Original Article



  • Bahtiyar Haberal
  • Yüksel Uğur Yaradılmış

Received Date: 10.12.2020 Accepted Date: 07.01.2021 J Turk Spinal Surg 2021;32(1):1-7


Although adolescent idiopathic scoliosis (AIS) is the most commonly observed spinal deformity, there is limited bibliographic analysis of AIS in the literature. The aims of this study were to identify and analyze the top 50 most cited articles on AIS.

Materials and Methods:

On February 6th, 2020, we searched the Thomson Reuters Web of Science-Science Citation Index Expanded database using the term, “AIS”. We listed the articles by their number of citations. The titles of the articles, citation number, citation density, article content, journal of publication, author name, publishing country, institute, publishing specialty, and year of publication were noted.


The mean citation number was 210.4±148 (range: 117-873); the mean citation density was 12.8±14 (range: 3-46). The contents of 25 articles (50%) were related to surgical treatment outcomes. Most of the articles (74%) were published in “Spine”, and the total citation number was 6978. Most of the articles (67%, 33 articles) were published from the United States (USA). The first specialty of the primary authors of 46 articles was orthopedic surgery; LG Lenke and YJ Kim had the most citations for AIS-related articles. There was only one level 1 study.


Our bibliographic analysis showed that most studies were based on surgical treatment for AIS in the USA, and that “Spine” had published more than 50% of these studies. Although the number of publications has increased rapidly over the years, prospective randomized trials for AIS treatment are still lacking.

Keywords: Adolescent idiopathic scoliosis, citation analysis, bibliographic analysis, classic papers


The most common type of scoliosis is adolescent idiopathic scoliosis (AIS) that develops in otherwise healthy children, mainly female, around puberty(1). Epidemiological studies estimate that 2-4% of the at-risk population (10-16-year-old females) will develop some degree of spinal curvature(2). AIS causes many problems, such as cosmetic, respiratory, and mobilization problems(3). Bracing for 23 hours per day is the conservative treatment of choice when the Cobb angle is between 20 and 40 degrees with remaining growth potential, whereas spinal fusion is in order when the Cobb angle is >40 degrees with remaining growth potential or >45 degrees at skeletal maturity(4,5). Studies reporting conservative treatment emphasize the importance of early diagnosis and treatment(6). Both the indications and procedures used for conservative treatment are clear. However, surgical treatment is complex and requires operative experience in scoliosis surgery. Lenke et al.(7) described a new classification for AIS to guide spinal surgery(7). There have been many studies describing surgical treatment and techniques, especially the pedicle screw technique and fusion levels according to the type of deformity(7-10).

The number of publications on AIS has continued to increase over the years. Bibliographic analysis can provide access to basic articles on popular topics, such as AIS, and identify the most influential journals, clinics, and authors for a given subject. In addition, it helps to identify the subjects that could inspire young surgeons to contribute to the literature with their own studies.

Examining the most cited articles is a frequently used method for bibliographic analysis(11). The number of citations of an article is an objective tool that shows how much the article is appreciated by the scientific community and determines the relevance of an article at the academic level(12). For this reason, bibliographic studies of popular topics have increasingly focused on the top 50 most cited articles in the literature. In orthopaedic literature, analyses of most cited papers have been performed for shoulder and hip arthroscopy, knee and hip arthroplasty, wrist surgery, spine surgeries, and some special topics such as anterior cruciate ligament, lumbar spondylolisthesis, and cervical dyspathy(13-21). In the spine deformity topic, bibliographic analyzes were made with different study protocols such as 100 top-cited Articles on Spinal Deformity and scoliosis research for 10 year period(22-24).

Although AIS is the most common spinal deformity, the aims of this study were to identify and analyze the top 50 most cited articles on AIS in the Thomson ISI Web of Science® Database.


Study Design

Institutional review board approval was not required given the public availability of the data. On February 6th, 2020, we searched the Thomson Reuters Web of Science-Science Citation Index Expanded database using the term, “AIS” and web of science categories of orthopaedics. Publications were sorted according to the citation numbers. The articles published in the English language between 1970 and 2020 were included in the present study. The articles published in languages other than the English language, before 1970, in the non-orthopaedics journal or with contents not related to AIS were excluded from the present study (Figure 1).


We noted the titles of the articles, citation number, citation density (citation number/duration of publication), article content, journal of publication, author name, publishing country, institute (institution), publishing branch (speciality), and year of publication.

Categorization for Some Variables

Article content: Surgical treatment outcomes, classification score system, radiological imaging, non-surgical treatment brace, surgical technique, progression, and complications.

Author name: For more than two first-author publications.

Institute: Institutes with more than two publications.

Decades between 1970 and 2020: 1970s, 1980s, 1990s, 2000s, and 2010s.

Study design: Randomized controlled, non-randomized controlled, prospective study, case-control, meta-analysis review, retrospective cohort, and retrospective cohort without a control group.

Levels of study: Level 1, level 2, level 3, level 4, and level 5.

Statistical Analysis

Data were analyzed statistically using SPSS v.22 software at a confidence interval of 95%. Qualitative data are described as frequency distributions, and quantitative data are presented as mean, minimum, and maximum values.


Citation Vount and Citation Density

The mean citation number was 210.4±148 (range: 117-873). The mean citation density was 12.8±14 (range: 3-46). The total number of citations and citation density of the articles are listed in Table 1.

Article Contents

The content of 25 articles (50%) was related to surgical treatment outcomes. The contents of other studies were as follows: radiology-imaging (n=6), classification-scoring systems (n=4), progression (n=4), complications (n=4), surgical techniques (n=4), and conservative treatment brace (n=4) (Figure 2).

Journals and Total Citation Number of the Journal

All articles appear to be published in a total of 4 journals (Table 2). The spine was the journal in which most of the articles (74%) were published; the total citation number was 6978. The second-highest number of articles (n=9) was published in the Journal of Bone and Joint Surgery; the total citation number is 2400. The other articles were published in the European Spine Journal (3 articles; total citation number of 1080) and Acta Orthopaedica Scandinavica (1 article; total citation number of 136).

Analysis of Authors

LG Lenke and YJ Kim were the authors who had participated in the highest number of scientific studies on AIS. LG Lenke was the first author in 5 articles and a co-author in 9 articles. YJ Kim was the first author in 7 articles and a co-author in 2 articles.


Most of the articles (67%, 33 articles) were published from the USA, followed by Sweden (13%, 6 articles), and Canada (8%, 4 articles). The remaining 8 articles were published from other countries (Figure 3).


There were 31 institutions that featured in all 50 articles, and 7 institutes were associated with more than 2 articles (Table 3). Washington University School of Medicine ranked first with 11 articles and Columbia University Medical Center followed with 4 articles each, Göteborg University with 3 articles and 4 institutes each associated with 2 articles.

The speciality of the primary authors

The highest number of publications (46) was by orthopaedic surgeons. The remaining 4 articles were associated with the following specialities: Neurosurgery (n=2), anaesthesia (n=1), and health care research (n=1).

Decade-wise number of citations

The articles were spread over a total of 40 years (1978-2011) despite cumulative to the 2000s (Figure 4).

Study design of the articles

A total of 7 study designs were observed in the articles in this analysis (Table 4): Meta-analysis review (n=6), randomized controlled (n=2), non-randomized controlled (n=2), prospective cohort (n=6), retrospective cohort (n=20), retrospective without control group cohort (n=13), and case series (n=1).

Level of evidence of the articles

Most studies had level 3 (n=19) and level 4 (n=18) evidence, other studies one study level 1, 12 studies level 2, none study level 5 (Figure 5).


Although AIS is the most discussed topic among scoliosis deformities(15), in this study, we listed the most cited 50 articles on AIS and determined the citation number, citation density, article count, country, institution, author, journal, study design, and level of evidence. In addition, we found that the most of the contents of these articles on AIS were based on surgical treatment outcomes and had been published by institutions in the USA; more than 50% of the articles had been published in “Spine”.

Scoliosis is a 3D spinal deformity and has the following subtypes: congenital, juvenile, adolescent idiopathic, neurogenic, and adult scoliosis. Two studies on spinal deformities had the highest number (100) of citations(22,23). The study by Zhang et al.(22) had examined deformity types in detail, including sagittal deformities; among its 100 citations, 37 articles were on AIS and 20 articles on adult scoliosis. In the other study, Tao et al.(24) presented a 10-year bibliographic analysis of scoliosis.

In our analysis, the mean number of citations was 210.4±148 (range: 117-873) for AIS. A higher mean citation count was observed for spondylolisthesis (range: 68-586) and thoracolumbar fracture (range: 81-267) compared to similar lumbar disease analyses(17,18). In contrast, there were fewer citations for sports surgeries related to the anterior cruciate ligament (range: 315-1670) and rotator cuff tear (range: 137-677).

Most of the articles’ contents were related to surgical treatment outcomes. In contrast, the most cited article title described AIS classification. For an article to be appreciated, it must fill a knowledge gap in the literature.

The most cited study was the study that described the classification developed by Lenke et al.(7) in 2001 to determine the level of spinal arthrodesis(7). Before the Lenke classification, the King classification presented in 1983 was used for AIS(25). The most important difference in the Lenke classification is its 2D examination of the deformity, which provides a better understanding of the deformity without having sharp limits for fusion levels.

The second most cited study was by Kim et al.(8) published in 2004 wherein the authors described free pedicle screw placement in the thoracic spine for which they used anatomical marks and specific entry points in 3204 patients over 10 years. In addition, Lenke and Kim were the most prolific authors in AIS research.

In our study, each of 3 countries-USA, Sweden, and Canada-was associated with more than 2 publications, with USA being more active with more than 50% of the publications in our analysis. The scientific leadership of the USA was also evident in other bibliographic analyses of lumbar and non-lumbar pathology(15-20). Washington University School of Medicine was affiliated with 11 studies. More than 50% of the institutions were English-speaking institutions. For AIS and other lumbar pathologies, “Spine” was the journal that had published the most number of articles in our analysis;(18-20) it was followed by the Journal of Bone and Joint Surgery and the European Spine Journal. Less and specific journals came to the fore for lumbar pathologies. From our analysis, it would appear that for an article to be highly cited, it is most likely to be published from an English-speaking institution in the USA in a subject-specific journal.

Similar to the findings of many bibliographic studies, very few articles in our analysis contained level 1 evidence(16,17), with only four randomized controlled studies in our study.

Study Limitation

Our bibliographic analysis has some limitations, as stated in similar studies(26). The search term used in such bibliographic analyses needs to be clearly identified, and the content of the articles should be checked. Although we used a specific search term, “AIS” in our study, 9 studies were still excluded because of their unsuitable content. On the other hand, some of the publications published in prestigious journals such as Lancet and The new England Journal of Medicine and receiving high citation are excluded from the evaluation because they do not meet the study criteria(27,28). Another limitation was that as older studies have an advantage with respect to the number of citations, mean citation number (total number citations/years since publication) must be calculated. The level of evidence and study design were difficult to find for some articles.


In this bibliographic analysis of AIS, most articles described the surgical treatment and had been published from the USA; more than 50% of the articles were published in “Spine”. Although the number of publications has increased rapidly over the years, we found that there were few prospective randomized trials.


Ethics Committee Approval: Institutional review board approval was not required given the public availability of the data.

Informed Consent: The study does not contain patient data by design.

Peer-review: Internally peer-reviewed.

Authorship Contributions

Concept: Y.U.Y., B.H., Design: Y.U.Y., B.H., Data Collection or Processing: Y.U.Y., B.H., Analysis or Interpretation: Y.U.Y., Literature Search: B.H., Writing: Y.U.Y.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.

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