Subsequent musculoskeletal injury after concussion in National Football League players.

OBJECTIVE: To assess whether National Football League (NFL) players diagnosed with a concussion have an increased risk of injury after return to football. METHODS: A retrospective cohort study analysed the hazard of subsequent time-loss lower extremity (LEX) or any musculoskeletal injury among NFL players diagnosed with a concussion in 2015-2021 preseason or regular season games compared with: (1) all non-concussed players participating in the same game and (2) players with time-loss upper extremity injury. Cox proportional hazards models were adjusted for number of injuries and concussions in the prior year, player tenure and roster position. Additional models accounted for time lost from participation after concussion. RESULTS: There was no statistical difference in the hazards of LEX injury or any musculoskeletal injury among concussed players compared with non-concussed players, though concussed players had a slightly elevated hazard of injury (LEX injury: HR=1.12, 95% CI 0.90 to 1.41; any musculoskeletal injury: HR=1.08, 95% CI: 0.89 to 1.31). When comparing to players with upper extremity injuries, the hazard of injury for concussed players was not statistically different, though HRs suggested a lower injury risk among concussed players (LEX injury: HR=0.78, 95% CI: 0.60 to 1.02; any musculoskeletal injury: HR=0.82, 95% CI: 0.65 to 1.04). CONCLUSION: We found no statistical difference in the risk of subsequent injury among NFL players returning from concussion compared with non-concussed players in the same game or players returning from upper extremity injury. These results suggest deconditioning or other factors associated with lost participation time may explain subsequent injury risk in concussed players observed in some settings after return to play.

Epidemiology of Stingers in the National Football League, 2015-2019.

BACKGROUND: Transient traumatic neuropraxia of either the brachial plexus or cervical nerve root(s) is commonly described as a "stinger" or "burner" by the athlete. Stingers in American Football commonly occur acutely as isolated injuries; however, concomitant injuries, including cervical spine pathologies, have also been reported. HYPOTHESIS: Among National Football League (NFL) athletes, the incidence rate of stingers is higher during the regular season than during the preseason and among positions with high velocity impacts such as running backs, linebackers, defensive backs, and receivers. STUDY DESIGN: Retrospective epidemiology study. LEVEL OF EVIDENCE: Level 4. METHODS: Aggregation of all in-game injuries with a clinical impression of "neck brachial plexus stretch" or "neck brachial plexus compression" entered into the NFL injury surveillance database through the centralized league-wide electronic medical record system over 5 years (2015-2019 seasons). Incidence rates per player-play were calculated and reported. RESULTS: A total of 691 in-game stingers occurred during the study period, with a mean of 138.2 per year. Average single-season injury risk for incident stinger was 3.74% (95% CI, 3.46%-4.05%). The incidence rate was higher during regular season games than during preseason games (12.26 per 100,000 player-plays [11.30-13.31] vs 8.87 [7.31-10.76], P < 0.01, respectively). The highest reported stinger incidence rates were among running backs and linebackers (both >15 per 100,000 player-plays). Among stingers, 76.41% did not miss time. Of those that resulted in time lost from football activities, mean time missed due to injury was 4.79 days (range, 3.17-6.41 days). Concomitant injuries were relatively low (7.09%). CONCLUSION: In-game stinger incidence was stable across the study period and occurred most frequently in running backs and linebackers. Stingers were more common during the regular season, and most players did not miss time. Concomitant injuries were relatively rare. CLINICAL RELEVANCE: An improved understanding of the expected time loss due to stinger and concomitant injuries may provide insight for medical personnel in managing these injuries.

Use of Publicly Obtained Data in Sports Medicine Research: A Systematic Review and Bibliometric Analysis.

BACKGROUND: Publicly obtained data (POD) have recently been utilized frequently by sports medicine researchers to describe injury patterns, risk factors, and outcomes in elite athletes. The relative ease of this type of research that is based solely on internet and media sources has resulted in a near exponential increase in the number of these POD studies. PURPOSE: To systematically review the sports medicine literature for studies based solely on POD. STUDY DESIGN: Systematic review and bibliometric analysis; Level of evidence, 4. METHODS: A systematic review of POD studies published since 2000 was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Studies of interest were those relying on publicly available injury reports or online media for data acquisition in collegiate, semiprofessional, and professional athletes. RESULTS: There were 209 POD studies published between 2000 and 2022, with 173 (82.8%) of these studies published after 2016. Studies were published most frequently on athletes participating in North American professional leagues: National Football League (n = 69 [28.4%]), Major League Baseball (n = 56 [23.0%]), National Basketball Association (n = 37 [15.2%]), and National Hockey League (n = 33 [13.6%]). The most common injuries assessed were head injuries/concussions (n = 43 [21.1%]), anterior cruciate ligament injuries (n = 33 [16.2%]), and ulnar collateral ligament injuries (n = 23 [11.3%]). One-quarter of the studies (n = 53 [25.4%]) reported only 1 POD source, and 1 study (0.5%) reported no source. Additionally, 65 studies (31.1%) listed nonspecific POD resources or solely cited previous literature to describe the POD search methodology and data acquisition. CONCLUSION: POD studies are exponentially increasing in number, particularly across major North American professional sports leagues, with significant variability in the injury of interest, search methodology, and number of data sources. The accuracy of the conclusions reached based on the POD methodology appears highly variable. Given the potential impact of these publications as both contributors to current knowledge and drivers of future research, the sports medicine community should be aware of the inherent biases and limitations of POD injury studies.

The National Football League Concussion Protocol: A Review.

Sport-related concussion remains an area of high concern for contact sport athletes and their families, as well as for the medical and scientific communities. The National Football League (NFL), along with the NFL Players Association and experts in the field, has developed protocols for the detection and management of sport-related concussions. This article reviews the NFL's most recent concussion protocol including preseason education and baseline testing for players, concussion surveillance by gameday medical teams and neurotrauma consultants and athletic trainers, gameday concussion protocol and procedures, and return to participation guidelines.

Validity of Research Based on Publicly Obtained Data in Sports Medicine: A Quantitative Assessment of Concussions in the National Football League.

CONTEXT: Numerous researchers have leveraged publicly available internet sources to publish clinical research concerning incidence and recovery from injuries in National Football League (NFL) players. OBJECTIVE: This study aims to (1) provide a comprehensive systematic review of all publicly obtained data studies (PODS) regarding concussions in NFL athletes and (2) quantify the percentage of injuries identified by these studies in comparison with published concussion data from the NFL injury database. STUDY SELECTION: A systematic review was conducted in accordance with PRISMA guidelines to identify all published studies utilizing publicly obtained data regarding concussions in NFL athletes. STUDY DESIGN: Systematic review. LEVEL OF EVIDENCE: Level 4. DATA EXTRACTION: Manuscript details, factors related to the athletes of interest (eg, study period, positions included), and results (eg, concussion rate, number of total concussions, return-to-play data) were extracted independently by 2 authors. Results were compared with incident concussions reported from 2015 to 2019 by each medical staff member to the NFL database linked to the League's electronic health record (EHR). RESULTS: A total of 20 concussion-focused manuscripts based on PODS were identified from 2014 to 2020. PODS captured between 20% and 90% of concussions (mean, 70%) reported by medical staff to the injury database. PODS reported that 55% of concussions occurred on offensive plays, 45% on defensive plays and <1% occurred during special teams plays, compared with 44%, 37%, and 18%, respectively, as indicated by published data from the NFL injury database. When analyzed by position groups, running backs and quarterbacks comprised the most over-represented positions concussed in PODS, while offensive linemen, defensive backs, and linebackers comprised the most under-represented positions. CONCLUSION: PODS captured approximately 70% of concussions reported by NFL medical staff to the NFL injury database. There is heterogeneity in the degree to which PODS were able to identify concussions, with a bias toward concussions among players at higher profile positions.

Anatomy of an American football game: Player-to-player contact before, during and after an NFL game in context of the 2020 COVID-19 pandemic.

OBJECTIVES: To quantify levels of potential exposure to SARS-CoV-2 surrounding a typical professional American football game, with a focus on interactions on-field between teammates and opposing players before, during, and immediately after competition. METHODS: We examined across-Club consecutive interactions ≥2 minutes within 6 feet [1.8 meters] between athletes on opposing Clubs for all 2020 NFL regular season games (n = 256). Cumulative interaction was measured for a representative subset (n = 119; 46%) of games. Wearable proximity tracking devices (Kinexon) were used to measure distance and duration of interactions; these data were combined with game schedule and Club rosters for analyses. Frequency and per-game mean, median, interquartile range for consecutive interactions ≥2/≥5 minutes and cumulative interactions ≥5/≥15 were described overall and stratified by pre-game, in-game, and post-game. RESULTS: Of the 1964 distinct player-to-opponent contacts ≥2 minutes in NFL regular season games, the majority (n = 1,699; 87%) were fewer than 5 minutes in consecutive length. Among the mean 7.7 distinct contacts ≥2 minutes with opponents each game (median = 4; IQR = 2, 8), very few were ≥5 consecutive minutes at any point (mean = 1.0; median = 0; IQR = 0, 0). Most (n = 849; 43.2%) distinct contacts were pre-game, 546 (27.8%) were during competition, and 569 (29%) were post-game. In games where cumulative interactions were analyzed, there was an average of 17.1 player/opponent interactions with cumulative exposure ≥5 minutes (median = 12; IQR = 4, 30), almost all of which occurred during competition. CONCLUSION: There is limited and short contact between and among competing players in professional American football. In the setting of infectious disease such as the COVID-19 pandemic, a robust prevention program integrating masking, distancing, hygiene, and ventilation when off-field can be created to minimize on- and off-field exposures, which effectively reduces transmission risk in outdoors and/or well-ventilated stadium settings.

Return to Full Participation Following Concussion in the National Football League, 2015 Through 2020.

OBJECTIVE: Quantify days missed, games missed, injury burden, and time to return to full participation (RTFP) among National Football League (NFL) players who sustained a concussion. DESIGN: Retrospective cohort study. SETTING: 2015 through 2020 NFL seasons. PARTICIPANTS: National Football League players diagnosed with a concussion from 2015 to 2020. INTERVENTIONS: National Football League-mandated graduated RTFP protocol. MAIN OUTCOME MEASURES: Days missed, games missed, burden, and time to RTFP, overall and by position. RESULTS: An annual average of 3639 player-days of participation and 255 games were missed across NFL because of concussion. Concussed players missed a median of 9 days (mean = 15.0), a relatively stable metric over 6 years, with slight variation by position. Offensive linemen, tight ends, running backs, and linebackers missed the most days per concussion; defensive secondary, offensive linemen, and wide receivers sustained the highest injury burden. Postconcussion, 59% of players missed one or more scheduled games. Among players concussed in a Sunday game, 38% played in a Sunday game one week later. CONCLUSIONS: The 9-day median time missed post-concussion may be related to emphasis on graduated phase-based concussion management. No concussed player returned to competition on the day of injury, and less than 40% participated in games the following week. Further work is needed to better understand characteristics of concussions that take longer to return and movement through stages of return.

Psychometric Properties of Computerized Cognitive Tools and Standard Neuropsychological Tests Used to Assess Sport Concussion: A Systematic Review.

Athletic programs are more frequently turning to computerized cognitive tools in order to increase efficiencies in concussion assessment. However, assessment using a traditional neuropsychological test battery may provide a more comprehensive and individualized evaluation. Our goal was to inform sport clinicians of the best practices for concussion assessment through a systematic literature review describing the psychometric properties of standard neuropsychological tests and computerized tools. We conducted our search in relevant databases including Ovid Medline, Web of Science, PsycINFO, and Scopus. Journal articles were included if they evaluated psychometric properties (e.g., reliability, sensitivity) of a cognitive assessment within pure athlete samples (up to 30 days post-injury). Searches yielded 4,758 unique results. Ultimately, 103 articles met inclusion criteria, all of which focused on adolescent or young adult participants. Test-retest reliability estimates ranged from .14 to .93 for computerized tools and .02 to .95 for standard neuropsychological tests, with strongest correlations on processing speed tasks for both modalities, although processing speed tasks were most susceptible to practice effects. Reliability was improved with a 2-factor model (processing speed and memory) and by aggregating multiple baseline exams, yet remained below acceptable limits for some studies. Sensitivity to decreased cognitive performance within 72 h of injury ranged from 45%-93% for computerized tools and 18%-80% for standard neuropsychological test batteries. The method for classifying cognitive decline (normative comparison, reliable change indices, regression-based methods) affected sensitivity estimates. Combining computerized tools and standard neuropsychological tests with the strongest psychometric performance provides the greatest value in clinical assessment. To this end, future studies should evaluate the efficacy of hybrid test batteries comprised of top-performing measures from both modalities.

Consensus Head Acceleration Measurement Practices (CHAMP): Origins, Methods, Transparency and Disclosure.

The use of head kinematic measurement devices has recently proliferated owing to technology advances that make such measurement more feasible. In parallel, demand to understand the biomechanics of head impacts and injury in sports and the military has increased as the burden of such loading on the brain has received focused attention. As a result, the field has matured to the point of needing methodological guidelines to improve the rigor and consistency of research and reduce the risk of scientific bias. To this end, a diverse group of scientists undertook a comprehensive effort to define current best practices in head kinematic measurement, culminating in a series of manuscripts outlining consensus methodologies and companion summary statements. Summary statements were discussed, revised, and voted upon at the Consensus Head Acceleration Measurement Practices (CHAMP) Conference in March 2022. This manuscript summarizes the motivation and methods of the consensus process and introduces recommended reporting checklists to be used to increase transparency and rigor of future experimental design and publication of work in this field. The checklists provide an accessible means for researchers to apply the best practices summarized in the companion manuscripts when reporting studies utilizing head kinematic measurement in sport and military settings.

Low incidence and transient elevation of autoantibodies post mRNA COVID-19 vaccination in inflammatory arthritis.

OBJECTIVES: Autoantibody seroconversion has been extensively studied in the context of COVID-19 infection but data regarding post-vaccination autoantibody production is lacking. Here we aimed to determine the incidence of common autoantibody formation following mRNA COVID-19 vaccines in patients with inflammatory arthritis (IA) and in healthy controls. METHODS: Autoantibody seroconversion was measured by serum ELISA in a longitudinal cohort of IA participants and healthy controls before and after COVID-19 mRNA-based immunization. RESULTS: Overall, there was a significantly lower incidence of ANA seroconversion in participants who did not contract COVID-19 prior to vaccination compared with those who been previously infected (7.4% vs 24.1%, P = 0.014). Incidence of de novo anti-CCP seroconversion in all participants was low at 4.9%. Autoantibody levels were typically of low titre, transient, and not associated with increase in IA flares. CONCLUSIONS: In both health and inflammatory arthritis, the risk of autoantibody seroconversion is lower following mRNA-based immunization than following natural SARS-CoV-2 infection. Importantly, seroconversion does not correlate with self-reported IA disease flare risk, further supporting the encouragement of mRNA-based COVID-19 immunization in the IA population.

Same-Year Repeat Concussions in the National Football League: Trends from 2015 Through 2019.

BACKGROUND: Sport-related concussion (SRC) prevention and management is a focus of the National Football League (NFL). While most prior reports evaluated sport-related concussion incidence, few have studied same-year repeat concussions. This study aimed to evaluate the frequency of same-year repeat concussions in the NFL. METHODS: A retrospective, observational cohort study of same-year repeat concussions in the NFL from 2015 to 2019 was performed. The NFL's electronic health record was reviewed for players sustaining concussions and same-year repeat concussions. Wilcoxon rank sum tests were used to calculate same-year repeat concussion rates, and risk ratios and 95% confidence intervals were estimated using log-binomial regression. RESULTS: From 2015 to 2019, the risk of sustaining a same-year repeat concussion in the NFL was 0.38%-0.69% per season. Among players who sustained a concussion, the risk of a same-year repeat concussion was 5.3%-8.3%, which did not differ significantly from the risk of sustaining a single concussion (6.2%-8.3%). There was a median of 38 participation days between initial and same-year repeat concussion. Players missed more time from same-year repeat concussions (median 12 days) compared with both single (median 9 days; P < 0.0001) and initial (median 9.5 days; P = 0.002) concussions. CONCLUSIONS: The risk of a repeat concussion was similar to the risk of sustaining a single concussion among NFL players. More time was missed following a same-year repeat concussion compared with single or initial concussions. Further research is needed to maximize player safety and minimize same-year repeat concussions.

Effectiveness and use of reverse transcriptase polymerase chain reaction point of care testing in a large-scale COVID-19 surveillance system.

BACKGROUND: Rapid COVID-19 testing platforms can identify infected individuals at the point of care (POC), allowing immediate isolation of infected individuals and reducing the risk of transmission. While lab-based nucleic acid amplification testing (NAAT) is often considered the gold standard to detect SARS-CoV-2 in the community, results typically take 2-7 days to return, rendering POC testing a critical diagnostic tool for infection control. The National Football League (NFL) and NFL Players Association deployed a new POC testing strategy using a newly available reverse transcriptase polymerase chain reaction (RT-PCR) rapid test during the 2020 season, and evaluated diagnostic effectiveness compared to other available devices using real-world population surveillance data. METHODS: RT-PCR POC test results were compared to NAAT results from same-day samples by calculation of positive and negative concordance. Sensitivity analyses were performed for three subgroups: (1) individuals symptomatic at time of positive test; (2) individuals tested during the pilot phase of rollout; and (3) individuals tested daily. RESULTS: Among 4989 same-day POC/NAAT pairs, 4957 (99.4%) were concordant, with 93.1% positive concordance and 99.6% negative concordance. Based on adjudicated case status, the false negative rate was 0.2% and false positive rate was 2.9%. In 43 instances, the immediate turnaround of results by POC allowed isolation of infected individuals 1 day sooner than lab-based testing. Positive/negative concordance in sensitivity analyses were relatively stable. CONCLUSION: RT-PCR POC testing provided timely results that were highly concordant with lab-based NAAT in population surveillance. Expanded use of effective RT-PCR POC can enable rapid isolation of infected individuals and reduce COVID-19 infection in the community.

Validity of Research Based on Public Data in Sports Medicine: A Quantitative Assessment of Anterior Cruciate Ligament Injuries in the National Football League.

BACKGROUND: Numerous researchers have leveraged publicly available Internet sources to publish publicly obtained data (POD) studies concerning various orthopaedic injuries in National Football League (NFL) players. PURPOSE: To provide a comprehensive systematic review of all POD studies regarding musculoskeletal injuries in NFL athletes and to use anterior cruciate ligament (ACL) injuries in NFL players to quantify the percentage of injuries identified by these studies. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: A systematic review was conducted to identify all published studies utilizing POD regarding ACL injury in NFL athletes from 2000 to 2019. Data regarding player demographics were extracted from each publication. These results were compared with prospectively collected data reported by the teams' medical staff to the NFL Injury Surveillance System database linked to the League's electronic health record. An ACL "capture rate" for each article was calculated by dividing the number of ACL injuries in the POD study by the total number of ACL injuries in the NFL injury database occurring in the study period of interest. RESULTS: A total of 42 studies were extracted that met the definition of a POD study: 28 evaluated a variety of injuries and 14 dealt specifically with ACL injuries, with 35 (83%) of the 42 studies published during or since 2015. POD studies captured a mean of 66% (range, 31%-90%) of ACL injuries reported by the teams' medical staff. This inability to capture all injury rates varied by position, with 86% capture of ACL injuries in skill athletes, 72% in midskill athletes, and 61% in linemen. POD studies captured 35% of injuries occurring during special teams play. CONCLUSION: The frequency of studies leveraging publicly obtained injury data in NFL players has rapidly increased since 2000. There is significant heterogeneity in the degree to which POD studies correctly identify ACL injuries from public reports. Sports medicine research relying solely on publicly obtained sources should be interpreted with an understanding of their inherent limitations and biases. These studies underreport the true incidence of injuries, with a bias toward capturing injuries in more popular players.

Observed Versus Expected COVID-19 Infections Among National Football League Players During the 2020 Season.

BACKGROUND: The National Football League (NFL) and National Football League Players Association implemented a set of strict protocols for the 2020 season with the intent to mitigate COVID-19 risk among players and staff. In that timeframe, the league's 32 teams completed 256 regular season games and several thousand meetings and practices. In parallel, community cases of COVID-19 were highly prevalent. We assess the risk of holding a 2020 NFL season by comparing community and player COVID-19 infections. METHODS: We used county-level COVID-19 test data from each team to establish baseline distributions of infection rates expected to occur in a population similar in age and sex to NFL players. We used a binomial distribution to simulate expected infections in each community cohort and compared these findings with observed COVID-19 infections in players. RESULTS: Over a 5-month period (1 August 2020 to 2 January 2021), positive NFL player infections (n = 256) were 55.7% lower than expected when compared with simulations from NFL community cohorts. For 30 of 32 teams (94%), observed counts fell at or below expectation, including 28 teams (88%) for which rates were lower. Two teams fell above baseline expectation. CONCLUSIONS: The NFL/NFLPA protocols that governed team facilities, travel, gameday, and activities outside of the workplace were associated with lower infection rates among NFL players compared with the surrounding community. The NFL's 2020-2021 season are consistent with the hypothesis that robust testing and behavioral protocols support a safe return to sport and work.

Selected Issues in Sport-Related Concussion (SRC | Mild Traumatic Brain Injury) for the Team Physician: A Consensus Statement.

ABSTRACT: Selected Issues in Sport-Related Concussion (SRC | Mild Traumatic Brain Injury) for the Team Physician: A Consensus Statement is title 22 in a series of annual consensus articles written for the practicing team physician. This document provides an overview of select medical issues important to team physicians who are responsible for athletes with sports-related concussion (SRC). This statement was developed by the Team Physician Consensus Conference (TPCC), an annual project-based alliance of six major professional associations. The goal of this TPCC statement is to assist the team physician in providing optimal medical care for the athlete with SRC.

Selected issues in sport-related concussion (SRC|mild traumatic brain injury) for the team physician: a consensus statement.

Selected Issues in Sport-Related Concussion (SRC|Mild Traumatic Brain Injury) for the Team Physician: A Consensus Statement is title 22 in a series of annual consensus documents written for the practicing team physician. This document provides an overview of selected medical issues important to team physicians who are responsible for athletes with sports-related concussion (SRC). This statement was developed by the Team Physician Consensus Conference (TPCC), an annual project-based alliance of six major professional associations. The goal of this TPCC statement is to assist the team physician in providing optimal medical care for the athlete with SRC.