Abstract
Background:
The number of article citations has been used as a measure for the impact of an article in the medical literature, with little emphasis on quality.
Purpose:
To (1) identify the top 50 most cited articles related to rotator cuff repair surgery, (2) determine whether there was a correlation between the top cited articles and level of evidence, and (3) determine whether there was a correlation between the top cited articles and study quality.
Study Design:
Cross-sectional study.
Methods:
The Web of Science and Scopus online databases were searched to identify the top 50 cited articles in rotator cuff repair surgery. Methodological quality was analyzed for each article using the Modified Coleman Methodology Score (MCMS), Jadad scale, and Methodological Index for Non-Randomized Studies (MINORS). Correlation coefficients were calculated to determine the degree of correlation between the top cited articles and level of evidence and study quality using each quality score.
Results:
The mean number of citations for each article in each of the 2 databases was 319 ± 187 (range, 177.5-1033.5). Twenty-nine articles (58%) were from the United States. The most common level of evidence was level 4 (54%), with 3 (6%) articles being level 1. There was no significant correlation between the mean number of citations and level of evidence (r s = –0.28), the MCMS (r s = –0.29), and the MINORS score (r s = –0.25). There was a weak negative correlation between the mean number of citations and the Jadad score (r s = –0.36).
Conclusion:
The top 50 cited articles in rotator cuff repair surgery comprise a variety of years, journals, countries of origin, and study types. Despite being the 50 most cited articles, the most common type of article was the level 4 case series with a poor mean quality assessment score. There was no significant correlation between the mean number of citations and level of evidence or methodological quality using a variety of scores.
Article citations by other authors have been used as a measure for the academic impact of an article in the medical literature. 1,7,10,30 Research productivity for authors and the impact factor for journals are calculated based on the number of citations associated with each publication. 25 Impact factor has been defined as the number of citations within a given year of items published by a journal in the preceding 2 years divided by the number of citable items published by the journal in these 2 years. 12
Recently, it has been suggested that the impact factor has gone from a measure of a journal’s citation influence to a surrogate that assesses the scholarly value of work published in that journal. 20 However, further evidence suggests that journal impact factors are related directly to a few highly cited articles within the journal and are not reflective of the quality of the majority of the articles published in the journal. 6 As such, several new metrics have been created to objectively assign a value to journals based on the number of citations of a journal over a given time period, including the Immediacy Index, SCImago Journal Rank, CiteScore, Source Normalized Impact per Paper, h-index, 2-year impact factor, 5-year impact factor, and ResearchGate Score. This has led to several studies analyzing the top cited articles in their respective fields. 4,18,23,24
Improved understanding of musculoskeletal basic science and the development of new surgical implants and techniques have led to rapid increases in the orthopaedic literature. 11,21 As such, several authors have attempted to analyze the most cited articles in shoulder, elbow, pediatric, and foot and ankle surgery. 3,5,14,16,22
As the number of publications on rotator cuff repair continues to rise, it is important to analyze the quality of the most cited articles on this topic. Also, as researchers are increasingly evaluated and compared by their studies’ academic impact, “top 50” or “top 25” lists of articles on a specific topic are of high value to the readership if, upon critical analysis, their methodological quality supports their top ranking.
The purpose of this study was to (1) identify the top 50 most cited articles related to rotator cuff repair surgery, (2) determine if there was a correlation between the top 50 cited articles and level of evidence, and (3) determine if there was a correlation between the top cited articles and study quality. We hypothesized that there would be a weak to no significant correlation between the top cited articles in rotator cuff repair surgery and level of evidence and study methodological quality.
Methods
The Web of Science and Scopus online databases were searched in December 2017 according to previously described methods without date restrictions. 3,16,17,29 The terms “rotator cuff repair,” “rotator cuff surgery,” “arthroscopic rotator cuff repair,” and “arthroscopic rotator cuff surgery” were individually searched in each database. All articles and all journals were included. Articles were sorted by the number of times cited, from highest to lowest. Each article was evaluated to determine whether it was appropriately related to rotator cuff surgery. The number of citations for each article was then averaged between the 2 search engines to create a list of the top 50 cited articles in rotator cuff repair surgery.
Characteristics from each article were recorded: number of times cited, year of publication, name of journal, country of origin, and study type (review, technique, animal study, cadaveric study, case series, retrospective cohort, prospective cohort, case control, and randomized controlled trial). Studies were categorized into therapy/prevention, diagnostic, prognostic, and economic based on the Oxford Centre for Evidence-based Medicine levels of evidence (http://www.cebm.net/oxford-centre-evidence-based-medicine-levels-evidence-march-2009/). Level of evidence for each study was also evaluated based on The Journal of Bone & Joint Surgery–American Volume guidelines. 19 Study methodological quality was analyzed for each article using the Modified Coleman Methodology Score (MCMS), Jadad scale, and Methodological Index for Non-Randomized Studies (MINORS). 8,15,27,28 Technique studies, reviews, animal studies, and cadaveric studies were not evaluated for methodological quality.
Data were tested for normal distribution using the Kolmogorov-Smirnov test (http://www.physics.csbsju.edu/stats/KS-test.n.plot_form.html). The Pearson correlation coefficient (r) was used to determine the degree of correlation between the top cited articles and level of evidence and the degree of correlation between study quality and the top cited articles when the data were normally distributed. The Spearman correlation coefficient (r s) was used to determine the degree of correlation between the top cited articles and level of evidence and the degree of correlation between study quality and the top cited articles when the data were not normally distributed. Correlation was defined as a perfect negative linear relationship (r, r s = –1), strong negative linear relationship (r, r s = –0.70), moderate negative linear relationship (r, r s = –0.50), weak negative linear relationship (r, r s = –0.30), no linear relationship (r, r s = 0), weak positive linear relationship (r, r s = +0.30), moderate positive linear relationship (r, r s = +0.50), strong positive linear relationship (r, r s = +0.70), and perfect positive linear relationship (r, r s = +1). Student t tests were carried out for 2 group comparisons. A P value <.05 was defined as significant.
Results
The 50 most cited articles in rotator cuff repair surgery were published between 1984 and 2011 (Table 1). The decade from 2000 to 2009 accounted for the greatest number of articles (n = 30) (Figure 1). The selected articles were published in 12 journals (Figure 2). Most were published in The Journal of Bone & Joint Surgery–American Volume, with 19 articles (38%). The overall mean number of citations for each article was 319 ± 187 (range, 177.5-1033.5) (Table 1). There were 8 countries represented, with 29 (58%) of the top 50 cited articles originating from the United States (USA) (Figure 3).
Top 50 Most Cited Articles in Rotator Cuff Repair Surgery a
a MCMS, Modified Coleman Methodology Score; MINORS, Methodological Index for Non-Randomized Studies; N/A, not applicable.
b Number of citations for each article averaged between the Web of Science and the Scopus online databases.

Number of most cited articles and decade of publication.

Number of top 50 cited articles in each journal. AJR, American Journal of Roentgenology; AJSM, The American Journal of Sports Medicine; ARD, Annals of the Rheumatic Diseases; BMJ, The British Medical Journal; CORR, Clinical Orthopaedics and Related Research; CSM, Clinics in Sports Medicine; JBE, Journal of Biomechanical Engineering; JBJS-Am, The Journal of Bone & Joint Surgery–American Volume; JBJS-Br, The Journal of Bone & Joint Surgery–British Volume; JBMR, Journal of Biomedical Materials Research; JSES, Journal of Shoulder and Elbow Surgery.

Countries represented in top 50 most cited articles.
The most common type of article was the retrospective case series, with 28 (56%) (Figure 4). There were studies of all levels of evidence (1-5), with the most common being level 4 (54%) (Figure 5). There were 3 studies (6%) that were level 1 evidence in the top 50 cited articles. Forty-three (86%) of the studies were prognostic, with the remaining being diagnostic. There was no significant correlation between the mean number of citations and level of evidence (r s = –0.28, n = 50, P = .047) among the studies included in the review.

Top 50 cited articles by article type. RCT, randomized controlled trial.

Top 50 cited articles by level of evidence.
Thirty-six studies were available for an analysis of methodological quality. The 14 studies excluded were 6 cadaveric studies, 3 animal studies, 3 reviews, and 2 technique studies. The mean MCMS was 56.3 ± 7.5 (poor; range, 43-81). There was no significant correlation between the mean number of citations and the MCMS (r s = –0.29, n = 36, P = .087). The mean Jadad score was 1.2 ± 0.7 (range, 1-4). There was a weak negative correlation between the mean number of citations and the Jadad score (r s = –0.36, n = 36, P = .027). The mean MINORS score was 13.1 ± 4.2 (range, 8-24). There was no significant correlation between the mean number of citations and the MINORS score (r s = –0.25, n = 36, P = .147).
Studies were analyzed for change over time. There was no significant correlation between year published and level of evidence (r s = –0.20, n = 50, P = .175). There was a moderate positive correlation between year published and the MCMS (r s = 0.51, n = 36, P < .01). There was a weak positive correlation between year published and the Jadad score (r s = 0.32, n = 36, P = .054). There was a weak positive correlation between year published and the MINORS score (r s = 0.36, n = 36, P = .032).
Differences between level of evidence, the MCMS, the Jadad score, and the MINORS score were evaluated by country of origin. Countries were defined as either USA (n = 29) or non-USA (n = 21), which comprised France, Switzerland, Japan, Italy, Australia, Canada, and the United Kingdom. The mean level of evidence was 3.8 ± 1.1 for USA studies and 3.9 ± 1.1 for non-USA studies (P = .701). There was no significant difference (P = .776) between the mean MCMS for USA studies (56.0 ± 7.9) and the mean MCMS for non-USA studies (56.7 ± 7.1). There was no significant difference (P = .871) between the mean Jadad score for USA studies (1.2 ± 0.8) and the mean Jadad score for non-USA studies (1.2 ± 0.6). There was no significant difference (P = .648) between the mean MINORS score for USA studies (13.3 ± 4.6) and the mean MINORS score for non-USA studies (12.7 ± 3.8).
Discussion
This study identified the top 50 most cited articles related to rotator cuff repair surgery. This study demonstrated that there was no significant correlation between the top 50 cited articles and level of evidence, confirming our hypothesis. This study also demonstrated that there was no significant correlation between the MINORS score and MCMS and the top 50 cited articles. However, there was a weak negative correlation between the mean number of citations and the Jadad score, which partially confirmed our hypothesis.
Two previous studies have evaluated the top cited articles in shoulder surgery. Namdari et al 22 demonstrated that the majority of the top 50 cited articles in shoulder surgery were published in the 1990s (n = 18) and 1980s (n = 17). Additionally, a study by Kraeutler et al, 16 which assessed the top 50 cited articles in rotator cuff surgery, showed 29 articles published in the 2000s and 16 published in the 1990s. 22 Kraeutler et al 16 had similar results as in the present study, with most articles published in the 2000s (n = 30) and 1990s (n = 17). Neither of these studies evaluated the quality of the top articles currently in the literature. This current study furthers the argument of the need for an emphasis on higher quality studies in the top orthopaedic journals.
These results were interesting, as time since publication intuitively would provide an advantage by increasing the likelihood of citations. However, our findings may be related to an increase in the overall number of publications (“inflation”) over the past decade. 11,21 Additionally, it may reflect a paradigm shift in rotator repair surgery over the past decade from open to arthroscopic surgery, with 43% of articles cited in the past decade evaluating outcomes after arthroscopic repair. This is further supported by Colvin et al, 9 with arthroscopic rotator cuff repairs increasing 600% compared with 34% for open repairs from 1996 to 2006.
In the current study, the majority of articles were published in The Journal of Bone & Joint Surgery–American Volume (38%), Arthroscopy (16%), and Journal of Shoulder and Elbow Surgery (14%). This same trend was seen in prior studies assessing shoulder surgery and rotator cuff surgery, with 57% and 40% of the top cited articles from The Journal of Bone & Joint Surgery–American Volume, respectively. 16,22 Similar to the current study, these articles also had Journal of Shoulder and Elbow Surgery and The American Journal of Sports Medicine as major sources of top cited articles. This is to be expected, as these journals consistently have the highest impact factors in the orthopaedic surgery literature. 26
Most (58%) of the authors of the top 50 cited articles were from the USA. This trend has also been seen in previous studies in shoulder surgery, plastic surgery, and general surgery and in the top 100 articles in orthopaedic surgery. 16 –18,22,24 This indicates a possible bias toward American authors, as several of the top journals in orthopaedic surgery are based in the United States and published in the English language.
Previous studies have shown that the majority of the top cited articles in orthopaedic and shoulder surgery are level 4 case series. 16,17,22 This was similar to the present study on rotator cuff repair, in which 28 (56%) of the articles were level 4 case series. There has been a recent focus on evidence-based medicine, as reflected in the positive correlation seen in this study between year of publication and methodological quality, with more recent studies being of higher quality (higher Jadad score, MCMS, and MINORS score). However, low-level studies still dominate the literature and should serve as an impetus to improve the methodological quality of studies investigating this topic.
It is possible that if this study were to be repeated at a later date, the number of investigations with low levels of evidence would decrease. This trend is apparent when comparing the study by Namdari et al 22 published in 2012 (0 level 1 studies) to a more recent study by Kraeutler et al 16 published in 2016 (3 level 1 studies) and the current study (3 level 1 studies). 17 In addition, analogous to the calculation of the impact factor, more recent citation data (2 or 5 years rather than the past 30 years as used in the current study) would be highly likely to change the composition of the current investigation’s top 50 cited list.
In contrast to previous studies, the current study analyzed the methodological quality of the top cited articles. According to the MCMS, articles ranged from poor (scores <55) to good (scores of 70-84), with the overall mean MCMS classified as poor (56.3). Although not investigated in other articles on top citations within the field, a prior study by Harris et al 13 found similar results in articular cartilage studies, with poor methodological quality overall. The methodological quality deficiencies identified in this study should guide the design, conduct, and reporting of future rotator cuff repair studies.
Additionally, the current study aimed to determine if there was any correlation between level of evidence and methodological quality with number of citations. As expected, there was no significant correlation (r s = –0.28) between level of evidence and number of citations. This is in contrast to a prior study by Arshi et al 2 that evaluated the top cited articles in cartilage surgery, in which the number of citations was correlated with a stronger level of evidence. However, in that investigation, there was an increased number of level 1 and 2 studies compared with the present study. We found no significant correlation between the mean number of citations and the MCMS (r s = –0.29) and MINORS score (r s = –0.25) and only a weak negative correlation between the mean number of citations and the Jadad score (r s = –0.36). The poor correlation between level of evidence and number of citations is because of the few number of level 1 and 2 studies compared with the lower level studies. Additionally, the poor correlation between number of citations and methodological quality is likely secondary to the MCMS and Jadad scale’s favoring randomized controlled trials (only 3 are present in this study) while the MINORS favors nonrandomized controlled trials.
This study emphasizes the importance of critically evaluating the literature and encourages the orthopaedic community to rely more on the results from higher quality studies with a high level of evidence as opposed to just the top cited articles or highest impact journals in the literature. The methodological quality deficiencies identified in this study should guide future rotator cuff studies to improve their methodology and design and achieve higher quality articles. The current study should also serve as a template for future investigations that attempt to analyze the quality of the literature in orthopaedics and sports medicine–related topics.
The current study has a number of strengths and limitations. This was the first study to analyze the quality of the most cited articles in rotator cuff repair surgery. The number of articles (N = 50) was arbitrarily chosen and may have eliminated other influential articles. However, this number is based on several previously published studies. 3,14,16,22 This study also only utilized 2 databases: Web of Science and Scopus. However, Scopus is the world’s largest scientific database, and by combining with Web of Science, we feel that few to no citations were missed.
Additionally, the search protocol in this study was not limited to “known” orthopaedic journals of previously published articles, as we did not want to limit the potential for missed relevant articles. The number of citations can be influenced by several factors. One possible factor is high-volume authors citing their own work (“self-citation”), which was not accounted for in this study. Also, there appears to be a “snowball effect” to citations, as other authors are more likely to cite an article because of previous citations rather than for its content or quality. 17 There is also a disadvantage to newer published articles having less time to accrue citations, although this did not seem to be a factor in this study. Using a 2-year or 5-year (or any arbitrarily chosen time duration) selection eligibility period could change the composition of the top 50 studies in the current investigation’s list. There were 14 studies (28%) eliminated from the quality evaluation because of no available methodological quality of the evidence scoring system for nonclinical studies. A final limitation is that the number of times that an article is cited is always changing and is dependent on shifts in the field that change over time rather than the quality or content of the article.
The top 50 cited articles in rotator cuff repair surgery comprise a variety of years, journals, countries of origin, and study types. Despite being the 50 most cited articles, the most common type of article was the level 4 case series with a poor mean quality assessment score. There was no significant correlation between the mean number of citations and level of evidence or methodological quality using a variety of scoring measures.
Footnotes
One or more of the authors has declared the following potential conflict of interest or source of funding: J.D.H. receives research support from DePuy and Smith & Nephew, is a paid consultant for NIA Magellan and Smith & Nephew, receives publishing royalties from SLACK, is a paid presenter/speaker for Smith & Nephew and Ossur, and receives educational support from Arthrex and MedInc.
Ethical approval was not sought for the present study.
