The 100 most cited papers in spinal deformity surgery: a bibliometric analysis.

Spinal deformity is a condition that has been recognized for many millennia. There have been major advances in the treatment of spinal deformity in recent years and studies outlining new ideas can inspire others to further advance the speciality. The number of citations a paper receives may indicate the influence of that paper. It is therefore important that we evaluate and analyze the most cited works in our field. The aim of this study is to identify the 100 most cited papers relevant to spinal deformity surgery in the literature. A search through the Thomson Reuters Web of Science™ for citations related to spinal deformity surgery was performed. The number of citations, mean citation number (total number citations/years since publication), journal, authors, year of publication and country of origin of the top 100 papers was recorded. The top 100 papers were cited a combined 17,646 times, ranging from 453 to 112. The majority of papers originated from the United States (71) and were published in 20 different journals. The decade 1990-1999 was the most prolific, with 36 of the 100 papers published during this time. Papers pertaining to the management of scoliosis (49) were the most common. This study identifies the top 100 most cited papers in the field of spinal deformity surgery. While citation is not a specific marker of the scientific quality of a paper, it is a surrogate for the influence a paper has had on the orthopedic community. This list of papers provides an invaluable resource for both those in training and those actively practicing and involved in the further development of spinal deformity surgery.

Introduction

Spinal deformity is a condition that has been recognized for many millennia,[1] with documented attempts at scoliosis correction dating back at least 5000 years.[2] Our understanding of the development and progression of spinal deformity has increased significantly in recent years, along with major advancements in corrective techniques for this debilitating condition. Undoubtedly, much is learned from those who went before us, with the published literature acting as an invaluable tool in the advancement of knowledge and innovation in a particular area. Ranking papers by the number of citations they receive allows us to develop a list of the most influential papers in our field of interest.

A citation is an acknowledgement by an author of another author’s contribution to their work. Citations contribute to the impact factor a journal receives and therefore influences the journals that we read. Citation analysis, the bibliometric process analyzing citations credited to a given paper, directly determines the impact factor of journals. Impact factor is calculated by dividing the total number of citations of papers published in that journal over the past year divided by the total number of papers published by that journal over the past two years.[3] There have been a number of recent publications examining the most influential papers as determined by citation analysis in orthopedic surgery,[4] and the subspecialties of arthroscopy,[5] foot and ankle,[6] arthroplasty,[7] and pediatric orthopedics.[8] Similarly, lists of classic papers have been developed in other specialties such as general surgery,[9] radiology,[10] and plastic surgery.[11] One publication looked at the most cited articles in spine.[12] This publication devised the list based on the generality of spine surgery and limited their search to certain subject categories and journals. This is the first publication in the literature to devise a list of the most influential papers specific to spinal deformity surgery.

The aim of this study was to identify the 100 most cited papers relevant to spinal deformity surgery, by performing a bibliometric analysis of the literature using the Science Citation Index (SCI) database.

Materials and Methods

The top 100 most cited papers relevant to spinal deformity surgery were identified from a search of the SCI of the Institute for Scientific Information (ISI), using the Thomson Reuters Web of Science™ search engine from 1945-2014. The following search strategy was performed in March 2014: Spinal deformity OR Scoliosis OR Kyphoscoliosis OR Kyphosis OR Lordosis OR Sagittal plane deformity OR Sagittal imbalance OR Coronal plane deformity OR Coronal imbalance OR spondylolisthesis. No limitation was applied to the search in terms of subject category or journal. Results were listed by citation number and assessed by two independent authors (SCON and JSB) for relevance to spinal deformity surgery with complete agreement between authors required for inclusion of a paper.

Papers not relevant to the topic were excluded. The resulting most cited 100 papers were then assessed for; title, journal, number of citations, mean citation number (total number citations/years since publication), authors, year of publication and country of origin.

Results

The top 100 papers in spinal deformity surgery have been cited a combined 17,646 times. The top 100 papers and the number of citations are presented in Table 1. [13-111] The most cited paper was by Harrington with 453 citations,[13] while the 100th paper by Lee et al. was cited 112 times.[107] The mean number of citations was 176, with a mean citation number of 8.33/year.

Table 1.

The top 100 most cited papers.

1st author	Citations	1st author	Citations	1st author	Citations
Harrington[13]	453	Haher[14]	183	Lowe[15]	131
Lenke[16]	408	Stokes[17]	182	Aebi[18]	130
King[19]	391	Suk[20]	181	Bunnell[21]	129
O’sullivan[22]	388	Kumar[23]	176	Kim[24]	128
Herkowitz[25]	347	Weinstein[26]	175	Gill[27]	128
Fischgrund[28]	346	Collis[29]	174	Asher[30]	127
Lonstein[31]	337	Weinstein[32]	172	West[33]	126
Beutler[34]	310	Weinstein[35]	165	Suk[36]	124
Jackson[37]	274	Betz[38]	162	Albert[39]	121
Bergofsky[40]	269	Dickson[41]	155	Mack[42]	121
Nuwer[43]	261	Vialle[44]	151	Riseborough[45]	121
Suk[46]	259	Wiltse[47]	151	Gaines[48]	120
Stagnara[49]	251	Mcmaster[50]	150	Mcdonnell[51]	120
Wiltse[47]	245	Etebar[52]	149	Rosenberg[53]	120
Nachemson[54]	239	Aris[55]	148	Moller[56]	119
Warren[57]	238	Wiltse[58]	148	Black[59]	119
Boyd[60]	233	Kim[61]	146	Benzel[62]	119
Macewen[63]	225	Mardjetko[64]	146	Roussouly[65]	118
Gelb[66]	224	Wiltse[67]	145	Myers[68]	118
Bridwell[69]	223	Brooks[70]	145	Katsuura[71]	117
Ponseti[72]	222	Lenke[73]	143	Nilsonne[74]	116
Cochran[75]	218	Vaz[76]	142	Vedantam[77]	115
Kim[78]	216	Brodke[79]	141	Ransford[80]	115
Thomsen[81]	209	Ponseti[82]	140	Fon[83]	115
Boxall[84]	207	Rowe[85]	139	Asher[86]	114
Morrissy[87]	206	Emans[88]	139	Herman[89]	114
Glassman[90]	201	Lonstein[91]	138	Collier[92]	114
Glassman[93]	201	Bunnell[94]	138	Dwyer[95]	114
Carman[96]	200	Engler[97]	138	Theodorou[98]	113
Liljenqvist[99]	196	Winter[100]	138	Levine[101]	113
Rogala[102]	194	Nachemson[103]	138	James[104]	113
Sharma[105]	192	Zdeblick[106]	137	Lee[107]	112
Newman[108]	186	Shands[109]	135	Jackson[110]	112
		Campbell[111]	131

The oldest paper included in the list was by Ponseti et al. Prognosis in idiopathic scoliosis published in 1950 with the most recent published in 2007 by Weinstein et al.

The 1990s accounted for the most number of papers (36) with the 20 years between 1990-2010 accounting for 58% of the top 100 papers. Citations increased exponentially decade by decade with 79 in the 1950s and 8359 in the 2000s. The number of papers listed by decade published is presented in Figure 1.

Figure 1.

Publication number by decade.

Overall twelve countries contributed papers. The majority of the top 100 papers originated from the United States (71), followed by United Kingdom, France and Sweden (5 papers each); South Korea (4 papers); Australia, Canada, Germany (2 papers each); Switzerland, Japan, Denmark and Scotland (1 paper each).

Sixty-nine separate institutions contributed papers to the list. Washington University contributed the most papers (8), with the University of Iowa contributing 5. The Long Beach Memorial Medical Center contributed 4 studies, while other 9 papers were published by The Royal National Orthopedic Hospital, Stanmore, London (3 papers), the University of Louisville (3 papers) and the University of Gothenburg (3 papers).

The top 100 papers were published in 20 different journals, which represented orthopedic, general and other sub-specialty interests. The journal of bone and joint surgery - American volume published the greatest number of papers (39), followed closely by Spine journal (32), The journal of bone and joint surgery - British volume (5) and the European Spine Journal (4). A complete list of journals can be find in Table 2.

Table 2.

Journals of publication.

Journal	Papers
Journal of Bone and Joint Surgery-American Volume	39
Spine	32
Journal of Bone and Joint Surgery-British Volume	5
European Spine Journal	4
New England Journal of Medicine	2
Journal of Spinal Disorders	2
Journal of Neurosurgery	2
Acta Orthopaedica Scandinavica	2
Medicine	1
Evoked Potentials-Electroencephalography and Clinical Neurophysiology	1
Journal of Neurology Neurosurgery and Psychiatry	1
American Journal of Pathology	1
Annals of Internal Medicine	1
Clinical Orthopaedics and Related Research	1
International Orthopaedics	1
Annals of Thoracic Surgery	1
Journal of Bone and Mineral Research	1
American Journal of Roentgenology	1
Radiology	1
Clinical Imaging	1

A number of authors were represented on multiple papers in the top 100. Lenke and Bridwell both appeared on 8 of the papers on the list, with Ponseti and Winter appearing on 5. Wiltse published the greatest number of papers as first author (4). Suk, Nachemson, Moe, Kim, Herkowitz, Glassman, Dimar, Bunnell and Bradford appear in 3 papers each.

While a variety of spinal deformity topics are represented in the top 100, papers specifically relating to scoliosis management (49) were the most common topic.

Discussion

In our study, the Science Citation Index was interrogated to assess the most cited papers in spinal deformity surgery in order to attempt to produce a list of citation classics in the field. It provides an insight into some of the most influential papers in the area of spinal deformity surgery and chronicles the practice-changing work that has been published over the past 70 years.

The most cited paper was Treatment of scoliosis - correction and internal fixation by spine instrumentation by Harrington in 1962, which was cited 453 times.[13] The paper described a new operative technique for the treatment of scoliosis. Harrington described the use of internal fixation and distraction using rods to correct the deformity. While his initial results were mixed it marked the beginning of a new era in the surgical treatment of scoliotic deformity. Numerous alterations were made to Harrington’s instrumentation and innovation in internal fixation for scoliosis correction continues today.

The second most cited paper was by Lenke et al. Adolescent idiopathic scoliosis published in 2001, cited 408 times. This paper proposed a new two-dimensional classification system for adolescent idiopathic scoliosis that attempted to determine the level of fusion required at the time of surgery. It sought to improve upon the limitations of the existing classification proposed by King et al.,[19] a paper which has been cited 391 times and is the third most cited paper in our study. Comparative studies have shown the new classification system by Lenke et al. to be more reproducible and reliable than King et al. There is as significant time period between the publication year of the 1st and 2nd paper on our list. Although Harrington’s paper has more citations in absolute terms, this has been achieved over a 50-year period. In contrast to this, Lenke et al. published 13 years ago and thus the mean number of citations per year of this paper is 29.14, which is significantly higher than the mean citation of 8.55 for Harrington. This finding suggests that the mean citation number may be useful in assessing the immediacy of the impact a paper has, when comparing publications from different time periods.

A total of 12 countries contributed papers to the top 100 most cited papers in spinal deformity surgery. All countries are from the developed world with a high degree of health care expenditure. The United States contributed 71 papers to the list, which is more than twice the number of all the other countries combined. This is in keeping with other similar studies across a number of medical specialties,[7,8,11] and correlates to the volume of orthopedic practice and research output that exists in the United States. In terms of decade of publication, 77 of the top 100 papers have been published since the 1980s, with 1990s the most prolific period for publication, accounting for 36 papers. High impact factor orthopedic journals dominated the list with The journal of bone and joint surgery - American volume and Spine publishing the most articles, emphasizing the prestige and influence these journal exert in the field of orthopedic surgery. From our analysis, it would appear that for an author to achieve a highly cited paper, it is most likely to be published from a United States, English speaking institution and published in a high impact journal.

There are a number of inherent limitations to this form of citation analysis, which have been highlighted in previous papers using similar methods.[11] The SCI citation database was searched in this study using the Thomson Reuters Web of Science™ search engine. The ISI began collecting citation information in 1945 and therefore articles published prior to this were not included in this study. Previous studies limited the search to journals within specific subject categories. We placed no restriction on our search and feel this resulted in less likelihood of excluding potentially relevant articles and therefore achieving a more representative list of articles for analysis. It has been suggested that more recent papers are at a disadvantage with older papers more likely to be cited.[112] The use of mean citation number (total number citations/years since publication) in our analysis takes into account year of publication and allows a relative comparison of citation to be made between recent and more historic papers.

Self-citation, journal bias and language bias were not controlled for in this study. Articles published in high impact journals are more likely to reach a wider audience and therefore have a greater potential for citation. All papers in the top 100 were written in the English language. There are also a number of phenomenon that can influence citation analysis. Obliteration by incorporation is one such phenomenon. It describes the observation that some highly influential or classic papers become so ingrained into common knowledge that they are no longer deemed necessary to cite.[113] Incomplete citing can also occur. It describes the situation when citations are made by the author to persuade the reader rather than to give accurate acknowledgement to those that influenced their work.[114]

Conclusions

This study identifies the top 100 most cited papers in the field of spinal deformity surgery. While citation is not a specific marker of the scientific quality of a paper, it is a surrogate for the influence a paper has had on the orthopedic community. This present study provides a list of some of the most influential papers that have helped shape the speciality over the past 70 years. This list of papers provides an invaluable resource for both those in training and those actively practicing and involved in the further development of spinal deformity surgery.