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"Brennan, James H."
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Frequency and Magnitude of Game-Related Head Impacts in Male Contact Sports Athletes: A Systematic Review and Meta-Analysis
Background
Sensor devices have enabled estimations of head impact kinematics across contact sports.
Objectives
To quantitatively report the magnitude (linear and rotational acceleration) and frequency of game-related head impacts recorded in male contact sports athletes.
Methods
A systematic review was conducted in June 2017. Inclusion criteria were English-language in vivo studies published after 1990 with a study population of male athletes aged ≥ 16 years, in any sport, where athletes were instrumented with an accelerometer device for measuring head impacts. Study populations were not limited to players with a clinical diagnosis of concussion.
Results
Twenty-one studies met the inclusion criteria with 12 conducted on American Football athletes. Six of these studies were included for meta-analysis. At a threshold of 10
g
, amateur rugby players sustained the most impacts per player per game (mean = 77, SD = 42), followed by amateur Australian Football (mean = 29, SD = 37) and collegiate lacrosse athletes (mean = 11.5, SD = 3.6). At thresholds of greater than 14.4
g
, high school American Football athletes sustained between 19 (SD = 19.1) and 24.4 (SD = 22.4) impacts per player per game. Statistically significant heterogeneity was observed among the included studies, and meta-analysis of impact magnitude was limited.
Conclusions
The frequency of “head acceleration events” was quantified and demonstrated substantial variation in methodology and reporting of results. Future research with standardised reporting of head impacts and inclusion of non-helmeted sports is warranted to enable more robust comparisons across sports.
Prospero ID
CRD42017070065.
Journal Article
Accelerometers for the Assessment of Concussion in Male Athletes: A Systematic Review and Meta-Analysis
Background
Concussion is common in the sporting arena and is often challenging to diagnose. The development of wearable head impact measurement systems has enabled measurement of head kinematics in contact sports.
Objectives
The objective of this systematic review was to determine the characteristics of head kinematics measured by an accelerometer system among male athletes diagnosed with concussion.
Methods
A systematic search was conducted in July 2015. Inclusion criteria were English-language studies published after 1990 with a study population of male athletes, in any sport, where objectively measured biomechanical forces were reported in the setting of a concussive event. The random effects meta-analysis model was used to combine estimates of biomechanical force measurements in concussed athletes.
Results
Thirteen studies met the inclusion criteria, the majority of which were conducted with high school and college football teams in the US. Included studies measured a combination of linear and rotational acceleration. The meta-analysed mean peak linear head acceleration associated with a concussive episode was 98.68 g (95 % CI 82.36–115.00) and mean peak rotational head acceleration was 5776.60 rads/s
2
(95 % CI 4583.53–6969.67). The estimates of the biomechanical forces were consistent across studies, with
I
2
values of 0 % for both meta-analyses.
Conclusions
Head impact monitoring through accelerometery has been shown to be useful with regard to characterising the kinematic load to the head associated with concussion. Future research with improved clinical outcome measures and head kinematic data may improve accuracy when evaluating concussion, and may assist with both interpretation of biomechanical data and the development and utilisation of implementation strategies for the technology.
Journal Article
An assessment of the utility and functionality of wearable head impact sensors in Australian Football
To assess the utility and functionality of the X-Patch® as a measurement tool to study head impact exposure in Australian Football. Accuracy, precision, reliability and validity were examined.
Laboratory tests and prospective observational study.
Laboratory tests on X-Patch® were undertaken using an instrumented Hybrid III head and neck and linear impactor. Differences between X-Patch® and reference data were analysed. Australian Football players wore the X-Patch® devices and games were video-recorded. Video recordings were analysed qualitatively for head impact events and these were correlated with X-Patch® head acceleration events. Wearability of the X-Patch® was assessed using the Comfort Rating Scale for Wearable Computers.
Laboratory head impacts, performed at multiple impact sites and velocities, identified significant correlations between headform-measured and device-measured kinematic parameters (p<0.05 for all). On average, the X-Patch®-recorded peak linear acceleration (PLA) was 17% greater than the reference PLA, 28% less for peak rotational acceleration (PRA) and 101% greater for the Head Injury Criterion (HIC). For video analysis, 118 head acceleration events (HAE) were included with PLA ≥30g across 53 players. Video recordings of X-Patch®-measured HAEs (PLA ≥30g) determined that 31.4% were direct head impacts, 9.3% were indirect impacts, 44.1% were unknown or unclear and 15.3% were neither direct nor indirect head impacts. The X-Patch® system was deemed wearable by 95–100% of respondents.
This study reinforces evidence that use of the current X-Patch® devices should be limited to research only and in conjunction with video analysis.
Journal Article
Correlating clinical assessment and MRI findings in diagnosing calf injuries in elite male Australian rules footballers
ObjectiveCalf complex injuries represent a significant injury burden among Australian Rules athletes. To date, there has been limited research correlating clinical and radiological findings of pathology within the calf. The objective of this study is to determine how accurately magnetic resonance imaging (MRI) findings correlate with clinical measures of calf muscle complex pathology in elite male athletes.Materials and methodsA prospective cohort study was conducted on Australian rules elite athletes. A cohort of 45 athletes underwent a high-load training session of approximately 10 km of running. Athletes were then assessed by a sports physiotherapist who made a diagnosis of no pathology, delayed onset muscle soreness, strain or other. Subsequently, the athletes underwent MRI of their bilateral calf complexes. Radiologists interpreted the MRI findings and radiological diagnosis were correlated with clinical diagnosis.ResultsA total of 90 calf MRIs were performed. Correlation of clinical and radiological diagnosis occurred in 57 cases. Of the 33 cases which did not correlate, there were 4 radiologically significant acute calf strains in clinically asymptomatic athletes, 3 of which involved old scar tissue.ConclusionMRI may detect clinically insignificant injuries within the calf complex. If an athlete does not have any clinically relevant symptoms, abnormal signal on MRI may represent a different diagnosis to muscle strain. Signal change on MRI proximal to scar tissue may represent reactive oedema. Clinical history and examination should be correlated with radiological findings is recommended when diagnosing calf injury in elite athletes.
Journal Article
Comment on \Frequency and Magnitude of Game-Related Head Impacts in Male Contact Sports Athletes: A Systematic Review and Meta-Analysis\/Reply
We read the recent meta-analysis [1] on the frequency and magnitude of in vivo head impacts in contact sports with great interest, as there is a lack of multi-sport head impact exposure comparisons in the literature. This is in large part due to the wide variance in methodologies used to collect head kinematics data and differentiate true head impacts from false impacts. These inconsistencies greatly limit the comparisons that can be made across sports and even across studies within the same sport. In their review [1], the authors compared the impact exposure for contact sports athletes in 21 different studies of various sports. The cited studies used a variety of sensor systems for measuring head kinematics. Sensor devices were installed within the helmet, on skinmounted patches, or in players' mouthguard with a simple 10-15 g threshold used to record an acceleration event (AE). However, methods for distinguishing real head impacts from false positive AEs varied widely between studies; for example, only a third of the studies used video verification of impacts, while many considered all AEs over the 10-15 g threshold to be true impacts. This major limitation calls into question the key findings of this review and sheds light on a major issue plaguing this field of research.
Journal Article
What Makes LTD a Special Benefits Problem
Like the current spate of jokes, but joking aside, there is both good and bad news about long-term disability insurance plans. On the positive side, it can be reported that LTD is today a firmly established and integral part of the employee benefits package, whether insured, self-insured, or part of the pension plan. (For example, the number of new participants under insured LTD plans alone in recent years has been growing at the rate of 1,000,000 annually.) As for the bad news, many employers who once thought LTD was a relatively inexpensive benefit are now faced with sizable rate increases from insurance companies and some insurers, primarily...
Journal Article
