Effectiveness of mouthguards in reducing neurocognitive deficits following sports-related cerebral concussion

Although it is widely accepted that mouthguards decrease the incidence of dental injuries, there is a controversy among sports medicine professionals as to the effectiveness of mouthguards in decreasing the incidence or severity of sports-related cerebral concussion (SRCC). While some experimental data suggest that this may be the case, there exist a number of reports suggesting that mouthguards do not serve this purpose. These conclusions have been drawn, however, without actually measuring the extent of neurocognitive dysfunction in athletes following sports-related concussion. The purpose of this study was to determine whether mouthguard use reduces the neurocognitive and symptomatic impairments that follow an injurious episode of SRCC. Preseason baseline data were collected as part of an ongoing clinical program that uses a computerized neurocognitive test to assess various faculties of brain function and symptoms reported at the time of testing. Follow-up testing from 180 student-athletes who had sustained an SRCC was analyzed for the purpose of this study. These athletes were separated into one of two groups: those who reported using mouthguards and those who did not. Neurocognitive testing was accomplished using the Immediate Post-Concussion and Assessment Test (ImPACT). Results suggest that neurocognitive deficits at the time of the athletes' first follow-up assessment did not differ between mouthguard users and non-users, suggesting that mouthguard use does little to reduce the severity of neurocognitive dysfunction and onset of symptoms following sports-related head trauma. However, an interesting finding in this study was that athletes experienced significantly lower neurocognitive test scores and reported higher symptom scores following SRCC regardless of mouthguard use. This emphasizes a thorough clinical evaluation of athletes that have sustained an SRCC. Although it was found in this study that mouthguard use does not decrease the severity of concussion, it is important to note that the use of mouthguards is paramount in reducing maxillofacial and dental trauma and their use should continue to be mandated by athletic associations and supported by all dental and sports medicine professionals.

Management of cervical spine injuries in athletes

OBJECTIVE

Although the incidence of catastrophic cervical spine injury in sport has been significantly reduced over the past 3 decades, the injury warrants continued attention because of the altered quality of life that often accompanies such an injury. The purpose of our literature review was to provide athletic trainers with an understanding of the mechanisms, anatomical structures, and complications often associated with sport-related cervical spine injury. We also present the most current recommendations for management and treatment of these potentially catastrophic injuries.

DATA SOURCES

A review of the most pertinent literature between 1970 and 2005 was conducted using MEDLINE and the search terms spinal cord injury, cervical spine injury, neurosurgical trauma, cervical spinal stenosis, and catastrophic spine injury.

DATA SYNTHESIS

Flexion of the head places the cervical spine into a straight line and prevents the neck musculature from assisting in force absorption. This mechanism is the primary cause of cervical fracture, dislocation, and quadriplegia. The most serious of the syndromes described in the literature involves a complete spinal cord injury with transverse myelopathy. This injury typically results in total loss of spinal function below the level of the lesion.

CONCLUSIONS/RECOMMENDATIONS

Spinal trauma may result in a variety of clinical syndromes, according to the type and severity of the impact and bony displacement, as well as subsequent secondary insults such as hemorrhage, ischemia, and edema. Athletic trainers should be prepared to promptly recognize these potentially catastrophic injuries and follow the recommendations of the Inter-Association Task Force for the Appropriate Care of the Spine Injured Athlete in managing such injuries.

Neuropsychological performance, postural stability, and symptoms after dehydration

CONTEXT

Dehydration and concussion are common in athletic performance. Some experts have speculated that dehydration may negatively influence performance on tests commonly used for concussion assessment.

OBJECTIVE

To determine how the signs and symptoms, neuropsychological performance, and postural stability are affected by dehydration.

DESIGN

Repeated-measures design assessing subjects in the euhydrated and dehydrated conditions.

SETTING

Sports Medicine Research Laboratory.

PATIENTS OR OTHER PARTICIPANTS

Twenty-four healthy, male recreational athletes participated in the study.

INTERVENTION(S)

Subjects participated in 2 counterbalanced sessions (euhydrated and dehydrated) separated by at least 7 days. Subjects were dehydrated using fluid restriction and an exercise task. No direct intervention was provided for the euhydrated condition.

MAIN OUTCOME MEASURE(S)

We used the Standardized Assessment of Concussion to test mental status, the Automated Neuropsychological Assessment Metrics (ANAM) to evaluate neuropsychological performance, the NeuroCom Sensory Organization Test and Balance Error Scoring System to test postural stability, the Graded Symptom Checklist to assess symptom presence and severity in our participants, and urine specific gravity and body mass to determine hydration status.

RESULTS

No differences were noted for the Standardized Assessment of Concussion, total Balance Error Scoring System errors, composite Sensory Organization Test, and composite ANAM scores between conditions. Subjects in the dehydrated condition had significant deterioration in visual memory (t(23) = 2.130, P < .001) and fatigue measures (t(23) = -7.880, P < .001) as assessed by ANAM. The dehydrated condition resulted in subjects reporting a significantly higher number (t(23) = -8.585, P < .001) and severity (t(23) = -7.673, P < .001) of symptoms than the euhydrated subjects on the Graded Symptom Checklist.

CONCLUSIONS

Our results suggest that moderate dehydration (-2.5 +/- 0.63%) significantly influenced the self-report of symptoms commonly associated with concussion. Dehydration resulted in a deterioration of visual memory and increases in the self-report of fatigue. Despite these findings, dehydration did not affect other neuropsychological and postural stability objective testing measures for concussion.

Psychometric and measurement properties of concussion assessment tools in youth sports

CONTEXT

Establishing psychometric and measurement properties of concussion assessments is important before these assessments are used by clinicians. To date, data have been limited regarding these issues with respect to neurocognitive and postural stability testing, especially in a younger athletic population.

OBJECTIVE

To determine the test-retest reliability and reliable change indices of concussion assessments in athletes participating in youth sports. A secondary objective was to determine the relationship between the Standardized Assessment of Concussion (SAC) and neuropsychological assessments in young athletes.

DESIGN

We used a repeated-measures design to evaluate the test-retest reliability of the concussion assessments in young athletes. Correlations were calculated to determine the relationship between the measures. All subjects underwent 2 test sessions 60 days apart.

SETTING

Sports medicine laboratory and school or home environment.

PATIENTS OR OTHER PARTICIPANTS

Fifty healthy young athletes between the ages of 9 and 14 years.

MAIN OUTCOME MEASURE(S)

Scores from the SAC, Balance Error Scoring System, Buschke Selective Reminding Test, Trail Making Test B, and Coding and Symbol Search subsets of the Wechsler Intelligence Scale for Children were used in the analysis.

RESULTS

Our test-retest indices for each of the 6 scores were poor to good, ranging from r = .46 to .83. Good reliability was found for the Coding and Symbol Search tests. The reliable change scores provided a way of determining a meaningful change in score for each assessment. We found a weak relationship ( r < .36) between the SAC and each of the neuropsychological assessments; however, stronger relationships ( r > .70) were found between certain neuropsychological measures.

CONCLUSIONS

We found moderate test-retest reliability on the cognitive tests that assessed attention, concentration, and visual processing and the Balance Error Scoring System. Our results demonstrated only a weak relationship between performance on the SAC and the selected neuropsychological tests, so it is likely that these tests assess somewhat different areas of cognitive function. Our correlational findings provide more evidence for using the SAC along with a more complex neuropsychological assessment battery in the evaluation of concussion in young athletes.

Functional balance training, with or without exercise sandals, for subjects with stable or unstable ankles

CONTEXT

Improving postural stability through balance training may prevent ankle sprains. Exercise Sandals may increase the demands placed on ankle muscles during rehabilitation, which could improve postural stability.

OBJECTIVE

To examine the effects of functional balance training, with and without the use of Exercise Sandals, on postural stability in subjects with stable or unstable ankles.

DESIGN

Prospective, nonrandomized clinical trial.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Sixteen subjects with functional ankle instability and 16 subjects with no history of ankle sprains.

INTERVENTION(S)

Subjects were assigned to an Exercise Sandal functional balance training group or a shoe functional balance training group. Subjects trained 3 times per week for 8 weeks and then performed a single-limb stance posttest.

MAIN OUTCOME MEASURE(S)

Subjects were required to remain as motionless as possible during a single-limb stance pretest. Anterior-posterior and medial-lateral center-of-pressure excursions were measured.

RESULTS

Exercise Sandal balance training improved anterior-posterior postural stability in both ankle groups ( P < .05). Both training interventions improved medial-lateral postural stability in stable and unstable ankles ( P < .05).

CONCLUSIONS

Postural stability improved after subjects performed functional balance training programs, both with and without Exercise Sandals. Training with Exercise Sandals might not be any more effective in improving postural stability than performing functional balance training without Exercise Sandals. However, Exercise Sandals did not impair postural stability and, consequently, might serve as an alternative therapy to improve postural stability.

Sport-related concussion in the young athlete

PURPOSE OF REVIEW

The purpose of this review is to present an overview of sport-related concussion in the young athlete and review recent publications of clinical and scientific importance.

RECENT FINDINGS

Recent findings show that young athletes are more susceptible to concussions than older athletes and more likely to develop second impact syndrome, as well as long-term negative cumulative consequences. Further, ongoing research suggests a more prolonged disturbance of brain function following a concussion than previously believed.

SUMMARY

Given the increased vulnerability of the young athlete, current research suggests conservative management of concussion and return-to-play decisions. A decision tree diagram to assist the practitioner in making return-to-play recommendations for the young athlete is included in this review.

Association between recurrent concussion and late-life cognitive impairment in retired professional football players

OBJECTIVE

Cerebral concussion is common in collision sports such as football, yet the chronic neurological effects of recurrent concussion are not well understood. The purpose of our study was to investigate the association between previous head injury and the likelihood of developing mild cognitive impairment (MCI) and Alzheimer's disease in a unique group of retired professional football players with previous head injury exposure.

METHODS

A general health questionnaire was completed by 2552 retired professional football players with an average age of 53.8 (+/-13.4) years and an average professional football playing career of 6.6 (+/- 3.6) years. A second questionnaire focusing on memory and issues related to MCI was then completed by a subset of 758 retired professional football players (> or = 50 yr of age). Results on MCI were then cross-tabulated with results from the original health questionnaire for this subset of older retirees.

RESULTS

Of the former players, 61% sustained at least one concussion during their professional football career, and 24% sustained three or more concussions. Statistical analysis of the data identified an association between recurrent concussion and clinically diagnosed MCI (chi = 7.82, df = 2, P = 0.02) and self-reported significant memory impairments (chi = 19.75, df = 2, P = 0.001). Retired players with three or more reported concussions had a fivefold prevalence of MCI diagnosis and a threefold prevalence of reported significant memory problems compared with retirees without a history of concussion. Although there was not an association between recurrent concussion and Alzheimer's disease, we observed an earlier onset of Alzheimer's disease in the retirees than in the general American male population.

CONCLUSION

Our findings suggest that the onset of dementia-related syndromes may be initiated by repetitive cerebral concussions in professional football players.

Recovery of postural control after cerebral concussion: new insights using approximate entropy

CONTEXT

The return-to-play decision after sport-related cerebral concussion depends in part on knowing when an athlete has fully recovered postural control after injury.

OBJECTIVE

To describe the postconcussion recovery of postural control using approximate entropy (ApEn), a regularity statistic from nonlinear dynamics.

DESIGN

Retrospective case series analysis.

SETTING

Sports medicine research laboratory.

PATIENTS OR OTHER PARTICIPANTS

Collegiate athletes from whom center-of-pressure and symptom data were collected at preseason, less than 48 hours after injury, and 48 to 96 hours after injury.

MAIN OUTCOME MEASURE(S)

Approximate entropy values reflecting the amount of randomness contained in center-of-pressure oscillations were calculated for anterior-posterior (AP) and medial-lateral (ML) time series. Equilibrium scores reflecting the amplitude of center-of-pressure AP oscillations were used to indicate postural stability. The number and severity of symptoms were described.

RESULTS

Compared with the healthy preseason state, ApEn values for the AP and ML time series generally declined immediately after injury in both steady and unsteady injured athletes. At 48 to 96 hours after injury, ApEn values for the ML time series remained significantly depressed (mean difference compared with preseason = -0.268, standard error = 0.072), even among athletes whose initial postural instability had resolved. We found few significant relationships between changes in ApEn values and changes in symptoms before and after injury.

CONCLUSIONS

The effects of cerebral concussion on postural control appear to persist for longer than 3 to 4 days, even among athletes with no signs of unsteadiness. Our results may reflect changes in neurophysiologic or mechanical constraints on postural control. Approximate entropy provides a theoretically distinct, valuable measurement alternative that may prove useful for reducing uncertainty in the return-to-play decision.

Effect of coordination training with and without stochastic resonance stimulation on dynamic postural stability of subjects with functional ankle instability and subjects with stable ankles

OBJECTIVE

To examine the effects of coordination training with and without stochastic resonance (SR) stimulation on dynamic postural stability.

DESIGN

Experimental with repeated measures.

SETTING

Research Laboratory.

PARTICIPANTS

Thirty subjects with functional ankle instability (FAI) and 30 healthy subjects.

INTERVENTIONS

Subjects were assigned to a conventional coordination training group, SR stimulation coordination training group, or control group. Training groups performed coordination exercises for 6 weeks. Single leg jump-landing tests were performed before training began (pretest), and then once every 2 weeks. Jump-landing tests required subjects to land on a single leg on a force plate and stabilize quickly.

MAIN OUTCOME MEASURES

Anterior/posterior (A/P) and medial/lateral (M/L) time-to-stabilization (TTS).

RESULTS

The FAI group improved their A/P TTS over their pretest by 16% (test 2), 22% (test 3), and 22% (posttest). They also improved their M/L TTS over their pretest by 16% (test 3) and 22% (posttest). Control groups did not improve their TTS (P>0.05). SR stimulation did not statistically influence TTS (P>0.05). Effect sizes (ES), however, for our 3-way interaction analyses for A/P TTS (ES=0.40) and M/L TTS (ES=0.30) suggested that SR stimulation improved the FAI group's M/L TTS after 2 weeks of training, and improved their A/P TTS and M/L TTS to a greater degree after 4 weeks than coordination training alone.

CONCLUSION

Coordination training can improve dynamic postural instabilities associated with FAI. SR stimulation might be an alternative therapy for FAI, as this stimulation might improve dynamic postural stability more quickly and to a greater extent than coordination training without SR stimulation.

Issues in estimating risks and rates in sports injury research

OBJECTIVE

To describe 3 measures of incidence used in sports injury epidemiology.

BACKGROUND

To promote safety in sports, athletic trainers must be able to accurately interpret and apply injury data and statistics. Doing so allows them to more efficiently articulate this information to school administrators in recommending increases in medical resources, such as more personnel, better services, and safer facilities and equipment.

DESCRIPTION

Using data from a study of high school sports injuries, we review incidence rates, epidemiologic incidence proportions, and clinical incidence. The incidence rate is the number of injuries divided by the number of athlete-exposures and is based on the epidemiologic concept of person-time at risk. It accounts for variation in exposure between athletes and teams and is widely used by researchers. The epidemiologic incidence proportion is the number of injured athletes divided by the number of athletes at risk. It is a valid estimator of average injury risk, yet it is rarely used in sports injury epidemiology to communicate information about such risks to nonscientists. Clinical incidence is a hybrid between the epidemiologic incidence proportion and the incidence rate in that it uses the number of injuries in the numerator but the number of athletes at risk in the denominator. It has been widely used in research on high school football injury but is neither a valid estimator of risk nor a true rate.

ADVANTAGES

Athletic trainers who understand the causes of and risk factors for sport-related injury are better positioned to make safe return-to-play decisions and decrease the likelihood of reinjury in athletes.

Structural validity of a self-report concussion-related symptom scale

PURPOSE

This study evaluated the factorial validity of a self-report measure of concussion-related symptom severity among a large sample of male, high-school athletes.

METHODS

Participants (N = 1089) were nonconcussed, male, high-school football players. All participants completed a single baseline self-report measure of concussion-related symptom severity, namely the graded symptom checklist (GSC). We tested the factorial validity of the measure with confirmatory factor analysis using LISREL 8.50.

RESULTS

The analysis indicated that a theoretically derived, three-factor model provided a good, but not excellent, fit for the 16-item GSC. Excellent model-data fit was demonstrated for the three-factor model for a 9-item version of the GSC. In both instances, the three factors were best described by a single second-order factor, namely concussion symptomatology.

CONCLUSIONS

This study provides additional evidence for the factorial validity of a summative self-reported measure of concussion-related symptoms. The factor structure represents a cohesive group of nine symptoms that can be explained by three underlying latent variables, namely somatic symptoms, neurobehavioral symptoms, and "cognitive" symptoms, subsumed under a single higher-order factor, namely concussion symptoms.

A nonlinear dynamic approach for evaluating postural control: new directions for the management of sport-related cerebral concussion

Recent research suggests that traditional biomechanical models of postural stability do not fully characterise the nonlinear properties of postural control. In sports medicine, this limitation is manifest in the postural steadiness assessment approach, which may not be sufficient for detecting the presence of subtle physiological change after injury. The limitation is especially relevant given that return-to-play decisions are being made based on assessment results. This update first reviews the theoretical foundation and limitations of the traditional postural stability paradigm. It then offers, using the clinical example of athletes recovering from cerebral concussion, an alternative theoretical proposition for measuring changes in postural control by applying a nonlinear dynamic measure known as 'approximate entropy'. Approximate entropy shows promise as a valuable means of detecting previously unrecognised, subtle physiological changes after concussion. It is recommended as an important supplemental assessment tool for determining an athlete's readiness to resume competitive activity.

Comparison of triceps surae structural stiffness and material modulus across sex

BACKGROUND

Dynamic joint stability is derived, in part, from active muscle stiffness. Previous research has identified greater structural musculotendinous stiffness in males than in females, suggesting potential sex differences in joint stability. However, structural stiffness is influenced by anthropometrics, and it is currently unclear if sex differences in musculotendinous stiffness are purely functions of anthropometrics or related to additional factors. The purpose of this investigation was to compare structural stiffness and material modulus of the triceps surae between sexes to determine the relative influence of anthropometrics. It was hypothesized that males would demonstrate greater structural stiffness and material modulus.

METHODS

Twenty male and 20 female individuals volunteered for participation. Active triceps surae structural stiffness was estimated from the damped frequency of oscillation of the shank about the ankle. Material modulus was calculated as the ratio of stress to strain, derived from estimates of triceps surae length and physiological cross-sectional area.

FINDINGS

Structural stiffness was significantly greater in males [mean (SD)] [137.41 (26.99) N/cm] than females [91.06 (20.10) N/cm]. Similarly, material modulus was significantly greater in males [2778.51 (549.95) Pa] than females [1968.58 (439.61) Pa].

INTERPRETATION

Greater structural stiffness in males identified in previous literature appears to be a true phenomenon. Identification of greater material modulus in males suggests that these differences are likely attributable to sex differences in tendon stiffness and muscle architecture. These results indicate that male musculature is more effective at resisting changes in its length, a finding which may have implications for joint stability.

Detecting altered postural control after cerebral concussion in athletes with normal postural stability

OBJECTIVE

To determine if approximate entropy (ApEn), a regularity statistic from non-linear dynamics, could detect changes in postural control during quiet standing in athletes with normal postural stability after cerebral concussion.

METHODS

The study was a retrospective, case series analysis of centre of pressure (COP) data collected during the Sensory Organization Test (SOT) from NCAA Division I (USA) athletes prior to and within 48 h after injury. Subjects were 21 male and six female athletes from a variety of sports who sustained a cerebral concussion between 1997 and 2003. After injury, athletes displayed normal postural stability equivalent to preseason levels. For comparison, COP data also were collected from 15 male and 15 female healthy non-athletes on two occasions. ApEn values were calculated for COP anterior-posterior (AP) and medial-lateral (ML) time series.

RESULTS

Compared to healthy subjects, COP oscillations among athletes generally became more regular (lower ApEn value) after injury despite the absence of postural instability. For AP time series, declines in ApEn values were much larger in SOT conditions 1 and 2 (approximately three times as large as the standard error of the mean) than for all other conditions. For ML time series, ApEn values declined after injury in all sensory conditions (F(1,55) = 6.36, p = 0.02).

CONCLUSIONS

Athletes who demonstrated normal postural stability after concussion nonetheless displayed subtle changes in postural control. Changes in ApEn may have represented a clinically abnormal finding. ApEn analysis of COP oscillations may be a valuable supplement to existing concussion assessment protocols for athletes.

Current trends in athletic training practice for concussion assessment and management

CONTEXT

Athletic trainers surveyed in 1999 demonstrated little consensus on the use of concussion grading scales and return-to-play criteria. Most relied on clinical examination or symptom checklists to evaluate athletes with concussion.

OBJECTIVE

To investigate the current trends of certified athletic trainers in concussion assessment and management.

DESIGN

Subjects were invited to participate in a 32-question Internet survey.

SETTING

An Internet link to the survey was e-mailed to the subjects.

PATIENTS OR OTHER PARTICIPANTS

A total of 2750 certified athletic trainers and members of the National Athletic Trainers' Association were randomly e-mailed and invited to participate.

MAIN OUTCOME MEASURE(S)

Survey questions addressed topics including years of certification, number of concussions evaluated each year, methods of assessing concussion, and guidelines used for return to play. Compliance with the recent position statement of the National Athletic Trainers' Association on sport-related concussion was also evaluated.

RESULTS

Certified athletic trainers averaged 9.9 +/- 7.3 years of certification and evaluated an average of 8.2 +/- 6.5 concussions per year. To assess concussion, 95% reported using the clinical examination, 85% used symptom checklists, 48% used the Standardized Assessment of Concussion, 18% used neuropsychological testing, and 16% used the Balance Error Scoring System. The most frequently used concussion grading scale and return-to-play guideline belonged to the American Academy of Neurology (30%). When deciding whether to return an athlete to play, certified athletic trainers most often used the clinical examination (95%), return-to-play guidelines (88%), symptom checklists (80%), and player self-report (62%). The most important tools for making a return-to-play decision were the clinical examination (59%), symptom checklists (13%), and return-to-play guidelines (12%). Only 3% of certified athletic trainers surveyed complied with the recent position statement, which advocated using symptom checklists, neuropsychological testing, and balance testing for managing sport-related concussion.

CONCLUSIONS

Our findings suggest that only a small percentage of certified athletic trainers currently follow the guidelines proposed by the National Athletic Trainers' Association. Various assessment methods and tools are currently being used, but clinicians must continue to implement a combination of methods and tools in order to comply with the position statement.

Single-leg jump-landing stabilization times in subjects with functionally unstable ankles

CONTEXT

Factors contributing to functional ankle instability may cause individuals with the condition to land from a jump differently than those with stable ankles.

OBJECTIVE

To determine stabilization time differences during single-leg jump landings between stable and unstable ankle groups and to report the reliability and precision of time-to-stabilization measures.

DESIGN

A mixed design with 1 between factor (ankle group) and 1 within factor (direction) was used to analyze the comparison between our 10 subjects with functional ankle instability and 10 subjects with stable ankles. Time to stabilization (seconds) was the dependent measure. Reliability for time-to-stabilization measures of our 12 additional subjects with stable ankles were assessed using intraclass correlation coefficients (ICC 2,7). Standard errors of measurements were also calculated for time-to-stabilization measures.

SETTING

Sports medicine research laboratory. PATIENTS OR OTHER PARTICIPANT(S): Ten subjects with functional ankle instability who reported at least 2 sprains and "giving way'' sensations at their ankles constituted the functional ankle instability group. Ten subjects without a history of ankle sprain injury served as healthy subjects. Twelve additional healthy subjects participated in the reliability study.

INTERVENTION(S)

Subjects performed a jump-landing test, which required them to jump 50% to 55% of their maximum vertical jump height and then land on a single leg on a force plate. After landing, they stabilized quickly and remained as motionless as possible in a single-leg stance for 20 s.

MAIN OUTCOME MEASURE(S)

Anterior-posterior and medial/ lateral vibration magnitude curve fit time-to-stabilization.

RESULTS

Time to stabilization was longer for the functional ankle instability group (1.98 +/- 0.81 s) than for the stable ankle group (1.45 +/- 0.30 s) (P < .05). Reliability (standard error of the measurement) values for anterior/posterior and medial/lateral time-to-stabilization were 0.79 (0.15 s) and 0.65 (0.26 s), respectively.

CONCLUSIONS

Time to stabilization was longer for subjects with functional ankle instability than subjects with stable ankles. The ankle instability may have impaired the subjects' ability to stabilize after a single-leg jump landing. Reliabilities and standard errors of the measurements of time-to-stabilization measures were moderate and low, respectively.

Age and gender effects on lower extremity kinematics of youth soccer players in a stop-jump task

BACKGROUND

Gender differences in lower extremity motion patterns were previously identified as a possible risk factor for non-contact anterior cruciate ligament injuries in sports.

HYPOTHESIS

Gender differences in lower extremity kinematics in the stop-jump task are functions of age for youth soccer players between 11 and 16 years of age.

STUDY DESIGN

Descriptive laboratory study.

METHODS

Three-dimensional videographic data were collected for 30 male and 30 female adolescent soccer players between 11 and 16 years of age performing a stop-jump task. The age effects on hip and knee joint angular motions were compared between genders using multiple regression analyses with dummy variables.

RESULTS

Gender and age have significant interaction effects on standing height (P = .00), body mass (P = .00), knee flexion angle at initial foot contact with the ground (P = .00), maximum knee flexion angle (P = .00), knee valgus-varus angle (P = .00), knee valgus-varus motion (P = .00), and hip flexion angle at initial foot contact with the ground (P = .00).

CONCLUSION

Youth female recreational soccer players have decreased knee and hip flexion angles at initial ground contact and decreased knee and hip flexion motions during the landing of the stop-jump task compared to those of their male counterparts. These gender differences in knee and hip flexion motion patterns of youth recreational soccer players occur after 12 years of age and increase with age before 16 years.

CLINICAL RELEVANCE

The results of this study provide significant information for research on the prevention of noncontact anterior cruciate ligament injuries.

Influences of experimental factors on spinal stretch reflex latency and amplitude in the human triceps surae

The spinal stretch reflex (SSR) is commonly assessed via electromyographic (EMG) analysis of joint perturbations inducing changes in muscle length. Previous literature indicates that when large experimental changes in magnitude of agonist background EMG, perturbation velocity, and perturbation amplitude are employed, SSR latency and amplitude are significantly altered. The purpose of this investigation was to evaluate the relative dependence of SSR latency and amplitude on inherent variability in these experimental variables. Soleus SSR latency and amplitude were assessed in 40 healthy subjects following dorsiflexion perturbation under an active state ( approximately 14% MVC). Experimental variables displayed limited variability (means +/- SD): soleus background EMG (13.47 +/- 7.08% MVC), perturbation velocity (96.1 +/- 30 degrees /s), and perturbation amplitude (4 +/- 1 degrees ). SSR latency was not significantly related to soleus background EMG (r = 0.189), perturbation velocity (r = 0.213), or perturbation amplitude (r = 0.202). Similarly, SSR amplitude was not significantly related to soleus background EMG (r = 0.306), perturbation velocity (r = 0.053), or perturbation amplitude (r = 0.056). Variability in experimental variables was much smaller than what has been reported in the literature to significantly impact SSR characteristics. These results suggest that SSR latency and amplitude are independent of agonist background EMG, perturbation velocity, and perturbation amplitude when experimental variability is relatively limited.

Instruction of jump-landing technique using videotape feedback: altering lower extremity motion patterns

BACKGROUND

Anterior cruciate ligament injury prevention programs have used videotapes of jump-landing technique as a key instructional component to improve landing performance.

HYPOTHESIS

All videotape feedback model groups will increase knee flexion angles at initial contact and overall knee flexion motion and decrease peak vertical ground reaction forces and peak proximal anterior tibial shear forces to a greater extent than will a nonfeedback group. The secondary hypothesis is that the videotape feedback using the combination of the expert and self models will create the greatest change in each variable.

STUDY DESIGN

Controlled laboratory study.

METHODS

Knee kinematics and kinetics of college-aged recreational athletes randomly placed in 3 different videotape feedback model groups (expert only, self only, combination of expert and self) and a nonfeedback group were collected while participants performed a basketball jump-landing task on 3 testing occasions.

RESULTS

All feedback groups significantly increased knee angular displacement flexion angles [F(6,70) = 8.03, P = .001] and decreased peak vertical ground reaction forces [F(6,78) = 2.68, P = .021] during performance and retention tests. The self and combination groups significantly increased knee angular displacement flexion angles more than the control group did; the expert model group did not change significantly more than the control group did. All feedback groups and the nonfeedback group significantly reduced peak vertical forces across performance and retention tests. There were no statistically significant changes in knee flexion angle at initial ground contact (P = .111) and peak proximal anterior tibial shear forces (P = .509) for both testing sessions for each group.

CONCLUSION

The use of self or combination videotape feedback is most useful for increasing knee angular displacement flexion angles and reducing peak vertical forces during landing.

CLINICAL RELEVANCE

The use of self or combination modeling is more effective than is expert-only modeling for the implementation of instructional programs aimed at reducing the risk of jump-landing anterior cruciate ligament injuries.

The relationships between active extensibility, and passive and active stiffness of the knee flexors

Insufficient active knee flexor stiffness may predispose the anterior cruciate ligament to injury. Insufficient passive stiffness may result in insufficient active stiffness. Similarly, higher levels of musculotendinous extensibility may inhibit active and passive muscle stiffness, potentially contributing to an increased risk of injury. The literature is both limited and inconsistent concerning relationships between extensibility, passive stiffness, and active stiffness. Extensibility was measured as the maximal active knee extension angle from a supine position with the hip flexed to 90 degrees . Passive stiffness was calculated as the slope of the moment-angle curve resulting from passive knee extension. Active stiffness was assessed via acceleration associated with damped oscillatory motion about the knee. Stepwise multiple regression indicated that passive stiffness accounted for 25% of active muscle stiffness variance. The linear combination of extensibility and passive stiffness explained only 2% more variance compared to passive stiffness alone. Musculotendinous extensibility was moderately related to passive muscle stiffness, and weakly related to active muscle stiffness. The moderate relationship observed between active and passive stiffness emphasizes the dependence of active muscle stiffness on cross-bridge formation, and the relatively smaller contribution from parallel elastic tissues. Additionally, heightened extensibility does not appear to be a predisposing factor for reduced muscle stiffness.

Examination of static and dynamic postural stability in individuals with functionally stable and unstable ankles

OBJECTIVE

To determine static and dynamic postural stability differences between functional ankle instability and stable ankle groups.

DESIGN

Subjects were required to balance on a single leg and remain motionless for 20 seconds. After completing 3 trials, they performed a jump-landing test, which required them to jump 50% to 55% of their maximum vertical jump height. They landed on a single leg, stabilized quickly, and remained motionless for 20 seconds.

SETTING

Sports Medicine Research Laboratory.

PARTICIPANTS

Subjects with functional ankle instability (n = 14) who reported at least 2 sprains and "giving way" sensations at their ankle joint within the year prior to testing. Fourteen subjects with no history of ankle sprain injury were matched to subjects with functional ankle instability.

MAIN OUTCOME MEASURES

Anterior/posterior and medial/lateral mean sway quantified static postural stability during single-leg stance. Dynamic postural stability was quantified with anterior/posterior and medial/lateral time to stabilization during single-leg jump landing.

RESULTS

Mean sway was not significantly different between groups in the anterior/posterior (P = 0.28) and medial/lateral (P = 0.65) directions. The functional ankle instability group took significantly longer to stabilize in the anterior/posterior (3.27 +/- 0.72 seconds vs. 2.33 +/- 0.33 seconds; P < 0.001) and medial/lateral (2.48 +/- 0.50 seconds vs. 2.00 +/- 0.65 seconds; P = 0.04) directions.

CONCLUSIONS

Individuals with functional ankle instability took significantly longer to stabilize than individuals with stable ankles after a single-leg jump landing. Differences between groups were not detected with mean sway measured during single-leg stance.

Serial administration of clinical concussion assessments and learning effects in healthy young athletes

OBJECTIVE

To determine if serial administration of the Standardized Assessment of Concussion (SAC) and Balance Error Scoring System (BESS) would elicit a learning effect in young athletes and to determine the intratester reliability of scoring the BESS.

DESIGN

A prospective study of 50 healthy young athletes who were assigned to either the control or practice group. All subjects were administered the assessments on 2 occasions, 60 days apart. In addition, subjects in the practice group received serial administration of the assessments on 3 occasions in the week following the initial assessment.

SETTING

University Sports Medicine/Athletic Training Research Laboratory.

SUBJECTS

Fifty uninjured young athletes between 9 and 14 years of age.

MAIN OUTCOME MEASURED

Scores on 2 clinical concussion assessments, the SAC and the BESS.

RESULTS

We found a significant learning effect upon serial BESS testing in the practice group. BESS error scores were significantly lower than baseline (15.0 +/- 4.6) on days 5 (11.3 +/- 5.33), 7 (12.4 +/- 6.2), and 60 (12.6 +/- 6.2). We also found a significant learning effect upon the day 60 BESS administration across all subjects. We did not find a practice or learning effect with serial SAC test administration. The intratester reliability of the investigator's ability to score repeated observations of the same BESS test ranged from 0.87 to 0.98.

CONCLUSIONS

Our results demonstrated that serial administration of the BESS elicited a learning effect, which was more prominent during the tandem conditions. Clinicians utilizing the BESS as a measure of postural stability should be aware of the potential for improvement with repeated testing. Clinicians should not expect improvement with the SAC, as scores remained relatively stable across all trials.

Sex comparison of extensibility, passive, and active stiffness of the knee flexors

OBJECTIVE

To compare extensibility, and passive and active stiffness of the knee flexors between males and females.

DESIGN

An experimental design utilized 15 males and 15 females to identify sex differences in active extensibility, and active and passive stiffness of the knee flexors.

BACKGROUND

Muscle stiffness appears to contribute to joint stability from both mechanical and neuromuscular perspectives. Differences in knee flexor stiffness may partially explain higher female anterior cruciate ligament injury rates.

METHODS

Active knee flexor extensibility was assessed as subjects extend the knee from a fixed hip position, measuring the final knee position. Passive knee flexor stiffness was calculated as the slope of the moment-angle curve resulting from controlled passive knee extension. Active knee flexor stiffness was assessed by loading the lower extremity with 10% total body mass, and measuring the damping effect of the knee flexors on imposed vibratory motion about the knee joint.

RESULTS

Females displayed greater active extensibility (P<0.05), while males displayed greater active (P<0.05) and passive (P<0.05) knee flexor stiffness. Sex differences in active and passive knee flexor stiffness were not significant following normalization to anthropometric characteristics.

CONCLUSIONS

The knee flexor musculature in males is less extensible and displays greater active and passive stiffness compared to females. However, these differences may be functions of greater mass and height in males.

Acute effects and recovery time following concussion in collegiate football players: the NCAA Concussion Study

CONTEXT

Lack of empirical data on recovery time following sport-related concussion hampers clinical decision making about return to play after injury.

OBJECTIVE

To prospectively measure immediate effects and natural recovery course relating to symptoms, cognitive functioning, and postural stability following sport-related concussion.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study of 1631 football players from 15 US colleges. All players underwent preseason baseline testing on concussion assessment measures in 1999, 2000, and 2001. Ninety-four players with concussion (based on American Academy of Neurology criteria) and 56 noninjured controls underwent assessment of symptoms, cognitive functioning, and postural stability immediately, 3 hours, and 1, 2, 3, 5, 7, and 90 days after injury.

MAIN OUTCOME MEASURES

Scores on the Graded Symptom Checklist (GSC), Standardized Assessment of Concussion (SAC), Balance Error Scoring System (BESS), and a neuropsychological test battery.

RESULTS

No player with concussion was excluded from participation; 79 players with concussion (84%) completed the protocol through day 90. Players with concussion exhibited more severe symptoms (mean GSC score 20.93 [95% confidence interval [CI], 15.65-26.21] points higher than that of controls), cognitive impairment (mean SAC score 2.94 [95% CI, 1.50-4.38] points lower than that of controls), and balance problems (mean BESS score 5.81 [95% CI, -0.67 to 12.30] points higher than that of controls) immediately after concussion. On average, symptoms gradually resolved by day 7 (GSC mean difference, 0.33; 95% CI, -1.41 to 2.06), cognitive functioning improved to baseline levels within 5 to 7 days (day 7 SAC mean difference, -0.03; 95% CI, -1.33 to 1.26), and balance deficits dissipated within 3 to 5 days after injury (day 5 BESS mean difference, -0.31; 95% CI, -3.02 to 2.40). Mild impairments in cognitive processing and verbal memory evident on neuropsychological testing 2 days after concussion resolved by day 7. There were no significant differences in symptoms or functional impairments in the concussion and control groups 90 days after concussion.

CONCLUSIONS

Collegiate football players may require several days for recovery of symptoms, cognitive dysfunction, and postural instability after concussion. Further research is required to determine factors that predict variability in recovery time after concussion. Standardized measurement of postconcussive symptoms, cognitive functioning, and postural stability may enhance clinical management of athletes recovering from concussion.

Cumulative effects associated with recurrent concussion in collegiate football players: the NCAA Concussion Study

CONTEXT

Approximately 300 000 sport-related concussions occur annually in the United States, and the likelihood of serious sequelae may increase with repeated head injury.

OBJECTIVE

To estimate the incidence of concussion and time to recovery after concussion in collegiate football players.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study of 2905 football players from 25 US colleges were tested at preseason baseline in 1999, 2000, and 2001 on a variety of measures and followed up prospectively to ascertain concussion occurrence. Players injured with a concussion were monitored until their concussion symptoms resolved and were followed up for repeat concussions until completion of their collegiate football career or until the end of the 2001 football season.

MAIN OUTCOME MEASURES

Incidence of concussion and repeat concussion; type and duration of symptoms and course of recovery among players who were injured with a concussion during the seasons.

RESULTS

During follow-up of 4251 player-seasons, 184 players (6.3%) had a concussion, and 12 (6.5%) of these players had a repeat concussion within the same season. There was an association between reported number of previous concussions and likelihood of incident concussion. Players reporting a history of 3 or more previous concussions were 3.0 (95% confidence interval, 1.6-5.6) times more likely to have an incident concussion than players with no concussion history. Headache was the most commonly reported symptom at the time of injury (85.2%), and mean overall symptom duration was 82 hours. Slowed recovery was associated with a history of multiple previous concussions (30.0% of those with > or =3 previous concussions had symptoms lasting >1 week compared with 14.6% of those with 1 previous concussion). Of the 12 incident within-season repeat concussions, 11 (91.7%) occurred within 10 days of the first injury, and 9 (75.0%) occurred within 7 days of the first injury.

CONCLUSIONS

Our study suggests that players with a history of previous concussions are more likely to have future concussive injuries than those with no history; 1 in 15 players with a concussion may have additional concussions in the same playing season; and previous concussions may be associated with slower recovery of neurological function.

Exercise Sandals Increase Lower Extremity Electromyographic Activity During Functional Activities

OBJECTIVE: Anecdotal evidence suggests that use of Exercise Sandals results in a number of positive clinical outcomes. However, little research has been conducted to determine their efficacy objectively. Our purposes were to determine the effect of Exercise Sandals on lower leg electromyography (EMG) during activities in the Exercise Sandals and to compare EMG associated with Exercise Sandals with traditional lower extremity rehabilitation exercises. DESIGN AND SETTING: Two within-subjects, repeated-measures designs were used to identify differences in lower extremity EMG: (1) between activities with and without Exercise Sandals and (2) between Exercise Sandals activities and traditional rehabilitation activities. All data were collected in the Sports Medicine Research Laboratory. SUBJECTS: Eighteen subjects involved in rehabilitation using Exercise Sandals for at least 2 weeks within the year before data collection. MEASUREMENTS: Mean EMG amplitudes from the tibialis anterior, peroneus longus, soleus, and lateral gastrocnemius muscles were measured during single-leg stance, side stepping, and "high knees," all performed with and without the Exercise Sandals, as well as single-leg stance on a foam surface and T-band kicks in the sagittal and frontal planes. RESULTS: Exercise Sandals increased lower leg EMG activity, particularly in the ankle invertors and evertors. Also, activities involving the Exercise Sandals resulted in EMG activity similar to or exceeding that associated with traditional ankle-rehabilitation exercises. CONCLUSIONS: These results, coupled with the fact that Exercise Sandals are used in a functional closed kinetic chain manner, suggest that they are an effective means of increasing lower extremity muscle activity.

Assessment of postural stability following sport-related concussion

Despite the increased amount of research being conducted in the area of sport-related concussion, there is still a limited understanding regarding its effect on the injured brain's ability to control motor functions and coordination. This review determines the efficacy of postural stability testing as an adjunct to concussion assessment of athletes. Multiple studies, using both sophisticated force plate technology, as well as those using less sophisticated clinical balance tests, have identified postural stability deficits lasting several days following sport-related concussion. It appears that postural stability testing provides a useful tool for objectively assessing the motor domain of neurologic functioning, and should be considered a reliable and valid adjunct to the assessment of athletes suffering from concussion. Although symptom severity, neurocognitive function, and postural stability are often affected initially following concussion, they are not necessarily related or even affected to the same degree. Each of these should be considered when attempting to make return-to-play decisions following concussion.

One-arm hop test: reliability and effects of arm dominance

STUDY DESIGN

Test-retest reliability analysis and 2-factor ANOVA contrast of athletic group and limb dominance.

OBJECTIVES

To determine the reliability of the one-arm hop test and the effects of upper-extremity dominance on test scores for 2 athletic groups.

BACKGROUND

Limited information is available regarding functional performance tests of the upper extremity that involve axial loading.

METHODS AND MEASURES

Thirteen male collegiate wrestlers (mean age, 20.3 +/- 1.6 years) and 13 male collegiate football players (mean age, 20.0 +/-1.7 years) without upper-extremity pathology participated in the study. Subjects were trained to perform the one-arm hop test, starting from a one-arm push-up position and then hopping as quickly as possible onto and off of a 10.2-cm platform 5 times. Subjects returned to the test site 1 to 2 days later and were timed for 2 trials of the one-arm hop test for each upper extremity.

RESULTS

Within-session ICC2,1 reliability values were 0.78 for the football players and 0.81 for the wrestlers. Mean absolute differences between trials were 0.64 seconds for the football players and 0.47 seconds for the wrestlers. Trial 2 performance times were significantly faster than trial 1 times for the wrestlers. Although performance time for the nondominant side was on average 4.4% slower than that of the dominant side, performance times for the dominant side were not significantly different from those of the nondominant upper extremities.

CONCLUSIONS

The results provide preliminary evidence that the one-arm hop test may be a reliable upper-extremity functional performance test with sufficient training of the subject. Uninjured upper-extremity performance for the one-arm hop test may be useful as a basis for comparing performance of an injured contralateral upper extremity.

No evidence of impaired neurocognitive performance in collegiate soccer players

A high incidence of cerebral concussion has been reported among soccer players. We studied whether long-term or chronic neuropsychological dysfunction was present in collegiate soccer players. Two hundred forty subjects from a National Collegiate Athletic Association division I institution were stratified into three groups: soccer athletes (91), nonsoccer athletes (96 women's field hockey, women's lacrosse, and baseball players), and controls (53 college students). Subjects completed a concussion history questionnaire and underwent preseason baseline neuropsychological testing before the start of either the freshman or sophomore year. Data were collected on the results of six neuropsychological tests and from a concussion history questionnaire for number of previous concussions, Scholastic Aptitude Test results, and exposure to soccer and heading. Despite an average of 15.3 seasons of soccer exposure and a higher prevalence of previous concussions, the soccer athletes did not demonstrate impaired neurocognitive function or scholastic aptitude when compared with the nonsoccer athletes or the student nonathletes. Additionally, there was no significant relationship between a history of soccer-related concussion and either neurocognitive performance or scholastic aptitude. Neither participation in soccer nor a history of soccer-related concussions was associated with impaired performance of neurocognitive function in high-level United States soccer players.

Augmented feedback reduces jump landing forces

STUDY DESIGN

Randomized, experimental design using a 1-way ANCOVA to determine the influence of various forms of feedback on jump landing forces.

OBJECTIVE

To investigate the effects of augmented feedback versus sensory feedback on the reduction of jump landing forces.

BACKGROUND

Several investigators have reported an increased risk of lower extremity injury associated with landing from a jump.

METHODS AND MEASURES

Nonimpaired college students (N=63) were randomly assigned to 1 of 4 feedback groups. Subjects were instructed to perform maximal vertical jumps onto a force plate for 3 testing sessions (baseline, 2-minute post-test, and 1-week post-test). Three feedback groups (augmented, sensory, and control I) were tested during all 3 testing sessions, while a fourth feedback group (control II) was evaluated at only 2 sessions (baseline and 1-week post-test). Subjects in the augmented feedback condition were provided information via video and verbal analysis of how to land softer. Subjects in the sensory feedback condition were asked to use the experience of their baseline jumps to document how they could land softer. Subjects in each of the control groups were not provided any extraneous feedback. Peak vertical ground reaction force data were collected for analysis.

RESULTS

The subjects in the augmented feedback group significantly reduced their peak vertical ground reaction force in both post-test conditions (2-minute post-test reduction, 0.85+/-0.62; 1-week post-test reduction, 0.74+/-0.58) as compared to the sensory, control I, and control II feedback groups.

CONCLUSIONS

High impact landing forces may be reduced by the implementation of augmented feedback information instructing individuals about how to land properly. The reduction of jump landing forces with the use of augmented feedback may prove beneficial in the creation of instructional landing programs.

Postural stability assessment following concussion: one piece of the puzzle

Clinicians regularly assess concussion according to the symptoms that an athlete manifests at the time of injury, as well as during subsequent evaluations. The subjectivity involved with symptom assessment, however, often leaves the clinician without a clear picture of the athlete's true mental status. Neuropsychologic testing has become very popular in the sports medicine community for assessing the cognitive domain of neurologic functioning, and postural stability testing is gaining credence for assessing the motor domain. The objective of this review was to determine the efficacy of postural stability testing as an adjunct to concussion assessment of athletes. Multiple studies, using both sophisticated force plate technology, as well as those using less sophisticated clinical balance tests, have identified postural stability deficits lasting several days following sport-related concussion. It appears that postural stability testing provides a useful tool for objectively assessing the motor domain of neurologic functioning, and should be considered a reliable and valid adjunct to the assessment of athletes suffering from concussion. Although symptom severity, neurocognitive function, and postural stability are often affected initially following concussion, they are not necessarily related or even affected to the same degree.

A Survey of Practice Patterns in Concussion Assessment and Management

OBJECTIVES: To identify methods used by athletic trainers to assess concussions and the use of that information to assist in return-to-play decisions and to determine athletic trainers' familiarity with new standardized methods of concussion assessment. DESIGN AND SETTING: A 21-item questionnaire was distributed to attendees of a minicourse at the 1999 National Athletic Trainers' Association Annual Meeting and Clinical Symposia entitled "Use of Standardized Assessment of Concussion (SAC) in the Immediate Sideline Evaluation of Injured Athletes." SUBJECTS: A total of 339 valid surveys were returned by the attendees of the minicourse. MEASUREMENTS: We used frequency analysis and descriptive statistics. RESULTS: Clinical examination (33%) and a symptom checklist (15.3%) were the most common evaluative tools used to assess concussions. The Colorado Guidelines (28%) were used more than other concussion management guidelines. Athletic trainers (34%) and team physicians (40%) were primarily responsible for making decisions regarding return to play. A large number of respondents (83.5%) believed that the use of a standardized method of concussion assessment provided more information than routine clinical and physical examination alone. CONCLUSIONS: Athletic trainers are using a variety of clinical tools to evaluate concussions in athletes. Clinical evaluation and collaboration with physicians still appear to be the primary methods used for return-to-play decisions. However, athletic trainers are beginning to use standardized methods of concussion to evaluate these injuries and to assist them in assessing the severity of injury and deciding when it is safe to return to play.

Postural Stability and Neuropsychological Deficits After Concussion in Collegiate Athletes

OBJECTIVE: Postural stability and neuropsychological testing are gradually becoming integral parts of postconcussion assessment in athletes. Clinicians, however, sometimes question the viability of instituting preseason baseline testing and the value of these results in making return-to-play decisions. Our purpose was to examine the course of recovery on various postural stability and neuropsychological measures after sport-related concussion. A secondary goal was to determine if loss of consciousness and amnesia, both of which are heavily weighted in most of the concussion classification systems, affect the rate of recovery. DESIGN AND SETTING: All subjects underwent a battery of baseline postural stability and neuropsychological tests before the start of their respective seasons. Any athletes subsequently injured were followed up at postinjury days 1, 3, and 5. Matched control subjects were assessed using the same test battery at the same time intervals. SUBJECTS: We studied 36 Division I collegiate athletes who sustained a concussion and 36 matched control subjects. MEASUREMENTS: We assessed postural stability using the Sensory Organization Test on the NeuroCom Smart Balance Master System and the Balance Error Scoring System. Neurocognitive functioning was measured with several neuropsychological tests: Trail-Making Test, Wechsler Digit Span Test, Stroop Color Word Test, and Hopkins Verbal Learning Test. RESULTS: Injured subjects demonstrated postural stability deficits, as measured on both the Sensory Organization Test and Balance Error Scoring System. These deficits were significantly worse than both preseason scores and matched control subjects' scores on postinjury day 1. Only the results on the Trail-Making Test B and Wechsler Digit Span Test Backward resulted in a logical recovery curve that could explain lowered neuropsychological performance due to concussive injury. Significant differences were revealed between the control and injured groups at day 1 postinjury, but a significant decline between baseline and postinjury scores was not demonstrated. Loss of consciousness and amnesia were not associated with increased deficits or slowed recovery on measures of postural stability or neurocognitive functioning. CONCLUSIONS: Athletes with cerebral concussion demonstrated acute balance deficits, which are likely the result of not using information from the vestibular and visual systems effectively. Neurocognitive deficits are more difficult to identify in the acute stages of concussion, although concentration, working memory, immediate memory recall, and rapid visual processing appear to be mildly affected. More research is necessary to determine the best neuropsychological test battery for assessing sport-related concussion.

Stress fracture of the eighth rib in a female collegiate rower: a case report

OBJECTIVE

To present the case of a stress fracture of the eighth rib in a female collegiate rower.

BACKGROUND

A female collegiate rower experienced severe pain in her chest, increasing with movement, deep breathing, and erect posture. No acute mechanism of injury was apparent. The team physician diagnosed a rib stress reaction based on clinical examination. The athlete rested for 2 days and then was able to resume rowing workouts. Five months later, she experienced the same sharp pain, with the diagnosis and treatment being the same. The athlete was able to compete in the championships 3 weeks later. At the end of the season, a bone scan revealed a stress fracture of the eighth rib. The athlete rested for 3 weeks and then returned to activity.

DIFFERENTIAL DIAGNOSIS

Intercostal muscle strain, serratus anterior muscle strain.

TREATMENT

Active rest, involving pain-free cardiovascular workouts and weight training, cessation of rowing until the athlete was asymptomatic, strengthening of dynamic support structures, and analgesic modalities.

UNIQUENESS

Most stress fractures occur in the lower extremity. Those that do occur in the rib cage most often involve the first rib. A limited number of published works have addressed stress fractures to the remaining ribs; of these, posterior and posterolateral fracture sites are most often reported. This case is unique in that the fracture site was on the anterolateral aspect of the eighth rib.

CONCLUSIONS

Stress fractures are thought to result from a variety of causes, including muscular fatigue, sudden changes in training intensity or duration, and microtrauma to bone at the muscular origin and insertion sites ("wear-and- tear" theory). In addition, hormonal factors in women can predispose an athlete with amenorrhea to a decrease in bone mineral content. Athletic trainers should be aware of these potential causes and focus on the prevention of stress fractures.