Clinical Application of Rapid Upper Limb Assessment and Nordic Musculoskeletal Questionnaire in Work-Related Musculoskeletal Disorders: A Bibliometric Study

Assessment of work-related musculoskeletal disorders (WMSDs) using the Rapid Upper Limb Assessment (RULA) and the Nordic Musculoskeletal Questionnaire (NMQ) has become widely accepted and reported in the literature. The objectives of this study are to (1) recognize and describe the topmost 50 cited scientific articles in WMSDs using the RULA and NMQ and (2) explore the factors that contribute to making an article influential. In this bibliometric study, we used the Web of Science and MEDLINE databases to identify the top 50 cited articles published from 1993 to 2022. The data collected were the title of the journal, number of citations, year of publication, type of the study, institution where the work was conducted, level of evidence, contribution of primary authors, and country of origin of the work. Our results showed that the top 50 cited articles were published between 1980 and 2010. The 2000s was the most valuable decade. Regarding journals, the Work journal had the highest number of articles concerning the use of RULA and NMQ in healthcare professionals. The maximum number of citations regarding RULA occurred in the Journal of Robotic Surgery (n = 50) and the maximum for NMQ occurred in the Journal of Safety Research (n = 106). Most articles originated from the United States, followed by England and the Netherlands. Eight authors had two publications published in the top 50 list. The majority of the topmost cited research articles were cross-sectional studies. Most of these studies were level III evidence. The bibliometric analysis from this study provides insights to researchers to choose the most appropriate and influential journal for submitting work on WMSDs.


Introduction
Work-related musculoskeletal disorders are considered to be a major issue worldwide [1]. Awkward non-physiological postures while working, hereditary causes, aging, and psychological issues could be the responsible factors causing work-related musculoskeletal disorders (WMSDs). These disorders include damage to various components of the locomotor system such as muscles, joints, nerves, and other connective tissues [2].
Healthcare specialists with prolonged interaction with patients had the greatest percentage of WMSDs [3]. WMSDs are recognized as a major occupational hazard in various countries [4][5][6][7] since there is a considerable economic burden imposed by these conditions [8,9].
The use of a validated, uniform evaluation tool is recommended in order to diagnose and devise effective interventions to tackle WMSDs [10]. Two such important evaluation tools that have been utilized for many years are the Rapid Upper Limb Assessment (RULA) [11] and the Nordic Musculoskeletal Questionnaire (NMQ) [12]. Both these tools demonstrated greater reliability in evaluating ergonomic hazards in various healthcare practitioners [4,13,14].
The RULA was developed by Corlett and McAtamney in 1993, primarily as an observational tool. It was utilized to assess the person's susceptibility to loads due to the posture of the upper extremity and spine and the assistance of the lower extremities required to cope with the extra load during one's work. The overall RULA score ranges from one to seven. Higher scores suggest a greater likelihood of a musculoskeletal problem. RULA scores either equal to or greater than five necessitate a change in posture during work [11].
The Nordic Musculoskeletal Questionnaire (NMQ) was developed by Kuorinka et al. in 1987. It is an easy, well-defined questionnaire comprising a body map describing nine functional sites revealing both sides' upper limbs, lower limbs, upper back, and lower back. It incorporates questions on symptoms felt by the individuals in the previous 12 months and the past seven days, along with constraints in activity levels in the previous 12 months. The responses to these questions are documented. NMQ can be administered either by a conversation method or can be self-administered [12].
Numerous articles on WMSDs have been published previously, and there seems to be a steady increase in the number of publications on the subject. A bibliometric review on RULA by Gómez-Galan et al. [15] only reported a country-wise, year-wise, and journal-wise analysis, while citations and other analyses were not reported. Despite their importance, the most influential research articles on the use of RULA and NMQ in healthcare practitioners have not been previously reported. The total number of citations of a research article is an indicator of the influence wielded in the area of interest [16]. A citation breakdown is a bibliometric analysis to calculate the comparative reputation of a scientific research paper by investigating the citations credited to that research paper [17]. In recent years, the highest-cited research articles have been detected by utilizing citation scrutiny in numerous medical fields [18][19][20][21][22].
Assessing bibliometrics is the arena of the medical field, which utilizes approaches such as citation analysis to estimate the implementation of research [23]. The total number of citations of formerly published work in scientific papers indicates its following identification in a particular area of study. It has an additional effect on the scientific community [24]. Bibliometric studies are mainly valuable for guiding healthcare specialists in creating evidence-based judgments in clinical practice. Along with this, the topmost cited papers in research are generally considered the most influential research within a particular field, raising innovative research ideas [25]. Therefore, a detailed bibliometric analysis of the topmost cited research articles can benefit the understanding of a specific discipline, which aids in generating useful guidelines in the field of biomedical research [26].
Therefore, we conducted analyses on the citations, subject-wise contribution, quartilewise contribution, primary author contribution, institutional-wise, study type, and evidence level of the top 50 most-cited articles regarding the RULA and NMQ.

Collection of Articles
We searched for all the relevant articles on the RULA and NMQ using Web of Science and MEDLINE records to identify the top 50 most commonly cited research articles in various healthcare-related specialties [27][28][29]. The following search terms were used: Ergonomics, assessment, workplace, musculoskeletal disorders, RULA, and NMQ. The search was executed on 20 June 2021 and yielded 429 results related to the RULA and 710 concerning the NMQ.

Inclusion Criteria
Only original articles reporting the use of the RULA and/or NMQ in healthcare professionals were included in this bibliometric analysis.

Exclusion Criteria
Original articles reporting the use of the RULA and/or NMQ in non-healthcare practitioners, narrative reviews, systematic reviews, meta-analyses, letters to the editor, short-communication-type articles, and abstracts of scientific meetings were omitted from the bibliometric analysis [30].

Organization of Articles
In total, 1139 studies were identified during the initial screening. Out of these, 376 studies were excluded for not having reported musculoskeletal outcomes. After a careful screening of the remaining 763 studies based on the inclusion standards, 544 studies were excluded due to inadequate data, failure to address the research question, dealing with non-healthcare practitioners, or duplicates, and the remaining 219 studies met the inclusion criteria. These articles were organized according to the number of citations, and the top 50 most-cited articles regarding the RULA and NMQ were incorporated into the final analysis (Figure 1).

Collection of Articles
We searched for all the relevant articles on the RULA and NMQ using Web of Science and MEDLINE records to identify the top 50 most commonly cited research articles in various healthcare-related specialties [27][28][29]. The following search terms were used: Ergonomics, assessment, workplace, musculoskeletal disorders, RULA, and NMQ. The search was executed on 20 June 2021 and yielded 429 results related to the RULA and 710 concerning the NMQ.

Inclusion Criteria
Only original articles reporting the use of the RULA and/or NMQ in healthcare professionals were included in this bibliometric analysis.

Exclusion Criteria
Original articles reporting the use of the RULA and/or NMQ in non-healthcare practitioners, narrative reviews, systematic reviews, meta-analyses, letters to the editor, shortcommunication-type articles, and abstracts of scientific meetings were omitted from the bibliometric analysis [30].

Organization of Articles
In total, 1139 studies were identified during the initial screening. Out of these, 376 studies were excluded for not having reported musculoskeletal outcomes. After a careful screening of the remaining 763 studies based on the inclusion standards, 544 studies were excluded due to inadequate data, failure to address the research question, dealing with non-healthcare practitioners, or duplicates, and the remaining 219 studies met the inclusion criteria. These articles were organized according to the number of citations, and the top 50 most-cited articles regarding the RULA and NMQ were incorporated into the final analysis ( Figure 1).

Extraction of Articles
Two autonomous assessors selected suitable studies based on the inclusion and exclusion criteria. Then, the reviewers identified the full texts of all relevant articles and selected the top 50 cited publications regarding the RULA and NMQ.
The following data were extracted from the included articles: Title of the paper, primary author's name, journal name, time of publication, impact feature of the journal in 2020, the total number of citations of the research paper, study design, article type, average citations per year, mentions, country, organization of basis, authorship, journal, and level of evidence. Citation statistics for all the selected research articles were achieved by exploring the SCOPUS records. The level of evidence of the articles was determined based on the Centre for Evidence-Based Medicine (CEBM) guidelines, Oxford, UK.

Statistical Analysis
Two reviewers individually agreed on the level of evidence for the research articles. The agreement was outstanding for the level of evidence, with an intraclass correlation coefficient of 0.90 [30]. Two assessors decided on all variances through conversation, and another assessor was involved when no agreement was reached. Data analysis was performed using SPSS software (version 24.0 for Windows; SPSS, Inc., Chicago, IL, USA).

Results
A total of 1139 articles were found from the search, established on the citations, then the 50 most prominent articles concerning the RULA and NMQ regarding WMSDs were selected for the study.

Citation Breakdown
The 50 most commonly cited articles using the RULA and NMQ in regard to WMSDs have 2011 citations overall (Table 1). These range from 1 to 50 concerning the RULA with a mean of 11.36 (SD = 11.32) mentions per article, with a total of 552 citations, as shown in Table 1. Regarding NMQ, the number of citations ranged from 13 to 106, with a mean of 30.66 (SD = 18.30) for each article, with a total of 1518 citations, as shown in Table 1.

Title & Year Journal Total Citations
Design and ergonomic assessment of an infusion set connector tool used in nursing work. Otolaryngol. Head. Neck. Surg. 1 SOPEZ: study for the optimization of ergonomics in the dental practice-musculoskeletal disorders in dentists and dental assistants: a study protocol.
The significance of dividing the journals into quartiles indicates where a journal's standing lies in a specific subject classification. These quartiles rank the journals from highest to lowest, established on their impact factor or impact index. A quartile is a category of scientific journals that shows their credibility, reliability, and quality. The quartile also reflects the demand for the journal by the scientific community.

Authors
Five authors published more than one research article related to the RULA (Table 6). Two authors published more than one research article related to the NMQ (Table 6).

Authors
Five authors published more than one research article related to the RULA (Table 6). Two authors published more than one research article related to the NMQ (Table 6).

Countries
The top-cited articles in WMSDs in healthcare practitioners in regard to the RULA originated from 13 countries. The country delivering the most articles was the USA (n = 18), followed by Iran (n = 11), India and Brazil (n = 4), Sweden (n = 3), and Germany and England (n = 2). The remaining articles were from other respective countries. Therefore, the geographic distribution of these most-cited articles is represented in Figure 3a.
The top-cited articles in WMSDs in healthcare practitioners in regard to the NMQ originated from 20 countries. The countries delivering the highest number of articles were Iran (n = 3), followed by Australia (n = 7), the USA (n = 5), France, Portugal, and Brazil (n = 3). The remaining articles were from the other respective countries. Therefore, the geographic distribution of these most-cited articles is represented in Figure 3b.

Countries
The top-cited articles in WMSDs in healthcare practitioners in regard to the RULA originated from 13 countries. The country delivering the most articles was the USA (n = 18), followed by Iran (n = 11), India and Brazil (n = 4), Sweden (n = 3), and Germany and England (n = 2). The remaining articles were from other respective countries. Therefore, the geographic distribution of these most-cited articles is represented in Figure 3a.

Institutions
A total of 50 institutions produced the top-cited articles in WMSDs concerning the RULA. Three institutions published three or more of the most commonly cited articles. Thirteen (26%) of these institutions were located in the USA, followed by 8 (16%) in Iran, 4 (8%) in Brazil and India, 3 (6%) in Sweden, and 2 (4%) in Germany, Canada, Turkey, Canada, South Korea, and England. The remaining countries contributed one article each. The institutions producing the most articles were Ohio State University, Tehran University, and the University of Pittsburgh (n = 3), followed by the University of North Carolina and Iran University of Medical Sciences (n = 2), and the remaining Universities contributed one article each (Table 7).   A total of 49 institutions were involved in producing the top-cited articles in WMSDS concerning the NMQ. Three institutions published three or more of the most commonly cited articles. Seven (14.2%) of these institutions were located in Iran, followed by six (12.2%) in Australia, five (10.2%) in the USA, three (6.1%) in Sweden, China, and Iran, and two (4%) in France, Saudi Arabia, and Egypt. The remaining countries contributed one article each. The institutions producing the most articles were Tehran University, Shiraz University, and Babol University (n = 3), followed by Universidade Nova de Lisboa, Queensland University, National Institute of Industrial Health, and King Abdulaziz University (n = 2), and the remaining universities contributed one article each (Table 7).
Ranking institutions by country may help to build global brand visibility, forge strategic partnerships, and recruit international talent. It also allows for analyses according to academic reputation, employer reputation, research citations per paper, h-index, and the International Research Network.

Study Designs of Articles
The main stream of the top 50 cited research articles associated with both the RULA and the NMQ were cross-sectional studies, followed by observational, comparative, experimental, and other types of studies [33] (Table 8). Table 8. Study design of top-cited articles of RULA and NMQ in WMSDs in regard to healthcare practitioners.

Study Design Articles
University, and Babol University (n = 3), followed by Universid Queensland University, National Institute of Industrial Health, an versity (n = 2), and the remaining universities contributed one arti Ranking institutions by country may help to build global bran tegic partnerships, and recruit international talent. It also allows fo academic reputation, employer reputation, research citations per p International Research Network.

Study Designs of Articles
The main stream of the top 50 cited research articles associate and the NMQ were cross-sectional studies, followed by observati perimental, and other types of studies [33] (Table 8).

Level of Evidence
The top 50 most-cited articles could be classified into all evid The majority of the articles were within evidence level III (n = 70), level IV (n = 23), evidence level 1B (n = 4), and evidence level IIB (n

Discussion
To the best of our knowledge, this is the first bibliometric analy related musculoskeletal disorders concerning the RULA and NMQ citations for each paper, the unique bibliometric indicator, is a valu the impact of publications. From the analysis of these top 50 most-c we attempted to determine what fundamentals of a research articl tive. The top-cited article in our list in relation to the RULA had 50 related to the NMQ had 106 citations [32]. This number is much lo in relation to non-healthcare specialties [35,36]. The citations varie predominantly reliant on the number of investigators in exact thera Identifying those classic articles is beneficial for better insight int gress of evaluation of WMSDs by using RULA and NMQ among h and also for planning future research.

Level of Evidence
The top 50 most-cited articles could be classified into all evidence levels ( Table 9). The majority of the articles were within evidence level III (n = 70), followed by evidence level IV (n = 23), evidence level 1B (n = 4), and evidence level IIB (n = 3) [34].

Discussion
To the best of our knowledge, this is the first bibliometric analysis of papers on workrelated musculoskeletal disorders concerning the RULA and NMQ. The total number of citations for each paper, the unique bibliometric indicator, is a valuable tool to determine the impact of publications. From the analysis of these top 50 most-cited articles published, we attempted to determine what fundamentals of a research article make it vastly effective. The top-cited article in our list in relation to the RULA had 50 citations [31], and that related to the NMQ had 106 citations [32]. This number is much lower than the WMSDs in relation to non-healthcare specialties [35,36]. The citations varied between specialties, predominantly reliant on the number of investigators in exact therapeutic fields [4,37,38]. Identifying those classic articles is beneficial for better insight into the history and progress of evaluation of WMSDs by using RULA and NMQ among healthcare practitioners and also for planning future research.
In relation to our present study, open access may be another significant factor in drawing citations [39,40]. It is widely known that open-access scientific papers are more easily accessible and cited compared to non-open scientific papers [41,42]. However, we also found that articles concerning otolaryngologists and neurosurgeons in open-access format did not obtain considerably more citations than non-open-access articles in the same specialties [38,43]. It can thereby be inferred that the extent to which open-access articles increase citations varies depending on the specialty.
All top 50 cited articles in WMSDs in relation to the RULA and NMQ were published in English. This establishes that English is the most commonly used scholarly language in WMSDs. Additionally, all of the most-cited papers occurred in 35 journals in relation to RULA and 40 in relation to NMQ. In relation to individual contributions of the journal published, the most productive journal was Work-A Journal of Prevention, Assessment & Rehabilitation, with ten articles (both RULA and NMQ) in the top list. This result suggests that this journal was the most preferred in regard to WMSDs.
In relation to quartile classifications, these were analyzed for individual journals in each theme classification, corresponding to which quartile of the scientific journal dominates in the impact factor division of that subject category [44]. The total number of publications and/or the distribution of total publications in a particular quartile generally corresponded to the first quartile (Q1) in regard to the RULA and the third quartile (Q3) in regard to the NMQ. Moreover, in the present study, the overall greater number of cited articles occurred in the third quartile (Q3).
With relation to authors and institutions, good publication track records in WMSDs related to healthcare practitioners have been determined in the present study [45][46][47][48][49]. Tehran University has great priority in this field by contributing six publications overall. Musculoskeletal disorders are the most prevalent theme, with approximately 18 articles related to the RULA and 41 related to the NMQ, which emphasizes the significance of musculoskeletal disorders in subspecialties such as joints, bones, muscles, etc.
In regard to study type, we demonstrated that cross-sectional studies were the most popular study type in this study. This finding is consistent with many studies assessing WMSDs [50][51][52][53]. Furthermore, most of the top cited articles were level III evidence. This result indicates that the level of evidence is certainly not a positive aspect of the total number of citations [54]. This is likely because original ideas and assessments are initially published as cross-sectional studies and still catch the attention of practitioners or researchers.
In relation to the sequential allocation of citations, the 2001-2010 time period had the highest number of mentions on our 50 top-cited research articles list related to WMSDs in healthcare practitioners; 33 articles were related to the RULA, and 37 were related to the NMQ. There are various reasons for this result in the present study. First, it could take approximately 10 years or further for prominent article citations to reach their peak, as acknowledged through bibliometric examination [31,32]. Second, researchers tend to underestimate the influence of the most recent studies compared to old studies [55]. Third, some research scholars believe that the accurate importance of the research papers cannot be considered until at least 10-20 years afterward the date of publication in the journal [56]. Therefore, research articles published recently need additional time to gather citations to establish their importance.
Lastly, in relation to the geographical distribution, more than one-third of the topcited WMSD-related articles were from the United States. It is no wonder that the United States has benefited in the rankings, as various healthcare sectors have found similar results [57,58] due to various aspects: (1) The American research and scientific community is substantially bigger than that of any other community in the world; (2) the availability of more funding for research; and (3) previous research studies have pointed out that there is a predisposition for researchers from the United States to cite local articles [59]. This may result in the authors from the US having an essential advantage when trying to publish the most cited and dominant research articles.

Limitations of the Study
There are several limitations in the present study. First, we only utilized the Web of Science and MEDLINE for our analysis; consequently, some research papers indexed by Google Scholar or SCOPUS or basic medical journal databases may have been missed. Second, there was an association with the publication phase, with newly published research articles experiencing a disadvantage in relation to the citation calculation. With this issue, possibly more appropriate and prominent research articles published recently may not have been included in the top 50 cited articles list because they have not had sufficient time to gather the required number of citations. Lastly, possible factors that influence the citations cannot be exactly established in this analysis; these include researcher selfmentions, citations in workbooks, meeting notes, lectures, symposiums, and web-based writings [57,60]. Nevertheless, the statistics delivered in the present work do provide insight into the most important investigation areas of WMSDs.

Conclusions
The top-cited papers were all published in the English language, originated from institutions in the United States, and were primarily cross-sectional studies with level III evidence. Most articles were published in Work-A Journal of Prevention, Assessment & Rehabilitation. This top citation list offers valuable insight into the assessment of WMSDs using the RULA and NMQ, especially in the healthcare sector, and serves as a crucial basis of evidence for investigators and research scholars for future research on WMSDs.