The Effect of Playing Surface on the Incidence of ACL Injuries in National Collegiate Athletic Association American Football
Dragoo JL, Braun HJ, & Harris AHS. The Knee. 2012. Epub ahead of print doi:10.1016/j.knee.2012.07.006
An Analysis of Specific Lower Extremity Injury Rates on Grass and Field Turf Playing Surfaces in National Football League Games: 2000 – 2009 Seasons
Hershman EB, Anderson R, Bergfeld JA, Bradly JP, Coughlin MJ, Johnson RJ, Spindler KP, Wojtys E, & Powell JW. American Journal of Sports Medicine. 2012, Epub ahead of print. doi: 10.1177/0363546512458888
Artificial playing surfaces are frequently used in athletics due to their cost-effectiveness and all-weather benefits. However, the question remains whether or not these surfaces affect injury rates. Several studies have demonstrated an increased rate of injury on artificial turf, where others have shown that there is no difference. These two papers by Dragoo and Hershman investigate this concept, and pay particular attention to “third generation” or infill artificial surfaces which have a mat of artificial fibers that is filled with rubber particles. The Dragoo et al. study used the NCAA Injury Surveillance System to gather anterior cruciate ligament (ACL) injury incidence data in football players across divisions and various playing surfaces from the 2004-2005 to 2008-2009 seasons. This study demonstrated significantly higher ACL injury incidence rate on artificial turf (1.73 per 10,000 athletic exposures) when compared to natural grass (1.24 per 10,000). This incidence rate is even higher when comparing infill surfaces (1.77 per 10,000) to either grass or other artificial surfaces without fill (1.43 per 10,000). Most of these injuries were non-contact ACL tears, however, the study did not report if they were first time ACL tears or not. The Hershman et al. article examined lower extremity injury rates (i.e., knee and ankle sprains) on playing surface types in National Football League games between 2000–2009. At the conclusion of the 2009 season, of the 6612 games played, approximately 60% of all games were played on natural grass, approximately 10% on older-generation turf, and 30% were played on infill artificial turf. This study found that the injury rate for ACL sprains was 67% higher on infill artificial turf than on natural grass (injury rate was not normalized) and that there were significantly greater rates of eversion ankle sprains on infill artificial turf than on natural grass.
Clinically, it appears that the artificial infill turf seems to have a higher ACL injury incidence rate; however, it is difficult to determine the cause of the higher injury rates. As the manufacturing of artificial turf has evolved, it is important to look at the subdivisions and specific types of artificial surfaces as these two articles have. The newer generation infill artificial turf is intended to be more like natural grass, yet clearly has different injury rates. Manufacturers of the artificial turf will naturally combat this due to financial interests, yet two independent groups are echoing that infill artificial turf has higher ACL injury incidence rates. As health care professionals, this may indicate a need to look closer at the possible reasons as to why ACL injury rates are higher. Some people think it may have to do with the shoe/surface interaction, possibly looking at things like friction, torque, and stiffness. Players likely wear cleats or spikes in natural grass, and wear some sort of turf sneaker on artificial surfaces. Do you think that the playing surface can affect injury rates, or do you attribute these higher rates to other reasons? Has anyone seen ACL injuries or any other injuries that seem to be more prevalent with athletes on artificial infill turf?
Written by: Nicole Cattano
Reviewed by: Stephen Thomas
Hershman EB, Anderson R, Bergfeld JA, Bradley JP, Coughlin MJ, Johnson RJ, Spindler KP, Wojtys E, Powell JW, & for the National Football League Injury and Safety Panel (2012). An Analysis of Specific Lower Extremity Injury Rates on Grass and FieldTurf Playing Surfaces in National Football League Games: 2000-2009 Seasons. The American Journal of Sports Medicine, 40 (10), 2200-2205 PMID: 22972855