Epidemiology of concussion in collegiate and high school football players

Despite evolutionary changes in protective equipment, head injury remains common in football. We investigated concussion in football and associated epidemiologic issues such as 1) incidence of injury, 2) common signs and symptoms, and 3) patterns in making return-to-play decisions. We received 242 of 392 surveys (62%) that were sent to high school and collegiate certified athletic trainers at the beginning of three football seasons. Of the 17,549 football players represented, 888 (5.1%) sustained at least one concussion, and 131 (14.7% of the 888) sustained a second injury during the same season. The greatest incidence of concussion was found at the high school (5.6%) and collegiate division III (5.5%) levels, suggesting that there is an association between level of play and the proportion of players injured. Players who sustained one concussion in a season were three times more likely to sustain a second concussion in the same season compared with uninjured players. Contact with artificial turf appears to be associated with a more serious concussion than contact with natural grass. Only 8.9% of all injuries involved loss of consciousness, while 86% involved a headache. Overall, 30.8% of all players sustaining a concussion returned to participation on the same day of injury.

A comparison of sideline versus clinical cognitive test performance in collegiate athletes

OBJECTIVE

To test whether performance on 5 cognitive tests administered in a controlled clinical environment differed compared with administration in an uncontrolled sideline environment. Additionally, we investigated the effect of testing environment order on the learning effect for each cognitive test.

DESIGN AND SETTING

Athletes were assessed on 2 test occasions (8 +/- 2 days apart), once in a sports medicine research laboratory and once on a lacrosse practice field site.

SUBJECTS

A total of 59 Division I collegiate student-athletes participated in this study.

MEASUREMENTS

Normative data were collected on 5 cognitive tests (Stroop Test, Trail-Making Test part A, Trail-Making Test part B, Wechsler Digit-Span Forward Test, and Digit-Span Backward Test).

RESULTS

An independent-samples t test for environment difference on test day 1 revealed no significant differences between tests performed in the controlled environment and those performed in the uncontrolled environment. A repeated- measures analysis of variance test revealed a significant learning effect for all 5 tests, as subjects tended to improve approximately 11 points on the Stroop Test, 3 seconds on the Trail-Making A Test, 7 seconds on the Trail-Making B Test, and 1 point each on the Wechsler Digit Span Forward and Backward Tests. A paired-samples t test using delta scores (first test minus second test), sorted by order of testing environment, revealed a significant difference for the Stroop Test, but not for the remaining cognitive tests.

CONCLUSIONS

There appears to be no difference in cognitive testing performance completed in a controlled clinical environment versus that performed in an uncontrolled sideline environment. This finding suggests that clinicians can administer cognitive tests to athletes with mild head injuries in uncontrolled sideline environments and expect valid results. Thus, clinicians can more thoroughly evaluate mildly head-injured athletes during the most crucial period after injury so that a safe return-to-play decision can be based on quantifiable, objective data.

Effects of mild head injury on postural stability as measured through clinical balance testing

OBJECTIVE

Although force-platform measures of postural stability provide objective information concerning mild head injury (MHI) resolution, their application has remained limited due to the high costs and impracticality for sideline use. Therefore, we investigated the efficacy of a clinical balance testing procedure for the detection of acute postural stability disruptions after MHI.

DESIGN AND SETTING

We used a posttest control group design with repeated measures. Postural stability was tested at 3 postinjury time intervals (days 1, 3, and 5) using 2 procedures in a sports medicine laboratory: 1) a clinical balance battery consisting of 3 stances (double leg, single leg, and tandem) on 2 surfaces (firm and foam), and 2) the Sensory Organization Test using a sophisticated force-platform system.

SUBJECTS

Sixteen MHI and 16 matched control subjects participated in this study.

MEASUREMENTS

We measured performance with the Balance Error Scoring System for each of the clinical balance tests and the NeuroCom Smart Balance Master for Sensory Organization Testing.

RESULTS

We found significantly higher postural instability in the MHI subjects revealed through the clinical test battery, with the 3 stances on the foam surface eliciting significant differences through day 3 postinjury. Results of the Sensory Organization Test revealed significant group differences on day 1 postinjury.

CONCLUSIONS

Our results revealed that the Balance Error Scoring System may be a useful clinical procedure to assist clinicians in making return-to-play decisions in athletes with MHI in the absence of force-platform equipment.

Proprioception and neuromuscular control of the shoulder after muscle fatigue

OBJECTIVE

To examine the effects of fatigue on proprioception and neuromuscular control of the shoulder.

DESIGN AND SETTING

Subjects were randomly assigned to either an experimental group or control group. Subjects were tested using either the active angle-reproduction or the single- arm dynamic stability test. The subjects were then fatigued using a dynamometer performing continuous, concentric rotation exercises of the shoulder. Once fatigued, the subjects were posttested using the same test. One week later, the subjects returned and were pretested, fatigued, and posttested using the other test.

SUBJECTS

Thirty-two college-age (18 to 25 years) subjects (16 males, 16 females) with no history of glenohumeral instability or upper extremity injury volunteered for this study.

MEASUREMENTS

Absolute angular error was measured using an electrogoniometer present within the isokinetic dynamometer, while sway velocity was measured using a force-plate system.

RESULTS

Repeated-measures analysis of variance revealed a significant difference between the pretest and posttest values for absolute angular error in the experimental group, whereas no significant difference was revealed between pretest and posttest sway velocity for either the control or experimental group.

CONCLUSIONS

Fatigue of the internal and external rotators of the shoulder decreased proprioception of the shoulder, while having no significant effect on neuromuscular control.

Syncope and atypical chest pain in an intercollegiate wrestler: a case report

OBJECTIVE

To present the case of a 20-year-old collegiate wrestler who suffered from atypical chest pains and syncope after rigorous exercise, dehydration, and ingestion of a metabolic stimulant.

BACKGROUND

As a result of pressure to obtain a lower body weight for competition, wrestlers often pursue practices to lose a substantial amount of weight in a short period of time. These practices include rigorous exercise, starvation, dehydration, laxatives, diuretics, and over-the-counter stimulants. Our case involves an athlete who ingested a metabolic stimulant containing ma huang (ephedrine) and suffered from syncope and atypical chest pains during a bout of rigorous exercise and dehydration to lose weight for competition.

DIFFERENTIAL DIAGNOSIS

Hypertrophic cardiomyopathy, electrolyte imbalance, drug overdose, traumatic head injury, myocardial infarction, syncope.

TREATMENT

The emergency medical services transported the athlete to the emergency room, and he was hospitalized for 2 days. After discharge, the team physician counseled the athlete in the dangers of metabolic stimulants and excessive weight-loss techniques.

UNIQUENESS

This case is unique because it presents an athlete who ingested an over-the-counter stimulant to lose weight and suffered from syncope and atypical chest pains during a bout of rigorous exercise and dehydration.

CONCLUSIONS

Athletic trainers must understand not only the dangers of excessive weight loss, but also the dangers of using unregulated ephedrine-containing stimulants to aid in weight loss.

Comparison of 3 methods of external support for management of acute lateral ankle sprains

OBJECTIVE

To examine the efficacy of 3 different types of injury support systems (standard elastic wrap with horseshoe, Aircast Sport Stirrup, and Omni Multiphase orthosis) used in treating acute inversion ankle sprains.

SUBJECTS

We recruited 30 physically active college-aged subjects who had sustained a grade 1 + or 2 lateral ankle sprain within the previous 24 hours for the study.

DESIGN AND SETTING

Subjects were randomly placed into one of 3 groups, the first treated with standard elastic wrap with horseshoe, the second with an Aircast Sport Stirrup, and the third with an Omni Multiphase orthosis. Subjects reported to the athletic training room on days 1, 2, 3, 5, and 7 postinjury.

MEASUREMENTS

We assessed subjects for ankle volume, functional performance, and self-perception of symptoms during the 5 postinjury assessments.

RESULTS

We found no significant differences among the 3 groups on measures of volume, level of function, and self-perception of symptoms.

CONCLUSIONS

Our results suggest that none of these methods is superior to the others for reducing swelling, restoring function, or relieving symptoms during the acute management of lateral ankle sprains.

Establishment of normative data on cognitive tests for comparison with athletes sustaining mild head injury

OBJECTIVE

To provide normal data for comparison with objective measures of an athlete's cognitive ability after mild head injury (MHI).

SUBJECTS

Seventy-two Division I college athletes.

DESIGN AND SETTING

Athletes were assessed on three test dates (two days apart) in a sports medicine research laboratory.

MEASUREMENTS

Normative data were collected on four cognitive tests (Hopkins Verbal Learning Test, Stroop Test, Reitan Trail-Making Tests, and Wechsler Digit Span Tests).

RESULTS

A repeated-measures analysis of variance revealed significant learning effects on all tests except the Hopkins Verbal Learning Test. A high correlation was noted between the Stroop and the Trail-Making Tests.

CONCLUSIONS

These normative data can be used as comparisions to provide an objective measure of an athlete's cognitive ability following MHI. By adding this test battery to the athlete's other physical and neurologic tests, the decision to return an athlete to competition after MHI can be made with greater confidence and with less risk of reinjury.

Alternative approaches to the assessment of mild head injury in athletes

OBJECTIVES

Athletic trainers and team physicians are often faced with decisions concerning the severity and timing of an athletes return to play following mild head injury (MHI). These decisions can be the most difficult ones facing clinicians because of the limited amount of quantitative information indicating injury severity. Several authors have published guidelines for return to play following MHI, however these guidelines are based on limited scientific data. The purpose of this paper was to examine the effects of MHI on two objective measures, postural stability and cognitive function, to determine their usefulness in MHI assessment. The data gathered from these two measures has the potential to establish recovery curves based on objective data.

METHODS

Eleven Division I collegiate athletes who sustained a MHI and eleven matched control subjects were assessed for postural stability and cognitive function at four intervals following injury. Postural stability was assessed using the Sensory Organization Test on the NeuroCom Smart Balance Master. Cognitive functioning was measured through the use of four neuropsychological tests: Stroop Test, Trail Making Test, Digits Span and Hopkins Verbal Learning Test. Separate mixed model repeated measures ANOVAs were calculated for the composite score and three ratio (vestibular, visual and somato-sensory) scores from the Sensory Organization Test and the scores from the neuropsychological test to reveal significant differences between groups and across days postinjury.

RESULTS

A significant group by day interaction for overall postural stability (composite score) revealed that MHI athletes displayed increased postural instability for the first few days following MHI (p < .05). Analysis of the ratio scores revealed a significant interaction for the visual ratio. No significant group differences were revealed for any of the neuropsychological tests (p > .05), however significant day differences were revealed (p < .05).

CONCLUSIONS

The results from this study indicate that athletes demonstrate decreased stability until 3 days postinjury. It appears this deficit is related to a sensory interaction problem, whereby the injured athlete fails to use their visual system effectively. These findings suggest that measures of postural stability may provide clinicians with a useful clinical tool for determining when an athlete may safely return to competition, although these findings need to be confirmed in larger groups of athletes.

Effect of mild head injury on postural stability in athletes

OBJECTIVE

Athletic trainers and team physicians are often faced with the dilemma of when to return athletes to participation following mild head injury. Unfortunately, clinicians rarely have quantitative information on which to base their decisions. The purpose of this investigation was to identify postural stability changes in athletes with acute mild head injury.

DESIGN AND SETTING

High school and college male athletes were prescreened for postural stability before the start of their season. Subjects suffering injury during the season returned for testing on days 1, 3, 5, and 10 following injury, and 1 month postseason. Control subjects were selected for comparisons.

SUBJECTS

Ten prescreened subjects (age = 17.4 +/- 2.2 yr; ht = 183.8 + 8.1 cm; wt = 87.7 + 17.3 kg) returned for testing following an injury. Ten matched control subjects (age = 18.6 +/- 2.6 yr; ht = 185.7 +/- 6.7 cm; wt = 84.5 +/- 19.5 kg) were selected for comparisons. Additionally, nine subjects (eight male and one female) (age = 19.9 +/- 4.2 yr; ht = 182.3 + 10.9 cm; wt = 89.6 +/- 25.2 kg) who had sustained a mild head injury from other varsity sports teams were recruited. Nine matched controls (age = 22.1 +/- 3.3 yr; ht = 181.0 +/- 9.9 cm; wt = 84.9 +/- 25.6 kg) were again utilized.

MEASUREMENTS

Sway index and center of balance were measured using the Chattecx Balance System during three eye conditions and three surface conditions for all subjects.

RESULTS

Repeated measures analyses of variance (ANOVA) for each prescreened subject's sway index revealed significant differences between injured subjects and control subjects on day 1 postinjury as compared with the prescreening and/or subsequent tests. The analysis for sway index and center of balance inclusive of all 19 subjects with mild head injury and all 19 control subjects demonstrated increased postural sway compared with control subjects on day 1 postinjury during all plafform conditions, and on day 3 during the foam platform condition. The analysis for center of balance using the same subjects revealed that injured subjects maintained their center of balance farther away on day 1 postinjury compared with subsequent tests (p < .05).

CONCLUSIONS

These findings suggest that computerized dynamic posturography is a useful tool in objectively assessing postural stability in subjects with mild head injuries. Subjects with mild head injury appear to demonstrate impaired postural stability 1 to 3 days following injury. This information should aid clinicians in determining when an athlete can safely return to participation.

Effect of orthotics on postural sway following inversion ankle sprain

Orthotic devices have been shown to successfully modify selected aspects of lower extremity mechanics and enhance foot stability during the support phase of running. It was hypothesized that orthotic intervention would relieve excessive strain on the ankle ligaments and reduce postural sway, especially in subjects with acute ankle sprains. The primary purpose of this study was to determine if orthotics would reduce postural sway in injured and uninjured subjects. Thirteen subjects with acute inversion ankle sprain and 12 uninjured subjects were assessed for postural sway on the Balance System under two treatment conditions (orthotic and nonorthotic) and four platform movements. A three-factor repeated measures analysis of variance revealed a significant group X treatment interaction, suggesting that postural sway with orthotic intervention improved significantly more in injured subjects than in uninjured subjects. A significant platform movement X treatment interaction, furthermore, revealed that postural sway for the four movement conditions was dependent upon treatment (orthotic vs. no orthotic). Tukey post hoc analysis revealed that orthotic intervention significantly reduced postural sway when the platform moved in the medial/lateral plane and inversion/eversion plane. This research suggests that custom-fit orthotics may restrict undesirable motion at the foot and ankle and enhance joint mechanoreceptors to detect perturbations and provide structural support for detecting and controlling postural sway in ankle-injured subjects.

Effect of ACL Reconstruction and Tibial Rotation on Anterior Knee Laxity

The anterior cruciate ligament (ACL) is the primary restraint to anterior translation of the tibia on the femur. Research suggests that resistance to anterior translation changes as the tibia is rotated internally and externally. This study assessed the degree to which ACL reconstruction and tibial rotation affects anterior knee laxity. Nine subjects with ACL lesions and functional instabilities participated in the study. Subjects were measured 1 to 10 days before surgery and 6 to 8 months after ACL reconstruction using the KT-1000 knee arthrometer. A mechanical leg stabilizer was used to assess anterior translation at 20 degrees of knee flexion in three positions: internal rotation of 15 degrees , neutral, and external rotation of 15 degrees . Subjects were measured at 89 and 67 N of anterior force. Data were analyzed with a three-factor (test x position x force) repeated measures ANOVA. Following surgery, reduction in laxity (mm) for the three positions (internal rotation, neutral, and external rotation) was 1.9, 2.8, and 3.4, respectively, at 89 N and 1.5, 2.0, and 2.6, respectively, at 67 N. The degree of reduction in laxity (presurgery to postsurgery) was dependent upon rotation and force, and was greatest in external rotation and least in internal rotation pre- to postsurgery. We concluded that ACL reconstruction using a patellar tendon graft significantly decreased anterior tibial translation at all three positions, but a greater amount of reduction was observed postsurgically at the externally rotated position. This supports the theory that mechanical blocks and secondary restraints such as a taut mid-third of the iliotibial tract may interfere with clinical laxity tests in some positions of tibial rotation. Fixing the tibia in an externally rotated position may decrease the effect of secondary restraints and improve sensitivity in testing for ACL laxity.