Introduction

With more than 1.3 billion citizens, China is the world’s most populous country, and the second-largest in land mass, with an area approximately equal to the entire European continent. China’s economy has been the world’s second largest since 2010, and it continues to grow [36, 40]. In addition, there has been rapid development in the biomedical fields [14, 23, 38]. Orthopaedic surgery in China also is developing rapidly, and has made great advances in recent decades, with increasing importance and more attention in the world community [8, 18, 21, 27]. Additionally, there are more than 50,000 Chinese orthopaedic surgeons according to 2010 statistical data [20]. Owing to its vast population and emerging status, mainland China is becoming a leading force in medical research, including orthopaedics [28, 32, 39].

However, the impact of orthopaedic studies from mainland China has not been investigated, to our knowledge. There are many methods to evaluate the influence of a scientific article; the use of that article by other researchers is one such measure, since it indicates the contributing effect of a previous work on ongoing research. Citation analysis has been widely used to evaluate the academic importance of an article [7, 11, 12]. This bibliometric approach examines the frequency and patterns of citations in articles. The number of citations received by an article is an indicator of its scientific impact and provides a useful approach for evaluating a paper’s influence in its field [17, 37]. Citation analyses have been performed in orthopaedic surgery [17, 19] and its subspecialties, including pediatric orthopaedics [16], fracture surgery [1], shoulder surgery [25], foot and ankle surgery [3], spine surgery [24], hand surgery [15], joint arthroplasty [13], and arthroscopy [6]. However, there were no orthopaedic articles from China included in previous “most-cited” studies [17, 19], and as far as we know, no study has been performed specifically to analyze the most-cited papers in orthopaedic surgery from mainland China.

In light of this, we therefore sought to (1) identify the 50 most-cited orthopaedic articles originating in mainland China and (2) analyze these articles in terms of their language of publication, source journals, and topics.

Methods

In July 31, 2014, we performed a citation search using the Science Citation Index Expanded of the ISI Web of Science (Thomson Reuters, Philadelphia, PA, USA), a method that has been used in similar studies [16, 17, 24, 30]. There were 67 journals under the subject category of “Orthopedics” in Journal Citation Reports for 2013. Additionally, we also searched three leading journals in clinical medicine, The New England Journal of Medicine, The Lancet, and The Journal of the American Medical Association, because of the increasing number of Chinese-authored articles appearing in these respected journals [38]. Therefore, 70 journals were used to identify the most-cited articles in our study (Appendix 1).

Using a previous protocol from similar studies [16, 17, 19], articles from the 70 journals were ranked based on the number of citations. To exclude articles written outside mainland China, a filter of “Countries/territories” was applied first by choosing “Peoples R China” in searching the ISI Web of Science. Each article next was evaluated and articles without a primary address or a reprint address from mainland China were excluded. This process excluded articles originating outside mainland China, and also prevented articles with one or more Chinese coauthors from inclusion in our study based solely on their names.

The 50 most-cited articles from mainland China were retrieved and reviewed. Following the methods of previous studies [16, 17], basic information was collected, including the title, authors, year of publication, article type, source journal of the article, city, institution, number of citations, decade published, and topic or subspecialty of the research.

Results

The top 50 papers and their corresponding number of citations were determined (Table 1); the number of citations for the top 50 papers ranged from 181 to 31 (mean, 52). The oldest paper in our study collection was written in 1981 and ranked 12th, while the most recent paper was written in 2010, and ranked 47th. The most articles were written in the 2000s (n = 36; 72%), followed by the 1990s (n = 8; 16%), the 1980s (n = 4; 8%) and 2010 (n = 2; 4%).

Table 1 The top 50 articles in orthopaedics from mainland China
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All articles in the top 50 were published in English. The articles were published in 16 of the 70 journals (Table 2), with most articles published in Spine (n = 12; 24%), followed by Clinical Orthopaedics and Related Research ® (n = 7; 14%), The Journal of Hand Surgery (n = 5; 10%), The Journal of Bone & Joint Surgery, American Volume (n = 4; 8%), and International Orthopaedics (n = 4; 8%). Lancet had the highest impact factor among any of the journals that published the articles we identified, at 39.207, in 2013 (Table 2).

Table 2 Journals publishing orthopaedics articles by authors from mainland China
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The top 50 articles originated from 11 Chinese cities (Table 3). The number of articles by city of origin was Beijing (n = 16; 32%), followed by Shanghai (n = 12; 24%), and Nantong (n = 8; 16%). There were 28 institutions responsible for the top-cited papers. Institutions associated with more than one paper were the Affiliated Hospital of Nantong University (n = 8; 16%), Peking University Third Hospital (n = 6; 12%), Xinhua Hospital (n = 5; 10%), 304th Hospital (n = 4; 8%), Shanghai Sixth People’s Hospital (n = 3; 6%), and Jishuitan Hospital (n = 2; 4%) (Table 4).

Table 3 Cities of origin of articles
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Table 4 Institutions associated with more than one article
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Five first authors accounted for 18 of the 50 papers (36%). The top first author was JB Tang, with six publications on the list, followed by LY Dai (n = 5; 10%), BG Peng (n = 3; 6%), HW Sung (n = 2; 4%), and LX Chen (n = 2; 4%). Of the top 50 papers, 27 reported basic research and 23 were clinical studies. Bone (n = 9; 18%) was the most-discussed topic in basic research (Table 5) and the spine (n = 14; 28%) was the most-common topic covered in clinical studies (Table 6).

Table 5 Classification of basic research by topic
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Table 6 Classification of clinical studies by subspecialty
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Discussion

Orthopaedic surgery research originating from mainland China has shown increasing importance in the international orthopaedic community and has gotten more attention worldwide [8, 18, 21, 27]. Although citation analysis of the top-cited articles has been performed in multiple medical fields and reported for global orthopaedics [2, 4, 9, 17, 19, 26, 29–31, 34, 35], to our knowledge no Chinese article was included among the global most-cited orthopaedic papers [17, 19], and no citation analysis evaluating the top-cited articles from mainland China has been published. We therefore sought to identify the 50 most-cited articles from mainland China, and to describe them in terms of the language the articles were published in, the journals that published them, and the main topics they covered.

There are several limitations to our study. First, although a well-defined method was used to identify influential papers, important articles from mainland China that have been cited less often were not included. On the contrary, the highly cited articles do not always mean that articles are of high scientific quality. Sometimes articles are cited because they represent a disproved or failed paradigm. Second, we restricted our search to ISI-indexed orthopaedic journals in addition to a small number of high-impact general medical journals. Using this approach, we would not have identified articles published in nonindexed journals. However, it is our impression that articles in those journals, in general, would be unlikely to gain as many citations as journals on the roster we considered. Third, numerous factors influence total number of citations. Our study could not evaluate citations in textbooks, lectures, and other web-based literature [10, 19, 25]. Similarly, authors may be likely to cite articles from the journal in which they hope to publish their study [33]. Fourth, total number of citations used as a measure of impact would be expected to favor older articles that accumulate a larger number of citations with time; however, we found it interesting and somewhat counterintuitive that the most-recent decade in our search garnered the largest number of top-cited articles, This is a strong suggestion that research coming from mainland China is gaining visibility and impact in more recent years. Fifth, our study had a cross-sectional design with our search being done one time. The rank of articles on the list may change if the search is repeated at a subsequent time.

The 50 most-cited articles were published between 1981 and 2010, with the 2000s representing the most-productive decade. This result is inconsistent with trends elsewhere in orthopaedics, which have found articles from the 1980s to have garnered the most citations in one bibliometric analysis [19]. A possible explanation for this difference is that research funding has increased sharply since the 1980s, a reflection of China’s growing economy in recent years [21, 27]. In other words, as biomedical research more generally (and orthopaedics specifically) have developed [8, 23, 27], the bibliometric impact of the research published there has increased.

The top 50 articles were cited between 31 and 181 times. These numbers obviously are lower than those of the global orthopaedic community, where the smallest number of citations needed to make the top 100 was 353 [19]. Based on those numbers, it is no surprise that there were no Chinese articles previously appearing in the lists of top citations [19]. Our results show there still is a need to improve the quality of Chinese research, despite its increase in quantity [8, 18]. Even so, every paper on the top-50 list from mainland China that appeared in an orthopaedic journal was likely to have improved the impact factor of the journal in which it appeared, since the orthopaedic journal with the highest impact factor in 2013 averaged between four and five citations per article (Table 2).

All the articles were written in English, probably because English is the most frequently used language in the orthopaedic literature, including orthopaedic subspecialties [1, 3, 6, 13, 16, 17, 19, 24, 25]. Moreover, the predominance of English-language articles may be one reason that fewer Chinese-authored orthopaedic articles appear in international journals compared with western countries, because writing in a foreign language may be a hindrance for Chinese researchers.

The journal that published the largest number of articles on our list was Spine. The top three journals, including Spine, Clinical Orthopaedics and Related Research ®, and The Journal of Hand Surgery published almost ½ of the articles on our list. Previous studies have shown that the impact factor of the journal is the strongest predictor of citations and most of the top-cited articles were published in journals with a high impact factor [5, 17, 35]; however, this did not prove true in our study (Table 2). The Lancet, with only one article, was the journal with the highest impact factor (39.207), whereas the impact factor of Spine, with the most articles published (n = 12; 24%), was much lower (2.447). This suggests that authors who publish highly cited articles may not be motivated solely by the impact factor of a journal when considering where to submit their manuscripts; rather, other factors, including topical interest, the audience a journal reaches, and the journal’s interest or lack thereof in a particular study, may influence these results [17, 19, 24, 25].

Eleven cities contributed to the top 50 list of highest-cited articles, led by Beijing, the capital city of China, followed by Shanghai. This confirms the important influence of both cities relative to orthopaedic medicine and research in mainland China. Beijing and Shanghai also have large orthopaedic communities and sufficient financial support [17, 20, 21, 30].

Our top-50 list included more basic research articles than clinical studies. Surprisingly, this finding is at odds with findings from previous studies in global orthopaedics or subspecialties [1, 3, 6, 13, 15–17, 19, 24, 25]. In Chinese clinical research, basic science encompassed more than clinical studies, according to a study published in 2011 [14], with the average ratio of 1.3:1 (range, 0.7:1–1.5:1), which was similar to our result (1.17). There may be several reasons for the status of clinical research in mainland China. Clinical trials involving long periods of treatment and followup are highly complex and tightly regulated endeavors. Although mainland China has an advantage in population for recruitment of participants, most individuals do not have access to high-quality, Western-style healthcare [32] which helps participants join clinical trials. Insufficient funding, lack of available time, an unsupportive research environment, and a deficient clinical research teaching program may have influenced the finding of fewer clinical studies on our list from mainland China to this point [14, 22]. However, the environment is changing with respect to these issues. With the progress of medical reform [28], development of the experience and capacity for clinical trials [32, 39], and increased available funding [28, 32], we hope that future bibliometric analyses will show increased citations and more-impactful clinical research.

To our knowledge, this is the first citation analysis of the top-cited orthopaedic articles originating from mainland China. The 50 articles we identified should be considered influential based on the absolute numbers of citations they garnered. However, compared with similar lists from the specialty in aggregate, the citation numbers here show that orthopaedic research in mainland China remains lower impact than the most-cited articles in our specialty overall [19]. Nevertheless, because the latest decade was the most productive one we evaluated in terms of citation rate among articles from mainland China, and because funding is increasing for biomedical research in mainland China [28, 32], one imagines that orthopaedic research from mainland China will continue to grow in its impact on the specialty in terms of citation counts in the future.