of the carved costal cartilage framework to prevent complications, improve esthetics, and reduce the learning curve.

METHODS

From 2018 to 2021, 406 patients with microtia who underwent costal cartilage carving were enrolled. The helix is formed by the eighth costal cartilage. The complex of the antihelix was fabricated from part of the eighth costal cartilage or the ninth costal cartilage. The tragus was constructed using residual cartilage pieces from the base frame. These components were measured, and those from the new ear graded "excellent" were used for data analysis. The statistical analysis was principally processed using Excel software.

RESULTS

A total of 112 ears were graded "excellent". The following are the mean and standard deviation of each group of data: antihelix thickness, 0.31 ± 0.06 cm; antihelix width, 0.40 ± 0.06 cm; superior crus thickness, 0.18 ± 0.04 cm; superior crus width, 0.38 ± 0.09 cm; inferior crus width, 0.22 ± 0.04 cm; inferior crus thickness, 0.28 ± 0.05 cm; helix thickness, 0.31 ± 0.04 cm; the four-point height of the helix, 0.52 ± 0.08 cm/0.51 ± 0.07 cm/0.46 ± 0.06 cm/0.41 ± 0.06 cm; and tragus height, 0.98 ± 0.15 cm.

CONCLUSION

These data may help beginners in reducing the learning curve of ear reconstruction. Framework fabrication based on these data allows attaining a harmonious ear framework and satisfactory three-dimensional auricle outline, yielding acceptable results and few complications.

LEVEL OF EVIDENCE

4 Laryngoscope, 133:569-575, 2023.

Evaluation of the Usability of a Low-Cost 3D Printer in a Tissue Engineering Approach for External Ear Reconstruction

The use of alloplastic materials instead of autologous cartilage grafts offers a new perspective in craniofacial reconstructive surgery. Particularly for regenerative approaches, customized implants enable the surgeon to restore the cartilaginous framework of the ear without donor site morbidity. However, high development and production costs of commercially available implants impede clinical translation. For this reason, the usability of a low-cost 3D printer (Ultimaker 2+) as an inhouse-production tool for cheap surgical implants was investigated. The open software architecture of the 3D printer was modified in order to enable printing of biocompatible and biologically degradable polycaprolactone (PCL). Firstly, the printing accuracy and limitations of a PCL implant were compared to reference materials acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA). Then the self-made PCL-scaffold was seeded with adipose-tissue derived stem cells (ASCs), and biocompatibility was compared to a commercially available PCL-scaffold using a cell viability staining (FDA/PI) and a dsDNA quantification assay (PicoGreen). Secondly, porous and solid patient-customized ear constructs were manufactured from mirrored CT-imagining data using a computer-assisted design (CAD) and computer-assisted manufacturing (CAM) approach to evaluate printing accuracy and reproducibility. The results show that printing of a porous PCL scaffolds was possible, with an accuracy equivalent to the reference materials at an edge length of 10 mm and a pore size of 0.67 mm. Cell viability, adhesion, and proliferation of the ASCs were equivalent on self-made and the commercially available PCL-scaffolds. Patient-customized ear constructs could be produced well in solid form and with limited accuracy in porous form from all three thermoplastic materials. Printing dimensions and quality of the modified low-cost 3D printer are sufficient for selected tissue engineering applications, and the manufacturing of personalized ear models for surgical simulation at manufacturing costs of EUR 0.04 per cell culture scaffold and EUR 0.90 (0.56) per solid (porous) ear construct made from PCL. Therefore, in-house production of PCL-based tissue engineering scaffolds and surgical implants should be further investigated to facilitate the use of new materials and 3D printing in daily clinical routine.

Long-term aesthetics, patient-reported outcomes, and auricular sensitivity after microtia reconstruction: A systematic review

BACKGROUND

Auricular reconstruction for microtia is most frequently performed using autologous costal cartilage (ACC) or porous polyethylene (PPE) implants. Short-term results are generally promising, but long-term results remain unclear. Long-term outcomes were explored in this systematic review, and minimal reporting criteria were suggested for future original data studies.

METHODS

A systematic literature search was conducted in MEDLINE, EMBASE, and the Cochrane Central Register of Controlled Trials from inception through October 14, 2020. Articles on auricular reconstruction in patients with microtia using ACC or PPE were included if postsurgical follow-up was at least 1 year. Outcome reporting was split into separate publications, and results on complications were reported previously. This publication focused on long-term aesthetic, patient-reported, and sensitivity outcomes.

RESULTS

Forty-one publications reported on these outcomes. Both materials led to aesthetically pleasing results and high rates of patient satisfaction. ACC frameworks grew similarly to contralateral ears, and the anterior surface of auricles regained sensitivity. Furthermore, postoperative health-related quality of life (HRQoL) outcomes were generally good. Data synthesis was limited due to considerable variability between studies and poor study quality. No conclusions could be drawn on the superiority of either method due to the lack of comparative analyses.

CONCLUSION

Future studies should minimally report (1) surgical efficacy measured using the tool provided in the UK Care Standards for the Management of Patients with Microtia and Atresia; (2) complications including framework extrusion or exposure, graft loss, framework resorption, wire exposure and scalp/auricular scar complications and (3) HRQoL before and after treatment using the EAR-Q patient-reported outcome measure (PROM).

Long-term complications of microtia reconstruction: A systematic review

BACKGROUND

Microtia is a rare disorder characterized by malformation or even complete absence of the auricle. Reconstruction is often performed using autologous costal cartilage (ACC) or porous polyethylene implants (PPE). However, the long-term outcomes of both methods are unclear.

OBJECTIVE

This systematic review aimed to analyze long-term complications and suggest minimal reporting criteria for future original data studies.

METHODS

A systematic literature search was conducted in MEDLINE, EMBASE and the Cochrane Central Register of Controlled Trials from inception through October 14, 2020. Articles on auricular reconstruction in patients with microtia using ACC or PPE were included provided that the follow-up period was at least one year. This publication focused on long-term complications reported in patients with a postoperative follow-up period of at least one year.

RESULTS

Twenty-nine publications reported on complications during long-term follow-up. Overall long-term complication rates were not reported. The incidence of individual complications during long-term follow-up was less than 10% after ACC reconstruction and less than 15% in PPE reconstruction. Framework resorption and wire exposure were reported even after an extended follow-up of more than five years after ACC reconstruction, while reports on the extended long-term results of PPE reconstruction are limited. Data synthesis was limited due to heterogeneity and poor study quality.

CONCLUSIONS

Future studies should report on long-term complications including framework exposure or extrusion, graft loss, framework resorption, wire exposure and scalp and auricular scar complications. We recommend a surgical follow-up of at least five years.