Association of artificial turf and concussion in competitive contact sports: a systematic review and meta-analysis

Impact of Playing Surface on Concussion Symptoms in Young American Football Players

OBJECTIVE

It has been suggested that sport-related concussion (SRC) occurs more commonly on natural grass compared with artificial turf in contact sports. As playing surface is a potentially modifiable risk factor, this study sought to identify differences in symptoms following SRC on these 2 surfaces in a sample of young American football players.

DESIGN

Prospective.

SETTING

Part of the multi-institutional North Texas Concussion Registry (ConTex) research project.

PARTICIPANTS

Ten-year-old to 24-year-old male American football players (n = 62) who had sustained a helmet-to-ground SRC and presented to a specialty concussion clinic within 14 days of injury.

INDEPENDENT VARIABLES

Helmeted impact with grass (n = 33) or artificial turf (n = 29).

MAIN OUTCOME MEASURES

Severity and number of symptoms endorsed on the Sport Concussion Assessment Tool 5th Edition (SCAT5) Symptom Evaluation at the time of initial clinical evaluation.

RESULTS

Both groups were similar in mean time since injury, concussion history, and history of headache, but the artificial turf group was slightly older, with a mean age of 14.6 versus 13.6 years ( P = 0.039). Athletes who sustained a SRC on grass reported significantly higher mean total symptom severity scores (26.6 vs 11.6, P = 0.005) and total number of symptoms (10.3 vs 5.9, P = 0.006) compared with those who were injured on artificial turf.

CONCLUSIONS

This may be the first study to examine postconcussive symptoms after SRC as they relate to playing surface. This small sample of young American football players reported higher symptom severity scores and higher total number of symptoms after SRC on natural grass compared with artificial turf.

Impact Deceleration Differences on Natural Grass Versus Synthetic Turf High School Football Fields

American football has the highest rate of concussions in United States high school sports. Within American football, impact against the playing surface is the second-most common mechanism of injury. The objective of this study was to determine if there is a difference in impact deceleration between natural grass and synthetic turf high school football fields. A Century Body Opponent Bag (BOB) manikin was equipped with a Riddell football helmet and 3 accelerometers were placed on the forehead, apex of the head, and right ear. The manikin was dropped from a stationary position onto its front, back, and left side onto natural grass (n = 10) and synthetic turf (n = 9) outdoor football fields owned and maintained by public and private institutions on O'ahu, Hawai'i. Data was collected on 1,710 total drops. All accelerometers in forward and backward falls, and 1 accelerometer in side falls showed significantly greater impact deceleration on synthetic turf compared to the natural grass surfaces (P < .05). The results of this study provide evidence-based rationale to inform youth sports policies, particularly those aimed at injury prevention through safer playing environments and equipment.

Interaction of Surface Type, Temperature, and Week of Season on Concussion Risk in the National Football League: A Bayesian Analysis

BACKGROUND

Artificial turf fields and environmental conditions may influence sports concussion risk, but existing research is limited by uncontrolled confounding factors, limited sample size, and the assumption that risk factors are independent of one another. The purpose of this study was to examine how playing surface, time of season, and game temperature relate to diagnosed concussion risk in the National Football League (NFL).

METHODS

This retrospective cohort study examined data from the 2012 to the 2019 NFL regular season. We fit Bayesian negative binomial regression models to relate how playing surface, game temperature, and week of the season independently related to diagnosed concussion risk and any interactions among these factors.

RESULTS

We identified 1096 diagnosed concussions in 1830 games. There was a >99% probability that concussion risk was reduced on grass surface (median incidence rate ratio [IRR] = 0.78 [95% credible interval: 0.68, 0.89]), >99% probability that concussion risk was lower at higher temperatures (IRR = 0.85 [0.76,0.95] for each 7.9 °C), and >91% probability that concussion risk increased with each week of the season (IRR = 1.02 [1.00,1.04]). There was an >84% probability for a surface × temperature interaction (IRR = 1.01 [0.96, 1.28]) and >75% probability for a surface × week interaction (IRR = 1.02 [0.99, 1.05]).

CONCLUSIONS

Diagnosed concussion risk is increased on artificial turf compared with natural grass, and this is exacerbated in cold weather and, independently, later in the season. The complex interplay between these factors necessitates accounting for multiple factors and their interactions when investigating sports injury risk factors and devising mitigation methods.

Do Climate and Environmental Characteristics Influence Concussion Incidence in Outdoor Contact Sports? A Systematic Review

OBJECTIVE

To obtain a comprehensive understanding of the implications of environmental and climate factors on sport-related concussion incidence in outdoor contact sports.

DATA SOURCES

MEDLINE (via Ovid), Embase (via Elsevier), CINAHL Complete (via EBSCOhost), SPORTDiscus (via EBSCOhost), and Scopus (via Elsevier).

STUDY SELECTION

Studies that report incidence of sport-related concussion, assess data from athletes participating in outdoor contact sports, report on 1 or more climate or environmental factors, and report a diagnosis of concussion performed by a licensed medical professional were included. Reasons for exclusion included no report on extrinsic or environmental factors, no data on sport-related concussion incidence, and self-report of concussion diagnosis.

DATA EXTRACTION

This systematic review was conducted using Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines using 2 reviewers at each phase and a third reviewer for conflict resolution.

DATA SYNTHESIS

A total of 7558 articles were reviewed, and 20 met the inclusion criteria. There was moderate to strong strength of evidence concluding no difference between surface type (grass versus artificial) on sport-related concussion risk. Moderate to strong strength of evidence was found supporting no difference in sport-related concussion incidence based on game location (home versus away). There was no consensus on the effects of altitude or temperature on sport-related concussion incidence. One high-quality study found a decreased risk of sport-related concussion when playing in wet versus dry conditions. Heterogenous populations and data collection methods prevented extraction and meta-analysis.

CONCLUSIONS

Although a consensus on specific environmental and climate factors that influence sport-related concussion incidence was limited, the majority of studies were of high quality and gave insight into opportunities for future investigation. Administrators of large injury surveillance databases should consider including specific environmental and climate factors to provide investigators with robust data sets to better understand potential associations with sport-related concussion.

Lower Extremity Injury Rates on Artificial Turf Versus Natural Grass Playing Surfaces: A Systematic Review

BACKGROUND

No study has provided a comprehensive systematic review of sports injuries on artificial turf versus natural grass.

PURPOSE

To comprehensively examine the risk of overall injuries and multiple types of lower extremity injuries across all sports, all levels of competition, and on both old-generation and new-generation artificial turf.

STUDY DESIGN

Systematic review; Level of evidence, 3.

METHODS

A systematic review of the English-language literature was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. All included articles compared overall injury rates or lower extremity (hip, knee, or foot and ankle) injury rates on artificial turf and natural grass. All sports, levels of competition, and turf types were included. Studies were excluded if they did not include overall injury rates or lower extremity injury rates. Because of the heterogeneity of the included studies, no attempt was made to aggregate risk ratios to conduct a quantitative meta-analysis.

RESULTS

A total of 53 articles published between 1972 and 2020 were identified for study inclusion. Most studies on new-generation turf (13/18 articles) found similar overall injury rates between playing surfaces. When individual anatomic injury locations were analyzed, the greatest proportion of articles reported a higher foot and ankle injury rate on artificial turf compared with natural grass, both with old-generation (3/4 articles) and new-generation (9/19 articles) turf. Similar knee and hip injury rates were reported between playing surfaces for soccer athletes on new-generation turf, but football players, particularly those at high levels of competition, were more likely to sustain a knee injury on artificial turf than on natural grass.

CONCLUSION

The available body of literature suggests a higher rate of foot and ankle injuries on artificial turf, both old-generation and new-generation turf, compared with natural grass. High-quality studies also suggest that the rates of knee injuries and hip injuries are similar between playing surfaces, although elite-level football athletes may be more predisposed to knee injuries on artificial turf compared with natural grass. Only a few articles in the literature reported a higher overall injury rate on natural grass compared with artificial turf, and all of these studies received financial support from the artificial turf industry.

Athletic Play Surfaces and Injury Risk

ABSTRACT

Advancements in technology and the economic desires to maximize use of athletic playing surfaces have led to the development of various playing surfaces across the spectrum of sports. Each of these surfaces possesses specific safety profiles which are sport and population specific. Despite the growing medical literature on outdoor playing surfaces, inconsistent data exist on both orthopedic injuries and general medical concerns, such as surface component exposure toxicity and infection risk. Unfortunately, there is a paucity of data regarding various indoor playing surfaces and their effects on injury risk; this is an area ripe for further medical investigation. Understanding the differences in various play surfaces and their associated injury and health concerns is crucial for all medical staff providing care to athletes across the spectrum of skill and competition.