The top 100 most impactful articles on the anterior cruciate ligament: An altmetric analysis of online media.

Objectives: To identify the top 100 most impactful anterior cruciate ligament articles in online media as measured by the Altmetric Attention Score and compare their characteristics to the most-cited anterior cruciate ligament articles in the scientific literature.
Methods: The Altmetric database was queried to identify all published articles pertaining to the anterior cruciate ligament. The search yielded 9445 articles, which were stratified by highest to lowest Altmetric Attention Score. The top 100 articles were included. Collected data included article type, article topic, journal name, and online mentions in news, blogs, Twitter, Facebook, Wikipedia, and other sources. The geographic origin of each article was also determined based on the institutional affiliation of the first author.
Results: Altmetric Attention Score of the top 100 anterior cruciate ligament articles ranged from 109 to 2193 (median 172.0, interquartile range 137.5-271.5). Of the 100 articles, 65 were published in three journals: American Journal of Sports Medicine, British Journal of Sports Medicine, and Journal of Orthopaedic & Sports Physical Therapy. The most prevalent article type was original research (60%), followed by systematic review/meta-analysis (18%). The most prevalent article topic was rehabilitation and return to play after anterior cruciate ligament reconstruction (22%), followed by epidemiology/risk factors (16%), injury prevention (14%), and biomechanics of anterior cruciate ligament injuries (14%). Of the top 100 articles, 54% were American, 31% were European, and 15% were published in other countries outside of the United States and Europe.
Conclusion: This study used Altmetric Attention Score to identify the 100 most engaged anterior cruciate ligament articles in online media. The characteristics of these articles differed substantially from the most-cited anterior cruciate ligament articles in the literature with regard to article type, article topic, geographic origin, and publication journal. These findings suggest that alternative metrics measure distinct components of anterior cruciate ligament article engagement and add an important dimension to understanding the overall impact of published research on the anterior cruciate ligament.

Introduction

Bibliometric analysis has been used to assess the academic impact of various types of orthopedic research.[1 –8] This type of analysis provides insight into the value of specific articles within various scientific communities and is a growing trend in other medical specialties in the last 5 years, including medical imaging, gastroenterology, and neurosciences.[9 –11] However, social media platforms, such as Twitter, are increasingly used as a means of disseminating scientific research, and conventional bibliometrics do not account for the engagement of physicians and scientists with academic research that occurs in the online setting.[12 –14] Overall, little is known about the proliferation of orthopedic research in online media.

Previous studies have used the Altmetric Attention Score (AAS) to examine the most mentioned articles in online media pertaining to other medical specialties, such as cardiology, neurology, and spine surgery, but no study has reported the online engagement of articles pertaining to a particular topic in sports medicine. The anterior cruciate ligament (ACL) is one of the most commonly injured ligaments in the human body, with over 120,000 ACL injuries occurring annually in the United States and peak incidence in high school athletes. The implications of ACL injuries in the realm of competitive athletics may generate a robust online discussion surrounding ACL research that has not yet been captured or quantified in a systematic way.

The purpose of this study was to use an established alternative metrics database to evaluate the online engagement of ACL research articles. We aimed to identify the 100 most engaged ACL articles in online media as measured by the AAS and compare their characteristics to the most-cited ACL articles in the literature. Our goal was to achieve a better understanding of the online dissemination of ACL research as an added dimension of ACL research impact.

Methods

The Altmetric database (Altmetric.com), which tracks online attention generated by a research article and calculates a quantitative AAS, was queried on 17 June 2020, to identify articles pertaining to the ACL. The search was performed using the PubMed MeSH terms “ACL” or “anterior cruciate ligament” and yielded 9445 articles published between 2005 and 2020. These articles were stratified by highest to lowest AAS, and the 100 articles with the highest scores were included for analysis. All articles that focused on other orthopedic topics were sequentially excluded until 100 relevant articles were gathered.

Collected data included title, authors, year of publication, journal name, institutional affiliations, article type, article topic, and online mentions (e.g. the number of times the article was mentioned in news, blogs, Twitter, Facebook, and Wikipedia). Article type was identified from the article abstract and classified as original research (further subclassified as randomized controlled trial, prospective cohort, retrospective cohort, case–control, case series, case report, or laboratory study), descriptive epidemiology, systematic review/meta-analysis, review, editorial/expert opinion, clinical commentary, or other. Article topics were classified as anatomy, basic science, biomechanics, cost, diagnostics, treatment, neuromechanics, epidemiology/risk factors, injury prevention, rehabilitation/return to play, patient satisfaction/quality of life, or other. The geographic origin of the article was determined by the institutional affiliation of the first author, categorized as American (originating in the United States), European (originating in Europe), or other.

Statistical analysis

STATA 15.1 (STATACorp) was used for calculations and statistical analysis. Median and quartiles were calculated for AAS. Spearman correlation and logarithmic regression were used to determine the relationship between online mentions and AAS, and analysis of variance (ANOVA) was used to determine whether article type or topic was associated with AAS. All calculations were performed at a significance level of p < 0.05.

Results

The AAS of the top 100 ACL articles ranged from 109 to 2193 (median 172.0, interquartile range (IQR) 137.5–271.5) (Table 1). (In context, the highest AAS in medical and health sciences in 2019 belonged to an article published in Nature entitled “Scientists rise up against statistical significance,” yielding an AAS of 13,155.) The selected articles were published in 27 journals. Three journals accounted for 65 of the 100 articles: American Journal of Sports Medicine (AJSM) (34 articles), British Journal of Sports Medicine (BJSM) (21 articles), and Journal of Orthopaedic & Sports Physical Therapy (JOSPT) (10 articles). The Journal of Bone and Joint Surgery (JBJS) was represented by one article, and other established orthopedic journals also had lower representation on the list.

Table 1.

Top 100 most influential ACL articles by Altmetric Attention Score (AAS).

Rank	AAS	Authors	Article title	Year published	Journal
1	2193	Magnussen et al. 21	ACL graft metabolic activity assessed by 18 FDG PET–MRI	2017	Knee
2	1276	Grindem et al. 22	Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: The Delaware-Oslo ACL cohort study	2016	British Journal of Sports Medicine
3	832	Webster and Hewett 23	Meta-analysis of meta-analyses of anterior cruciate ligament injury reduction training programs	2018	Journal of Orthopaedic Research
4	730	van Melick et al. 24	Evidence-based clinical practice update: Practice guidelines for anterior cruciate ligament rehabilitation based on a systematic review and multidisciplinary consensus	2016	British Journal of Sports Medicine
5	579	Ardern et al. 25	2018 International Olympic Committee consensus statement on prevention, diagnosis, and management of pediatric anterior cruciate ligament (ACL) injuries	2018	British Journal of Sports Medicine
6	569	Owusu-Akyaw et al. 26	Determination of the position of the knee at the time of an anterior cruciate ligament rupture for male versus female patients by an analysis of bone bruises	2018	American Journal of Sports Medicine
7	478	Sugimoto et al. 27	Specific exercise effects of preventive neuromuscular training intervention on anterior cruciate ligament injury risk reduction in young females: Meta-analysis and subgroup analysis	2014	British Journal of Sports Medicine
8	461	Nagelli and Hewett 28	Should return to sport be delayed until 2 years after anterior cruciate ligament reconstruction? Biological and functional considerations	2016	Sports Medicine
9	439	Liederbach et al. 29	Incidence of anterior cruciate ligament injuries among elite ballet and modern dancers	2017	American Journal of Sports Medicine
10	427	Dingenen and Gokeler 30	Optimization of the return-to-sport paradigm after anterior cruciate ligament reconstruction: A critical step back to move forward	2017	Sports Medicine
11	403	Kyritsis et al. 31	Likelihood of ACL graft rupture: not meeting six clinical discharge criteria before return to sport is associated with a 4 times greater risk of rupture	2016	British Journal of Sports Medicine
12	399	Moatshe et al. 32	The influence of graft tensioning sequence on tibiofemoral orientation during bicruciate and posterolateral corner knee ligament reconstruction: A biomechanical study	2018	American Journal of Sports Medicine
13	391	Ohta et al. 33	Low-load resistance muscular training with moderate restriction of blood flow after anterior cruciate ligament reconstruction	2009	Acta Orthopaedica Scandinavica
14	386	Taylor et al. 34	Isolated tears of the anterior cruciate ligament	2017	American Journal of Sports Medicine
15	383	Walden et al. 35	Three distinct mechanisms predominate in noncontact anterior cruciate ligament injuries in male professional football players: A systematic video analysis of 39 cases	2015	British Journal of Sports Medicine
16	380	Petushek et al. 36	Evidence-based best-practice guidelines for preventing anterior cruciate ligament injuries in young female athletes: A systematic review and meta-analysis	2018	American Journal of Sports Medicine
17	373	Frobell et al. 37	Treatment for acute anterior cruciate ligament tear: Five-year outcome of randomized trial	2013	British Medical Journal
18	343	Salzler et al. 38	Management of anterior cruciate ligament injuries in adults aged > 40 years	2018	Journal of the American Academy of Orthopaedic Surgeons
19	336	Padua et al. 39	National athletic trainers’ association position statement: Prevention of anterior cruciate ligament injury	2018	Journal of Athletic Training
20	319	Arundale et al. 40	Exercise-based knee and anterior cruciate ligament injury prevention	2018	Journal of Orthopaedic & Sports Physical Therapy
21	310	Eitzen et al. 41	A progressive 5-week exercise therapy program leads to significant improvement in knee function early after anterior cruciate ligament injury	2010	Journal of Orthopaedic & Sports Physical Therapy
22	302	Beischer et al. 42	Young athletes who return to sport before 9 months after anterior cruciate ligament reconstruction have a rate of new injury 7 times that of those who delay return	2020	Journal of Orthopaedic & Sports Physical Therapy
23	295	Walden et al. 43	ACL injuries in men’s professional football: A 15-year prospective study on time trends and return-to-play rates reveals only 65% of players still play at the top level 3 years after ACL rupture	2016	British Journal of Sports Medicine
24	280	Grooms et al. 44	Neuroplasticity associated with anterior cruciate ligament reconstruction	2017	Journal of Orthopaedic & Sports Physical Therapy
25	272	Johnston et al. 45	Video analysis of anterior cruciate ligament tears in professional American football athletes	2018	American Journal of Sports Medicine
26	271	Weinhandl et al. 46	Reduced hamstring strength increases anterior cruciate ligament loading during anticipated sidestep cutting	2014	Clinical Biomechanics
27	271	DeFroda et al. 47	Oral contraceptives provide protection against anterior cruciate ligament tears: A national database study of 165,748 female patients	2019	Physician & Sports Medicine
28	257	Kotsifaki et al. 48	Measuring only hop distance during single-leg hop testing is insufficient to detect deficits in knee function after ACL reconstruction: A systematic review and meta-analysis	2019	British Journal of Sports Medicine
29	256	Escamilla et al. 49	Anterior cruciate ligament strain and tensile forces for weight-bearing and non-weight-bearing exercises: A guide to exercise selection	2012	Journal of Orthopaedic & Sports Physical Therapy
30	252	van Yperen et al. 50	Twenty-year follow-up study comparing operative versus non-operative treatment of anterior cruciate ligament ruptures in high-level athletes	2018	American Journal of Sports Medicine
31	239	Failla et al. 51	Does extended preoperative rehabilitation influence outcomes 2 years after ACL reconstruction?	2016	American Journal of Sports Medicine
32	223	Webster et al. 52	What is the evidence for and validity of return-to-sport testing after anterior cruciate ligament reconstruction surgery? A systematic review and meta-analysis	2019	Sports Medicine
33	220	Hewett et al. 53	Current concepts for injury prevention in athletes after anterior cruciate ligament reconstruction	2012	American Journal of Sports Medicine
34	219	Joseph et al. 54	A multisport epidemiologic comparison of anterior cruciate ligament injuries in high school athletics	2013	Journal of Athletic Training
35	215	LaBella et al. 55	Anterior cruciate ligament injuries: Diagnosis, treatment, and prevention	2014	Pediatrics
36	211	Hewett et al. 56	Mechanisms, prediction, and prevention of ACL injuries: Cut risk with three sharpened and validated tools	2016	Journal of Orthopaedic Research
37	210	Hewett et al. 57	Preventive biomechanics: A paradigm shift with a translational approach to injury prevention	2017	American Journal of Sports Medicine
38	208	Benjaminse et al. 58	Optimization of the anterior cruciate ligament injury prevention paradigm: Novel feedback techniques to enhance motor learning and reduce injury risk	2015	Journal of Orthopaedic & Sports Physical Therapy
39	204	Frobell et al. 59	A randomized trial of treatment for acute anterior cruciate ligament tears	2010	New England Journal of Medicine
40	201	Omi et al. 60	Effect of hip-focused injury prevention training for anterior cruciate ligament injury reduction in female basketball players: A 12-year prospective intervention study	2018	American Journal of Sports Medicine
41	195	Rambaud et al. 61	Criteria for return to running after anterior cruciate ligament reconstruction: a scoping review	2018	British Journal of Sports Medicine
42	193	Toole et al. 62	Young athletes after anterior cruciate ligament reconstruction cleared for sports participation: How many actually meet recommended return-to-sport criteria cutoffs?	2017	Journal of Orthopaedic & Sports Physical Therapy
43	192	Khayambashi et al. 63	Hip muscle strength predicts noncontact anterior cruciate ligament injury in male and female athletes	2015	American Journal of Sports Medicine
44	192	Gray et al. 64	Effects of oral contraceptive use on anterior cruciate ligament injury epidemiology	2016	Medicine and Science in Sports & Exercise
45	190	Grooms et al. 65	Neuroplasticity following anterior cruciate ligament injury: A framework for visual-motor training approaches in rehabilitation	2015	Journal of Orthopaedic & Sports Physical Therapy
46	184	Hewett et al. 66	Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: A prospective study	2005	American Journal of Sports Medicine
47	184	Paterno et al. 67	Incidence of second ACL Injuries 2 years after primary ACL reconstruction and return to sport	2014	American Journal of Sports Medicine
48	178	Wu et al. 68	Randomized control trial to evaluate the effects of acute testosterone administration in men on muscle mass, strength, and physical function following ACL reconstructive surgery: rationale, design, methods	2014	BMC Surgery
49	174	Allen et al. 69	Are female soccer players at an increased risk of second anterior cruciate ligament injury compared with their athletic peers?	2016	American Journal of Sports Medicine
50	172	Wiggins et al. 70	Risk of secondary injury in younger athletes after anterior cruciate ligament reconstruction	2016	American Journal of Sports Medicine
51	171	Mørtvedt et al. 71	I spy with my little eye . . . a knee about to go “pop”? Can coaches and sports medicine professionals predict who is at greater risk of ACL rupture?	2019	British Journal of Sports Medicine
52	170	Ardern et al. 72	Fifty-five percent return to competitive sport following anterior cruciate ligament reconstruction surgery: An updated systematic review and meta-analysis including aspects of physical functioning and contextual factors	2014	British Journal of Sports Medicine
53	169	Weiler et al. 73	Non-operative management of a complete anterior cruciate ligament injury in an English Premier League football player with return to play in less than 8 weeks: Applying common sense in the absence of evidence	2015	BMJ Case Reports
54	167	Hewett et al. 74	Utilization of ACL injury biomechanical and neuromuscular risk profile analysis to determine the effectiveness of neuromuscular training	2016	American Journal of Sports Medicine
55	167	Grindem et al. 75	Alarming underutilisation of rehabilitation in athletes with anterior cruciate ligament reconstruction: Four ways to change the game	2018	British Journal of Sports Medicine
56	165	Hewett et al. 76	Effectiveness of neuromuscular training based on the neuromuscular risk profile	2017	American Journal of Sports Medicine
57	165	Lai et al. 77	Eighty-three percent of elite athletes return to preinjury sport after anterior cruciate ligament reconstruction: A systematic review with meta-analysis of return to sport rates, graft rupture rates, and performance outcomes	2017	British Journal of Sports Medicine
58	165	Sugimoto et al. 78	Dosage effects of neuromuscular training intervention to reduce anterior cruciate ligament injuries in female athletes: Meta- and subgroup analyses	2013	Sports Medicine
59	163	Filbay et al. 79	Delaying ACL reconstruction and treating with exercise therapy alone may alter prognostic factors for 5-year outcome: An exploratory analysis of the KANON trial	2017	British Journal of Sports Medicine
60	161	Mendias et al. 80	The use of recombinant human growth hormone to protect against muscle weakness in patients undergoing anterior cruciate ligament reconstruction: A pilot, randomized placebo-controlled trial	2020	American Journal of Sports Medicine
61	159	Fukuda et al. 81	Open kinetic chain exercises in a restricted range of motion after anterior cruciate ligament reconstruction	2013	American Journal of Sports Medicine
62	158	Cinque et al. 82	High rates of osteoarthritis develop after anterior cruciate ligament surgery: An analysis of 4108 patients	2017	American Journal of Sports Medicine
63	158	Baar et al. 83	Minimizing injury and maximizing return to play: Lessons from engineered ligaments	2017	Sports Medicine
64	156	Shelbourne et al. 84	Results of anterior cruciate ligament reconstruction with patellar tendon autografts: Objective factors associated with the development of osteoarthritis at 20 to 33 years after surgery	2017	American Journal of Sports Medicine
65	154	Samuelsen et al. 85	Hamstring autograft versus patellar tendon autograft for ACL reconstruction: Is there a difference in graft failure rate? A meta-analysis of 47,613 patients	2017	Clinical Orthopaedics & Related Research
66	151	Kia et al. 86	Size of initial bone bruise predicts future lateral chondral degeneration in ACL injuries: A radiographic analysis	2020	Orthopaedic Journal of Sports Medicine
67	149	Thompson et al. 87	Biomechanical effects of an injury prevention program in preadolescent female soccer athletes	2016	American Journal of Sports Medicine
68	148	Sugimoto et al. 88	Critical components of neuromuscular training to reduce ACL injury risk in female athletes: meta-regression analysis	2016	British Journal of Sports Medicine
69	148	Lien-Iversen et al. 89	Does surgery reduce knee osteoarthritis, meniscal injury, and subsequent complications compared with non-surgery after ACL rupture with at least 10 years of follow-up? A systematic review and meta-analysis	2020	British Journal of Sports Medicine
70	147	Hewett et al. 90	Anterior cruciate ligament injuries in female athletes	2006	American Journal of Sports Medicine
71	144	Huang et al. 91	A majority of anterior cruciate ligament injuries can be prevented by injury prevention programs: A systematic review of randomized controlled trials and cluster–randomized controlled trials with meta-analysis	2020	American Journal of Sports Medicine
72	144	Krosshaug et al. 92	The vertical drop jump is a poor screening test for ACL injuries in female elite soccer and handball players	2016	American Journal of Sports Medicine
73	144	Perriman et al. 93	The effect of open- versus closed-kinetic-chain exercises on anterior tibial laxity, strength, and function following anterior cruciate ligament reconstruction: A systematic review and meta-analysis	2018	Journal of Orthopaedic & Sports Physical Therapy
74	142	Buckthorpe 94	Optimizing the late-stage rehabilitation and return-to-sport training and testing process after ACL reconstruction	2019	Sports Medicine
75	138	Yosmaoglu et al. 95	Tracking ability, motor coordination, and functional determinants after anterior cruciate ligament reconstruction.	2011	Journal of Sport Rehabilitation
76	137	Silvers-Granelli et al. 96	Does the FIFA 11 + injury prevention program reduce the incidence of ACL injury in male soccer players?	2017	Clinical Orthopaedics& Related Research
77	136	Konrath et al. 97	Morphologic characteristics and strength of the hamstring muscles remain altered at 2 years after use of a hamstring tendon graft in anterior cruciate ligament reconstruction	2016	American Journal of Sports Medicine
78	136	Khan et al. 98	ACL and meniscal injuries increase the risk of primary total knee replacement for osteoarthritis: A matched case–control study using the Clinical Practice Research Datalink (CPRD)	2019	British Journal of Sports Medicine
79	135	Beck et al. 99	ACL tears in school-aged children and adolescents over 20 years	2017	Pediatrics
80	134	Chung et al. 100	A biodegradable tri-component graft for anterior cruciate ligament reconstruction	2014	Journal of Tissue Engineering and Regenerative Medicine
81	131	Cordasco et al. 101	Return to sport and reoperation rates in patients under the age of 20 after primary anterior cruciate ligament reconstruction: Risk profile comparing three patient groups predicated upon skeletal age	2019	American Journal of Sports Medicine
82	129	Webster et al. 102	Exploring the high reinjury rate in younger patients undergoing anterior cruciate ligament reconstruction	2016	American Journal of Sports Medicine
83	129	Lepley et al. 103	Corticospinal tract structure and excitability in patients with anterior cruciate ligament reconstruction: A DTI and TMS study	2020	NeuroImage: Clinical
84	127	Lee et al. 104	Estrogen inhibits lysyl oxidase and decreases mechanical function in engineered ligaments	2015	Journal of Applied Physiology
85	125	Kapreli et al. 105	Anterior cruciate ligament deficiency causes brain plasticity	2009	American Journal of Sports Medicine
86	123	Brophy et al. 106	Changes in transcriptome-wide gene expression of anterior cruciate ligament tears based on time from injury	2016	American Journal of Sports Medicine
87	123	Culvenor et al. 107	Accelerated return to sport after anterior cruciate ligament injury: A risk factor for early knee osteoarthritis?	2016	British Journal of Sports Medicine
88	121	Lopes et al. 108	The effects of injury prevention programs on the biomechanics of landing tasks: A systematic review with meta-analysis	2017	American Journal of Sports Medicine
89	119	Culvenor et al. 109	Loss of patellofemoral cartilage thickness over 5 years following ACL injury depends on the initial treatment strategy: results from the KANON trial	2019	British Journal of Sports Medicine
90	118	Thoma et al. 110	Coper classification early after anterior cruciate ligament rupture changes with progressive neuromuscular and strength training and is associated with 2-year success: The Delaware-Oslo ACL Cohort Study	2019	American Journal of Sports Medicine
91	114	Gokeler et al. 111	Principles of motor learning to support neuroplasticity after ACL injury: implications for optimizing performance and reducing risk of second ACL injury	2019	Sports Medicine
92	113	Trigsted et al. 112	Greater fear of reinjury is related to stiffened jump-landing biomechanics and muscle activation in women after ACL reconstruction	2018	Knee Surgery, Sports Traumatology, Arthroscopy
93	112	Wellsandt et al. 113	Does anterior cruciate ligament reconstruction improve functional and radiographic outcomes over non-operative management 5 years after injury?	2018	American Journal of Sports Medicine
94	112	Grindem et al. 114	How does a combined preoperative and postoperative rehabilitation program influence the outcome of ACL reconstruction 2 years after surgery? A comparison between patients in the Delaware-Oslo ACL Cohort and the Norwegian National Knee Ligament Registry	2014	British Journal of Sports Medicine
95	112	Wellsandt et al. 115	Limb symmetry indexes can overestimate knee function after anterior cruciate ligament injury	2017	Journal of Orthopaedic & Sports Physical Therapy
96	111	Janssen et al. 116	ACL reconstruction with hamstring tendon autograft and accelerated brace-free rehabilitation: A systematic review of clinical outcomes	2018	BMJ Open Sport & Exercise Medicine
97	111	Maniar et al. 117	Non-knee-spanning muscles contribute to tibiofemoral shear as well as valgus and rotational joint reaction moments during unanticipated sidestep cutting	2018	Scientific Reports
98	110	Mather et al. 118	Societal and economic impact of anterior cruciate ligament tears	2013	Journal of Bone & Joint Surgery, American Volume
99	110	Dingenen et al. 119	Test–retest reliability and discriminative ability of forward, medial and rotational single-leg hop tests	2019	Knee
100	109	Myklebust et al. 120	Return to play guidelines after anterior cruciate ligament surgery	2005	British Journal of Sports Medicine

AAS: Altmetric Attention Score; ACL: anterior cruciate ligament.

Among the 100 selected articles, the most prevalent article type was original research (60%), of which prospective cohort study was the most common subgroup (40%; 24/60) (Figure 1(a), (b)). Systematic review/meta-analysis was the next most common article type (18%; 18/100). Three review articles discussed more than one topic, which resulted in a total of 105 article topics for the 100 included articles. The most prevalent article topic was rehabilitation and return to play after ACL reconstruction (22%; 23/105), followed by epidemiology/risk factors (16%; 17/105), injury prevention (14%; 15/105), and biomechanics of ACL injuries (14%; 15/105) (Figure 2). Fifty-four percent of the included articles were American, 31% were European, and 15% were published in other countries outside of the United States and Europe. Article type, topic, and geographic origin were not significantly associated with AAS (all p > 0.05).

Figure 1.

(a) A representation of the types of articles comprising the top 100 articles related to the ACL by Altmetric Attention Score (AAS); (b) Representation of article subtypes of the Original Research article type.

Figure 2.

Characteristics of the article topics within the top 100 articles pertaining to the ACL according to Altmetric Attention Score (AAS).

Among the 100 most engaged articles, there were 37,801 Twitter mentions (median 259.5, IQR 183.0–421.5), 1765 Facebook mentions (median 8.0; IQR 4.0–17.5), and 735 mentions in online news outlets (median 1.0; IQR 0–3.0). Among online media sources, YouTube video description mentions (r = 0.78, R  = 0.60) correlated most strongly with AAS, followed by Twitter mentions (r = 0.75, R  = 0.56) and blog mentions (r = 0.75, R  = 0.56).

Discussion

Although some of the online discussion surrounding ACL research occurs among members of the general public who follow or report on sports, social media is also being used increasingly by orthopedic surgeons for general discussion and educational purposes. The results of this study suggest that the online dissemination of ACL research adds an important dimension to the online engagement of published articles pertaining to the ACL. Our findings support the use of alternative metrics as a supplement to conventional bibliometrics in order to achieve a more complete assessment of the overall impact of ACL research within the academic community.

Among the 100 most mentioned ACL articles identified in this study, original research was the most prevalent article type and the most common topics were rehabilitation/return to play, epidemiology/risk factors, and injury prevention. Online interest in ACL research was broad, with no association observed between article type, topic, or geographic origin and AAS. Three specialty-specific sports medicine journals (AJSM, BJSM, and JOSPT) accounted for 65% of the 100 articles. Our data suggest that the topics most talked about online tend to be American studies published in sports medicine journals that focus on practical concerns related to the effect of ACL injury on athletic participation.

Our findings pertaining to article topic contrast with a previous report of the 50 most-cited ACL articles, in which the most common topics were anatomy/biomechanics (38%) and surgical technique (26%). The readership of sports medicine journals, comprised predominantly of orthopedic surgeons and other musculoskeletal healthcare providers, may be likely to view the aspects of ACL injury that fall within their domain as the most important: understanding the anatomical and biomechanical factors underlying the injury and providing the optimal surgical treatment. In online media, however, attention appears to be focused on the aspects of ACL rupture that directly impact an athlete’s ability to perform.

Citation rate has been shown to have no correlation to AAS, supported in our study by the incongruence in the article topics and types that constitute to the most impactful articles as determined by AAS or citation rate. Compared with previous studies that examined the most impactful ACL articles by citation density,[18,124] the results of the present study demonstrate a predominance of clinically focused studies and a relatively lower degree of interest in laboratory studies. This finding is congruent with the historical trend of ACL research toward higher levels of evidence. Among the 100 ACL articles with the highest AAS, the most common article type was original research (Figure 1(a)), and basic science studies accounted for just 10% of these articles (Figure 1(b)). By comparison, basic science accounted for a higher proportion of studies (42% and 36%, respectively) in previous reports on the 50 most-cited ACL articles.[18,124] One possible explanation for this finding is that laboratory findings, which are farther removed from the clinical setting, may hold less interest to an online audience that is more focused on ACL research with immediate clinical relevance.

The current findings also suggest that the online distribution of ACL research may facilitate broader access to readership compared with traditional citation-based methods. In their previous studies of the most-cited ACL articles, Vielgut et al. and Voleti et al. reported a strong predominance of American publications (80% and 68%, respectively), followed distantly by studies originating in Europe (16% and 18%, respectively).[18,124] A predominance of highly cited articles originating in the United States is not unique to the ACL literature and has been demonstrated in other topics related to orthopedic, general, and plastic surgery.[126 –128] By comparison, a greater proportion of articles in the present study (46%) originated outside the United States, with nearly one-third of all articles being European in origin and 15% originating from other countries outside the United States and Europe. BJSM articles accounted for 21% of the top 100 ACL articles in this study, and four of the top five ACL articles with highest AAS originated in Europe.

There are many considerations to address before using Altmetric as a standalone metric of article impact. Although social media attention provides a benchmark of article attention, the AAS could be used deliberately to promote some publications over others. Moreover, the AAS for individual articles could be manipulated by utilizing Twitter bots or through self-promoting online journal clubs. There are other internal factors of Altmetric to consider, including its dynamic nature which has the potential to produce a different list of top 100 articles depending on which date the search is performed. In addition, articles published in the years preceding Altmetrics release in 2012 are likely to have lower AAS. The Altmetric algorithm itself is not publicly available, giving question to internal bias or shortcomings to adequately capture every online mention which constitutes to an article’s AAS. Finally, Altmetric does not account for the content of the online conversation or the positive or negative nature of the conversation.[132 –135] Thus, the articles with highest AAS scores may not indicate high study quality or scientific importance.

Conclusion

The 100 most impactful online ACL articles, as measured by AAS, differed substantially from the most-cited ACL articles in the literature with regard to article type, article topic, geographic origin, and publication journal. These findings suggest that alternative metrics measure distinct components of ACL article engagement and add an important dimension to understanding the overall impact of published research on the ACL.