Neuromuscular Control Deficits and the Risk of Subsequent Injury after a Concussion: A Scoping Review

Subsequent musculoskeletal injury after concussion in National Football League players

OBJECTIVE

To assess whether National Football League (NFL) players diagnosed with a concussion have an increased risk of injury after return to football.

METHODS

A retrospective cohort study analysed the hazard of subsequent time-loss lower extremity (LEX) or any musculoskeletal injury among NFL players diagnosed with a concussion in 2015-2021 preseason or regular season games compared with: (1) all non-concussed players participating in the same game and (2) players with time-loss upper extremity injury. Cox proportional hazards models were adjusted for number of injuries and concussions in the prior year, player tenure and roster position. Additional models accounted for time lost from participation after concussion.

RESULTS

There was no statistical difference in the hazards of LEX injury or any musculoskeletal injury among concussed players compared with non-concussed players, though concussed players had a slightly elevated hazard of injury (LEX injury: HR=1.12, 95% CI 0.90 to 1.41; any musculoskeletal injury: HR=1.08, 95% CI: 0.89 to 1.31). When comparing to players with upper extremity injuries, the hazard of injury for concussed players was not statistically different, though HRs suggested a lower injury risk among concussed players (LEX injury: HR=0.78, 95% CI: 0.60 to 1.02; any musculoskeletal injury: HR=0.82, 95% CI: 0.65 to 1.04).

CONCLUSION

We found no statistical difference in the risk of subsequent injury among NFL players returning from concussion compared with non-concussed players in the same game or players returning from upper extremity injury. These results suggest deconditioning or other factors associated with lost participation time may explain subsequent injury risk in concussed players observed in some settings after return to play.

Does Neuromuscular Training Reduce the Risk of Lower-Extremity Musculoskeletal Injury in High School Female Athletes With a History of Sport-Related Concussion?

CONTEXT

There is a well-established increased risk of lower-extremity (LE) musculoskeletal (MSK) injury following a sport-related concussion (SRC). Neuromuscular training programs improve biomechanics associated with LE MSK injury and reduce LE MSK injury incidence, but their relative effectiveness in athletes with history of SRC is unknown. The purpose of this study was to evaluate LE MSK injury incidence in female adolescent athletes with history of SRC following a neuromuscular training intervention.

DESIGN

Prospective case-control.

METHODS

Seventy-seven adolescent female athletes aged 12-18 years who participated in soccer, volleyball, or basketball were recruited from a single institutional sports medicine research and performance center to complete a 6-week neuromuscular training program prior to competitive athletic season. Group (Control, History of SRC) comparisons of athlete exposure and relative LE MSK injury risk and rates during the competitive athletic season were assessed.

RESULTS

Ten injuries were recorded by 9 athletes. Female athletes who reported history of SRC had increased injury risk (Risk Ratio 3.9, 95% CI, 1.1-13.8, P = .01) and increased injury rate (rate ratio 4.1, 95% CI, 1.1-15.8, P = .03) compared with female athletes without history of SRC.

CONCLUSIONS

Female adolescent athletes with history of SRC showed a greater risk of LE MSK injury compared with athletes with no history of SRC. Future work is still needed to understand the underlying mechanisms associated with future LE MSK injury following SRC and interventions that ameliorate elevated injury risk.

The Influence of Induced Head Acceleration on Lower-Extremity Biomechanics during a Cutting Task

Sports-related concussions are caused by one substantial impact or several smaller-magnitude impacts to the head or body that lead to an acceleration of the head, causing shaking of the brain. Athletes with a history of sports-related concussion demonstrate lower-extremity biomechanics during landing tasks that are conducive to elevated injury risk. However, the effect of head acceleration on lower-extremity biomechanics during landing tasks is unknown. Twenty participants were evenly separated into a vertical hopping group and a lateral hopping group. Participants performed several land-and-cut maneuvers before and after a hopping intervention. Vertical head acceleration (g) was measured via an accelerometer during the hopping interventions. Comparisons in head acceleration during the hopping tasks were made between groups. Additionally, kinematic and kinetic variables were compared pre- and post-intervention within groups as well as post-intervention between groups. The vertical hopping group demonstrated greater vertical head acceleration compared to the lateral hopping group (p = 0.04). Additionally, the vertical hopping group demonstrated greater knee abduction angles during landing post-intervention compared to the lateral hopping group (p < 0.000). Inducing head acceleration via continuous hopping had an influence on lower-extremity biomechanics during a landing task.

Playing surface and sport contact status modulate time to lower extremity musculoskeletal injury at a greater level than concussion history among collegiate student-athletes

OBJECTIVES

While previous investigations have demonstrated a positive correlation between previous concussion and risk of subsequent lower extremity musculoskeletal injury (LEMSKI), the effect of sport- and patient-specific factors on time to injury has not been thoroughly described. This study's main objective was to evaluate the relationship between prior concussion and time to LEMSKI among a population of collegiate student-athletes. Secondary objectives were to evaluate the relationship between playing surface, sport contact status, and biologic sex on time to LEMSKI. We hypothesized that those with previous concussions, those competing on synthetic surfaces, and those competing in collision sports would experience decreased latency to LEMSKI overall.

METHODS

A retrospective observational analysis of National Collegiate Athletic Association (NCAA) Division I student-athletes was conducted utilizing a mixed linear model analysis with contrasts. Inclusion criteria included participation in the Pac-12 Health Analytics Program with a documented LEMSKI between 2017 and 2020. Exclusion criteria included concurrent concussion and LEMSKI, injury resulting in serious morbidity or mortality, and incomplete medical record. Participants were classified by whether they sustained a concussion prior to LEMSKI in each athletic season.

RESULTS

Of 1179 athletes included, 1140 had no previous concussion and 37 had a previous concussion. There was no observed effect of previous concussion (F ​= ​0.038; p ​= ​0.846) on time to LEMSKI overall. Student-athletes competing on constructed surfaces sustained a subsequent LEMSKI 14.5 days sooner (SE ​= ​5.255; p ​= ​0.045), and those competing on organic surfaces sustained a subsequent LEMSKI 23.5 days sooner (SE ​= ​4.018; p ​< ​0.001) in the season than those competing on synthetic surfaces. Contact sport student-athletes sustained a subsequent LEMSKI 52.1 days sooner than collision sport student-athletes (SE ​= ​5.248; p ​< ​0.001), and limited contact sport student-athletes sustained a subsequent LEMSKI 42.29 days sooner than collision sport student-athletes (SE ​= ​4.463; p ​< ​0.001). There was no observed effect of biologic sex (F ​= ​0.602; p ​= ​0.438) on time to LEMSKI overall.

CONCLUSION

There was no observed impact of concussion on time on LEMSKI overall in this collegiate athletic population. Contact sports were associated with decreased time to LEMSK, while synthetic surfaces were associated with increased time to LEMSKI in this population. There was no observed impact of biologic sex on time to LEMSKI.

LEVEL OF EVIDENCE

Case-control, level of evidence III.

Cervical spine proprioception and vestibular/oculomotor function: An observational study comparing young adults with and without a concussion history

OBJECTIVE

To investigate dizziness, vestibular/oculomotor symptoms, and cervical spine proprioception among adults with/without a concussion history.

METHODS

Adults ages 18-40 years with/without a concussion history completed: dizziness handicap inventory (DHI), visio-vestibular exam (VVE), and head repositioning accuracy (HRA, assesses cervical spine proprioception). Linear regression models were used to assess relationships between (1) concussion/no concussion history group and VVE, HRA, and DHI, and (2) DHI with HRA and VVE for the concussion history group.

RESULTS

We enrolled 42 participants with concussion history (age = 26.5 ± 4.5 years, 79% female, mean = 1.4± 0.8 years post-concussion) and 46 without (age = 27.0± 3.8 years, 74% female). Concussion history was associated with worse HRA (β = 1.23, 95% confidence interval [CI]: 0.77, 1.68; p < 0.001), more positive VVE subtests (β = 3.01, 95%CI: 2.32, 3.70; p < 0.001), and higher DHI scores (β = 9.79, 95%CI: 6.27, 13.32; p < 0.001) after covariate adjustment. For the concussion history group, number of positive VVE subtests was significantly associated with DHI score (β = 3.78, 95%CI: 2.30, 5.26; p < 0.001) after covariate adjustment, while HRA error was not (β = 1.10, 95%CI: -2.32, 4.51; p = 0.52).

CONCLUSIONS

Vestibular/oculomotor symptom provocation and cervical spine proprioception impairments may persist chronically (i.e., 3 years) after concussion. Assessing dizziness, vestibular/oculomotor and cervical spine function after concussion may inform patient-specific treatments to address ongoing dysfunction.

Trunk and Lower Extremity Biomechanics in Female Athletes With and Without a Concussion History

CONTEXT

Athletes with a history of concussion are at a greater risk for lower extremity musculoskeletal injury. Female athletes may be at an even greater risk than male athletes. Previous researchers on postconcussion landing biomechanics have focused on the lower extremities, but the trunk plays a crucial role as an injury risk factor.

OBJECTIVE

To compare lower extremity and trunk biomechanics during jump-landing and cutting maneuvers between female athletes with and those without a concussion history.

DESIGN

Cross-sectional study.

SETTING

Biomechanics laboratory.

PATIENTS OR OTHER PARTICIPANTS

A total of 26 athletes (mean ± SD age = 19.0 ± 1.3 years, height = 1.68 ± 0.07 m, mass = 64.02 ± 6.76 kg, body mass index = 22.58 ± 1.97 kg/m2; median [interquartile range] time since most recent concussion = 37.5 months [25.0 months, 65.8 months]) with a concussion history and 38 athletes (age = 19.0 ± 1.1 years, height = 1.71 ± 0.08 m, mass = 64.72 ± 9.45 kg, body mass index = 22.14 ± 1.80 kg/m2) without a concussion history.

MAIN OUTCOME MEASURE(S)

Peak kinetics (vertical ground reaction force, vertical loading rate, external knee-abduction moment, and external knee-flexion moment) and kinematics (trunk-flexion angle, trunk lateral-bending angle, ankle-dorsiflexion angle, knee-flexion angle, knee-abduction angle, and hip-flexion angle) were obtained during the eccentric portion of jump-landing and cutting tasks. Separate 2 (group) × 2 (limb) between- and within-factors analyses of covariance were used to compare outcomes between groups. We covaried for time since the most recent concussion and the limb that had a history of musculoskeletal injury.

RESULTS

Athletes with a concussion history displayed a greater peak knee-abduction angle in their nondominant limb than their dominant limb (P = .01, ηp2 = 0.107) and the nondominant limb of athletes without a concussion history (P = .02, ηp2 = 0.083) during jump landing. They also had less trunk lateral bending during cutting compared with athletes without a concussion history (P = .005, ηp2 = 0.126).

CONCLUSIONS

Our results indicated landing biomechanics are different between female athletes with and those without a concussion history. This finding may be due to impairments in neuromuscular control postconcussion that may ultimately increase the risk of subsequent lower extremity injury, although further research is warranted given the cross-sectional nature of our study.

The Influence of Sports-Related Concussion on Cognition and Landing Biomechanics in Collegiate Athletes

Injury surveillance data indicate that collegiate athletes are at greater risk for lower extremity (LE) injuries following sports-related concussion (SRC). While the association between SRC and LE injury appears to be clinically relevant up to 1-year post-SRC, little evidence has been provided to determine possible mechanistic rationales. Thus, we aimed to compare collegiate athletes with a history of SRC to matched controls on biomechanical and cognitive performance measures associated with LE injury risk. Athletes with a history of SRC (n = 20) and matched controls (n = 20) performed unanticipated bilateral land-and-cut tasks and cognitive assessments. Group-based analyses (ANOVA) and predictive modeling (C5.0 decision tree algorithm) were used to compare group differences on biomechanical and cognitive measures. Collegiate athletes with a history of SRC demonstrated approximately six degrees less peak knee flexion on both dominant (p = 0.03, d = 0.71) and nondominant (p = 0.02, d = 0.78) limbs during the land-and-cut tasks compared to controls. Verbal Memory, knee flexion, and Go/No Go total score (C5.0 decision tree algorithm) were identified as the strongest indicators of previous SRC injury history. Reduced knee flexion during sport-specific land-and-cut tasks may be a mechanism for increased LE injury risk in athletes with a history of SRC. There appears to be multiple biomechanical and cognitive predictors for identifying previous SRC in collegiate athletes, providing evidence to support a multifactorial SRC management strategy to reduce future injury risk.

Exercising More Than 150 min/wk After Concussion Is Associated With Sleep Quality Improvements

OBJECTIVE

To examine whether a high volume of aerobic exercise after concussion (>150 min/wk) is associated with improved sleep quality over a 1-month period. We hypothesized that more than 150 min/wk of exercise would be associated with improved sleep quality across concussion recovery.

DESIGN

Prospective cohort observational study.

SETTING

Sports medicine clinic.

PARTICIPANTS

Adolescents initially tested 8.4 ± 3.5 (range, 2-18) days postconcussion who returned for a follow-up assessment 34.3 ± 7.7 (range: 20-49) days postconcussion.

MAIN OUTCOME MEASURES

Participants completed the Pittsburgh Sleep Quality Index and the Post-Concussion Symptom Inventory. No specific exercise or sleep recommendations were given beyond what their treating physician provided. Between study visits, participants recorded exercise performed via wrist-worn actigraphy. We calculated average exercise minutes per week and grouped participants as those who exercised more than 150 min/wk versus those who exercised 150 min/wk or less.

RESULTS

Thirty-six adolescents participated. Fifteen (42%) recorded more than 150 min/wk of aerobic exercise (age = 14.0 ± 1.7 years; 47% female; mean = 5.6 ± 1.2 d/wk of exercise; mean = 49.2 ± 17.5 min/session), and 21 recorded 150 min/wk or less of aerobic exercise (age = 15.0 ± 1.9 years; 76% female; mean = 2.7 ± 1.6 d/wk of exercise; mean = 30.2 ± 7.8 min/session). There were no significant group differences in the proportion of those who self-reported beginning physical activity prior to enrollment (47% vs 33%; P = .42) or for initial sleep quality rating (8.0 ± 3.7 vs 8.6 ± 4.1; P = .67) or initial concussion symptom severity rating (34.9 ± 28.0 vs 42.6 ± 25.9; P = .40). The group that exercised more than 150 min/wk between visits demonstrated significantly greater median PSQI rating improvements than those who exercised 150 min/wk or less, with a large effect size noted (median change [interquartile range] = 5 [3, 7] vs 1 [0, 4]; P = .008; Cohen d = 0.96).

CONCLUSION

Current recommendations suggest that subsymptom aerobic exercise can be beneficial after concussion. Our findings indicate that an exercise volume of more than 150 min/wk led to greater sleep quality improvements than those who exercised below this level.

Objective Clinical Measurement Tools for Functional Evaluation of the Surgical Patient

Following knee surgery, clinicians have traditionally used visually rated or time-based assessments of lower extremity movement quality to measure surgical outcomes, plan rehabilitation interventions, and measure success. These methods of assessment are prone to error and do not fully capture a patient's inefficient movement patterns post surgery. Further, currently available systems which objectively measure kinematics during these tasks are expensive and unidimensional. For these reasons, recent research has called for the development of objective and low-cost precision rehabilitation tools to improve clinical measurement of movement tasks. The purpose of this article is to highlight two such tools and their applications to knee surgery. The systems highlighted within this article are the Mizzou Point-of-Care Assessment System (MPASS) and the Mizzou Knee Arthrometer Testing System (MKATS). MPASS has demonstrated high levels of agreement with the gold-standard Vicon system in measuring kinematics during sit-to-stand (R > 0.71), lateral step-down (intraclass correlation coefficient [ICC] > 0.55, apart from ankle flexion), and drop vertical jump tasks (ICC > 0.62), as well as gait (R > 0.87). MKATS has been used to quantify differences in tibiofemoral motion between groups during lateral step-down, step-up-and-over, and step-up/step-down tasks. Objective measurement of clinical tasks using portable and inexpensive instruments, such as the MPASS and MKATS, can help clinicians identify inefficient movement patterns and asymmetries which may damage and wear down supporting structures within the knee and throughout the kinetic chain causing pain and discomfort. Identifying these issues can help clinicians to plan interventions and measure their progress at a lower cost than currently available systems. The MPASS and MKATS are useful tools which have many applications to knee surgery.

Wearable Loop Sensors for Knee Flexion Monitoring: Dynamic Measurements on Human Subjects

Goals: We have recently introduced a new class of wearable loop sensors for joint flexion monitoring that overcomes limitations in the state-of-the-art. Our previous studies reported a proof-of-concept on a cylindrical phantom limb, under static scenarios and with a rigid sensor. In this work, we evaluate our sensors, for the first time, on human subjects, under dynamic scenarios, using a flexible textile-based prototype tethered to a network analyzer. An untethered version is also presented and validated on phantoms, aiming towards a fully wearable design. Methods: Three dynamic activities (walking, brisk walking, and full flexion/extension, all performed in place) are used to validate the tethered sensor on ten (10) adults. The untethered sensor is validated upon a cylindrical phantom that is bent manually at random speed. A calibration mechanism is developed to derive the sensor-measured angles. These angles are then compared to gold-standard angles simultaneously captured by a light detection and ranging (LiDAR) depth camera using root mean square error (RMSE) and Pearson's correlation coefficient as metrics. Results: We find excellent correlation (≥ 0.981) to gold-standard angles. The sensor achieves an RMSE of 4.463° ± 1.266° for walking, 5.541° ± 2.082° for brisk walking, 3.657° ± 1.815° for full flexion/extension activities, and 0.670° ± 0.366° for the phantom bending test. Conclusion: The tethered sensor achieves similar to slightly higher RMSE as compared to other wearable flexion sensors on human subjects, while the untethered version achieves excellent RMSE on the phantom model. Concurrently, our sensors are reliable over time and injury-safe, and do not obstruct natural movement. Our results set the ground for future improvements in angular resolution and for realizing fully wearable designs, while maintaining the abovementioned advantages over the state-of-the-art.

Relationship between severity of concussion's symptoms and functional performance in children

INTRODUCTION

Concussion is a common brain injury that has significant effects on multiple functional domains in children. However, limited research exists on the relationship between concussion severity and functional performance in this population. This study aimed to examine the relationship between the severity of concussion symptoms and children's balance and functional performance.

METHODS

This cross-sectional study recruited 23 children (9 males and 14 females; mean age 13.9 ± 2.2 years) with clinically diagnosed concussions from a tertiary balance center in 2016. Participants underwent clinical and functional evaluations by specialized physical therapists. Symptom severity was assessed using the Post-Concussion Symptom Scale (PCSS), while functional performance was measured using the Functional Gait Assessment (FGA).

RESULTS

There was a trend suggesting a negative correlation between symptom severity (PCSS) and functional performance (FGA), indicating potentially better performance in individuals with milder symptoms. However, this trend was not significant (rs (21) = -.072, p = 0.744). Furthermore, no significant correlation was found between FGA scores and the severity of individual symptoms.

CONCLUSION

The findings suggest that concussion symptom severity may not be directly related to functional performance in children. Therefore, it is crucial to incorporate functional performance measures alongside symptom assessment for comprehensive concussion management.

Impaired Neuromotor Control During Gait in Concussed Adolescents-A Frequency Analysis

Disruptions in gait function are common after concussion in adolescents; however, the neuromotor control deficits driving these gait disruptions are not well known. Fifteen concussed (age mean [SD]): 17.4 [0.6], 13 females, days since injury: 26.3 [9.9]) and 17 uninjured (age: 18.0 [0.7], 10 females) adolescents completed 3 trials each of single-task gait and dual-task gait (DT). During DT, participants simultaneously walked while completing a serial subtraction task. Gait metrics and variability in instantaneous mean frequency in lower extremity muscles were captured by inertial sensors and surface electromyography, respectively. A 2-way analysis of covariance was used to compare gait metrics across groups and conditions. Functional principal components analysis was used to identify regions of variability in instantaneous mean frequency curves. Functional principal component scores were compared across groups using a Welch statistic. Both groups displayed worse performance on gait metrics during DT condition compared to single-task, with no differences between groups (P < .001). Concussed adolescents displayed significantly greater instantaneous mean frequency, indicated by functional principal component 1, in the tibialis anterior, biceps femoris, and semitendinosus (P < .05) during single-task and DT compared with uninjured adolescents. Our observations suggest that concussed adolescents display inefficient motor unit recruitment lasting longer than 2 weeks following injury, regardless of the addition of a secondary task.

Concussion incidence and mechanisms differ between elite females and males in Australian Football

OBJECTIVES

To investigate the incidence and the game circumstances of concussion in the professional female (AFLW) and male (AFL) competitions of Australian Football, to identify potential targets for risk reduction.

DESIGN

Retrospective cohort.

METHODS

Concussion data were obtained from the AFL injury database, which included all concussions sustained by AFL (Male) players from 2015 to 18 and AFLW (Female) players from 2017 to 19. Concussions were diagnosed by experienced clinicians utilising standardised concussion assessment tools and injury definitions, as well as video review. Video footage was analysed to determine the circumstances each concussion occurred, which included the action and the contact-point of impact.

RESULTS

The incidence of concussion was higher in the AFLW (Female) compared to the AFL (Male) (IRR = 2.12, 95 %CI 1.54 to 2.92). Video footage was available for 194/252 (77 %) concussions in the AFL and 35/44 (80 %) concussions in the AFLW. Male players were most frequently concussed during marking contests (28 %) with primary impact from the upper limb (22 %) or the shoulder (19 %). Conversely, being bumped (23 %) or tackled (20 %) were the main actions associated with concussion in female players, with the head (29 %) or the ground (23 %) the most common contact-points of impact.

CONCLUSIONS

In elite Australian Football a higher incidence of concussion was demonstrated in female compared to male players. The mechanisms associated with concussion were also found to differ between male and female competitions, suggesting that different injury prevention interventions may be beneficial. In particular, a review of tackling and bumping skills training and education in the AFLW may reduce the risk of concussion.

High magnitude exposure to repetitive head impacts alters female adolescent brain activity for lower extremity motor control

Contact and collision sport participation among adolescent athletes has raised concerns about the potential negative effects of cumulative repetitive head impacts (RHIs) on brain function. Impairments from RHIs and sports-related concussions (SRC) may propagate into lingering neuromuscular control. However, the neural mechanisms that link RHIs to altered motor control processes remain unknown. The purpose of this study was to isolate changes in neural activity for a lower extremity motor control task associated with the frequency and magnitude of RHI exposure. A cohort of fifteen high school female soccer players participated in a prospective longitudinal study and underwent pre- and post-season functional magnetic resonance imaging (fMRI). During fMRI, athletes completed simultaneous bilateral ankle, knee, and hip flexion/extension movements against resistance (bilateral leg press) to characterize neural activity associated with lower extremity motor control. RHI data were binned into continuous categories between 20 g - 120 g (defined by progressively greater intervals), with the number of impacts independently modeled within the fMRI analyses. Results revealed that differential exposure to high magnitude RHIs (≥90 g - < 110 g and ≥ 110 g) was associated with acute changes in neural activity for the bilateral leg press (broadly inclusive of motor, visual, and cognitive regions; all p < 0.05 & z > 3.1). Greater exposure to high magnitude RHIs may impair lower extremity motor control through maladaptive neural mechanisms. Future work is warranted to extend these mechanistic findings and examine the linkages between RHI exposure and neural activity as it relates to subsequent neuromuscular control deficits.

Associations Between Prior Head Injury, Physical Functioning, and Frailty in the Atherosclerosis Risk in Communities Study

BACKGROUND

Older adults have the highest rates of head injury and are at the greatest risk for subsequent dysfunction, yet research on subsequent physical decline is limited. We sought to examine cross-sectional and prospective associations of head injury with physical functioning and frailty among older adults.

METHODS

A total of 5 598 Atherosclerosis Risk in Communities Study participants from Visit 5 (2011-13) underwent assessments of physical functioning (Short Physical Performance Battery [SPPB], comprised of gait speed, chair stands, and balance) and frailty (defined using established criteria) were followed through Visit 7 (2018-19). Head injury was self-reported or based on ICD-9 codes. Adjusted linear and multinomial logistic regression models were used to estimate associations. Prospective models incorporated inverse probability of attrition weights to account for death or attrition.

RESULTS

Participants were a mean age of 75 years, 58% were women, 22% were Black, and 27% had a prior head injury. Compared to individuals without head injury, individuals with head injury had worse physical functioning (SPPB total score, β-coefficient = -0.22, 95% CI: -0.35 to -0.09) and were more likely to be pre-frail (OR = 1.19, 95% CI: 1.04 to 1.35) or frail (OR = 1.40, 95% CI: 1.08 to 1.80) compared to robust. Prospectively, head injury was associated with a 0.02 m/s greater decline (95% CI: -0.04 to -0.01) in gait speed over a median of 5 years. Among baseline robust individuals (n = 1 847), head injury was associated with increased odds of becoming pre-frail (OR = 1.32, 95% CI: 1.04 to 1.67) or frail (OR = 1.92, 95% CI: 1.05 to 3.51) compared to robust.

CONCLUSIONS

Older adults with prior head injury had worse physical functioning and greater frailty at baseline and were more likely to become frail and walk slower over time, compared to individuals without head injury.

Normative Values for the Head Shake Sensory Organization Test in an Active Duty Military Cohort

INTRODUCTION

The Head Shake Sensory Organization Test (HS-SOT) assesses postural stability while the head is moving and may also identify deficits in attention associated with the dual task conditions of moving the head at a specified speed while maintaining balance. Normative values for the HS-SOT have not been established in a healthy military population or other highly trained populations such as athletes. Establishing normative values in a military population will enable clinicians to compare the scores of patients with medical conditions that affect postural stability and sensory integration such as concussion or traumatic brain injury, vestibular dysfunction, or migraine to those of a healthy population to determine a need for intervention and for return to duty considerations. The purposes of this cross-sectional study were to establish normative values for the HS-SOT within the military population, to determine whether HS-SOT scores differed between men and women or among age groups, and to determine whether HS-SOT scores differed from scores on similar conditions of the Sensory Organization Test (SOT).

MATERIALS AND METHODS

Active duty service members (n = 237, 54 female) at Joint Base Lewis-McChord, Washington, Fort Campbell, Kentucky, and the National Capitol Region (Washington, D.C, Maryland, and Virginia) completed the SOT and HS-SOT on the NeuroCom® Balance Master™. Parametric and non-parametric comparisons were analyzed for the equilibrium scores for the SOT and HS-SOT conditions 2 (SOT-2, HS-SOT-2, respectively) and 5 (SOT-5, HS-SOT-5, respectively) and the equilibrium score ratios (ESRs) for HS-SOT-2 and HS-SOT-5 for the total sample, men and women, and age group categories (18-26 years, 27-35 years, and 36-45 years).

RESULTS

There were no differences in HS-SOT-2 or HS-SOT-5 equilibrium ratio scores between men (0.99 ±.029 and 0.83 ±0.25, respectively) and women (1.00 ±0.03 and 0.81 ±0.21, respectively). There were no differences in the SOT-2 equilibrium scores (F = 2.29, P = 0.10) or SOT-5 equilibrium scores (Kruskal-Wallis H = 3.26, P = 0.20) among the different age groups. SOT-2 equilibrium scores were higher than the HS-SOT-2 equilibrium scores (Z = -4.10, P < 0.001). SOT-5 equilibrium scores were also higher than HS-SOT-5 equilibrium scores (Z = -12.22, P < 0.001), and the HS-SOT-2 and HS-SOT-5 equilibrium scores differed from each other (Z = -13.26, P < 0.001).

CONCLUSIONS

This study established normative values for the HS-SOT in a military population. Equilibrium scores did not differ between men and women or among age groups, suggesting that these values can be used as reference points for most service members. Postural stability was found to be significantly challenged during head motion, indicating the HS-SOT is a valuable tool for identifying subtle impairments in postural stability. These findings have important implications for early detection and intervention in individuals with medical conditions affecting balance, particularly concussions or vestibular disorders.

Concussion history and virtual reality metrics predict core or lower extremity injury occurrence among high school athletes

Introduction

A history of concussion is recognized as a risk factor for musculoskeletal injury, which is likely associated with physiological effects that warrant better understanding. This study aimed to assess the potential of measurements obtained from an immersive virtual reality (VR) test to identify a subtle perceptual-motor impairment that may be prospectively associated with the occurrence of a core or lower extremity sprain or strain.

Methods

A cohort of 68 high school athletes (41 female soccer players and 27 male football players) provided survey responses and completed an immersive VR test several days prior to the initiation of preseason practice sessions. Measurements of eye, neck, arm, and whole-body displacements were obtained during 40 successive lunging/reaching responses to visual stimuli moving horizontally across the VR headset display. Injury occurrences were electronically documented from the initial preseason practice session to the final game of the season.

Results

A statistically significant and intrinsically credible two-factor prediction model for core or lower extremity injury occurrence included an interaction between female sex and a self-reported history of two or more concussions, along with slow response time (RT) for arm reach (OR = 4.67; 95% CI, 1.51-14.43). Follow-up analyses identified sex-specific cut points for arm reach RT associated with elevated injury risk, which were ≥1.385 s for females and ≥1.257 s for males.

Discussion

High school female soccer players who have sustained more than one concussion appear to be highly vulnerable to core or lower extremity sprain or strain, with the risk of injury compounded by a slow arm reach RT. Male football players as a group demonstrated significantly faster arm reach RT than that of female soccer players, but slow perceptual-motor RT for arm reach was also identified as a potentially important injury risk factor for male players. Immersive VR appears to provide precise measurements of behavioral performance characteristics that depend on brain processing efficiency. Given that the speed, accuracy, and consistency of perceptual-motor responses may be modifiable, future research should explore the potential benefits of VR training for reducing the risk of sport-related injuries.

NCAA football players are at higher risk of upper extremity injury after first-time concussion

BACKGROUND

Previous research has demonstrated that concussions increase the risk of subsequent lower extremity musculoskeletal injury in athletes. However, the risk of upper extremity injury in athletes' post-concussion is poorly understood.

METHODS

All concussed football players within a National Collegiate Athletic Association (NCAA) Division I conference athletic database were identified between 2017 and 2021. After exclusions, each athlete experiencing their first concussion was then retrospectively reviewed for upper extremity injuries in the year prior to their concussion and in the year beginning at 90 days after their concussion. All upper extremity injuries were identified and the odds ratio, 95% confidence interval, and statistical significance between groups were calculated in Microsoft Excel.

RESULTS

160 de-identified football players from a single conference who were first diagnosed with concussions in the seasons from 2017 through 2021 met inclusion criteria. In these athletes the odds of upper extremity injury in year following first diagnosed concussion were 2.36 times higher than in the year prior (95% CI 1.13-4.95, p = 0.02). Shoulder was the most common site of injury with 57.7% of injuries compared to 19.2% in the hand, 15.4% in the elbow, 7.7% in the forearm, and 0% in the wrist.

CONCLUSION

This study demonstrates that collegiate football players are at a 2.36 times greater risk of upper extremity injury in the year following their first diagnosed concussion compared to the year preceding it. The most common site of upper extremity injury after concussion was the shoulder.

LEVEL OF EVIDENCE

III.

Initial investigation of kinesiophobia as a predictor of functional reaction time one year after concussion

Aim

The relationship between post-concussion kinesiophobia and clinical and functional reaction time (RT) beyond clinical recovery remains to be elucidated.

Methods

College-aged participants with (n = 20) and without (n = 20) a concussion history completed patient-reported outcomes, and RT tasks. Kinesiophobia, symptoms and RTs were compared using t-tests. Linear regressions were performed to determine if kinesiophobia predicted RT measures and dual-task cost.

Results

The concussion history group reported higher scores (p < 0.01) for all patient-reported outcomes. We observed significant single-task RT differences between groups (p = 0.013) such that those without a concussion history (m = 0.51s ± 0.08) were faster (m = 0.59s ± 0.12). There were no clinical or dual-task RT differences between groups (p > 0.05). Kinesiophobia significantly predicted single-task RT (R2 = 0.22).

Discussion

Kinesiophobia should be considered when measuring RT.

Instrumented Balance Error Scoring System in Children and Adolescents-A Cross Sectional Study

Background: The Balance Error Scoring System (BESS) is a commonly used method for clinically evaluating balance after traumatic brain injury. The utilization of force plates, characterized by their cost-effectiveness and portability, facilitates the integration of instrumentation into the BESS protocol. Despite the enhanced precision associated with instrumented measures, there remains a need to determine the clinical significance and feasibility of such measures within pediatric cohorts. Objective: To report a comprehensive set of posturographic measures obtained during instrumented BESS and to examine the concurrent validity, reliability, and feasibility of instrumented BESS in the pediatric point of care setting. Methods: Thirty-seven participants (18 female; aged 13.32 ± 3.31 years) performed BESS while standing on a force plate to simultaneously compute stabilometric measures (instrumented BESS). Ellipse area (EA), path length (PL), and sway velocity (VM) were obtained for each of the six BESS positions and compared with the respective BESS scores. Additionally, the effects of sex and age were explored. A second BESS repetition was performed to evaluate the test-retest reliability. Feedback questionnaires were handed out after testing to evaluate the feasibility of the proposed protocol. Results: The BESS total score was 20.81 ± 6.28. While there was no statistically significant age or sex dependency in the BESS results, instrumented posturography demonstrated an age dependency in EA, VM, and PL. The one-leg stance on a soft surface resulted in the highest BESS score (8.38 ± 1.76), EA (218.78 cm2 ± 168.65), PL (4386.91 mm ± 1859.00), and VM (21.93 mm/s ± 9.29). The Spearman's coefficient displayed moderate to high correlations between the EA (rs = 0.429-0.770, p = 0.001-0.009), PL (rs = 0.451-0.809, p = 0.001-0.006), and VM (rs = 0.451-0.809, p = 0.001-0.006) when compared with the BESS scores for all testing positions, except for the one-leg stance on a soft surface. The BESS total score significantly correlated during the first and second repetition (rs = 0.734, p ≤ 0.001), as did errors during the different testing positions (rs = 0.489-0.799, p ≤ 0.001-0.002), except during the two-legged stance on a soft surface. VM and PL correlated significantly in all testing positions (rs = 0.465-0.675, p ≤ 0.001-0.004; (rs = 0.465-0.675, p ≤ 0.001-0.004), as did EA for all positions except for the two-legged stance on a soft surface (rs = 0.392-0.581, p ≤ 0.001-0.016). A total of 92% of participants stated that the instructions for the testing procedure were very well-explained, while 78% of participants enjoyed the balance testing, and 61% of participants could not decide whether the testing was easy or hard to perform. Conclusions: Instrumented posturography may complement clinical assessment in investigating postural control in children and adolescents. While the BESS score only allows for the consideration of a total score approximating postural control, instrumented posturography offers several parameters representing the responsiveness and magnitude of body sway as well as a more differentiated analysis of movement trajectory. Concise instrumented posturography protocols should be developed to augment neuropediatric assessments in cases where a deficiency in postural control is suspected, potentially stemming from disruptions in the processing of visual, proprioceptive, and/or vestibular information.

Wearable Loop Sensor for Bilateral Knee Flexion Monitoring

We have previously reported wearable loop sensors that can accurately monitor knee flexion with unique merits over the state of the art. However, validation to date has been limited to single-leg configurations, discrete flexion angles, and in vitro (phantom-based) experiments. In this work, we take a major step forward to explore the bilateral monitoring of knee flexion angles, in a continuous manner, in vivo. The manuscript provides the theoretical framework of bilateral sensor operation and reports a detailed error analysis that has not been previously reported for wearable loop sensors. This includes the flatness of calibration curves that limits resolution at small angles (such as during walking) as well as the presence of motional electromotive force (EMF) noise at high angular velocities (such as during running). A novel fabrication method for flexible and mechanically robust loops is also introduced. Electromagnetic simulations and phantom-based experimental studies optimize the setup and evaluate feasibility. Proof-of-concept in vivo validation is then conducted for a human subject performing three activities (walking, brisk walking, and running), each lasting 30 s and repeated three times. The results demonstrate a promising root mean square error (RMSE) of less than 3° in most cases.

Sport Type and Risk of Subsequent Injury in Collegiate Athletes Following Concussion: a LIMBIC MATARS Consortium Investigation

OBJECTIVE

To investigate the association between sport type (collision, contact, non-contact) and subsequent injury risk following concussion in collegiate athletes.

MATERIALS AND METHODS

This retrospective chart review of 248 collegiate athletes with diagnosed concussions (age: 20.0 ± 1.4 years; height: 179.6 ± 10.9 cm; mass: 79.0 ± 13.6 kg, 63% male) from NCAA athletic programs (n = 11) occurred between the 2015-2020 athletic seasons. Acute injuries that occurred within six months following concussion were evaluated. Subsequent injuries were grouped by lower extremity, upper extremity, trunk, or concussion. The independent variable was sport type: collision, contact, non-contact. A Cox proportional hazard model was used to assess the risk of subsequent injury between sport types.

RESULTS

Approximately 28% (70/248) of athletes sustained a subsequent acute injury within six months post-concussion. Collision sport athletes had a significantly higher risk of sustaining any injury (HR: 0.41, p < 0.001, 95% CI: 0.28, 0.62), lower extremity (HR: 0.55, p = 0.04, 95% CI: 0.32, 0.97), and upper extremity (HR: 0.41, p = 0.01, 95% CI: 0.20, 0.81) injuries following concussion. No differences between sport types were observed for other injuries.

CONCLUSION

Collision sport athletes had a higher rate of any subsequent injury, lower, and upper extremity injuries following concussion. Future research should focus on sport-specific secondary injury prevention efforts.

A Multifaceted Approach to Interpreting Reaction Time Deficits After Adolescent Concussion

CONTEXT

Reaction time (RT) is a critical element of return to participation (RTP), and impairments have been linked to subsequent injury after a concussion. Current RT assessments have limitations in clinical feasibility and in the identification of subtle deficits after concussion symptom resolution.

OBJECTIVES

To examine the utility of RT measurements (clinical drop stick, simple stimulus-response, single-task Stroop, and dual-task Stroop) to differentiate between adolescents with concussion and uninjured control individuals at initial assessment and RTP.

DESIGN

Prospective cohort study.

SETTING

A pediatric sports medicine center associated with a regional tertiary care hospital.

PATIENTS OR OTHER PARTICIPANTS

Twenty-seven adolescents with a concussion (mean age = 14.8 ± 2.1 years; 52% female; tested 7.0 ± 3.3 days postconcussion) and 21 uninjured control individuals (mean age = 15.5 ± 1.6 years; 48% female).

MAIN OUTCOME MEASURE(S)

Participants completed the Post-Concussion Symptoms Inventory (PCSI) and a battery of RT tests: clinical drop stick, simple stimulus-response, single-task Stroop, and dual-task Stroop.

RESULTS

The concussion group demonstrated slower clinical drop stick (β = 58.8; 95% CI = 29.2, 88.3; P < .001) and dual-task Stroop (β = 464.2; 95% CI = 318.4, 610.0; P < .001) RT measures at the initial assessment than the uninjured control group. At 1-month follow up, the concussion group displayed slower clinical drop stick (238.9 ± 25.9 versus 188.1 ± 21.7 milliseconds; P < .001; d = 2.10), single-task Stroop (1527.8 ± 204.5 versus 1319.8 ± 133.5 milliseconds; P = .001; d = 1.20), and dual-task Stroop (1549.9 ± 264.7 versus 1341.5 ± 114.7 milliseconds; P = .002; d = 1.04) RT than the control group, respectively, while symptom severity was similar between groups (7.4 ± 11.2 versus 5.3 ± 6.5; P = .44; d = 0.24). Classification accuracy and area under the curve (AUC) values were highest for the clinical drop stick (85.1% accuracy, AUC = 0.86, P < .001) and dual-task Stroop (87.2% accuracy, AUC = 0.92, P < .002) RT variables at initial evaluation.

CONCLUSIONS

Adolescents recovering from concussion may have initial RT deficits that persist despite symptom recovery. The clinical drop stick and dual-task Stroop RT measures demonstrated high clinical utility given high classification accuracy, sensitivity, and specificity to detect postconcussion RT deficits and may be considered for initial and RTP assessment.

Estimating the Relationship Between the Symptom-Free Waiting Period and Injury Rates After Return-to-Play from Concussion: A Simulation Analysis Using CARE Consortium Data

BACKGROUND

A key component of return-to-play (RTP) from sport-related concussion is the symptom-free waiting period (SFWP), i.e., the period during which athletes must remain symptom-free before permitting RTP. Yet, the exact relationship between SFWP and post-RTP injury rates is unclear.

OBJECTIVE

We design computational simulations to estimate the relationship between the SFWP and rates of repeat concussion and non-concussion time-loss injury up to 30 days post-RTP for male and female collegiate athletes across 13 sports.

METHODS

We leverage N = 735 female and N = 1,094 male post-injury trajectories from the National Collegiate Athletic Association-Department of Defense Concussion Assessment, Research, and Education Consortium.

RESULTS

With a 6-day SFWP, the mean [95% CI] rate of repeat concussion per 1,000 simulations was greatest in ice hockey for females (20.31, [20.16, 20.46]) and American football for males (24.16, [24.05, 24.28]). Non-concussion time-loss injury rates were greatest in field hockey for females (153.66, [152.59, 154.74]) and wrestling for males (247.34, [246.20, 248.48]). Increasing to a 13-day SFWP, ice hockey for females (18.88, [18.79, 18.98]) and American football for males (23.16, [23.09, 24.22]) exhibit the greatest decrease in repeat concussion rates across all sports within their respective sexes. Field hockey for females (143.24, [142.53, 143.94]) and wrestling for males (237.73, [236.67, 237.90]) exhibit the greatest decrease in non-concussion time-loss injury rates. Males receive marginally smaller reductions in injury rates for increased SFWP compared to females (OR = 1.003, p ≤ 0.002).

CONCLUSION

Longer SFWPs lead to greater reductions in post-RTP injury rates for athletes in higher risk sports. Moreover, SFWPs should be tailored to sport-specific post-RTP injury risks.

Does prior concussion lead to biomechanical alterations associated with lateral ankle sprain and anterior cruciate ligament injury? A systematic review and meta-analysis

OBJECTIVE

To determine whether individuals with a prior concussion exhibit biomechanical alterations in balance, gait and jump-landing tasks with and without cognitive demands that are associated with risk of lateral ankle sprain (LAS) and anterior cruciate ligament (ACL) injury.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Five electronic databases (Web of Science, Scopus, PubMed, SPORTDiscus and CiNAHL) were searched in April 2023.

ELIGIBILITY CRITERIA

Included studies involved (1) concussed participants, (2) outcome measures of spatiotemporal, kinematic or kinetic data and (3) a comparison or the data necessary to compare biomechanical variables between individuals with and without concussion history or before and after a concussion.

RESULTS

Twenty-seven studies were included involving 1544 participants (concussion group (n=757); non-concussion group (n=787)). Individuals with a recent concussion history (within 2 months) had decreased postural stability (g=0.34, 95% CI 0.20 to 0.49, p<0.001) and slower locomotion-related performance (g=0.26, 95% CI 0.11 to 0.41, p<0.001), both of which are associated with LAS injury risk. Furthermore, alterations in frontal plane kinetics (g=0.41, 95% CI 0.03 to 0.79, p=0.033) and sagittal plane kinematics (g=0.30, 95% CI 0.11 to 0.50, p=0.002) were observed in individuals approximately 2 years following concussion, both of which are associated with ACL injury risk. The moderator analyses indicated cognitive demands (ie, working memory, inhibitory control tasks) affected frontal plane kinematics (p=0.009), but not sagittal plane kinematics and locomotion-related performance, between the concussion and non-concussion groups.

CONCLUSION

Following a recent concussion, individuals display decreased postural stability and slower locomotion-related performance, both of which are associated with LAS injury risk. Moreover, individuals within 2 years following a concussion also adopt a more erect landing posture with greater knee internal adduction moment, both of which are associated with ACL injury risk. While adding cognitive demands to jump-landing tasks affected frontal plane kinematics during landing, the altered movement patterns in locomotion and sagittal plane kinematics postconcussion persisted regardless of additional cognitive demands.

PROSPERO REGISTRATION NUMBER

CRD42021248916.

Associations Between Head Injury and Subsequent Risk of Falls: Results From the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND AND OBJECTIVES

Falls are a leading cause of head injury among older adults, but the risk of fall occurring after a head injury is less well-characterized. We sought to examine the association between head injury and subsequent risk of falls requiring hospital care among community-dwelling older adults.

METHODS

This analysis included 13,081 participants in the Atherosclerosis Risk in Communities Study enrolled in 1987-1989 and followed through 2019. The association of head injury (time-varying exposure, self-reported and/or ICD-9/10 code identified) with the risk of subsequent (occurring >1-month after head injury) falls requiring hospital care (ICD-9/10 code defined) was modeled using Cox proportional hazards regression. Secondary analyses included Fine and Gray proportional hazards regression to account for the competing risk of death, analysis of head injury frequency and severity, and formal testing for interaction by age, sex, and race. Models were adjusted for age, sex, race/center, education, military service, alcohol consumption, smoking, diabetes, hypertension, and psychotropic medication use.

RESULTS

The mean age of participants at baseline was 54 years, 58% were female, 28% were Black, and 14% had at least one head injury occurring over the study period. Over a median 23 years of follow-up, 29% of participants had a fall requiring medical care. In adjusted Cox proportional hazards models, individuals with head injury had 2.01 (95% CI 1.85-2.18) times the risk of falls compared with individuals without head injury. Accounting for the competing risk of mortality, individuals with head injury had 1.69 (95% CI 1.57-1.82) times the risk of falls compared with individuals without head injury. We observed stronger associations among men compared with women (men: hazard ratio [HR] = 2.60, 95% CI 2.25-3.00; women: HR = 1.80, 95% CI 1.63-1.99, p-interaction <0.001). We observed evidence of a dose-response association for head injury number and severity with fall risk (1 injury: HR = 1.68, 95% CI 1.53-1.84; 2+ injuries: HR = 2.37, 95% CI 1.92-2.94 and mild: HR = 1.97, 95% CI 1.78-2.18; moderate/severe/penetrating: HR = 2.50, 95% CI 2.06-3.02).

DISCUSSION

Among community-dwelling older adults followed over 30 years, head injury was associated with subsequent falls requiring medical care. We observed stronger associations among men and with increasing number and severity of head injuries. Whether older individuals with head injury might benefit from fall prevention measures should be a focus of future research.

An Absence of Persistent Postural Stability Deficits Following a Sport Concussion in Collegiate Athletes

OBJECTIVE

The purpose of our study was to determine whether persistent postural stability deficits exist in athletes following sport concussion (SC) in comparison with preinjury (baseline) values using Sample Entropy (SampEn).

SETTING

Sports medicine clinic.

PATIENTS OR OTHER PARTICIPANTS

Participants consisted of 71 collegiate athletes (44 male, 27 female) with an average age of 19.9 ± 0.96 years who had a history of 1 concussion that occurred during their time as a collegiate athlete.

DESIGN

In our prospective, cohort design participants completed the Sensory Organization Test (SOT) at baseline, upon reporting symptom-free following a diagnosed SC, and upon establishing a new baseline prior to the start of the subsequent sport season.

MAIN OUTCOME MEASURES

The SOT's condition scores were calculated and analyzed in alignment with the manufacturer's instructions. SampEn was calculated in the anterior-posterior (AP) and medial-lateral (ML) directions from the center-of-pressure oscillations over the 20-second time series for each SOT condition. The SOT and SampEn outcome scores for each condition were analyzed with repeated-measures analyses of variance.

RESULTS

Significant main effects were observed for the SOT's conditions 3 ( F1.6, 114.8 = 7.83, P = .001, η2 = 0.10 [0.02-0.20]), 5 ( F1.8, 126.8 = 11.53, P < .001, η2 = 0.14 [0.04-0.25]), and 6 ( F1.9, 134.5 = 25.11, P < .001, η2 = 0.26 [0.14-0.37]), with significant improvements across time. Significant main effects were also observed for SampEn in the AP direction for conditions 3 ( F2, 140 = 7.59, P = .001, η2 = 0.10 [0.02-0.19]) and 6 ( F2, 140 = 6.22, P = .003, η2 = 0.08 [0.011-0.170]), with significant improvements across time.

CONCLUSIONS

Following a diagnosed SC, our results suggest that collegiate athletes returned if not exceeded baseline values at the symptom-free and new baseline assessments. The application of linear and nonlinear measures of postural stability following a SC yielded similar outcomes in conjunction with a baseline assessment. Our findings support the clinical utility of the baseline SC assessment when evaluating persisting balance deficits when using linear or nonlinear measures.

Neurophysiological and gait outcomes during a dual-task gait assessment in concussed adolescents

BACKGROUND

Gait deficits are common after concussion in adolescents. However, the neurophysiological underpinnings of these gait deficiencies are currently unknown. Thus, the goal of this study was to compare spatiotemporal gait metrics, prefrontal cortical activation, and neural efficiency between concussed adolescents several weeks from injury and uninjured adolescents during a dual-task gait assessment.

METHODS

Fifteen concussed (mean age[SD]: 17.4[0.6], 13 female, days since injury: 26.3[9.9]) and 17 uninjured adolescents (18.0[0.7], 10 female) completed a gait assessment with three conditions repeated thrice: single-task walking, single-task subtraction, and dual-task, which involved walking while completing a subtraction task simultaneously. Gait metrics were measured using an inertial sensor system. Prefrontal cortical activation was captured via functional near-infrared spectroscopy. Neural efficiency was calculated by relating gait metrics to prefrontal cortical activity. Differences between groups and conditions were examined, with corrections for multiple comparisons.

FINDINGS

There were no significant differences in gait metrics between groups. Compared to uninjured adolescents, concussed adolescents displayed significantly greater prefrontal cortical activation during the single-task subtraction (P = 0.01) and dual-task (P = 0.01) conditions with lower neural efficiency based on cadence (P = 0.02), gait cycle duration (P = 0.03), step duration (P = 0.03), and gait speed (P = 0.04) during the dual-task condition.

INTERPRETATION

Our findings suggest that several weeks after injury concussed adolescents demonstrate lower neural efficiency and display a cost to gait performance when cognitive demand is high, e.g., while multitasking, suggesting that the concussed adolescent brain is less able to compensate when attention is divided between two concurrent tasks.

The variability of dual-task walking parameters using in-shoe inertial sensors in nonconcussed individuals: A randomized within-subject repeated measures design

Background and Aims

There is a need for high utility and portability, and cost-effective technologies that are suitable for assessing dual-task gait after experiencing a concussion. Current technologies utilized such as 3D motion capture and force plates are too complex and expensive for most practitioners. The aim of this study was to quantify the variability of dual-task walking gait parameters using in-shoe inertial sensors in nonconcussed individuals.

Methods

This was a randomized within-subject repeated measures design conducted within a sports laboratory. Twenty healthy, uninjured, nonconcussed participants were recruited for this study. Gait variables of interest were measured across three 2-min continuous walking protocols (12 m, 30 m, 1 min out and back) while performing a cognitive task of counting backward in sevens from a randomly generated number between 300 and 500. Testing was completed over three occasions separated by 7 days, for a total of nine walking trials. Participants completed the testing protocols in a randomized, individual order. The primary outcome was to determine the variability of dual-task walking gait parameters using in-shoe inertial sensors in nonconcussed individuals across three protocols.

Results

Three to four participants were allocated to each randomized protocol order. Regarding the absolute consistency (coefficient of variation [CV]) between testing occasions, no gait measure was found to have variability above 6.5%. Relative consistency (intraclass correlation coefficient [ICC]) was acceptable (>0.70) in 95% of the variables of interest, with only three variables < 0.70. Similar variability was found across the three testing protocols.

Conclusion

In-shoe inertial sensors provide a viable option for monitoring gait parameters. This technology is also reliable across different testing distances, thus offering various testing options for practitioners. Further research needs to be conducted to examine the variability with concussed subjects.

Concussion Rehabilitation and the Application of Ten Movement Training Principles

Concussion awareness continues to grow in all aspects of healthcare, including the areas of prevention, acute care, and ongoing rehabilitation. Most of the concussion research to date has focussed on the challenges around screening and diagnosing what can be a complex mix of brain impairments that overlay with additional pre-existing comorbidities. While we expect further progress in concussion diagnosis, progress also continues to be made around proactive rehabilitation, with the emergence of interventions that can enhance the recovery process, maximise function and independence with a return to study, work, and play. Traditionally, optimal multimodal assessments of concussion have treated the physical, cognitive, and psychological domains of brain injury separately, which supports diagnosis, and informs appropriate follow-up care. Due to the complex nature of brain injury, multimodal assessments direct care toward professionals from many different disciplines including medicine, physiotherapy, psychology, neuropsychology, ophthalmology, and exercise physiology. In addition, these professionals may work in different fields such as sports, neurorehabilitation, vestibular, musculoskeletal, community, vocational, and general practice clinical settings. Rehabilitation interventions for concussions employed in practice are also likely to use a blend of theoretical principles from motor control, cognitive, and psychological sciences. This scale of diversity can make information dissemination, collaboration, and innovation challenging. The Ten Movement Training Principles (MTPs) have been proposed as a usable and relevant concept to guide and support clinical reasoning in neurorehabilitation. When applied to concussion rehabilitation, these same 10 principles provide a comprehensive overview of key rehabilitation strategies for current and future practice. Future collaborations can use these training principles to support clinical and research innovations including the rapid rise of technologies in this growing field of rehabilitation practice.

Racial identity and concussion diagnosis and recovery trajectories in collegiate athletes: a LIMBIC MATARS investigation

OBJECTIVE

To determine if there were concussion diagnosis and recovery disparities between collegiate athletes with Black and White racial identities.

DESIGN

Retrospective cohort study.

METHODS

Concussion information was extracted from NCAA athlete medical files at LIMBIC MATARS member institutions from the 2015-16' to 2019-20' academic years. A total of 410 concussions from 9 institutions were included that provided all independent (i.e. racial identity of Black or White) and dependent variable information (i.e. dates of injury, diagnosis, symptom resolution, and return to sport) that were analyzed using Mann-Whitney U tests. The sample consisted of 114 (27.8%) concussions sustained by Black athletes and 296 (72.1%) sustained by White athletes.

RESULTS

The overall sample had a median of 0 days between injury occurrence to diagnosis, 7 days to symptom resolution, and 12 days to return to sport. No significant timing differences were observed for concussion diagnosis (p = .14), symptom resolution (p = .39), or return to sport (p = 0.58) between collegiate athletes with Black versus White racial identities.

CONCLUSIONS

These findings may reflect equitable access to onsite sports medicine healthcare resources that facilitate concussion management in the collegiate sport setting. Future work should explore these associations with a larger and more diverse sample of collegiate athletes.

Validity and Reliability of Methods to Assess Movement Deficiencies Following Concussion: A COSMIN Systematic Review

BACKGROUND

There is an increased risk of subsequent concussion and musculoskeletal injury upon return to play following a sports-related concussion. Whilst there are numerous assessments available for clinicians for diagnosis and during return to play following concussion, many may lack the ability to detect these subclinical changes in function. Currently, there is no consensus or collated sources on the reliability, validity and feasibility of these assessments, which makes it difficult for clinicians and practitioners to select the most appropriate assessment for their needs.

OBJECTIVES

This systematic review aims to (1) consolidate the reliability and validity of motor function assessments across the time course of concussion management and (2) summarise their feasibility for clinicians and other end-users.

METHODS

A systematic search of five databases was conducted. Eligible studies were: (1) original research; (2) full-text English language; (3) peer-reviewed with level III evidence or higher; (4) assessed the validity of lower-limb motor assessments used to diagnose or determine readiness for athletes or military personnel who had sustained a concussion or; (5) assessed the test-retest reliability of lower-limb motor assessments used for concussion management amongst healthy athletes. Acceptable lower-limb motor assessments were dichotomised into instrumented and non-instrumented and then classified into static (stable around a fixed point), dynamic (movement around a fixed point), gait, and other categories. Each study was assessed using the COSMIN checklist to establish methodological and measurement quality.

RESULTS

A total of 1270 records were identified, with 637 duplicates removed. Titles and abstracts of 633 records were analysed, with 158 being retained for full-text review. A total of 67 records were included in this review; 37 records assessed reliability, and 35 records assessed the validity of lower-limb motor assessments. There were 42 different assessments included in the review, with 43% being non-instrumented, subjective assessments. Consistent evidence supported the use of instrumented assessments over non-instrumented, with gait-based assessments demonstrating sufficient reliability and validity compared to static or dynamic assessments.

CONCLUSION

These findings suggest that instrumented, gait-based assessments should be prioritised over static or dynamic balance assessments. The use of laboratory equipment (i.e. 3D motion capture, pressure sensitive walkways) on average exhibited sufficient reliability and validity, yet demonstrate poor feasibility. Further high-quality studies evaluating the reliability and validity of more readily available devices (i.e. inertial measurement units) are needed to fill the gap in current concussion management protocols. Practitioners can use this resource to understand the accuracy and precision of the assessments they have at their disposal to make informed decisions regarding the management of concussion.

TRAIL REGISTRATION

This systematic review was registered on PROSPERO (reg no. CRD42021256298).

Sports-Related Concussion Assessment: A New Physiological, Biomechanical, and Cognitive Methodology Incorporating a Randomized Controlled Trial Study Protocol

BACKGROUND

Taking part in moderate-to-vigorous exercise in contact sports on a regular basis may be linked to an increase in cerebrovascular injury and head trauma. Validated objective measures are lacking in the initial post-event diagnosis of head injury. The exercise style, duration, and intensity may also confound diagnostic indicators. As a result, we propose that the new Interdisciplinary Group in Movement & Performance from Acute & Chronic Head Trauma (IMPACT) analyze a variety of functional (biomechanical and motor control) tests as well as related biochemistry to see how they are affected by contact in sports and head injury. The study's goal will be to look into the performance and physiological changes in rugby players after a game for head trauma and injury.

METHODS

This one-of-a-kind study will use a randomized controlled trial (RCT) utilizing a sport participation group and a non-participation control group. Forty male rugby 7 s players will be recruited for the study and allocated randomly to the experimental groups. The intervention group will participate in three straight rugby matches during a local 7 s rugby event. At the pre-match baseline, demographic and anthropometric data will be collected. This will be followed by the pre-match baseline collection of biochemical, biomechanical, and cognitive-motor task data. After three consecutive matches, the same measures will be taken. During each match, a notational analysis will be undertaken to obtain contact information. All measurements will be taken again 24, 48, and 72 h after the third match.

DISCUSSION

When the number of games increases owing to weariness and/or stressful circumstances, we expect a decline in body movement, coordination, and cognitive-motor tasks. Changes in blood biochemistry are expected to correspond to changes in biomechanics and cognitive-motor processes. This research proposal will generate considerable, ecologically valid data on the occurrence of head trauma events under game conditions, as well as the influence of these events on the biological systems of the performers. This will lead to a greater understanding of how sports participants react to exercise-induced injuries. This study's scope will have far-reaching ramifications for doctors, coaches, managers, scientists, and sports regulatory bodies concerned with the health and well-being of athletic populations at all levels of competition, including all genders and ages.

Characteristics of the Functional Gait Assessment in adolescents with concussion

OBJECTIVES

To assesse the characteristics and validity of the Functional Gait Assessment (FGA). Concussion is a frequent brain injury that affect cognition, balance, and mobility. Prediction of the course of recovery after concussion could be achieved using a multidimensional examination. The FGA has been used to assess balance of individuals with concussion.

METHODS

A prospective cross-sectional study was commenced between 2015-2020 in Pittsburgh, PA, USA, including 27 high schoolers with current complaints of concussion and 86 healthy controls. Participants in both groups provided demographics and completed FGA, Gait Disorientation Test (GDT), and Gait Speed (GS) tests.

RESULTS

The FGA test correlated significantly with the GS and GDT. The FGA score in adolescents with concussion was significantly lower than healthy controls (U=1574.5, p=0.004). An FGA score less than 27 indicated a positive concussion injury with a sensitivity of 0.33 and a specificity of 0.92. The FGA showed a diagnostic odds ratio of 5.64. The positive and the negative likelihood ratios were of 3.03 and 0.54, respectively. For adolescents with concussion, the FGA showed no floor effect; however, a small ceiling effect (11.1%) was observed.

CONCLUSION

The FGA was valid and feasible to assess concussion injuries. It should be noted that a full score on the FGA should not be interpreted as full recovery from a concussion injury.

Mild Quadriceps and Hamstring Strength Deficits Do Not Persist After Sport-Related Concussion

BACKGROUND

Risk for lower extremity musculoskeletal injury increases after sport-related concussion (SRC) and may result from unresolved motor control deficits. Muscle weakness is a deficit that could contribute to musculoskeletal injury risk.

HYPOTHESIS

Athletes with SRC will demonstrate quadriceps and hamstring muscle weakness at the time of return to sport and 30 days later compared with controls.

STUDY DESIGN

Prospective matched cohort.

LEVEL OF EVIDENCE

Level 3.

METHODS

A total of 31 athletes with SRC (CONCUSSION) were matched by sex, age, and activity level to controls (CONTROL). Testing was conducted at initial assessment and 30 days later; initial assessment in CONCUSSION occurred when cleared for return to play. Isokinetic testing assessed quadriceps and hamstring strength of the dominant and nondominant legs at 60 and 180 deg/s. Peak torque values were normalized to body mass (N-m/kg). Data were analyzed with repeated measures general linear models (group × time), and effect sizes were calculated.

RESULTS

Analysis at 60 deg/s included 26 matched pairs (15 male per group) and at 180 deg/s included 30 matched pairs (17 males per group). Time from concussion to initial assessment was 21.3 (7.8) mean (standard deviation) days. No significant interactions or main effects were detected (P > 0.05). Across muscle groups, legs, and testing speeds, effect sizes at initial assessment were small (d = 0.117 to 0.353), equating to a strength deficit in CONCUSSION of 0.04 to 0.18 N-m/kg, and effect sizes were further reduced at 30-day follow-up (d = -0.191 to 0.252).

CONCLUSION

In athletes with SRC, quadriceps and hamstring strength were decreased only minimally at return to play compared with controls and the difference lessened over 30 days.

CLINICAL RELEVANCE

Strength deficits may not be a major contributor to increased lower extremity musculoskeletal injury risk after SRC. Strength training could be implemented before return to play after SRC to mitigate any strength deficits.

Rethinking recovery in adolescent concussions: Network-level functional connectivity alterations associated with motor deficits

Adolescents who are clinically recovered from concussion continue to show subtle motor impairment on neurophysiological and behavioral measures. However, there is limited information on brain-behavior relationships of persistent motor impairment following clinical recovery from concussion. We examined the relationship between subtle motor performance and functional connectivity of the brain in adolescents with a history of concussion, status post-symptom resolution, and subjective return to baseline. Participants included 27 adolescents who were clinically recovered from concussion and 29 never-concussed, typically developing controls (10-17 years); all participants were examined using the Physical and Neurologic Examination of Subtle Signs (PANESS). Functional connectivity between the default mode network (DMN) or dorsal attention network (DAN) and regions of interest within the motor network was assessed using resting-state functional magnetic resonance imaging (rsfMRI). Compared to controls, adolescents clinically recovered from concussion showed greater subtle motor deficits as evaluated by the PANESS and increased connectivity between the DMN and left lateral premotor cortex. DMN to left lateral premotor cortex connectivity was significantly correlated with the total PANESS score, with more atypical connectivity associated with more motor abnormalities. This suggests that altered functional connectivity of the brain may underlie subtle motor deficits in adolescents who have clinically recovered from concussion. More investigation is required to understand the persistence and longer-term clinical relevance of altered functional connectivity and associated subtle motor deficits to inform whether functional connectivity may serve as an important biomarker related to longer-term outcomes after clinical recovery from concussion.

The Identification and Comparison of Factors Affecting Musculoskeletal and Concussion Injury Disclosure

CONTEXT

Despite the increased risk of musculoskeletal (MSK) injury after a concussion, little is known about the determinants of such a risk. Moreover, the authors of previous reports of increased risk of MSK injury after a concussion have neglected to account for the high level of undisclosed concussions.

OBJECTIVE

To explore the association between the intention to disclose a possible concussion and the intention to disclose an MSK injury.

DESIGN

Cross-sectional study.

SETTING

Online survey.

PATIENTS OR OTHER PARTICIPANTS

One hundred seven National Collegiate Athletic Association Division I athletes (females = 79%, age = 19.4 ± 1.4 years).

MAIN OUTCOME MEASURE(S)

Online survey exploring determinants such as injury knowledge, attitudes, perceived social norms, and perceived behavioral control surrounding concussive and MSK injury disclosure.

RESULTS

A significant association between high intention to disclose a concussion and high intention to disclose an MSK injury (χ2 = 19.276, P < .001, Cramer V = 0.482) was observed. Spearman rank correlations suggested no correlation between concussion nondisclosure (25%) and MSK injury nondisclosure (52%). Multivariate binomial regressions indicated that perceived social norms were the strongest determinant (β = 1.365, P = .002) of high intention to disclose concussion, while attitudes toward MSK injury (β = 1.067, P = .005) and perceived social norms (β = 1.099, P = .013) were the strongest determinants of high intention to report MSK injury.

CONCLUSIONS

Individuals with high intention to report concussion symptoms also demonstrated high intention to report MSK injury. Strong positive associations were seen between known determinants of intention to disclose concussion and adapted versions of those same determinant domains in intention to disclose MSK injury. As those with high intention to disclose concussion also displayed high intention to disclose MSK injury, intention to disclose injuries generally may play a role in explaining the increase in MSK injury after a concussion.

Risk of Upper Extremity Musculoskeletal Injury Within the First Year After a Concussion

Background

Emerging evidence suggests that athletes and military personnel are at increased risk for lower extremity musculoskeletal injury after a concussion; however, the association between concussion and subsequent upper extremity (UE) musculoskeletal injury is unknown.

Purpose

To prospectively examine the association between concussion and UE musculoskeletal injury risk within the first year after returning to unrestricted activity.

Study Design

Cohort study; Level of evidence, 3.

Methods

A total of 316 cases of concussion 42% (132/316 women) were observed among 5660 Concussion Assessment, Research and Education Consortium participants at the United States Military Academy from May 2015 to June 2018. Active injury surveillance within the cohort was conducted for 12 months after unrestricted return to activity to identify any incident cases of acute UE musculoskeletal injury. Injury surveillance during the follow-up period was also conducted for nonconcussed controls who were matched by sex and competitive sport level. Univariate and multivariable Cox proportional hazards regression models were used to estimate hazard ratios between concussed cases and nonconcussed controls for time to UE musculoskeletal injury.

Results

During the surveillance period, 19.3% of concussed cases and 9.2% of nonconcussed controls sustained a UE injury. In the univariate model, concussed cases were 2.25 times (95% CI, 1.45-3.51) more likely to sustain a UE injury during the 12-month follow-up period when compared with the nonconcussed controls. In the multivariable model, adjusted for history of concussion, sport level, somatization, and history of UE injury, concussed cases were 1.84 times (95% CI, 1.10-3.07) more likely to sustain a UE injury during the surveillance period compared with nonconcussed controls. Sport level remained an independent risk factor for UE musculoskeletal injury; however, concussion history, somatization, and history of UE injury were not independent risk factors.

Conclusion

Concussed cases were more than twice as likely to sustain an acute UE musculoskeletal injury within the first 12 months after unrestricted return to activity when compared with nonconcussed controls. The higher hazard of injury remained in the concussed group after adjusting for other potential risk factors.

Demographic Factors and Instantaneous Lower Extremity Injury Occurrence in a National Collegiate Athletic Association Division I Population

CONTEXT

Temporal prediction of the lower extremity (LE) injury risk will benefit clinicians by allowing them to better leverage limited resources and target those athletes most at risk.

OBJECTIVE

To characterize the instantaneous risk of LE injury by demographic factors of sex, sport, body mass index (BMI), and injury history.

DESIGN

Descriptive epidemiologic study.

SETTING

National Collegiate Athletic Association Division I athletic program.

PATIENTS OR OTHER PARTICIPANTS

A total of 278 National Collegiate Athletic Association Division I varsity student-athletes (119 males, 159 females; age = 19.07 ± 1.21 years, height = 175.48 ± 11.06 cm, mass = 72.24 ± 12.87 kg).

MAIN OUTCOME MEASURE(S)

Injuries to the LE were tracked for 237 ± 235 consecutive days. Sex-stratified univariate Cox regression models were used to investigate the association between time to first LE injury and sport, BMI, and LE injury history. The instantaneous LE injury risk was defined as the injury risk at any given point in time after the baseline measurement. Relative risk ratios and Kaplan-Meier curves were generated. Variables identified in the univariate analysis were included in a multivariate Cox regression model.

RESULTS

Female athletes displayed similar instantaneous LE injury risk to male athletes (hazard ratio [HR] = 1.29; 95% CI= 0.91, 1.83; P = .16). Overweight athletes (BMI >25 kg/m2) had similar instantaneous LE injury risk compared with athletes with a BMI of <25 kg/m2 (HR = 1.23; 95% CI = 0.84, 1.82; P = .29). Athletes with previous LE injuries were not more likely to sustain subsequent LE injury than athletes with no previous injury (HR = 1.09; 95% CI = 0.76, 1.54; P = .64). Basketball (HR = 3.12; 95% CI = 1.51, 6.44; P = .002) and soccer (HR = 2.78; 95% CI = 1.46, 5.31; P = .002) athletes had a higher risk of LE injury than cross-country athletes. In the multivariate model, instantaneous LE injury risk was greater in female than in male athletes (HR = 1.55; 95% CI = 1.00, 2.39; P = .05), and it was greater in male athletes with a BMI of >25 kg/m2 than that in all other athletes (HR = 0.44; 95% CI = 0.19, 1.00; P = .05), but these findings were not significantly different.

CONCLUSIONS

In a collegiate athlete population, previous LE injury was not a contributor to the risk of future LE injury, whereas being female or being male with a BMI of >25 kg/m2 resulted in an increased risk of LE injury. Clinicians can use these data to extrapolate the LE injury risk occurrence to specific populations.

Clinical Mental Health Measures and Prediction of Postconcussion Musculoskeletal Injury

CONTEXT

The rate of lower extremity musculoskeletal injury (LE MSK) is elevated after concussion; however, the underlying mechanism has not been elucidated. Physical characteristics have been investigated despite poorer mental health being a common postconcussion complaint and linked to MSKs.

OBJECTIVE

To evaluate the role of mental health as a predictor of postconcussion LE MSK.

DESIGN

Case-control study.

SETTING

Intercollegiate athletic training facility.

PATIENTS OR OTHER PARTICIPANTS

A total of 67 National Collegiate Athletic Association Division I student-athletes (n = 39 females) who had been diagnosed with a sport-related concussion.

MAIN OUTCOME MEASURE(S)

The Brief Symptom Inventory-18, Hospital Anxiety and Depression Scale, and Satisfaction With Life Scale (SWLS) measures were completed at baseline (preseason) and on the day participants were cleared for unrestricted return to play (RTP) after a concussion. Two binary logistic regressions were used to predict postconcussion LE MSK within a year, one for the baseline time point and the second for the RTP time point. A 2 (group: LE MSK, no LE MSK)-by-2 (time: baseline, RTP) repeated-measures analysis of variance compared performance between baseline and RTP.

RESULTS

Subsequent LE MSKs were sustained by 44 participants (65.7%). The only significant predictor of postconcussion LE MSK was the SWLS score at RTP, with Exp(B) = 0.64, indicating that an increased (improved) SWLS score was associated with a lower LE MSK rate. No significant interactions were present between mental health measures and subsequent MSK (P values = .105-.885).

CONCLUSIONS

Limited associations were evident between postconcussion LE MSK and scores on commonly used measures of anxiety, depression, and satisfaction with life. Reported increased satisfaction with life was associated with a decreased injury risk, which warrants further attention. Our results suggest that these measures of anxiety, depression, and satisfaction with life have limited value in assisting sports medicine clinicians with determining which student-athletes are at elevated risk of postconcussion LE MSK.

Concussion history is associated with increased lower-extremity injury incidence in Reserve Officers' Training Corps cadets

INTRODUCTION

Concussions have been associated with an increased risk of lower-extremity musculoskeletal injury (LE-MSI) in athletes and US Army soldiers, creating an added economic, physical and social burden. Yet, there is a paucity of evidence on this relationship among Reserve Officers' Training Corps (ROTC) cadets, a group which engages in activities with high-injury risk and will subsequently commission as active duty officers. This study aimed to examine the association between concussions and LE-MSI in ROTC cadets.

METHODS

125 (83 were male) Army and Air Force ROTC cadets (19.8±2.0 years) from two large state universities' Army and Air Force ROTC programmes participated in this study. Cadets completed a reliable injury history questionnaire to ascertain the following variables of interest: (1) any concussion history, (2) reported concussions, (3) undiagnosed concussions, and (4) potentially unrecognised concussion history and LE-MSI history (eg, ankle sprain, knee sprain or muscle strain). Data were analysed using a χ² test for association and binary logistic regression to determine ORs.

RESULTS

Cadets with any concussion history (n=42) had a significantly (p=0.035) higher association with LE-MSI (OR 2.47, 95% CI 1.05 to 5.83) than those without. Cadets who had a reported concussion (n=33) had a significantly (p=0.026) higher association with LE-MSI (OR 2.95, 95% CI 1.11 to 7.84) compared to cadets without.

CONCLUSIONS

ROTC cadets with a history of diagnosed concussion were more likely to have suffered an LE-MSI than cadets without a concussion history. ROTC cadre should be aware of this relationship and incorporate injury prevention protocols.

The impact of concussion on subsequent injury risk in elite junior Australian football athletes

OBJECTIVES

Concussion increases injury risk. However, this has not been investigated in junior Australian football and it is unknown whether the location, severity, and mechanism of subsequent injuries differ after concussion vs. non-concussion injury.

DESIGN

Prospective cohort.

METHODS

1455 elite adolescent male Australian footballers were tracked across seven seasons to determine whether subsequent injury risk was greater after concussion compared to non-concussion index injury using multilevel survival analysis. Mixed-effects logistic regression compared location and mechanism. Mixed-effects Poisson regression compared severity.

RESULTS

Of 1455 athletes, 632 were injured and included in subsequent-injury analysis. There were no differences in injury incidence after a concussion compared to upper- (hazard ratio = 1.0, 0.6 to 1.9, P = 0.892; trivial effect) and lower (hazard ratio = 1.1, 0.6 to 1.9, P = 0.810; trivial effect) index injury, or in location. Subsequent injuries were more likely to be contact-based after a non-concussion injury than concussion (odds ratio = 4.6, 1.3 to 16.0; P = 0.017; large effect). There was no difference in subsequent injury severity after lower- (3.4 ± 3.0 missed matches; incidence rate ratio = 1.4, 0.9 to 2.1; P ≤ 0.117; small effect) and upper-limb injuries (3.4 ± 3.1 missed matches; incidence rate ratio = 1.4, 0.9 to 2.2; P = 0.189; small effect) compared to concussion (2.4 ± 2.0 missed matches).

CONCLUSIONS

Subsequent injury risk, severity, and location in junior Australian football are similar following concussion compared to non-concussion index injuries, although contact injuries are less likely.

Investigating post-mild traumatic brain injury neuromuscular function and musculoskeletal injury risk: A protocol for a prospective, observational, case-controlled study in service members and active individuals

INTRODUCTION

Musculoskeletal injury (MSKI) risk is increased following mild traumatic brain injury (mTBI). Increased MSKI risk is present up to 2 years following post-mTBI return-to-duty/activity relative to both non-mTBI peers and to their pre-mTBI selves across a range of populations, including military service members, and professional, college and high school athletes. Despite the well documented increased post-mTBI MSKI risk, the underlying neuromuscular mechanisms contributing to this increased risk have yet to be definitively determined. A number of potential mechanisms have been suggested (eg, aberrant kinematics, dynamic balance impairments, lower voluntary muscle activation), but none have been confirmed with a comprehensive, prospective study. This study aims to: (1) elucidate the neuromuscular control mechanisms following mTBI that contribute to increased MSKI risk, and (2) prospectively track patient outcomes (up to 12 months; MSKI occurrences and patient-reported outcomes (PRO)).

METHODS AND ANALYSIS

This is a multicentre prospective, case-matched control observational study to identify deficiencies in neuromuscular function following mTBI that may contribute to increased MSKI risk. Participants (aim to recruit 148, complete data collection on 124) will be classified into two cohorts; mTBI and control. All participants will undergo longitudinal (initial, 6 weeks post-initial, 12 weeks post-initial) comprehensive three-dimensional biomechanical (jump-landing; single leg hop; cut; gait), neuromuscular (interpolated twitch technique, muscular ramp contraction) and sensory (joint repositioning; light touch sensation) assessments to elucidate the underlying neuromuscular control mechanisms post-mTBI that may contribute to increased MSKI. Occurrences of MSKI and PROs (National Institutes of Health Patient-Reported Outcome Measurement Information System: Physical Function, Pain Interference, Depression, Anxiety; Brief Resilience Scale; Tampa Scale of Kinesiophobia), will be tracked monthly (up to 1 year) via electronic data capture platforms.

ETHICS AND DISSEMINATION

The study received approval from the Walter Reed National Military Medical Center Institutional Review Board. Results will be made available to the associated funding agency and other researchers via conference proceedings and journal articles.

TRIAL REGISTRATION NUMBER

NCT05122728.

Methodological Critique of Concussive and Non-Concussive Dual Task Walking Assessments: A Scoping Review

OBJECTIVE

To understand the methodological approaches taken by various research groups and determine the kinematic variables that could consistently and reliably differentiate between concussed and non-concussed individuals.

METHODS

MEDLINE via PubMed, CINAHL Complete via EBSCO, EBSCOhost, SPORTDiscus, and Scopus were searched from inception until 31 December 2021, using key terms related to concussion, mild traumatic brain injury, gait, cognition and dual task. Studies that reported spatiotemporal kinematic outcomes were included. Data were extracted using a customised spreadsheet, including detailed information on participant characteristics, assessment protocols, equipment used, and outcomes.

RESULTS

Twenty-three studies involving 1030 participants met the inclusion criteria. Ten outcome measures were reported across these articles. Some metrics such as gait velocity and stride length may be promising but are limited by the status of the current research; the majority of the reported variables were not sensitive enough across technologies to consistently differentiate between concussed and non-concussed individuals. Understanding variable sensitivity was made more difficult given the absence of any reporting of reliability of the protocols and variables in the respective studies.

CONCLUSION

Given the current status of the literature and the methodologies reviewed, there would seem little consensus on which gait parameters are best to determine return to play readiness after concussion. There is potential in this area for such technologies and protocols to be utilised as a tool for identifying and monitoring concussion; however, improving understanding of the variability and validity of technologies and protocols underpins the suggested directions of future research. Inertial measurement units appear to be the most promising technology in this aspect and should guide the focus of future research.

IMPACT

Results of this study may have an impact on what technology is chosen and may be utilised to assist with concussion diagnosis and return to play protocols.

Do Sports-related Concussions Induce Subsequent Injuries in Elite Male Football Players?

To assess the players' risk of a subsequent injury after sustaining concussive injuries and their return-to-competition in German professional men's football. A prospective injury database in the 1^st Bundesliga was created encompassing 7 seasons (2014/15-2020/21). Cox proportional hazard model analyzed whether a concussive injury increased the risk of a subsequent injury in the first year after the index injury. 6,651 injuries were reported (n=182 concussive injuries). The incidence rate was 0.15 (95% CI 0.13-0.17) per 1000 football hours. A concussive injury was associated with only a slightly numerical higher risk of 7% (HR=1.07, 95% CI 0.78-1.47) in the subsequent year after the injury compared to a randomly selected non-concussive injury, but the effect was not significant. The risk was higher after 6-12 months post-SRC reaching 70% (HR=1.70, 95% CI 1.15-2.52). For 0-3 months (HR=0.76, 95% CI 0.48-1.20) and 3-6 months (HR=0.97, 95% CI 0.62-1.50) the injury risk was lower. The present data do not confirm previously published investigations about an increased injury risk after SRC. Contrasting effects of lower hazard ratios were found early after SRC, followed by an increase after 6-12 months. Further research should look into compliance rates with regards to return-to-competition protocols.

Lower Extremity Somatosensory Function Throughout Concussion Recovery: A Prospective Cohort Study

OBJECTIVE

Balance impairments may suggest somatosensory disruption beyond concussion clinical recovery, but somatosensory subsystems have never been directly assessed. Our objective was to examine somatosensory function between individuals with a concussion and healthy matched-controls at acute (<7 days) and asymptomatic (<72 hours of being symptom-free) time points.

SETTING

Laboratory.

PARTICIPANTS

Participants with a concussion and matched controls ( n = 24; 58% male, age: 19.3 ± 1.1 years, mass: 70.3 ± 16.4 kg, height: 177.3 ± 12.7 cm).

DESIGN

Prospective cohort.

MAIN MEASURES

Somatosensory assessments on the dominant limb at both time points included: (1) plantar touch sensation threshold via Semmes-Weinstein monofilaments, (2) plantar pressure pain threshold via algometry, and (3) knee absolute passive joint repositioning (PJR) error via Biodex across 3 arcs (105°-75°, 30°-60°, 90°-45° knee-flexion). We used mixed-model analyses of variance, post hoc Tukey honestly significant difference t tests with mean difference, 95% CI, and Hedges' g effect sizes to examine outcomes.

RESULTS

Touch sensation had a group effect with the concussion cohort needing 0.95 grams of force (gf) more relative to controls (95% CI: 0.03 to 1.87; P = .043). No touch sensation interaction was present, but medium and large effects were observed for greater gf needed among the concussed cohort at the acute (1.11 gf; 95% CI: 0.17 to 2.05; g = 0.96) and asymptomatic time points (0.79 gf; 95% CI: -0.15 to 1.73; g = 0.73). No plantar pressure pain threshold effects were observed ( P ≥ .311), with negligible pressure difference magnitudes at the acute (0.26 pound force [lbf]/cm 2 ; 95% CI: -1.54 to 2.06; g = 0.13) and medium magnitudes at the asymptomatic time points (0.99 lbf/cm 2 ; 95% CI: -0.81 to 2.80; g = 0.42) for the concussed cohort needing more pressure to detect pain. The 30° to 60° PJR had a time effect, with asymptomatic time point having 3.12° better accuracy (95% CI: 1.23° to 5.02; P = .002). The concussed cohort had small-to-medium magnitude differences relative to controls at the acute time point for PJR during 105° to 75° (0.89°; g = 0.30) and 90° to 45° (0.62°; g = 0.17), but not 30° to 60° (-1.75°; g = -0.40).

CONCLUSIONS

Individuals with a concussion exhibited large effects for diminished plantar touch sensation and small to medium effects for inhibited plantar pressure pain sensation compared with controls, which may indicate altered somatosensory function. Negligible PJR differences suggest knee joint position sense is not altered post-concussion. Pre- and postconcussion examination is warranted to understand causal somatosensory mechanisms.

Higher rates of concussion following COVID-19 infection in high school athletes

OBJECTIVE

To compare concussion rates (CRs) over one academic year in high school athletes with and without a COVID-19 infection prior to concussion.

METHODS

Illness and concussion were prospectively reported for male and female high school athletes across six states over one academic year in the Players Health Rehab surveillance system. Concussion was truncated to 60 days following recovery and return to sport from COVID-19. CRs were estimated per 1000 athletes per academic year and stratified by those who tested positive for COVID-19 infection (with COVID-19) and those who did not (no COVID-19). Poisson regression analyses estimated rate ratio (RR) of concussion controlling for state, gender and an offset of the log athlete participation (with COVID-19 and no COVID-19).

RESULTS

Of 72 522 athletes, 430 COVID-19 infections and 1273 concussions were reported. The CR was greater in athletes who reported COVID-19 (CR=74.4/1000 athletes/year, 95% CI 49.6 to 99.3) compared with those who did not (CR=17.2, 95% CI 16.3 to 18.2). Athletes with recent COVID-19 had a threefold higher rate of concussion (RR=3.1, 95% CI 2.0 to 4.7).

CONCLUSION

Athletes returning from COVID-19 had higher CRs than those who did not experience COVID-19. This may be related to ongoing COVID-19 sequelae or deconditioning related to reduced training and competition load during the illness and when returning to sport. Further research is needed to understand the association of recent COVID-19 infection and concussion in order to inform preventive strategies.

Lower Extremity Musculoskeletal Injuries After Concussion in Collegiate Student-Athletes

BACKGROUND

An association has been identified between concussion and lower extremity musculoskeletal injury (LEMSKI) after return to sports participation. However, the collegiate student-athlete studies have relied on relatively small single-institution studies, which limits generalizability.

PURPOSE

To assess odds of, and time to, LEMSKI after concussion in US collegiate athletes, using the National Collegiate Athletic Association (NCAA) Injury Surveillance Program (ISP).

STUDY DESIGN

Descriptive epidemiology study.

METHODS

Data from the NCAA ISP during the 2010-2011 through 2019-2020 athletic seasons were considered for analysis. Frequency distributions were examined for details related to the initial and subsequent injuries (injuries to bone, bursa, joint, ligament, muscle, or tendon). Multivariable logistic regression models and random-effects Poisson regression models examined odds of time loss (TL) and non-time loss (NTL) LEMSKI after concussion, as well as the time interval between initial concussion and subsequent LEMSKI in a single athletic season, or initial musculoskeletal injury (MSKI) and subsequent LEMSKI in a single athletic season. Analyses were performed separately for football and other sports.

RESULTS

A total of 31,556 initial injuries were recorded (football: 11,900; other sports: 19,656), which were followed by 0 or 1 injury in the same season. Overall, first injury type was not a significant predictor of subsequent LEMSKI, although certain contrasts yielded significant estimates. In football, the odds of NTL LEMSKI were higher after concussion than after upper extremity MSKI (UEMSKI; adjusted odds ratio [OR_Adj], 1.56; 95% CI, 1.06-2.31). In football, the odds of TL LEMSKI were lower after concussion than after UEMSKI (OR_Adj, 0.71; 95% CI, 0.51-0.99). No other significant effect estimates were observed for football or other sports.

CONCLUSION

First injury type, either concussion or upper extremity, was not associated with an elevated risk of LEMSKI. Specifically, the results of this study did not identify an elevated odds of LEMSKI after a concussion. However, the authors observed greater odds of NTL LEMSKI and lower odds of TL LEMSKI in football.

More Physical Activity Is Correlated With Reduction in Kinesiophobia for Adolescents With Persistent Symptoms After Concussion

CONTEXT

The relationship between physical activity (PA) and fear of pain with movement (ie, kinesiophobia) during concussion recovery is unknown. Kinesiophobia may limit PA, while PA after concussion may reduce kinesiophobia. Our purpose was to examine the correlation between PA and self-reported kinesiophobia during concussion recovery for adolescents with and without persistent symptoms.

DESIGN

Prospective cohort study of children ages 10-18 years within 14 days of concussion.

METHODS

Participants rated kinesiophobia using the Tampa Scale of Kinesiophobia (TSK) at initial (≤14 d postconcussion) and return to play (RTP) assessments, and wore activity monitors between assessments. Our primary outcome was TSK score change from initial to RTP assessments. We grouped participants based on whether they experienced persistent symptoms (symptoms ≥28 days) or not (symptoms <28 days) and calculated correlation coefficients (Pearson r for normally distributed and Spearman rho for nonnormally distributed variables) between PA variables and TSK change scores.

RESULTS

Among the 41 participants enrolled, 44% developed persistent symptoms (n = 18; age = 14.5 [2.0] y; 50% female; symptom duration = 57.3 [6.2] d; RTP = 66.8 [6.4] d) and 56% did not (n = 23; age = 14.9 [1.8] y; 48% female; symptom duration = 15.2 [1.5] d; RTP = 21.7 [1.9] d). For the persistent symptoms group, greater TSK change scores (mean = -2.5 [5.7] point change) were significantly and moderately correlated with higher daily step count (r = -.60, P = .008) and exercise frequency (r = -.63, P = .005), but were not correlated with exercise duration (ρ = -.12, P = .65). Among the no persistent symptoms group, TSK change scores (mean = -6.0 [5.0] point change) were not correlated with step count (r = -.18, P = .41) or exercise duration (ρ = .10, P = .67), and the correlation with frequency was low and not significant (r = -.34, P = .12).

CONCLUSIONS

Regular PA during concussion recovery, regardless of duration or intensity, may help reduce kinesiophobia for those experiencing persistent symptoms.

Single-Leg Hop Stabilization Throughout Concussion Recovery: A Preliminary Biomechanical Assessment

CONTEXT

Aberrant movement patterns among individuals with concussion history have been reported during sport-related movement. However, the acute postconcussion kinematic and kinetic biomechanical movement patterns during a rapid acceleration-deceleration task have not been profiled and leaves their progressive trajectory unknown. Our study aimed to examine single-leg hop stabilization kinematics and kinetics between concussed and healthy-matched controls acutely (≤7 d) and when asymptomatic (≤72 h of symptom resolution).

DESIGN

Prospective, cohort laboratory study.

METHODS

Ten concussed (60% male; 19.2 [0.9] y; 178.7 [14.0] cm; 71.3 [18.0] kg) and 10 matched controls (60% male; 19.5 [1.2] y; 176.1 [12.6] cm; 71.0 [17.0] kg) completed the single-leg hop stabilization task under single and dual task (subtracting by 6's or 7's) at both time points. Participants stood on a 30-cm tall box set 50% of their height behind force plates while in an athletic stance. A synchronized light was illuminated randomly, queuing participants to initiate the movement as rapidly as possible. Participants then jumped forward, landed on their nondominant leg, and were instructed to reach and maintain stabilization as fast as possible upon ground contact. We used 2 (group) × 2 (time) mixed-model analyses of variance to compare single-leg hop stabilization outcomes separately during single and dual task.

RESULTS

We observed a significant main group effect for single-task ankle plantarflexion moment, with greater normalized torque (mean difference = 0.03 N·m/body weight; P = .048, g = 1.18) for concussed individuals across time points. A significant interaction effect for single-task reaction time indicated that concussed individuals had slower performance acutely relative to asymptomatic (mean difference = 0.09 s; P = .015, g = 0.64), while control group performance was stable. No other main or interaction effects for single-leg hop stabilization task metrics were present during single and dual task (P ≥ .051).

CONCLUSIONS

Greater ankle plantarflexion torque coupled with slower reaction time may indicate stiff, conservative single-leg hop stabilization performance acutely following concussion. Our findings shed preliminary light on the recovery trajectories of biomechanical alterations following concussion and provide specific kinematic and kinetic focal points for future research.