Influence of Concussion Education Exposure on Concussion-Related Educational Targets and Self-Reported Concussion Disclosure among First-Year Service Academy Cadets

Introduction

Concussion disclosure is often essential for military personnel to receive appropriate care following concussive injury. Concussion-related education and training may play a role in improving disclosure and recognition among peers, allowing for more timely concussion identification and treatment. The objectives of this study were to: (1) describe concussion education exposure among first-year service academy cadets and (2) examine the association between exposure to concussion education sources (multiple vs. only one) and concussion-related knowledge, attitudes, perceived social norms, intention to disclose symptoms, and disclosure behaviors.

Materials and Methods

First-year service academy cadets completed a cross-sectional survey to assess perceptions of concussion disclosure during preseason concussion baseline testing sessions. Associations between key cadet characteristics and exposure to multiple concussion education sources were examined using odds ratios and 95% confidence intervals. Linear regression was used to model the continuous measures of concussion-related knowledge, attitudes, and perceived social norms. Log-binomial regression was used to model the categorical outcomes of high perceived control over concussion disclosure (higher vs. lower), intention to disclose (higher vs. lower), and disclosure of all possible concussive events at the time of injury (yes vs. no). The primary predictor for all models was exposure to multiple sources of concussion education (video, coach, medical professional, or other) vs. exposure to only one educational source. All models were adjusted for gender, high school contact sport participation, and previous concussion history.

Results

Of the 972 first-year cadets (85% response; age = 18.4 ± 0.9 years; 21.7% female, 29.0% NCAA student-athlete), 695 (71.5%) reported receiving some type of previous concussion education and 229 (23.6%) reported a previous concussion history (206/229 reported the actual number they experienced). Of those reporting previous concussion-related education (n = 695), 542 (78.0%) watched a video, 514 (74.0%) talked with a coach about concussion, 433 (62.3%) talked with a medical professional, and 61 (8.8%) reported other sources of education ranging from anatomy teachers to brochures. Overall, 527 (75.8%) reported receiving more than one source of concussion education. Having played a contact sport in high school and having a history of concussion were associated with having multiple concussion education exposures. Being female was associated with lower odds of multiple exposures. Exposure to multiple sources of concussion education was not associated with knowledge, attitudes, perceived norms, or higher intention to disclose concussion symptoms. However, among those with a concussion history, exposure to multiple sources of concussion education was associated with a nearly 40% higher prevalence of disclosing all concussions at the time of injury compared to only one source of educational exposure (67.1% vs. 48.3%; prevalence ratio = 1.4; 95% confidence interval: 0.9, 2.1). Thus, although multiple sources of education may not influence intermediate variables of knowledge, attitudes, perceived norms and intentions, exposure to multiple sources of concussion education may influence actual decision-making around concussion disclosure among first-year service academy cadets.

Conclusion

These data suggest disparities in concussion education exposure that can be addressed in first-year cadets. Additionally, findings support the importance and use of multiple sources of concussion education in improving cadet’s concussion-related decision-making.

Functional Outcomes After Isolated and Combined Posterior Cruciate Ligament Reconstruction in a Military Population

Background:

The rates of return to full activity, persistent disability, complications, and surgical revisions after operative management of posterior cruciate ligament (PCL) tears in a physically active population have not been reported.

Purpose:

To evaluate the clinical outcomes of active military patients with symptomatic PCL tears who underwent surgical reconstruction and compare outcomes between isolated PCL and multiligament injuries.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Individuals undergoing surgical reconstruction of the PCL (Current Procedural Terminology code 29889) were isolated from the Military Health System Management Analysis and Reporting Tool between fiscal years 2005 and 2010. Demographic variables and rates of postoperative complications, activity limitations, rates of revision surgery, physical disability ratings, and ultimate medical discharge were recorded from the electronic medical record and US Army Physical Disability Agency database.

Results:

A total of 182 patients underwent 193 surgeries, including 118 isolated PCL reconstructions and 75 multiligament knee reconstructions, with an average follow-up of 19.5 months. There were 174 primary procedures and 19 revision reconstructions. The mean ± SD patient age was 28.4 ± 7.2 years, with males comprising 96.2% of patients. The overall surgical complication rate was 12.4%, with a significantly higher rate in multiligament knee reconstructions compared with isolated PCL reconstructions (18.7% vs 8.5%; P = .045). Overall, 35.1% of patients were discharged from military service due to disability. Rates of discharge were significantly higher in those undergoing surgery at lower volume institutions (those that performed <2 PCL reconstructions per year during the study period) than those at higher volume institutions (41.1% vs 26%; P = .040). The overall revision rate was 10.9%, with no significant difference between the isolated PCL and multiligament knee reconstructions. Of the 103 patients with primary isolated PCL reconstructions, 35% underwent medical discharge for persistent knee complaints, and 12.6% required revision PCL reconstruction. The overall failure rate for primary isolated PCL reconstructions, which includes both revision surgery and knee-related medical discharge from military service, was 42.7%.

Conclusion:

In a physically active, military population, nearly one-third of patients were unable to return to previous level of military function, and 12.6% required revision at short-term follow-up due to persistent instability. Perioperative complication rates were significantly higher among patients with multiligament knee reconstructions.

Association Between Running Shoe Characteristics and Lower Extremity Injuries in United States Military Academy Cadets

BACKGROUND

Running-related overuse injuries are very common among recreational runners, with the reported annual injury rates ranging from 39% to 85%. Relatively few large prospective cohort studies have been conducted to investigate injury risk associated with different running shoe characteristics, and the results of the existing studies are often contradictory.

PURPOSE/HYPOTHESIS

The purpose was to investigate the relationship between running shoe characteristics and lower extremity musculoskeletal injury. It was hypothesized that the risk of injury would be increased in individuals wearing shoes with minimal torsional stiffness and heel height compared with those wearing shoes with greater levels of torsional stiffness and heel height.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

The study included 1025 incoming cadets. Shoe torsional stiffness and heel height were calculated and recorded. Demographic data were recorded and analyzed as potential covariates. Lower extremity injuries sustained over 9 weeks during cadet basic training were documented by use of the Armed Forces Health Longitudinal Technology Application and the Cadet Illness and Injury Tracking System. Kaplan-Meier survival curves were estimated, with time to incident lower extremity injury as the primary outcome by level of the independent predictor variables. Risk factors or potential covariates were carried forward into multivariable Cox proportional hazards regression models. Absolute and relative risk reduction and numbers needed to treat were calculated.

RESULTS

Approximately 18.1% of participants incurred a lower extremity injury. Cadets wearing shoes with moderate lateral torsional stiffness were 49% less likely to incur any type of lower extremity injury and 52% less likely to incur an overuse lower extremity injury than cadets wearing shoes with minimal lateral torsional stiffness, both of which were statistically significant observations. Injury risk was similar among cadets wearing shoes with minimal and extreme lateral torsional stiffness.

CONCLUSION

Shoes with mild to moderate lateral torsional stiffness may be appropriate in reducing risk of lower extremity injury in cadets. Shoes with minimal lateral torsional stiffness should be discouraged in this population.

Estimated Age of First Exposure to Contact Sports Is Not Associated with Greater Symptoms or Worse Cognitive Functioning in Male U.S. Service Academy Athletes

This study examined the association between estimated age of first exposure (eAFE) to contact sport participation and neurocognitive performance and symptom ratings in U.S. service academy National Collegiate Athletic Association (NCAA) athletes. Male cadets (N = 891), who participate in lacrosse (n = 211), wrestling (n = 170), ice hockey (n = 81), soccer (n = 119), rugby (n = 10), or non-contact sports (n = 298), completed the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) test before the season. Generalized linear modeling was used to predict each neurocognitive domain score and total symptom severity score. Predictor variables were entered in the following order: group (contact vs. non-contact); eAFE (eAFE <12 years vs. eAFE ≥12 years); group-by-eAFE; and covariates for learning accommodation status, concussion history, and age. The group-by-eAFE interaction was not significant for any of the ImPACT composite scores (Verbal Memory, Wald χ² = 0.073, p = 0.788; Visual Memory, Wald χ² = 2.71, p = 0.100; Visual Motor Speed, Wald χ² = 0.078, p = 0.780; Reaction Time, Wald χ² = 0.003, p = 0.955; Symptom Severity, Wald χ² = 2.87, p = 0.090). Learning accommodation history was associated with lower scores on Visual Motor Speed (χ² = 6.19, p = 0.013, B = -2.97). Older age was associated with faster reaction time (χ² = 4.40, p = 0.036, B = -0.006) and lesser symptom severity (χ² = 5.55, p = 0.019, B = -0.068). No other parameters were significant. We observed no association between eAFE, contact sport participation, neurocognitive functioning, or subjectively experienced symptoms in this cohort. Earlier eAFE to contact sport participation is not related to worse neurocognitive performance or greater subjectively experienced symptoms in male U.S. service academy NCAA athletes.

Increased Glenoid Retroversion Is Associated With Increased Rotator Cuff Strength in the Shoulder

BACKGROUND

The rotator cuff muscles are critical secondary stabilizers in the shoulder. Increased glenoid retroversion and rotator cuff strength have been associated with the risk of posterior shoulder instability; however, the effect of increased glenoid retroversion on rotator cuff strength remains unclear.

PURPOSE/HYPOTHESIS

The purpose was to examine the association between glenoid version and rotator cuff strength in the shoulder in a young and healthy population with no history of shoulder instability. The hypothesis was that increased glenoid retroversion would be associated with increases in rotator cuff muscle strength.

STUDY DESIGN

Cross-sectional study; Level of evidence, 3.

METHODS

A prospective cohort study was conducted over a 4-year period within a high-risk population to identify the risk factors for shoulder instability. Analyzed participants included 574 freshmen entering a United States service academy. Baseline data collected upon entry into the study included magnetic resonance imaging measurements of glenoid version. Rotator cuff strength was also assessed at baseline using a handheld dynamometer. Internal and external rotation strength were assessed with the glenohumeral joint positioned in neutral and in 45° of abduction. The current study represents an analysis of the baseline data from this cohort.

RESULTS

The mean age, height, and weight of participants was 18.77 ± 0.97 years, 176.81 ± 8.48 cm, and 73.80 ± 12.45 kg, respectively. The mean glenoid version at baseline was 7.79°± 4.85° of retroversion. Univariate linear regression analyses demonstrated that increased glenoid retroversion was associated with increased internal and external rotation strength of the rotator cuff in neutral and 45° of abduction (P < .001). Similar results were observed in multivariable models controlling for important confounding variables.

CONCLUSION

The results of this study demonstrate that as glenoid retroversion increases, internal and external rotation strength of the rotator cuff also increase in a young and healthy athletic population. These compensatory changes may contribute to increased glenohumeral dynamic stability in the presence of worse static stability with increasing retroversion.

Pathoanatomy of Shoulder Instability in Collegiate Female Athletes

BACKGROUND

Shoulder instability has been well described in young men; however, few studies have specifically evaluated the pathoanatomy and unique spectrum of injuries in women with shoulder instability.

PURPOSE

To describe the pathoanatomy of operative shoulder instability in a collegiate female cohort.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

The authors performed a retrospective analysis of a consecutive series of female students at a National Collegiate Athletic Association Division I military service academy treated operatively for shoulder instability by a single surgeon between September 2008 and September 2014. Preoperative data collected included patient age, sport, mechanism of injury, number and frequency of dislocations, direction of instability, and co-occurring surgical abnormalities at the time of arthroscopy. Outcome variables included recurrent instability after surgery and need for revision.

RESULTS

Thirty-six female student athletes with an average age of 20 years (range, 18-22 years) were included. The majority of instability events were traumatic in nature (69%), and 61% of the total events were subluxations. Rugby was the most common sport for experiencing instability (7 patients), followed by obstacle course training (6 patients). Thirty-two patients (89%) reported multiple instability events, averaging 4 per shoulder. The primary direction of instability was anterior in 26, combined anterior and posterior in 7, and 3 met criteria for multidirectional instability. At the time of surgery, 26 patients (72%) had a Bankart tear, 9 (25%) had a posterior labral tear, and 5 (14%) had superior labrum anterior to posterior tears. Nine patients (25%) were found to have humeral avulsion of the glenohumeral ligament (HAGL) lesions, 7 (19%) had partial-thickness articular-sided rotator cuff tears, and only 1 patient (3%) had evidence of true attritional glenoid bone loss. Hill-Sachs lesions were found in 16 patients (44%). Recurrent instability occurred in 9 patients (25%) following arthroscopic stabilization, and revision surgery was performed in 6 (17%).

CONCLUSION

Shoulder instability in female athletes presents commonly as multiple subluxation events. While soft tissue Bankart lesions were found in numbers equal to those in previous studies include both sexes, bony Bankart lesions were less common in women. Finally, the presence of combined anterior and posterior labral tears and HAGLs in women was more common than previously reported.

Descriptive Analysis of a Baseline Concussion Battery Among U.S. Service Academy Members: Results from the Concussion Assessment, Research, and Education (CARE) Consortium

Introduction

The prevalence and possible long-term consequences of concussion remain an increasing concern to the U.S. military, particularly as it pertains to maintaining a medically ready force. Baseline testing is being used both in the civilian and military domains to assess concussion injury and recovery. Accurate interpretation of these baseline assessments requires one to consider other influencing factors not related to concussion. To date, there is limited understanding, especially within the military, of what factors influence normative test performance. Given the significant physical and mental demands placed on service academy members (SAM), and their relatively high risk for concussion, it is important to describe demographics and normative profile of SAMs. Furthermore, the absence of available baseline normative data on female and non-varsity SAMs makes interpretation of post-injury assessments challenging. Understanding how individuals perform at baseline, given their unique individual characteristics (e.g., concussion history, sex, competition level), will inform post-concussion assessment and management. Thus, the primary aim of this manuscript is to characterize the SAM population and determine normative values on a concussion baseline testing battery.

Materials and Methods

All data were collected as part of the Concussion Assessment, Research and Education (CARE) Consortium. The baseline test battery included a post-concussion symptom checklist (Sport Concussion Assessment Tool (SCAT), psychological health screening inventory (Brief Symptom Inventory (BSI-18) and neurocognitive evaluation (ImPACT), Balance Error Scoring System (BESS), and Standardized Assessment of Concussion (SAC). Linear regression models were used to examine differences across sexes, competition levels, and varsity contact levels while controlling for academy, freshman status, race, and previous concussion. Zero inflated negative binomial models estimated symptom scores due to the high frequency of zero scores.

Results

Significant, but small, sex effects were observed on the ImPACT visual memory task. While, females performed worse than males (p < 0.0001, pη2 = 0.01), these differences were small and not larger than the effects of the covariates. A similar pattern was observed for competition level on the SAC. There was a small, but significant difference across competition level. SAMs participating in varsity athletics did significantly worse on the SAC compared to SAMs participating in club or intramural athletics (all p's < 0.001, η2 = 0.01). When examining symptom reporting, males were more than two times as likely to report zero symptoms on the SCAT or BSI-18. Intramural SAMs had the highest number of symptoms and severity compared to varsity SAMs (p < 0.0001, Cohen's d < 0.2). Contact level was not associated with SCAT or BSI-18 symptoms among varsity SAMs. Notably, the significant differences across competition level on SCAT and BSI-18 were sub-clinical and had small effect sizes.

Conclusion

The current analyses provide the first baseline concussion battery normative data among SAMs. While statistically significant differences may be observed on baseline tests, the effect sizes for competition and contact levels are very small, indicating that differences are likely not clinically meaningful at baseline. Identifying baseline differences and significant covariates is important for future concussion-related analyses to inform concussion evaluations for all athlete levels.

Level of Agreement Between Human-Rated and Instrumented Balance Error Scoring System Scores

Clinicians have used the Balance Error Scoring System (BESS) to quantify postural control for concussion management. However, the reliability of the human rated BESS has varied prompting the development of instrumented BESSs. A cross-sectional design was used to determine the level of agreement (LOA) between human rated and instrumented BESS scores. Sixty participants completed the BESS on video. An instrumented mat was used to quantify BESS errors while a live human rater simultaneously scored the BESS. A second human rated BESS performance via video. Bland-Altman LOA analyses evaluated agreement between scoring methods (Mat-Human, Mat-Video, Video-Live) for each stance. Mean biases between scores, for each stance, with 95% confidence intervals (95%CIs) were calculated. Agreement between scoring methods was not assessed for the Firm-Double-Limb stance because very few errors were recorded. Agreement between both human raters and the mat was poor based on mean bias estimates > ± 1 and/or wide 95%CIs for all stances including BESS-Total. Agreement between the human raters was better, having displayed consistently smaller mean bias estimates and tighter 95%CIs for all stances and BESS Total. As a result, human rated and instrumented BESS scores may not be comparable. One method should be used to measure BESS errors for consistency.

Use of Patient-Reported Outcome Measures in Athletic Training: Common Measures, Selection Considerations, and Practical Barriers

CONTEXT

Current evidence suggests that a low percentage of athletic trainers (ATs) routinely use patient-reported outcome measures (PROMs). An understanding of the perceptions of ATs who use (AT-USE) and who do not use (AT-NON) PROMs as well as any differences due to demographic characteristics (eg, use for patient care or research, job setting, highest education level) may help facilitate the use of PROMs in athletic training.

OBJECTIVE

To describe commonly used PROMs by AT-USE, the criteria by which AT-USE select PROMs, and reasons for non-use by AT-NON.

DESIGN

Cross-sectional study.

SETTING

Online survey.

PATIENTS OR OTHER PARTICIPANTS

A convenience sample of 1784 ATs (response rate = 10.7% [1784/17972]; completion rate = 92.2% [1784/1935]) who worked in a variety of settings.

MAIN OUTCOME MEASURE(S)

Participants completed an anonymous electronic online survey. Descriptive statistics were used to describe commonly used PROMs, PROM selection criteria, and reasons for PROM non-use.

RESULTS

Participants were classified as AT-USE (n = 370, 20.7%) or AT-NON (n = 1414, 79.3%). For the AT-USE group, the most common type of PROMs used were specific (eg, region, joint; n = 328, 88.6%), followed by single-item (n = 258, 69.7%) and generic (n = 232, 62.7%). Overall, the PROMs most frequently endorsed by the AT-USE group were the Numeric Pain Rating Scale (n = 128, 34.6%); Lower Extremity Functional Scale (n = 108, 29.2%); Disability of the Arm, Shoulder and Hand (n = 96, 25.9%); Owestry Disability Index (n = 80, 21.6%); and Foot and Ankle Ability Measure (n = 78, 21.1%). The most important criteria reported by AT-USE for selecting PROMs were that the measure was valid and reliable, easy for patients to understand, and easy for clinicians to understand and interpret. Common reasons for non-use were that PROMs were too time consuming for the clinician, too time consuming for the patient, and more effort than they were worth.

CONCLUSIONS

The Numeric Pain Rating Scale; Lower Extremity Functional Scale; Disability of the Arm, Shoulder and Hand; Owestry Disability Index; and Foot and Ankle Ability Measure were the PROMs most commonly endorsed by AT-USE and should be considered for athletic training use. To further facilitate the use of PROMs in athletic training, future authors should identify strategies to address organizational and time-constraint obstacles. Interpretation of our study findings may require caution due to a relatively low response rate and because "routine use" was not operationalized.

Prospective Evaluation of Glenoid Bone Loss After First-time and Recurrent Anterior Glenohumeral Instability Events

BACKGROUND

Determining the amount of glenoid bone loss in patients after anterior glenohumeral instability events is critical to guiding appropriate treatment. One of the challenges in treating the shoulder instability of young athletes is the absence of clear data showing the effect of each event.

PURPOSE

To prospectively determine the amount of bone loss associated with a single instability event in the setting of first-time and recurrent instability.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

The authors conducted a prospective cohort study of 714 athletes surveilled for 4 years. Baseline assessment included a subjective history of shoulder instability. Bilateral noncontrast shoulder magnetic resonance imaging (MRI) was obtained for all participants with and without a history of previous shoulder instability. The cohort was prospectively followed during the study period, and those who sustained an anterior glenohumeral instability event were identified. Postinjury MRI with contrast was obtained and compared with the screening MRI. Glenoid width was measured for each patient's pre- and postinjury MRI. The projected total glenoid bone loss was calculated and compared for patients with a history of shoulder instability.

RESULTS

Of the 714 athletes (1428 shoulders) who were prospectively followed during the 4-year period, 22 athletes (23 shoulders) sustained a first-time anterior instability event (5 dislocations, 18 subluxations), and 6 athletes (6 shoulders) with a history of instability sustained a recurrent anterior instability event (1 dislocation, 5 subluxations). On average, there was statistically significant glenoid bone loss (1.84 ± 1.47 mm) after a single instability event ( P < .001), equivalent to 6.8% (95% CI, 4.46%-9.04%; range, 0.71%-17.6%) of the glenoid width. After a first-time instability event, 12 shoulders (52%) demonstrated glenoid bone loss ≥5% and 4 shoulders, ≥13.5%; no shoulders had ≥20% glenoid bone loss. Preexisting glenoid bone loss among patients with a history of instability was 10.2% (95% CI, 1.96%-18.35%; range, 0.6%-21.0%). This bone loss increased to 22.8% (95% CI, 20.53%-25.15%; range, 21.2%-26.0%) after additional instability ( P = .0117). All 6 shoulders with recurrent instability had ≥20% glenoid bone loss.

CONCLUSION

Glenoid bone loss of 6.8% was observed after a first-time anterior instability event. In the setting of recurrent instability, the total calculated glenoid bone loss was 22.8%, with a high prevalence of bony Bankart lesions (5 of 6). The findings of this study support early stabilization of young active patients after a first-time anterior glenohumeral instability event.

Trends in the incidence of physician-diagnosed posttraumatic stress disorder among active-duty U.S. military personnel between 1999 and 2008

BACKGROUND

The impact of combat operations in Iraq and Afghanistan on the incidence of post-traumatic stress disorder (PTSD) in military service members has been poorly quantified. The purpose of this study was to examine trends in the incidence rate of physician-diagnosed PTSD in active-duty military personnel between 1999 and 2008.

METHODS

We conducted a retrospective cohort study utilizing data extracted from the Defense Medical Surveillance System to identify incident cases of PTSD within the study population. The incidence rate of physician-diagnosed PTSD was the primary outcome of interest. Multivariable Poisson regression was used to analyze the data.

RESULTS

The overall incidence rate of PTSD among all active-duty US military personnel was 3.84 (95% CI: 3.81, 3.87) cases per 1000 person-years. The adjusted average annual percentage increase in the incidence rate of PTSD prior to the initiation of Operation Iraqi Freedom (OIF) was a modest 5.02% (95% CI: 1.85, 8.29%). Following the initiation of OIF, the average annual percentage increase in the rate of PTSD was 43.03% (95% CI: 40.55, 45.56%). Compared to the baseline period between 1999 and 2002, the incidence rate of PTSD in 2008 was nearly 7 times higher (RR = 6.85, 95% CI: 6.49, 7.24). Significant increases in the incidence rate of PTSD were observed following the initiation of OIF regardless of sex, age, race, marital status, military rank, or branch of military service. Notably, the rate of PTSD among females was 6-7 times higher prior to OIF, but there was no difference by gender by 2008.

CONCLUSIONS

Overall, these data quantify the significant increase in the incidence rate of PTSD following the initiation of combat operations in Iraq and Afghanistan within the active-duty military population during the study period.

A cohort study to identify and evaluate concussion risk factors across multiple injury settings: findings from the CARE Consortium

Background

Concussion, or mild traumatic brain injury, is a major public health concern affecting 42 million individuals globally each year. However, little is known regarding concussion risk factors across all concussion settings as most concussion research has focused on only sport-related or military-related concussive injuries.

Methods

The current study is part of the Concussion, Assessment, Research, and Education (CARE) Consortium, a multi-site investigation on the natural history of concussion. Cadets at three participating service academies completed annual baseline assessments, which included demographics, medical history, and concussion history, along with the Sport Concussion Assessment Tool (SCAT) symptom checklist and Brief Symptom Inventory (BSI-18). Clinical and research staff recorded the date and injury setting at time of concussion. Generalized mixed models estimated concussion risk with service academy as a random effect. Since concussion was a rare event, the odds ratios were assumed to approximate relative risk.

Results

Beginning in 2014, 10,604 (n = 2421, 22.83% female) cadets enrolled over 3 years. A total of 738 (6.96%) cadets experienced a concussion, 301 (2.84%) concussed cadets were female. Female sex and previous concussion were the most consistent estimators of concussion risk across all concussion settings. Compared to males, females had 2.02 (95% CI: 1.70–2.40) times the risk of a concussion regardless of injury setting, and greater relative risk when the concussion occurred during sport (Odds Ratio (OR): 1.38 95% CI: 1.07–1.78). Previous concussion was associated with 1.98 (95% CI: 1.65–2.37) times increased risk for any incident concussion, and the magnitude was relatively stable across all concussion settings (OR: 1.73 to 2.01). Freshman status was also associated with increased overall concussion risk, but was driven by increased risk for academy training-related concussions (OR: 8.17 95% CI: 5.87–11.37). Medical history of headaches in the past 3 months, diagnosed ADD/ADHD, and BSI-18 Somatization symptoms increased overall concussion risk.

Conclusions

Various demographic and medical history factors are associated with increased concussion risk. While certain factors (e.g. sex and previous concussion) are consistently associated with increased concussion risk, regardless of concussion injury setting, other factors significantly influence concussion risk within specific injury settings. Further research is required to determine whether these risk factors may aid in concussion risk reduction or prevention.

Electronic supplementary material

The online version of this article (10.1186/s40621-018-0178-3) contains supplementary material, which is available to authorized users.

Reference values for the Balance Error Scoring System as measured by the Tekscan MobileMat™ in a physically active population

OBJECTIVES

The Balance Error Scoring System (BESS) is commonly used to measure postural stability; however, it has demonstrated inconsistent reliability values when administered by humans. The Tekscan MobileMat™ was developed to automate the assessment of BESS errors and eliminate rater subjectivity. The objective of this study was to report reference values for the BESS, as measured by the MobileMat™, and examine the effect of sex, concussion history, and competitive sport level on BESS performance.

METHODS

Four hundred and forty participants performed the BESS on the MobileMat™. Participants were asked to maintain each stance with their eyes closed for 20 s. The MobileMat™ was used to quantify the number of errors.

RESULTS

Concussion history (p = 0.279-0.979) and competitive sport level (p = 0.422-0.979) did not affect BESS performance. Males performed significantly better than females for the single-limb foam stance (p = 0.032). No sex differences were detected for the other BESS stances or BESS total score (p = 0.067-0.744).

CONCLUSIONS

Previously reported reference values in collegiate athletes and adolescents were slightly higher thus highlighting the value in establishing population norms and in developing new technologies to objectively quantify BESS performance. Furthermore, sex, concussion history, and competitive sport level do not appear to influence BESS performance as measured by the MobileMat™.

Determinants of intention to disclose concussion symptoms in a population of U.S. military cadets

OBJECTIVES

Non-disclosure of concussion complicates concussion management, but almost nothing is known about non-disclosure in military settings. This study describes concussion disclosure-related knowledge, attitudes, perceived social norms, perceived control, and intention. Additionally, the study identifies determinants of high intention to disclose concussion symptoms.

DESIGN

Cross sectional survey.

METHODS

First-year service academy cadets completed a cross-sectional survey to assess perceptions of concussion disclosure. Independent variables included: gender, race, ethnicity, high school athlete status, NCAA athlete status, previous concussion history, previous concussion education, socioeconomic proxy, concussion-related knowledge, attitudes about concussion, perceived social norms (perceived peer/organizational support and actions), and perceived control over disclosure. Log-binomial regression was used to identify determinants of high intention to disclose concussion symptoms.

RESULTS

A total of 972 first-year military service academy cadets completed the survey [85% response; age=18.4±0.9y]. In the simple models, previous concussion history was associated with lower intention to disclose concussion symptoms. High perceived control over disclosure, higher concussion knowledge, more favorable attitudes and social norms about concussion were associated with high intention to disclose. In the multivariable model, a 10% shift towards more favorable perceived social norms (PR=1.28; p<0.001) and attitudes (PR=1.07; p=0.05) about concussion were associated with high intention to disclose concussion symptoms. High perceived control over disclosure was associated with high intention to disclose concussion symptoms (PR=1.39; p=0.08).

CONCLUSIONS

Concussion-related perceived social norms, attitudes, and perceived control are associated with intention to disclose. Organizationally appropriate intervention strategies can be developed from these data.

Tibial Interference Screw Positioning Relative to the Bone Plug in ACL Reconstruction: A Biomechanical Comparison of Cortical Versus Cancellous-Sided Placement

The biomechanical strength of a bone-patellar tendon-bone graft in the tibia may vary depending on whether the interference screw abuts the cancellous vs the cortical surface of the bone plug. In a porcine model, 10×20-mm bone-patellar tendon-bone grafts were prepared and fixed in a 10-mm diameter tibial tunnel using a 9×25-mm titanium interference screw. The screw was positioned on the cancellous surface of the graft in group A (n=13) vs the cortical side of the graft in group B (n=14). Specimens underwent precycling, cyclic loading, and load-to-failure testing. The mean ultimate failure load was 493±245 N for group A vs 304±145 N for group B (P=.008). Sixty-nine percent of specimens in group A survived 1000 cycles of load testing compared with 21% of specimens in group B. Forty-three percent of specimens in group B sustained intratendinous failure adjacent to the bone plug compared with 15% of specimens in group A. Orientation of the tibial interference screw along the cancellous vs the cortical side of the graft results in superior cyclic loading and ultimate failure load characteristics. Additionally, screw placement along the cortical side may weaken the tendon interface and lead to tendon failure under load. This study indicates that placement of the tibial interference screw along the cancellous side of the graft is biomechanically favorable. However, the clinical ramifications of these findings are not clear. [Orthopedics. 2018; 41(6):337-342.].

Comparison of Head Impact Exposure Between Concussed Football Athletes and Matched Controls: Evidence for a Possible Second Mechanism of Sport-Related Concussion

Studies of football athletes have implicated repetitive head impact exposure in the onset of cognitive and brain structural changes, even in the absence of diagnosed concussion. Those studies imply accumulating damage from successive head impacts reduces tolerance and increases risk for concussion. Support for this premise is that biomechanics of head impacts resulting in concussion are often not remarkable when compared to impacts sustained by athletes without diagnosed concussion. Accordingly, this analysis quantified repetitive head impact exposure in a cohort of 50 concussed NCAA Division I FBS college football athletes compared to controls that were matched for team and position group. The analysis quantified the number of head impacts and risk weighted exposure both on the day of injury and for the season to the date of injury. 43% of concussed athletes had the most severe head impact exposure on the day of injury compared to their matched control group and 46% of concussed athletes had the most severe head impact exposure for the season to the date of injury compared to their matched control group. When accounting for date of injury or season to date of injury, 72% of all concussed athletes had the most or second most severe head impact exposure compared to their matched control group. These trends associating cumulative head impact exposure with concussion onset were stronger for athletes that participated in a greater number of contact activities. For example, 77% of athletes that participated in ten or more days of contact activities had greater head impact exposure than their matched control group. This unique analysis provided further evidence for the role of repetitive head impact exposure as a predisposing factor for the onset of concussion. The clinical implication of these findings supports contemporary trends of limiting head impact exposure for college football athletes during practice activities in an effort to also reduce risk of concussive injury.

Prospective Evaluation of Glenoid Bone Loss After First-Time and Recurrent Anterior Glenohumeral Instability Events

Objectives:

Determining the amount of glenoid bone loss in patients following anterior glenohumeral instability events is critical to guiding appropriate treatment. One of the challenges in managing shoulder instability in young athletes is the absence of clear data showing the impact of each event. The purpose of this study was to prospectively determine the amount of bone loss associated with a single instability event, in the setting of both first-time and recurrent instability.

Methods:

We conducted a prospective cohort study of 714 athletes followed for four years. Baseline assessment included a subjective history of shoulder instability. Bilateral shoulder MRIs were obtained in all participants with and without a history of previous shoulder instability. The cohort was prospectively followed during the study period and those who sustained an anterior glenohumeral instability event were identified. A post-injury MRI was obtained and compared to the screening MRI. Glenoid width was measured for each patient’s pre- and post-injury MRI. The projected total glenoid bone loss was calculated and compared for patients with a prior history of shoulder instability.

Results:

Of the 714 athletes that were prospectively followed during the four-year period, 23 shoulders in 22 subjects sustained a first-time anterior instability event (5 dislocations, 18 subluxations), and six subjects with a previous history of instability sustained a recurrent anterior instability event (1 dislocation, 5 subluxations). On average, there was statistically significant glenoid bone loss (1.84 ± 1.47 mm) following a single instability event (p<0.001), equivalent to 6.8% (95% CI: 4.46%, 9.04%, range 0.71%-17.6%) of the glenoid width. Twelve shoulders (52%) demonstrated glenoid bone loss ≥ 5%, 4 shoulders demonstrated glenoid bone loss ≥13.5% and no shoulders had ≥20% glenoid bone loss after a first-time instability event. Pre-existing glenoid bone loss in subjects with a history of instability was 10.2% (95% CI: 1.96%, 18.35%, range 0.6% - 21.0%). This bone loss increased to 22.8% (95% CI: 20.53%, 25.15%, range 21.2% to 26.0%) following an additional instability event (P=0.0117). All six shoulders with recurrent instability had >20% glenoid bone loss.

Conclusion:

Glenoid bone loss of 6.8% was observed after a first-time anterior instability event. In the setting of recurrent instability, the total calculated glenoid bone loss was 22.8% with a high prevalence of bony Bankart lesions (5/6). The findings of this study support early stabilization of young, active subjects following a first-time anterior glenohumeral instability event. [Figure: see text][Table: see text]

The Impact of Vaccine Refusal on Physician Office Visits During the Subsequent 12 Months

We hypothesized that families who are nonadherent to the routine vaccination schedule (RVS) present less frequently for physician visits. We conducted a retrospective chart review to compare the number of visits made over the subsequent 12-month period by families that refused the RVS versus those who were adherent. Subjects were aged 0 to 4 years, enrolled to Keller Army Hospital, and had a diagnosis indicating the RVS was refused. Age-matched controls, who were adherent to the RVS, were randomly chosen for each case. Subjects made significantly more total visits than CASES: 7 (interquartile range [IQR] = 1-20) versus 6 (IQR = 2-17), p = 0.0049. When each visit type was compared independently, there was no significant difference in the number of acute (p = 0.494) or emergency department (p = 0.077) visits between groups. However, subjects who refused to follow the RVS made significantly fewer routine care visits during the 1-year follow-up period compared to those that adhered to the RVS (p < 0.001).

Change in KOOS and WOMAC Scores in a Young Athletic Population With and Without Anterior Cruciate Ligament Injury

BACKGROUND

Several studies have examined changes in patient-reported outcome measures (PROMs) after anterior cruciate ligament (ACL) injury, but no studies to date have prospectively evaluated changes from preinjury baseline through injury and follow-up among ACL-injured patients compared to the baseline and follow-up changes of uninjured patients.

PURPOSE

To examine changes in PROMs over time from preinjury baseline to at least 2 years after ACL reconstruction and to compare these changes with those of an uninjured control group having similar physical activity requirements.

STUDY DESIGN

Cohort study; Level of evidence, 2.

METHODS

The authors conducted a prospective cohort study with a nested case-control analysis at a US service academy. All incoming first year students were recruited to participate in this study. Consenting participants completed a baseline questionnaire that included the KOOS (Knee injury and Osteoarthritis Outcome Score), WOMAC (Western Ontario and McMaster Universities Osteoarthritis Index), and MARS (Marx Activity Rating Scale). Participants who sustained a subsequent ACL injury completed assessments at the time of surgery and at 6, 12, and 24 months after surgery. Healthy participants were recruited to repeat the baseline assessments within 1 year of graduation. Inter- and intragroup differences at these time points were evaluated with dependent and independent t tests, respectively. We also compared these results with established minimum clinically important difference (MCID) values.

RESULTS

Of 1268 first year students entering the academy, 1005 with no previous injuries consented to participate in this study (82% male, mean ± SD age 19 ± 1 years). Of those enrolled, 30 suffered an ACL injury and met the inclusion criteria for this study. Ninety uninjured control students who met the inclusion criteria completed follow-up assessments. There were statistically significant differences across all KOOS and WOMAC subscales between ACL-injured group and uninjured group at the time of the final follow-up assessment. Four KOOS subscales (Pain, Symptoms, Sports and Recreation Function, and Knee-Related Quality of Life) and the WOMAC Stiffness subscale demonstrated >8-point differences between groups, which exceeded the established MCID for these instruments. There were no significant differences between the ACL-injured group and uninjured groups noted for the MARS ( P = .635). At the time of final follow-up, the ACL-injured group also reported significant deficits on the WOMAC Stiffness subscale ( P = .032), the MARS ( P = .030), and all KOOS subscales, with the exception of Functional Activities of Daily Living, as compared with their preinjury baseline scores. These deficits exceeded the established MCID values for 3 KOOS subscales and the MARS.

CONCLUSION

Patients with ACL injuries reported significant deficits on PROMs at least 2 years after surgical reconstruction in relation to preinjury baseline scores and an uninjured control group. Many of these deficits exceeded established MCID values.