Bibliometric Analysis of Microtia-Related Publications From 2006 to 2020

Abstract

Objective:

Microtia is a congenital auricular malformation with a hypoplastic external ear that ranges in severity from a slightly smaller auricle to complete the absence of the auricle. The present study was conducted to identify and analyze the characteristics of microtia-related articles published from 2006 to 2020 by using bibliometric analyses.

Method:

Microtia-related studies published from 2006 to 2020 were retrieved from the Web of Science Core Collection database. Keywords, first author, citations, date of publication, and publication journal were extracted and quantitatively analyzed using Bibliographic Item Co-Occurrence Matrix Builder software and the Bibliometric (https://bibliometric.com/app). VOSviewer was used to visualize research and form a network map on keywords and citations.

Results:

A total of 1031 articles from 2006 to 2020 were included. The number of articles showed an overall trend of growth over time. The United States and China are the top 2 countries in terms of the number of microtia-related articles. From the analysis of keyword clustering, keywords could be mainly divided into 4 clusters in the field of microtia research: surgery, tissue engineering, epidemiology, and rehabilitation including hearing-related treatments, evaluation of effects, and quality of life after surgery. The top 10 most frequently cited papers from 2006 to 2020 were also extracted and analyzed.

Conclusion:

A bibliometric research of microtia-related articles from 2006 to 2020 was conducted. This study may be helpful to understand the current research status of microtia and find the research trends in this field, thus proposing future directions for microtia research.

Keywords

microtia bibliometric network analysis web of science

Microtia is a congenital auricular malformation, characterized by a hypoplastic external ear that ranges in severity from a slightly smaller auricle to complete absence of the auricle. It can be associated with many syndromes such as Meier-Gorlin syndrome, Treacher Collins syndrome, and so on. The development of the auricle and the epidemiology of microtia are still not clear. The main treatment method is the reconstruction of the auricle, including autologous cartilage reconstruction or alloplastic implant placement. Although there have been many research articles on microtia in different journals, there is still a lack of bibliometric analysis in the field of microtia research.

Bibliometrics is the use of statistical methods to analyze publications. Quantitative analysis techniques, including keyword analysis, author analysis, journal analysis, and citation analysis, are used in bibliometric analysis to evaluate related publications and to identify the characteristics of researches.¹ Through citation analysis, bibliometric analysis may evaluate research quality and examine development in a certain field of study. Through keyword analysis, bibliometric methods can be used to identify development trends and ideas for future research.²

Bibliometrics analysis has been applied to many different research fields, such as COVID-19,^3,4 acute pancreatitis,⁵ breast reconstruction,⁶ medical education,⁷ cancer,^8,9 cleft lip,¹⁰ and so on. However, no bibliometric analyses have been conducted in the field of microtia. Therefore, the present study was aimed to identify and analyze the characteristics of microtia-related articles published from 2006 to 2020 by using bibliometric analyses.

Materials and Methods

Data Collection

The Web of Science Core Collection database was searched to collect articles related to microtia from 2006 to 2020 by using “microtia” as the searching term. The search was performed within one day to avoid searching bias caused by update of the database, and no search restrictions were set.

Data Extraction

The Bibliographic Item Co-Occurrence Matrix Builder (BICOMB)¹¹ was used to extract the relevant information from the data. Then, a co-occurrence matrix and a word matrix were constructed. The following information from related articles can be extracted by the BICOMB: keywords, first author, citations, date of publication, and publication journal.

Statistical Methods

The analysis of keywords, authors, the period of publication, countries, publication journal, research institutions, and citations was carried out by using the BICOMB and the Bibliometric (https://bibliometric.com/app). On this basis, VOSviewer was used to visualize research and form a network map on keywords and citations. In the network map, different nodes represented different elements, and the size of nodes reflected the frequency or number of publications.¹² Links between nodes indicated relationships such as co-reference, co-occurrence, and collaboration.

Results

Microtia-Related Article Statistics

Total 1031 articles from 2006 to 2020 were included and the catalog of related citations was downloaded in “txt” format. As showed in Figure 1, the number of published articles was 30 in 2006 and reached a maximum of 106 in 2018, showing an overall trend of growth over time.

Figure 1.

Number of published articles each year from 2006 to 2020.

Analysis of the data showed that the United States and China are the top 2 countries in terms of the number of microtia-related articles (Figure 2). During the 15 years, a total of 267 microtia-related publications were published in the United States and 223 in China. In addition to the United States and China, the United Kingdom, Japan, and Germany comprised the top 5 countries in terms of the number of microtia-related publications. Reflecting on the related institutions that published the articles, the United States and China each accounted for 4 of the top 10 institutions in terms of the number of microtia-related articles (Table 1).

Figure 2.

Number of published articles according to countries/regions from 2006 to 2020.

Table 1.

Top 10 Institutions of Published Articles From 2006 to 2020.

Institution	Number of article	Total number of citations	Average number of citations
University of Washington	67	511	7.63
Chinese Academy of Medical Sciences	57	188	3.30
Fudan University	55	126	2.29
Shanghai Jiao Tong University	43	204	4.74
Peking Union Medical College	39	111	2.85
Seattle Children’s Hospital	26	132	5.08
Seattle Children’s Research Institute	26	128	4.92
University Medical Center Utrecht	25	76	3.04
Baylor College of Medicine	25	27	1.08
Sungkyunkwan University	24	99	4.13

As showed in Table 2, the journal that published the most articles in microtia-related field was International Journal of Pediatric Otorhinolaryngology. The second journal of publication was Plastic and Reconstructive Surgery. In addition to the 2 above, the top 5 also included the Journal of Craniofacial Surgery, Journal of Plastic, Reconstructive & Aesthetic Surgery, and American Journal of Medical Genetics—Part A.

Table 2.

Top 10 Publications of Published Articles From 2006 to 2020.

Publication	Frequency	Percentage (%)	Cumulative percentage (%)
International Journal Of Pediatric Otorhinolaryngology	75	7.2674	7.2674
Plastic and Reconstructive Surgery	72	6.9767	14.2442
Journal of Plastic Reconstructive and Aesthetic Surgery	70	6.7829	21.0271
Journal of Craniofacial Surgery	64	6.2016	27.2287
American Journal of Medical Genetics Part A	47	4.5543	31.7829
Annals of Plastic Surgery	26	2.5194	34.3023
Acta Oto-Laryngologica	24	2.3256	36.6279
Aesthetic Plastic Surgery	24	2.3256	38.9535
Laryngoscope	22	2.1318	41.0853
Birth Defects Research Part A—Clinical and Molecular Teratology	22	2.1318	43.2171

Keywords Analysis

Keywords are words or phrases extracted from the text that reflects the main idea of the article. The analysis of keywords can show the interests of a certain research area. The change of keywords can also reflect the trend of the research area. The top 10 keywords are shown in Table 3, including microtia, ear reconstruction, ear, congenital aural atresia, hemifacial microsomia, Goldenhar syndrome, anotia, tissue engineering, birth defects, and epidemiology.

Table 3.

Top 10 High-Frequency Keywords.

Keyword	Frequency	Percentage (%)	Cumulative percentage (%)
Microtia	483	9.5967	9.5967
Ear reconstruction	233	4.6294	14.2261
Ear	57	1.1325	15.3586
Congenital aural atresia	36	0.7153	16.0739
Hemifacial microsomia	36	0.7153	16.7892
Goldenhar syndrome	34	0.6755	17.4647
Anotia	32	0.6358	18.1005
Tissue engineering	30	0.5961	18.6966
Birth defects	30	0.5961	19.2927
Epidemiology	24	0.4769	19.7695

In the network map of keywords based on VOSviewer (Figure 3A), there were 196 items, 6 clusters, and 3313 links. The total link strength was 7936. To further reflect the research trends in the field of microtia, the keywords were separately examined from 3 time periods: 2006 to 2010, 2011 to 2015, and 2016 to 2020 (Figure 3B-D).

Figure 3.

Network map of keywords based on VOSviewer: (A) Total publications, (B) publications from 2006 to 2010, (C) publications from 2011 to 2015, and (D) publications from 2016 to 2020.

Cited Paper Analysis

Using BICOMB software, the top 10 most frequently cited papers from 2006 to 2020 were extracted (Table 4). Nagata S and Brent B accounted for 7 of the top 10 articles. Six of these cited articles were published in Plastic and Reconstructive Surgery. To further reflect the relationship between the cited literature, a network map of cited papers based on VOSviewer was build, including 102 items, 4 clusters, and 3278 links. The total link strength was 18 070.

Table 4.

Top 10 High-Frequency Cited Papers From 2006 to 2020.

Cited paper	Frequency	Percentage (%)	Cumulative percentage (%)
Nagata (1993), Plast Reconstr Surg, 92, 187	106	0.8579	0.8579
Brent (1999), Plast Reconstr Surg, 104, 319	79	0.6394	1.4972
Nagata (1994), Plast Reconstr Surg, 93, 221	76	0.6151	2.1123
Brent (1980), Plast Reconstr Surg, 66, 1	64	0.5180	2.6303
Brent (2002), Clin Plast Surg, 29, 257	61	0.4937	3.1240
Tanzer (1959), Plast Reconstr Surg Transplant Bull, 23, 1	60	0.4856	3.6096
Brent (1992), Plast Reconstr Surg, 90, 355	59	0.4775	4.0871
Nagata (1994), Plast Reconstr Surg, 93, 231	56	0.4532	4.5403
Firmin (1998), Scand J Plast Reconstr, 32, 35	53	0.4289	4.9692
Harris (1996), J Med Genet, 33, 809	51	0.4128	5.3820

Discussion

In this study, bibliometric methods, including keyword and citation analyses, clustering and visual analysis, were used to build the knowledge structure of microtia. The Web of Science Core Collection database was used to research microtia-related articles for bibliometric analysis. In this analysis, total 1031 microtia-related publications from a 15-year period were retrieved for analysis. These analyses showed the development trend of microtia-related research in the past 15 years.

As the results showed, the number of papers has gradually increased over time, from 30 in 2006 to a maximum of 106 in 2018, indicating that interest in microtia research is increasing. According to country statistics, the United States and China published nearly half of the microtia-related articles. In terms of related research institutions, the United States and China each accounted for 4 of the top 10 institutions. These results showed that the United States and China were the 2 centers in the field of microtia research.

In this field, articles are published mainly in journals that cover 3 areas: plastic surgery, otolaryngology, and genetics and birth defects. Among the top 10 journals with the number of published articles, there are 5 journals in the field of plastic surgery, 3 in the field of otolaryngology, and 2 in the field of genetics and developmental defects. The top 4 most published journals, including International Journal of Pediatric Otorhinolaryngology, Plastic and Reconstructive Surgery, Journal of Plastic Reconstructive and Aesthetic Surgery, and Journal of Craniofacial Surgery, together published more than a quarter of the microtia-related articles. The content of the fifth journal, American Journal of Medical Genetics Part A, is mainly about the research of medical aspects of birth defects and genetic disorders.

From the analysis of keyword clustering, keywords could be mainly divided into 4 clusters in the field of microtia research: surgery, tissue engineering, epidemiology, and rehabilitation including hearing-related treatments, evaluation of effects, quality of life after surgery, and so on (Figure 3A). To show further the development in the field of microtia, the change of keywords over time was also analyzed. The keywords of the articles from 2006 to 2010 could be divided into 2 clusters: surgery and epidemiology research. Then, 3 clusters appeared from 2011 to 2015: surgery, epidemiology research, and hearing-related treatments. From 2016 to 2020, tissue engineering became the fourth cluster. The trend of diversification of keywords over time showed a broadening of the microtia-related research field.

By analyzing the high-frequency cited papers, we found that Nagata method and Brent method are the 2 main methods for the reconstruction of microtia. Nagata and Brent accounted for 7 of the top 10 cited articles. Nagata¹³ first published his method in 1993. Then, a series of articles were published in 1994 describing this method in detail.^14

-17 Brent¹⁸ reported personal experience with 600 cases in 1992. He then reported his experience twice more, in 1999 and 2002.^19,20 It can be seen that Brent’s 4-stage method (sometimes 3-stage) and Nagata’s 2-stage method are the classic surgical options for ear reconstruction. Around 2000, the reports of using skin expansion technology in ear reconstruction gradually increased. In 2008, Jiang et al²¹ reported 3332 cases of 10-year experience in microtia reconstruction using tissue expander and autogenous cartilage, which further promoted skin expansion ear reconstruction.

Through the analysis of citations in the past 5 years, it is found that with the development of the times, more attention has been paid to the rehabilitation of patients, including the improvement of hearing, evaluation surgical effects, and the improvement of postoperative quality of life. The preoperative 3-dimensional reconstruction of costal cartilage makes the choice of timing of surgery more objective in the reconstruction of the auricle in microtia. Digital technology²² makes it easier to locate and sculpt the new ears of patients with severe facial asymmetry. In addition, people have never stopped trying to substitute materials. After the failure of allogeneic cartilage and xenogeneic cartilage transplantation, no similar reports have been seen. Research on artificial material ear stents continues to be seen. Tissue engineering has gradually become an important research direction in the field of microtia research, and in the future, there will be more tissue engineering research in the field of microtia-related research, so as to provide usable tissue engineering cartilage instead of autologous costal cartilage for ear reconstruction. It can be expected that the development of microtia-related research field can provide better treatment for patients with microtia and enable them to better return to normal life.

There are also some limitations to our study. First, the database used in this study was the Web of Science Core Collection database and not all microtia-related articles were included, so the results may be affected. Second, low-frequency keywords may be neglected and some information may be lost because keyword co-occurrence analysis was based on the intercept frequency. These results also need to be updated over time. In the future, more tools and databases may be combined to improve the accuracy of results and identify development trends in microtia-related research.

Conclusions

A bibliometric analysis of microtia-related articles was conducted during 15-year period from 2006 to 2020. The results showed that literature related to microtia steadily increased over time. Keyword analysis reflected some hot topics in microtia research. Analysis of the cited papers reflected the research foundation of microtia. Therefore, the results of this study may be helpful to understand the current research status of microtia and find the research trends in this field, thus providing more ideas for further research of microtia.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

ORCID iD

Lei Liu

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