Incidence, Mechanisms, and Severity of Game-Related High School Football Injuries Across Artificial Turf Systems of Various Infill Weights

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.

Lisfranc injury: Prevalence and maintaining a high index of suspicion for optimal evaluation

OBJECTIVES

To quantify the long-term prevalence of game-related Lisfranc trauma in college football on artificial turf and natural grass.

METHODS

32 universities were evaluated over 10 competitive seasons across all Football Bowl Subdivision (FBS) conferences. Outcomes of interest included injury severity, injury category, primary type of injury, player and skill position, injury mechanism and situation, elective imaging and surgical procedures, and field conditions. Injury incidence rates (IIR) were calculated using injuries per 10 games = (number of injuries) number of games) × 10.

RESULTS

Of the 1577 games documented, 783 games (49.7%) were played on a 3-layer artificial turf (≥9.0 lbs/ft²) infill system versus 794 games (50.3%) played on natural grass. In sum, 78 Lisfranc cases were documented with 34 (43.6%) occurring on artificial turf, and 44 (56.4%) on natural grass. MANOVAs indicated significant main effects by injury category (F_3,74 = 6.439; P = .001), and injury mechanism (F_5,72 = 3.372; P = .009) observed between surfaces, but not by injury severity (F_2,75 = 0.720; P = .490), primary type of injury (F_4,73 = 0.772; P = .547), overall player (F_2,75 = 0.219; P = .804) and skill positions (F_8,69 = 0.850; P = .563), injury situation (F_10,67 = 1.030; P = .428), elective imaging and surgical procedures (F_3,74 = 0.515; P = .673), or field conditions (F_2,75 = 0.375; P = .688). Post hoc analyses indicated significantly greater incidences (P < .05) of Lisfranc trauma on natural grass attributed to shoe:surface interaction during noncontact play, and during no contact, foot rotation or planting. Ligament tears (n = 8; 57.1%), with minimal cases of subluxation/dislocations (n = 4; 28.6%) and fractures (n = 2; 14.3%) comprised grade 3 cases across both surfaces.

CONCLUSION

In regards to Lisfranc trauma, a 3-layer, heavyweight artificial infill surface is as safe or safer than natural grass. The findings of this study may be generalizable only to this level of football competition.

Surface-Related High School Football Game Injuries on Pad and No-Pad Fields

BACKGROUND

Artificial turf fields are increasingly being installed with lighter weight infill systems that incorporate a pad underlayer, which is reported to reduce surface shock and decrease injuries. At this time, the effects of a pad underlayer on football trauma are unknown.

HYPOTHESIS

Athletes would not experience differences in surface-related injuries between pad and no-pad fields.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

Artificial turf fields were divided into 2 groups based on a pad underlayer or no-pad system, with 58 high schools participating across 3 states over the course of 7 seasons. Outcomes of interest included injury severity, head and knee trauma, injury category, primary type of injury, injury mechanism, anatomic location of trauma, tissue type injured, and elective imaging and surgical procedures. Data underwent multivariate analyses of variance (MANOVA) using general linear model procedures and were expressed as injury incidence rates per 10-game season.

RESULTS

Of 658 varsity games, 260 games were played on fields containing pads, and 398 games were played on no-pad fields, with 795 surface-related injuries reported. MANOVA indicated significant main effects by injury severity (F_3,791 = 11.436; P < .0001), knee trauma (F_9,785 = 2.435; P = .045), injury category (F_3,791 = 3.073; P < .0001), primary type of injury (F_10,785 = 2.660; P < .0001), injury mechanism (F_13,781 = 2.053; P < .001), anatomic location (F_16,778 = 1.592; P < .001), type of tissue injured (F_4,790 = 4.485; P < .0001), and elective imaging and surgical procedures (F_4,790 = 4.248; P < .002). Post hoc analyses indicated significantly greater incidences (P < .05) of substantial and severe injury, player-to-turf trauma, patellofemoral syndrome, neck strain, lower leg strain, and elective imaging and surgical procedures when games were played on padded turf fields. No differences in concussion rate from turf impact between pad and no-pad fields were observed.

CONCLUSION

In contrast to conventional wisdom, the addition of a pad under an artificial turf surface increases injury rates when compared with nonpadded fields across most injury categories. At this time, findings do not support the current trend of installing lightweight padded infill systems at the high school level of play.

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

Objective

To determine the incidence of head injuries and concussion in contact sports, comparing natural grass with artificial turf surfaces.

Design

Systematic review and meta-analysis via the RevMan V.5.3 software.

Eligibility criteria for selecting studies

All studies describing competitive contact sports played on both natural grass and artificial turf. The primary outcome measured was occurrence of head injury and concussion.

Data sources

The databases include PubMed, Embase, Cochrane, Medline and Sport Discus. The last search took place on 23 May 2019. The Newcastle-Ottawa Quality Assessment Scale evaluated the methodological quality of the selected studies with a funnel plot designed to determine publication bias. Study screening and data extraction were performed by two independent reviewers.

Results

Initial screening generated 42 publications, with 12 meeting criteria for inclusion. Eight studies described concussion only. The rate ratio (RR) of head injury and concussion was less on artificial turf compared with natural grass (RR=0.89, 95% CI 0.77 to 1.04) as was the rate ratio of concussion only (RR=0.72, 95% CI 0.58 to 0.89).

Conclusion

Analysis of published data demonstrates a decreased incidence of head injury and concussion when contact sports are played on artificial turf. This difference was most marked for sports such as rugby and American football. However, artificial turf has no association with the incidence of head injury or concussion while playing soccer.