Introduction
Originally developed in Europe for the treatment of rotator cuff arthropathy, reverse total shoulder arthroplasty (RTSA) has been shown to be effective in reducing pain and improving shoulder function in patients with deficient rotator cuff function. (Baulot et al.; Boileau et al.) Since the approval of the RTSA by the FDA in 2003, the incidence of total shoulder arthroplasty in the United States has increased significantly. (Best et al.; Kim et al.; Schairer et al.) This can be partly attributed to an aging population, advancements in surgical techniques and implant design, the rapid implementation of RTSA nationwide, and a robust expansion of the surgical indications for RTSA to include a variety of cuff-deficient shoulder pathologies including proximal humerus fracture and fracture sequelae. (Best et al.; Dillon et al.; Kim et al.; Schairer et al.)
Proximal humerus fractures are among the most common fractures in persons aged older than 65 years. (Acevedo et al.) Within the aging population within this age group, it is expected that the incidence in this type of fracture will significantly increase over the next few decades. (Acevedo et al.; Jost et al.) Due to their advanced age, fracture patients in this demographic have been noted to exhibit poor bone quality, predisposing them to comminuted, complex 3- or 4-part fractures requiring surgical intervention. (Acevedo et al.) Historically, surgical options for the management of these fractures include open reduction and internal fixation (ORIF), hemiarthroplasty, and RTSA. In a systematic review in which the results of 34 trials encompassing 2165 proximal humerus fracture patients who underwent RTSA, ORIF hemiarthroplasty, intramedullary nailing, and non-operative treatment, the authors found that RTSA was associated with the highest Constant score, highest reduction in complication incidence, and the lowest number of reoperations, thus demonstrating the potentially greater effectiveness of RTSA over other historically employed strategies for proximal humerus fracture management. (Chen et al.)
The impact of the approval of RTSA on the landscape of shoulder arthroplasty has been immense and given that the usage of this procedure is expected to continue, it is crucial to identify substantially influential literature in this area to provide historical context and highlight the contributions that researchers and their publications have made in the advancement of this surgical technique. (Dillon et al.; Palsis et al.) Citation analysis is an effective tool to quantify the impact of publications in any field. Many past studies in orthopedic literature have quantified citation frequency in effort to identify the most influential articles within various subspecialties and their procedures. (Baldwin et al.; Ding et al.; Elshohna et al.; Gross et al.; Malik et al.) To date, there is an absence of bibliographic analysis specifically dedicated to RTSA for fracture. One bibliometric review evaluated the 50 most-cited articles in reverse total shoulder arthroplasty research, however only 10 papers in this study included specifically RTSA for proximal humerus fracture. (Gross et al.) Another citation analysis presented the 50 most-cited articles in RTSA and yielded interesting information regarding the level of evidence, publication year, and overall trends in the number of citations of the articles they examined, however this article featured only 11 of 50 studies that specifically evaluated RTSA for fracture. (Gross et al)
The purpose of this study is to identify the 50 most frequently cited articles related to RTSA for proximal humerus fracture and determine their implications on this field. The journal of publication, trends in publication year, and authorship of the top-50 cited articles will also be examined. Identifying and quantifying these highly cited articles will serve as a useful resource for orthopedic surgeons and researchers to stay up to date in the rapidly changing field of RTSA. We hypothesize that year of publication will have a significant impact on the total number of citations achieved by an article.
Methods
Institutional review board approval was not required due to the availability of this data to the public. The Clarivate Analytics Web of Science database was used to perform this analysis using methods similar to those utilized in previous orthopedic bibliometric analyses. (Barbera et al.; Gross et al.; Moore et al.; Namdari et al.) On 19 February 2023, several queries using different Boolean combinations were used to determine the broadest search that returned the greatest number of publications regarding RTSA for fracture within the Web of Science database. The following search was successful in obtaining the article and citation data used in this study: (TOPIC: (reverse OR reverse total OR inverted OR inverted total)) AND (TOPIC: (shoulder arthroplasty OR shoulder replacement)) AND (TOPIC: (fracture)). There were no restrictions placed on resulting publications regarding language, journal, publication date, or country of origin, and no additional filters were utilized to complete this search.
The publications were then sorted by the number of citations from most-cited to least-cited. Titles and abstracts were reviewed to identify articles that were unrelated to RTSA for the treatment of proximal humerus fracture and these studies were excluded. If a publication was a systematic review, a cadaveric study, only briefly mentioned RTSA for fracture, only included a small number or percentage of patients being treated for proximal humerus fracture, or if RTSA for fracture was not the primary focus of the article, then the article was excluded from the study. For example, a study discussing locking plate fixation for proximal humerus fracture that only briefly mentioned the use of RTSA was excluded from the study. (Jost et al.) Similar to inclusion criteria in previously conducted analyses, articles that presented information on indication for surgery, procedural descriptions, techniques, as well as outcomes of RTSA for fracture were included. (Barbera et al.; Gross et al.; Moore et al.; Namdari et al.) If there remained uncertainty with a specific publication after the initial screening process, the full article was reviewed by an additional author to determine whether it met the inclusion criteria used in this study.
The top 50 most-cited publications were reviewed by three authors to obtain the author’s name, the total number of citations, publication year, country of origin, journal name, article type (case series, cohort study, expert opinion, case-control study, randomized controlled trial, nonrandomized control trial), and the level of evidence for clinical studies determined using the Journal of Bone and Joint Surgery guidelines. (Wright et al.) Citation density (the total number of citations divided by years since publication) was calculated similarly to previous bibliographic analyses. (Gross et al.) Due to the relatively recent emergence of RTSA in the treatment of proximal humerus fracture, all bibliometric metrics were recorded per year. The level of evidence and article type were independently determined by three authors. If uncertainty remained regarding a classification, an additional author was called upon to make a final determination.
Results
The final search yielded 1360 publications. Of the resulting articles, the top 238 in terms of total number of citations were reviewed to identify the top 50 articles that met our inclusion criteria. The resulting list of 50 publications can be considered the Top 50 publications pertaining to RTSA used for treatment of proximal humeral fractures (Table 1). Each of the top 50 articles were published between the years 2006 and 2020, with the most publications occurring in the years 2014 and 2016 (6). Only 8 of the listed articles were published prior to 2010, and 27 of the top 50 articles were published since 2014. However, these articles amassed 1706 total citations, approximately 40.55% of the cumulative number of citations across the top 50 publications. The year with the most total citations amassed across the top 50 articles was 2020 with 495, followed closely by 2019 and 2021 with 488 citations and 477 citations respectively. There was a significant rise observed in the number of citations collected per year between 2006 and 2019, followed by a period characterized by small fluctuations in the total number of citations per year between the years 2020 and 2022 (Figure 1).
At the time of data collection, the total number of citations amassed by the top 50 articles was calculated to be 4207 with an average of 247.47 total citations per year and an average of 84.14 citations per publication. The most highly cited article was cited a total of 627 times (Boileau et al.), followed by publications with 308 (Bufquin et al.) and 216 (Levy et al.) citations respectively. The least cited articles (Savin et al.; Lopiz et al.) each garnered a total of 27 citations since their publications in 2016, exactly 600 fewer citations than the article with the highest number of citations (Boileau et al.).
The top 50 articles were also analyzed based on citation density, or the number of citations per the number of years since publication (Table 1). The study by Boileau et al. was the most prolific in terms of both total citations (627) and citation density (36.9 citations per year), and is notably the earliest-published study included in this list. The study conducted by Sebastia-Forcada et al. ranked second in terms of citation density with 19.9 citations per year, followed by the study by Bufquin et al. with 19.3 citations per year. In terms of citation density, the articles published before 2010 averaged a citation density of 13.4 citations per year and articles published since 2010 showed an average citation density of 7.31 citations per year.
The top 50 publications were evaluated based on study design. It was observed that case series were the most prevalent among the included articles, comprising 28 of the top 50 publications, followed by cohort studies, randomized controlled trials, and case control studies, which represented 17, 3, and 2 of the top 50 publications respectively (Table 2). It was noted that all randomized controlled trials in this analysis were published during or after the year 2014, and all 8 of the articles published before 2010 were among the case series group. The level of evidence of each of the top 50 publications was also recorded (Figure 2). Studies of Level IV evidence composed more than half of the top 50 publications, occupying 28 spots on this list. Following closely behind were Level III studies (17) and a small number of both Level I (3) and Level II studies (2). The Level I studies achieved the highest average citation density with an average of 15.9 citations per year per study, followed by the Level II studies (10.7 citations per year per study), Level IV studies (8.1 citations per year per study), and finally Level III studies (7.0 citations per year per study).
The top 50 articles were published in a total of 19 unique journals (Table 3), with the Journal of Shoulder and Elbow Surgery being the most prolific in terms of total publications included on this list, publishing 20 of the top 50 cited articles. The Journal of Bone & Joint Surgery (both the British and American volumes) published the second highest number of these articles with 7. Further, these 50 articles originated from 10 different countries (Table 4), with authors from the United States contributing the highest number of publications (16), followed by France (11), Germany (8), and Spain (5). Only 1 of the articles originating from the United States was published before the year 2010 (Levy et al.), with most of these articles (9) being published since 2014. Interestingly, 7 of the 8 articles published before 2010 originated from European authors from France and Germany while authors from these countries only produced 6 of the articles published since 2014.
Discussion
The reverse total shoulder arthroplasty has been shown to be effective in reducing pain and improving shoulder function in a variety of cuff-deficient shoulder pathologies and proximal humerus fractures and fracture sequelae. (Baulot et al.; Boileau et al.; Kozak et al.) Current indications for RTSA in fracture care include displaced three- and four-part proximal humerus fractures, as well as fracture malunion, nonunion, post-traumatic arthritis, avascular necrosis, and chronic locked dislocations. (Kozak et al.) In a recent review conducted by Kozak et al., the authors reviewed recent literature assessing the effectiveness of RTSA in many different shoulder pathologies including proximal humerus fracture and fracture sequelae. (Kozak et al.) In their review, Kozak et al. noted that RTSA for three- and four-part proximal humerus fractures in elderly patients has been suggested to result in superior outcomes when compared to the historically employed hemiarthroplasty, resulting in improvements in clinical outcomes, forward flexion, abduction, and tuberosity healing. (Kozak et al.) Furthermore, for fracture nonunion, malunion, post-traumatic arthritis, avascular necrosis, and chronic locked dislocations, previous literature indicates that improved function and adequate patient satisfaction is achievable despite elevated rates of postoperative prosthetic dislocation, as high as 34% in some studies. (Boileau et al.; Kozak et al.; Martinez et al.; Raiss et al.) Thus, due to the increasing prevalence and demonstrated effectiveness of RTSA in the management of proximal humerus fracture and fracture sequelae in elderly patients, this study serves to highlight influential literature in this field and orient readers to the history, clinical impact, and areas of improvement within this widely used surgical procedure.
This study revealed patterns consistent with previously conducted bibliography analyses demonstrating that the year of publication significantly impacts the number of citations that a publication receives. (Chalmers et al.; Gross et al.) Of the identified articles, 5 of the top 8 most cited articles were published between 2006 and 2009 with the top 3 most cited articles obtaining 627 (Boileau et al.), 308 (Bufquin et al.), and 216 (Levy et al.), citations and being published in 2006, 2007, and 2007, respectively. There could be a variety of reasons for this finding. One possibility is that since these articles were published during the early years of RTSA being applied for fracture care, these articles likely served as the basis from which this body of literature could be expanded, resulting in many citations for these studies. Thus, these articles became immensely influential in the first few years after the approval of RTSA within the United States, indicating the profound impact that these early articles had on the advancement of RTSA and potentially their role in guiding the knowledge and training of orthopedic surgeons.
It was observed that this list was largely dominated by case studies of Level IV evidence, including the top 4 most-cited articles. While the evidence level of these articles may be low, this should not detract from the influence these publications had on the field of orthopedic shoulder surgery. The use of RTSA in the care of fracture patients is still in its infancy, and thus, the early work in this field is expected to be focused on small numbers of cases with lower levels of evidence. However, it is from the observations and evidence demonstrating the success of RTSA in this specific patient population that the foundation of support for the use of RTSA for humeral fractures is built. Thus, these publications became very influential in the field and garnered many citations throughout the years despite their lower levels of evidence. Among the newer publications that emerged in 2014 and beyond, randomized control trials with significantly high citation densities began to emerge, introducing higher levels of evidence. As RTSA continues to evolve, more studies will draw upon the evidence presented by the older publications presented here to produce novel, higher level of evidence research that will likely expand the scope of RTSA through innovative developments that are likely to be referred to by clinicians and researchers around the world. Thus, future studies with higher levels of evidence will likely gain many citations and there is a strong possibility that the top 50 most-frequently cited articles on this list will see significant change as the use of this procedure continues to grow.
The number of citations an article achieves can further be influenced by the journal of publication and the country from which the article originates. Articles published by authors in the United States contributed the largest number of papers, followed by France, Germany, and Spain. With respect to date of publication, many of the older articles presented here originate from European authors, particularly from France and Germany, while many of the more recent articles were published by authors from the United States. Interestingly, this geographical and chronological distribution indicates that the maturation of research investigating RTSA for fracture was more prominent in European countries early on, yet US-based authors published the largest number of studies included on this list with many of them emerging after 2014. While the definitive cause for the prominence of recent US authorship among these publications remains unclear, it has become evident that the use of RTSA in fracture care is prevalent worldwide due to the contributions seen from publications originating from countries such as New Zealand, Spain, Korea, Italy, and Australia. The diversity in authors representing these studies demonstrates the potential for international collaboration to bolster innovation and potentially alter the standards of care for proximal humerus fracture patients moving forward.
There have been significant changes in the use of RTSA as a primary procedure for the treatment of proximal humeral fractures as demonstrated by these publications. Nearly half of the studies published before 2010 had a particular focus on the use of RTSA as salvage procedures for revising failed hemiarthroplasties or open reduction internal fixation of proximal humerus fractures. (Boileau.; Gohlke et al.; Levy et al.) Furthermore, many of these early articles focused on specific prosthesis designs and approaches to performing RTSA in these complicated patients. (Boileau et al.; Klein et al.; Cazeneuve et al.; Levy et al.) It is likely that these early studies investigating novel prosthesis designs and procedures to mitigate the complications of previously failed fracture repairs subsequently influenced the adoption of RTSA as a primary procedure for use in the setting proximal humerus fractures and contributed to their high number of citations early in the evolution of the RTSA procedure. Thus, the more recently published articles have built upon their predecessors by further describing the results of RTSA as a primary procedure for fracture care, resulting in more studies of Level I and Level II evidence that we are witnessing rising to prominence among the other publications on this list. As the RTSA procedure continues to grow, more articles evaluating its use as a primary intervention will likely join the top 50 most frequently cited articles about RTSA, thereby inciting advancements to clinical standards of practice.
This study does not come without its limitations, as citation analyses in general are associated with limitations. Most importantly, even though the inclusion and exclusion criteria were explicitly defined for all reviewers and were established based on previous orthopedic bibliometric analyses, there remained some variability in the selection of articles between authors. To combat this, multiple authors served as reviewers for each article. If discrepancies between reviewers arose, an additional author was consulted to aid in the final decision to minimize inconsistencies within the selection process. Furthermore, the use of 50 articles in this analysis was arbitrary, as there were several articles within a small number of total citations from the least-cited articles included in this list. It is very possible that there may have been publications that were omitted that may be currently rising to prominence within the field, and thus the ranks on this list may soon become outdated. Lastly, previous bibliographic analyses have described limitations in which the number of citations of certain articles may become elevated due to authors citing them on the basis of higher citation count rather than content and quality of evidence. (Amhad et al.; Gross et al.; Lefaivre et al.; Namdari et al.) Thus, the number of citations for articles listed here may not adequately reflect their relative contributions to the field of orthopedics.
Conclusion
Quantifying the top 50 most-cited articles in RTSA for proximal humerus fracture can provide insight into the origins and evolution of the RTSA for fracture care as its clinical utility continues to be explored. Many of the current most-cited publications within this body of literature are case series and cohort studies that present low levels of evidence. A majority of the older, most highly cited included in this analysis were published between 2006 and 2009 by European authors, likely due to the recent adoption of RTSA for use in the treatment of humeral fracture in the United States following FDA approval in 2003. As the use of RTSA continues to expand over time, more randomized controlled studies are expected to rise to prominence as the clinical utility of RTSA for proximal humerus fracture care is further investigated and the body of literature in this field matures. This may result in these studies of higher levels-of evidence eventually gaining enough citations to surpass the articles included in this analysis.
Conflicting interests
The Author(s) declare(s) that there is no conflict of interest.
Funding
This research received no specific grant from any funding agency in the public, commercial, or not for-profit sectors.
Informed consent
Not applicable.
Ethical approval
Not applicable. IRB approval was not required due to the public availability of the data used in this analysis.
Guarantor
RCR
Contributorship
JSB, LWB, and GD performed searches and reviewed publications. AVP reviewed publications in which there was uncertainty among the three primary reviewers. JSB, LWB, and AK wrote the first draft of the manuscript. All authors reviewed and edited the manuscript, as well as approved the final version of the manuscript.
Acknowledgements
None.