High School and Collegiate Football Athlete Concussions: A Biomechanical Review (original) (raw)
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Biomechanical Properties of Concussions in High School Football
Medicine & Science in Sports & Exercise, 2010
Introduction: Sport concussion represents the majority of brain injuries occurring in the United States with 1.6-3.8 million cases annually. Understanding the biomechanical properties of this injury will support the development of better diagnostics and preventative techniques. Methods: We monitored all football related head impacts in 78 high school athletes (mean age = 16.7 yr) from 2005 to 2008 to better understand the biomechanical characteristics of concussive impacts. Results: Using the Head Impact Telemetry System, a total of 54,247 impacts were recorded, and 13 concussive episodes were captured for analysis. A classification and regression tree analysis of impacts indicated that rotational acceleration (95582.3 radIs j2), linear acceleration (996.1g), and impact location (front, top, and back) yielded the highest predictive value of concussion. Conclusions: These threshold values are nearly identical with those reported at the collegiate and professional level. If the Head Impact Telemetry System were implemented for medical use, sideline personnel can expect to diagnose one of every five athletes with a concussion when the impact exceeds these tolerance levels. Why all athletes did not sustain a concussion when the impacts generated variables in excess of our threshold criteria is not entirely clear, although individual differences between participants may play a role. A similar threshold to concussion in adolescent athletes compared with their collegiate and professional counterparts suggests an equal concussion risk at all levels of play.
Neurosurgical Focus, 2012
Object The authors' goal was to better define the relationship between biomechanical parameters of a helmeted collision and the likelihood of concussion. Methods The English-language literature was reviewed in search of scholarly articles describing the rotational and translational accelerations observed during all monitored impact conditions that resulted in concussion at all levels of American football. Results High school players who suffer concussion experience an average of 93.9g of translational acceleration (TA) and 6505.2 rad/s2 of rotational acceleration (RA). College athletes experience an average of 118.4g of TA and 5311.6 rad/s2 of RA. While approximately 3% of collisions are associated with TAs greater than the mean TA associated with concussion, only about 0.02% of collisions actually result in a concussion. Associated variables that determine whether a player who experiences a severe collision also experiences a concussion remain hypothetical at present. Conclusio...
Head Impacts During High School Football: A Biomechanical Assessment
Journal of Athletic Training, 2009
Little is known about the impact biomechanics sustained by players during interscholastic football.Context: To characterize the location and magnitude of impacts sustained by players during an interscholastic football season.Objective: Observational design.Design: On the field.Setting: High school varsity football team (n = 35; age = 16.85 ± 0.75 years, height = 183.49 ± 5.31 cm, mass = 89.42 ± 12.88 kg).Patients or Other Participants: Biomechanical variables (linear acceleration, rotational acceleration, jerk, force, impulse, and impact duration) related to head impacts were categorized by session type, player position, and helmet impact location.Main Outcome Measure(s): Differences in grouping variables were found for each impact descriptor. Impacts occurred more frequently and with greater intensity during games. Linear acceleration was greatest in defensive linemen and offensive skill players and when the impact occurred at the top of the helmet. The largest rotational a...
Rotational Head Kinematics in Football Impacts: An Injury Risk Function for Concussion
Annals of Biomedical Engineering, 2011
Recent research has suggested a possible link between sports-related concussions and neurodegenerative processes, highlighting the importance of developing methods to accurately quantify head impact tolerance. The use of kinematic parameters of the head to predict brain injury has been suggested because they are indicative of the inertial response of the brain. The objective of this study is to characterize the rotational kinematics of the head associated with concussive impacts using a large head acceleration dataset collected from human subjects. The helmets of 335 football players were instrumented with accelerometer arrays that measured head acceleration following head impacts sustained during play, resulting in data for 300,977 subconcussive and 57 concussive head impacts. The average subconcussive impact had a rotational acceleration of 1230 rad/ s 2 and a rotational velocity of 5.5 rad/s, while the average concussive impact had a rotational acceleration of 5022 rad/ s 2 and a rotational velocity of 22.3 rad/s. An injury risk curve was developed and a nominal injury value of 6383 rad/s 2 associated with 28.3 rad/s represents 50% risk of concussion. These data provide an increased understanding of the biomechanics associated with concussion and they provide critical insight into injury mechanisms, human tolerance to mechanical stimuli, and injury prevention techniques.
The biomechanics of concussion in unhelmeted football players in Australia: a case-control study
BMJ open, 2014
Concussion is a prevalent brain injury in sport and the wider community. Despite this, little research has been conducted investigating the dynamics of impacts to the unprotected human head and injury causation in vivo, in particular the roles of linear and angular head acceleration. Professional contact football in Australia. Adult male professional Australian rules football players participating in 30 games randomly selected from 103 games. Cases selected based on an observable head impact, no observable symptoms (eg, loss-of-consciousness and convulsions), no on-field medical management and no injury recorded at the time. A data set for no-injury head impact cases comprising head impact locations and head impact dynamic parameters estimated through rigid body simulations using the MAthematical DYnamic MOdels (MADYMO) human facet model. This data set was compared to previously reported concussion case data. Qualitative analysis showed that the head was more vulnerable to lateral i...
Estimated Brain Tissue Response Following Impacts Associated With and Without Diagnosed Concussion
Annals of biomedical engineering, 2018
Kinematic measurements of head impacts are sensitive to sports concussion, but not highly specific. One potential reason is these measures reflect input conditions only and may have varying degrees of correlation to regional brain tissue deformation. In this study, previously reported head impact data recorded in the field from high school and collegiate football players were analyzed using two finite element head models (FEHM). Forty-five impacts associated with immediately diagnosed concussion were simulated along with 532 control impacts without identified concussion obtained from the same players. For each simulation, intracranial response measures (max principal strain, strain rate, von Mises stress, and pressure) were obtained for the whole brain and within four regions of interest (ROI; cerebrum, cerebellum, brain stem, corpus callosum). All response measures were sensitive to diagnosed concussion; however, large inter-athlete variability was observed and sensitivity strength...
Head impact characteristics of three American football player positions
Sport-related concussion has been implicated in long-term neural degeneration and cognitive impairment. Thus, research efforts directed at elucidating as many risk factors as possible is valuable. Epidemiological studies have identified particular playing positions in American football that are at a heightened risk of sustaining concussions. The purpose of this study was to examine dynamic response and brain tissue deformation metrics from head injury reconstructions representing head impacts for football players in the linebacker, wide receiver and lineman positions. These events were reconstructed using pendulum and linear impactor apparatus and a Hybrid III headform. The University College Dublin Brain Trauma Model was used to measure the resulting brain tissue deformations as maximum principal strain (MPS). Peak linear acceleration, peak rotational acceleration and MPS all varied according to playing position. The injury reconstruction for the linebacker position reported the highest values for all measures, followed by head impacts for the wide receiver and the lineman. A relatively high probability of concussion for the linebacker head impact event was observed. In contrast, the associated concussion risk for the impact to the lineman was low, despite a high impact mass. These results show an important distinction in mechanisms and nature of trauma sustained as a result of American football head injuries based on the injury reconstructions for each player position.
Head Impact Exposure Sustained by Football Players on Days of Diagnosed Concussion
Medicine & Science in Sports & Exercise, 2013
Purpose: This study compares the frequency and severity of head impacts sustained by football players on days with and without diagnosed concussion and to identify the sensitivity and specificity of single-impact severity measures to diagnosed injury. Methods: One thousand two hundred eight players from eight collegiate football teams and six high school football teams wore instrumented helmets to measure head impacts during all team sessions, of which 95 players were diagnosed with concussion. Eight players sustained two injuries and one sustained three, providing 105 injury cases. Measures of head kinematics (peak linear and rotational acceleration, Gadd severity index, head injury criteria (HIC 15), and change in head velocity ($v)) and the number of head impacts sustained by individual players were compared between days with and without diagnosed concussion. Receiver operating characteristic curves were generated to evaluate the sensitivity and specificity of each kinematic measure to diagnosed concussion using only those impacts that directly preceded diagnosis. Results: Players sustained a higher frequency of impacts and impacts with more severe kinematic properties on days of diagnosed concussion than on days without diagnosed concussion. Forty-five injury cases were immediately diagnosed after head impact. For these cases, peak linear acceleration and HIC 15 were most sensitive to immediately diagnosed concussion (area under the curve = 0.983). Peak rotational acceleration was less sensitive to diagnosed injury than all other kinematic measures (P = 0.01), which are derived from linear acceleration (peak linear, HIC 15 , Gadd severity index, and $v). Conclusions: Players sustained more impacts and impacts of higher severity on days of diagnosed concussion than on days without diagnosed concussion. In addition, of historical measures of impact severity, those associated with peak linear acceleration are the best predictors of immediately diagnosed concussion.