Assessing technology for detection, mitigation, and simulation of concussive rugby impacts. (2020)
Type of ContentTheses / Dissertations
Thesis DisciplineMechanical Engineering
Degree NameMaster of Engineering
PublisherUniversity of Canterbury
Traumatic brain injury (TBI) represents a major health issue for children and adolescents. Neuroimaging techniques in concordance with animal models have suggested the developing brain has a different response to concussive injury than the mature brain (Shrey, Griesbach et al. 2011, Choe, Babikian et al. 2012). Children exposed to TBI’s can face long-term developmental, health, and quality of life difficulties extending into adulthood (Anderson, Brown et al. 2009, Jones, Prah et al. 2019). Even a single TBI may disrupt the neurological mechanisms underlying ongoing development (Graham, Rivara et al. 2014). Furthermore, the risk of sustaining repeated injuries while recovering from a prior TBI is higher for children and adolescents than adults (Harmon, Drezner et al. 2013). Other studies of contact sport players found they were up to 60% more likely to sustain injuries following a concussive injury (Nordstrom, Nordstrom et al. 2014, Burman, Lysholm et al. 2016, Cross, Kemp et al. 2016) . One study of high school athletes found those with a history of concussion (3 or more) were more likely to suffer loss of consciousness, anterograde amnesia, mental changes lasting more than 5 minutes, and were 9.3 times more likely to demonstrate abnormal markers of injury severity (Collins, Lovell et al. 2002). Since concussions can be difficult to diagnose at the time, and symptoms can take up to 24 hours to manifest (ACC 2015), many players are likely to continue playing when they should be off the field.
A study based in Canterbury shows that rates of child and youth TBI in their Christchurch cohort were also higher than previously reported and contact sport-related concussions were one of the leading injury causes among 15-25 year olds (McKinlay, Grace et al. 2008). Additionally, there is evidence to suggest that outcomes are poorer for female players who are also at a higher risk of TBI (Zuckerman, Lee et al. 2012, Harmon, Drezner et al. 2013). In spite of the acknowledged high incident rates of TBI important gaps in the research remain evident especially for junior rugby players. While protective headgear is used in a number of sports such as snow sports, cycling and American Football, until recently, rugby headgear was designed only to protect against cuts and damage to the ears rather than to mitigate against concussion. Given the complexity of interaction between brain injury and brain development, understanding, monitoring, and mitigating the impacts of sporting TBI is critical. In the past few years especially, there has been increased attention on possible concussion mitigation through using protective headgear, with World Rugby introducing new testing standards for headgear as a medical device (Rugby 2019). This allows innovative headgear designs to be tested for medical benefits such as potential concussion mitigation.
In recent years, rugby headgear has seen significantly advancement in design and technology, with N-Pro and Gamebreaker releasing their headgear onto the market, claiming head impact force reduction. These claims, though currently unconfirmed by external researchers, if true, could mark the start of a new era of concussion awareness and mitigation in rugby.
The claims made by these new headgear manufacturers about impact force reduction are currently unsubstantiated by in published literature. This study therefore aimed to investigate the impact force reduction capabilities of new headgear types compared to headgear that has been widely used and approved by World Rugby. This provided a detailed assessment of the linear acceleration reduction achieved by the most common types of rugby headgear. A new rugby headgear testing protocol was designed providing a far more in depth analysis of headgear properties.
This headgear testing used a Hybrid III headform rigidly mounted to a drop carriage. This only allows for linear accelerations to occur. To more accurately recreate head impacts in a laboratory, a neckform should be used in conjunction with the headform. This allows for rotational motions of the head around a fixed point (representing the torso) and therefore allows rotational accelerations to be induced. Rotational kinematics have been widely theorised as more damaging to the brain tissues than linear kinematics through animal studies. The Hybrid III neck was been developed for the automotive industry based on early published data of various volunteers and cadavers (Humanetics 2019). Cadaver head and neck motions during impacts differ significantly from that of a living human. Additionally, the data used to develop these necks is outdated and has questionable reliability. Therefore, a basic validation model has been developed based on more recent published data for living humans. In addition, a new neckform was designed based on the Hybrid III design. This was assessed using the newly developed validation criteria.
The ability to accurately simulate sporting head impacts in the laboratory depends largely on how well impact conditions can be measured and reported during gameplay. Wearable sensor technology provides real time information about head impacts on the field. Some of these systems however demonstrated high error rates both in the laboratory and on the field demonstrating the need for validation (McCuen, Svaldi et al. 2015, Nevins, Smith et al. 2015, Schussler, Stark et al. 2017, Tyson, Duma et al. 2018). With a new instrumented mouthguards on the market showing promising preliminary results, a validation study was carried out in a controlled laboratory environment to assess the accuracy of the HitIQ Nexus A9 instrumented mouthguard. This was chosen as it displayed promising preliminary results for accuracy and detection rate. A new impact method was developed to recreate impact conditions previously measured on the field.