John W. Powell

Recovery from mild concussion in high school athletes

OBJECT A computerized neuropsychological test battery was conducted to evaluate memory dysfunction and self-reporting of symptoms in a group of high school athletes who had suffered concussion. METHODS Neuropsychological performance prior to and following concussion was compared with the test performance of an age-matched control group. Potentially important diagnostic markers of concussion severity are discussed and linked to recovery within the 1st week of injury. CONCLUSIONS High school athletes who had suffered mild concussion demonstrated significant declines in memory processes relative to a noninjured control group. Statistically significant differences between preseason and postinjury memory test results were still evident in the concussion group at 4 and 7 days postinjury. Self-reported neurological symptoms such as headache, dizziness, and nausea resolved by Day 4. Duration of on-field mental status changes such as retrograde amnesia and posttraumatic confusion was related to the presence of memory impairment at 36 hours and 4 and 7 days postinjury and was also related to slower resolution of self-reported symptoms. The results of this study suggest that caution should be exercised in returning high school athletes to the playing field following concussion. On-field mental status changes appear to have prognostic utility and should be taken into account when making return-to-play decisions following concussion. Athletes who exhibit on-field mental status changes for more than 5 minutes have longer-lasting postconcussion symptoms and memory decline.

Sex-Related Injury Patterns Among Selected High School Sports

This cohort observational study was undertaken to test the hypothesis that the incidence of injuries for girls participating in high school sports is greater than that for boys. From 1995 through 1997, players were included in our study if they were listed on the schools varsity team roster for boys’ or girls’ basketball, boys’ or girls’ soccer, boys’ baseball, or girls’ softball. Injuries and opportunities for injury were recorded daily. Certified athletic trainers reported injury and exposure data. Based on 39,032 player-seasons and 8988 reported injuries, the injury rates per 100 players for softball (16.7) and for girls’ soccer (26.7) were higher than for baseball (13.2) and boys’ soccer (23.4). The knee injury rates per 100 players for girls’ basketball (4.5) and girls’ soccer (5.2) were higher than for their male counterparts. Major injuries occurred more often in girls’ basketball (12.4%) and soccer (12.1%) than in boys’ basketball (9.9%) and soccer (10.4%). Baseball players (12.5%) had more major injuries than softball players (7.8%). There was a higher number of surgeries, particularly knee and anterior cruciate ligament surgeries, for female basketball and soccer players than for boys or girls in other sports.

Cerebral concussion in athletes: Evaluation and neuropsychological testing

OBJECTIVETo conduct a topic review of studies related to cerebral concussion in athletes, as an aid to improving decision-making and outcomes. METHODSWe review the literature to provide an historical perspective on the incidence and definition of and the management guidelines for mild traumatic brain injury in sports. In addition, metabolic changes resulting from cerebral concussion and the second-impact syndrome are reviewed, to provide additional principles for decision-making. Neuropsychological testing, as it applies to athletes, is discussed in detail, to delineate baseline assessments, the characteristics of the neuropsychological evaluation, the neuropsychological tests used, and the methods for in-season identification of cerebral concussion. Future directions in the management of concussions are presented. RESULTSThe incidence of cerebral concussions has been reduced from approximately 19 per 100 participants in football per season to approximately 4 per 100, i.e., 40,000 to 50,000 concussions per year in football alone. The most commonly used definitions of concussion are those proposed by Cantu and the American Academy of Neurology. Each has associated management guidelines. Concussion or loss of consciousness occurs when the extracellular potassium concentration increases beyond the upper normal limit of approximately 4 to 5 mmol/L, to levels of 20 to 50 mmol/L, inhibiting the action potential and leading to loss of consciousness. This phenomenon helps to explain the delayed effects of symptoms after trauma. CONCLUSIONNeuropsychological testing seems to be an effective way to obtain useful data on the short-term and long-term effects of mild traumatic brain injury. Moreover, knowledge of the various definitions and management strategies, as well as the utility of neuropsychological testing, is essential for those involved in decision-making with athletes with mild traumatic brain injuries.

Concussion in professional football: epidemiological features of game injuries and review of the literature--part 3.

OBJECTIVEA 6-year study was performed to determine the circumstances, causes, and outcomes of concussions in the National Football League. METHODSBetween 1996 and 2001, the epidemiological features of concussions were recorded by National Football League teams with a standardized reporting form. Symptoms were reported and grouped as general symptoms, cranial nerve symptoms, memory or cognitive problems, somatic complaints, and loss of consciousness. The medical actions taken were recorded. In total, 787 game-related cases were reported, with information on the players involved, type of helmet impact, symptoms, medical actions, and days lost. Concussion risks were calculated according to player game positions. RESULTSThere were 0.41 concussions per National Football League game. The relative risk was highest for quarterbacks (1.62 concussions/100 game-positions), followed by wide receivers (1.23 concussions/100 game-positions), tight ends (0.94 concussion/100 game-positions), and defensive secondaries (0.93 concussion/100 game-positions). The majority of concussions (67.7%) involved impact by another player’s helmet. The remainder involved impact by other body regions of the striking player (20.9%) or ground contact (11.4%). The three most common symptoms of mild traumatic brain injury were headaches (55.0%), dizziness (41.8%), and blurred vision (16.3%). The most common signs noted in physical examinations were problems with immediate recall (25.5%), retrograde amnesia (18.0%), and information-processing problems (17.5%). In 58 of the reported cases (9.3%), the players lost consciousness; 19 players (2.4%) were hospitalized. A total of 92% of concussed players returned to practice in less than 7 days, but that value decreased to 69% with unconsciousness. CONCLUSIONThe professional football players most vulnerable to concussions are quarterbacks, wide receivers, and defensive secondaries. Concussions involved 2.74 symptoms/injury, and players were generally removed from the game. More than one-half of the players returned to play within 1 day, and symptoms resolved in a short time in the vast majority of cases.

Hip Injuries and Labral Tears in the National Football League

Background Injuries to the hip account for approximately 10% of all injuries in football, but definitive diagnosis is often challenging. Although these injuries are often uncomplicated contusions or strains, intra-articular lesions are increasingly found to be sources of hip pain. Purpose The objective was to define the incidence and etiologic factors of intra- and extra-articular hip injuries in the National Football League (NFL). Study Design Descriptive epidemiology study. Methods The NFL Injury Surveillance System was used to define all hip-related injuries from 1997 to 2006. Injuries were included if the athlete missed more than 2 days. All hip and groin injuries were included for evaluation. The authors also report on NFL players with intra-articular injuries seen at their institution outside of the NFL Injury Surveillance System. Results There were a total of 23 806 injuries from 1997 to 2006, of which 738 were hip injuries (3.1 %) with an average of 12.3 days lost per injury. Muscle strains were the most common injury. Intra-articular injuries resulted in the most time lost. Contact injuries most likely resulted in a contusion, and noncontact injuries most often resulted in a muscle strain. In the authors’ institutional experience, many of the athletes with labral tears have persistent adductor strains that do not improve despite adequate therapy. Conclusion Hip injuries represent a small but substantial percentage of injuries that occur in the NFL. A majority of these injuries are minor, with a return to play within 2 weeks. Intra-articular injuries are more serious and result in a significant loss of playing time. The “sports hip triad” (labral tear, adductor strain, and rectus strain) is described as a common injury pattern in the elite athlete.

Hamstring muscle strains in professional football players: a 10-year review.

Background: Investigations into hamstring strain injuries at the elite level exist in sports such as Australian Rules football, rugby, and soccer, but no large-scale study exists on the incidence and circumstances surrounding these injuries in the National Football League (NFL). Hypothesis: Injury rates will vary between different player positions, times in the season, and across different playing situations. Study Design: Descriptive epidemiology study. Methods: Between 1989 and 1998, injury data were prospectively collected by athletic trainers for every NFL team and recorded in the NFL’s Injury Surveillance System. Data collected included team, date of injury, activity the player was engaged in at the time of injury, injury severity, position played, mechanism of injury, and history of previous injury. Injury rates were reported in injuries per athlete-exposure (A-E). An athlete-exposure was defined as 1 athlete participating in either 1 practice or 1 game. Results: Over the 10-year study period 1716 hamstring strains were reported for an injury rate (IR) of 0.77 per 1000 A-E. More than half (51.3%) of hamstring strains occurred during the 7-week preseason. The preseason practice IR was significantly elevated compared with the regular-season practice IR (0.82/1000 A-E and 0.18/1000 A-E, respectively). The most commonly injured positions were the defensive secondary, accounting for 23.1% of the injuries; the wide receivers, accounting for 20.8%; and special teams, constituting 13.0% of the injuries in the study. Conclusion: Hamstring strains are a considerable cause of disability in football, with the majority of injuries occurring during the short preseason. In particular, the speed position players, such as the wide receivers and defensive secondary, as well as players on the special teams units, are at elevated risk for injury. These positions and situations with a higher risk of injury provide foci for preventative interventions.

Football Playing Surface and Shoe Design Affect Rotational Traction

Background High rotational traction between football shoes and the playing surface may be a potential mechanism of injury for the lower extremity. Hypothesis Rotational traction at the shoe-surface interface depends on shoe design and surface type. Study Design Controlled laboratory study. Methods A mobile testing apparatus with a compliant ankle was used to apply rotations and measure the torque at the shoe-surface interface. The mechanical surrogate was used to compare 5 football cleat patterns (total of 10 shoe models) and 4 football surfaces (FieldTurf, AstroPlay, and 2 natural grass systems) on site at actual surface installations. Results Both artificial surfaces yielded significantly higher peak torque and rotational stiffness than the natural grass surfaces. The only cleat pattern that produced a peak torque significantly different than all others was the turf-style cleat, and it yielded the lowest torque. The model of shoe had a significant effect on rotational stiffness. Conclusion The infill artificial surfaces in this study exhibited greater rotational traction characteristics than natural grass. The cleat pattern did not predetermine a shoes peak torque or rotational stiffness. A potential shoe design factor that may influence rotational stiffness is the material(s) used to construct the shoes upper. Clinical Relevance The study provides data on the rotational traction of shoe-surface interfaces currently employed in football. As football shoe and surface designs continue to be updated, new evaluations of their performance must be assessed under simulated loading conditions to ensure that player performance needs are met while minimizing injury risk.

Concussion in professional football: repeat injuries—Part 4

OBJECTIVE:A 6-year study was conducted to determine the signs, symptoms, and management of repeat concussion in National Football League players. METHODS:From 1996 to 2001, concussions were reported by 30 National Football League teams using a standardized reporting form filled out by team physicians with input from athletic trainers. Signs and symptoms were grouped by general symptoms, somatic complaints, cranial nerve effects, cognition problems, memory problems, and unconsciousness. Medical actions taken and management were recorded. RESULTS:Data were captured for 887 concussions in practices and games involving 650 players. A total of 160 players experienced repeat injury, with 51 having three or more concussions during the study period. The median time between injuries was 374.5 days, with only six concussions occurring within 2 weeks of the initial injury. Repeat concussions were more prevalent in the secondary (16.9%), the kick unit on special teams (16.3%), and wide receivers (12.5%). The ball return carrier on special teams (odds ratio [OR] = 2.08, P = not significant) and quarterbacks (OR = 1.92, P < 0.1) had elevated odds for repeat injury, followed by the tight end (OR = 1.24, P = not significant) and linebackers (OR = 1.22, P = not significant). There were similar signs and symptoms with single and repeat concussion, except for a higher prevalence of somatic complaints in players on their repeat concussions compared with their first concussion (27.5% versus 18.8%, P < 0.05). More than 90% of players were managed by rest, and 57.5% of those with second injuries returned to play within a day. Players with three or more concussions had signs, symptoms, and treatment similar to those with only a single injury. CONCLUSION:The most vulnerable players for repeat concussion in professional football are the ball return carrier on special teams and quarterbacks. Single and repeat concussions are managed conservatively with rest, and most players return quickly to play.

Concussion in professional football: Injuries involving 7 or more days out - Part 5

OBJECTIVE: A 6-year study was conducted to determine the signs, symptoms, and outcome of concussions with 7 or more (7+) days out from play or extended postconcussion recovery in the National Football League (NFL). METHODS: From 1996 to 2001, reporting of concussion was performed by NFL teams using a special standardized reporting form filled out by team physicians. Signs and symptoms were grouped by general symptoms, somatic complaints, cranial nerve effects, cognition problems, memory problems, and unconsciousness. Medical action taken and management were recorded. In all, 887 concussions were reported in practices and games. RESULTS: There were 72 concussions (8.1%) involving 7+ days out from play. The highest frequency occurred in quarterbacks (14.8%), the return unit on special teams (11.8%), and secondary (10.8%). Quarterbacks had the highest odds ratio (OR) of 7+ days out with concussion (OR = 2.10, P = 0.049), whereas running backs had the lowest relative risk (OR = 0.13, P = 0.021). The greatest fraction of 7+ days out occurred in passing plays (36.1%) and kickoffs (22.2%). Many signs and symptoms occurred at a greater frequency on initial examination in players 7+ days out; the average number per player was 4.64 with 7+ days out versus 2.58 with fewer days out (t = 6.02, df = 77.1). The signs and symptoms with the highest incidence for 7+ days out were disorientation to time (&khgr;2 = 51.2, P = 001), retrograde amnesia (&khgr;2 = 33.2, P = 0.001), fatigue (&khgr;2 = 28.1, P = 0.001), and the general category of cognition problems (&khgr;2 = 21.7, P = 0.001). Loss of consciousness for more than 1 minute was a predictor of 7+ days out (&khgr;2 = 33.5, P = 0.001), although it occurred in only 7.9% of cases. Of players with 7+ days out, 72.2% were removed from the game and 12.5% were hospitalized. These frequencies were significantly greater than for players with fewer than 7 days out (&khgr;2 = 68.03, df = 3, P < 0.0001). Approximately 90% of players were managed by rest, irrespective of days out, but a greater fraction were given drug or medical therapies with prolonged days out. CONCLUSION: The most vulnerable players for 7+ days out with concussion were quarterbacks and the secondary in professional football. Although 8.1% of concussions involved 7+ days out, only 1.6% involved a prolonged postconcussion syndrome. They recovered from symptoms and had a consistent return to play in the NFL.

A multivariate risk analysis of selected playing surfaces in the National Football League: 1980 to 1989 An epidemiologic study of knee injuries

This study focuses on the injury rates for natural grass and AstroTurf surfaces and the risk factors of game position and type of play. We examined the game- related knee sprains, medial collateral ligament sprains, and anterior cruciate ligament sprains that occurred in the National Football League during the 1980 to 1989 seasons. The findings are controlled for categories of severity (number of games missed due to injury), posi tion, and situation (rushing or passing) at the time of injury. The analysis of the data incorporates epidemio logic techniques associated with incidence density ra tios. The data show that there is a statistically significant difference between the higher AstroTurf injury rates for knee sprains. When knee sprains are separated into medial collateral ligament sprains and anterior cruciate ligament sprains, only the anterior cruciate ligament sprains show a statistically significant higher injury rate for AstroTurf. When simultaneous control variables are considered, significantly more knee sprains occurred to backs on rushing plays and linemen on passing plays. When controlling the data for severity, only the Cate gory II injuries (three or more games missed) sustained by linemen on passing plays had statistically significant higher injury rates for the AstroTurf. For medial collat eral ligament sprains, only the Category II injuries for linemen on passing plays remain statistically significant. The data for the ACL sprains show statistically signifi cant differences between the injury rate on natural grass and the injury rate on AstroTurf under conditions of special teams play.