Andrew McIntosh

The dynamics of concussive head impacts in rugby and Australian rules football

A study was commenced in 1998 at the University of New South Wales (UNSW) to investigate the dynamics of head impacts in football which resulted in concussion. Sixty-eight cases of medically verified concussion from Australian Rules Football and 32 from Rugby Union and Rugby League were analyzed. Video of each injury event was analyzed to obtain descriptive data regarding the head impact site and striking object. The video was analyzed quantitatively to obtain estimates of the closing speeds. A secondary analysis was undertaken using the conservation of momentum and energy relationships to estimate the change in velocity of the head during the impact, the change in momentum of the head, and the energy imparted to the head. Ninety-seven cases involved direct head contact, whereas three cases involved impulsive loading via the trunk. The majority of impacts were to the tempero-parietal region, and the striking body segment was commonly the arm or shoulder/thorax. The mean change in velocity of the head and head impact energy for all 97 cases of direct head impact were 4 m x s(-1) and 56 J, respectively. Head impact energy can be used as a performance criteria for testing and developing headgear for rugby and Australian rules football.

Effectiveness of headgear in a pilot study of under 15 rugby union football

Objective—To determine whether protective headgear reduced the incidence of concussion in a pilot study of under 15 rugby union. Methods—Sixteen under 15 rugby union teams were recruited from three interschool competitions in metropolitan Sydney and the adjacent country region. A prospective study was undertaken over a single competitive season. The study had two arms: a headgear arm and a control arm. Headgear wearing rates and injury data were reported to the investigators and verified using spot checks. Results—A total of 294 players participated in the study. There were 1179 player exposures with headgear and 357 without headgear. In the study time frame, there were nine incidences of concussion; seven of the players involved wore headgear and two did not. There was no significant difference between concussion rates between the two study arms. Conclusions—Although there is some controversy about the desirability of wearing protective headgear in football, this pilot study strongly suggests that current headgear does not provide significant protection against concussion in rugby union at a junior level.

Preventing head and neck injury

A wide range of head and neck injury risks are present in sport, including catastrophic injury. The literature since 1980 on prevention of head and neck injury in sport was reviewed, focusing on catastrophic and brain injury and identifying the range of injury prevention methods in use. There have been few formal evaluations of injury prevention methods. Approaches that are considered, or have been proven, to be successful in preventing injury include: modification of the baseball; implementation of helmet standards in ice hockey and American football and increased wearing rates; use of full faceguards in ice hockey; changes in rules associated with body contact; implementation of rules to reduce the impact forces in rugby scrums. Helmets and other devices have been shown to reduce the risk of severe head and facial injury, but current designs appear to make little difference to rates of concussion. Research methods involving epidemiological, medical, and human factors are required in combination with biomechanical and technological approaches to reduce further injury risks in sport.

What do under 15 year old schoolboy rugby union players think about protective headgear

Objectives—When protective headgear is designed, the attitudes of the intended users needs to be taken into account, as well as safety performance criteria. The aim of this study was therefore to determine the attitudes of schoolboy rugby union players towards protective headgear. Methods—A survey of 140 rugby union players (82.4% response rate) from 10 randomly selected school teams in metropolitan Sydney was conducted at the end of the 1999 playing season. All players were aged 14–16 years. All teams had participated in a trial of headgear during the 1999 season in which six of the teams had been assigned to a headgear trial arm and four teams to a control arm. Players completed a self report questionnaire during a supervised session at school. The questionnaire collected information on recent head injuries, use of protective equipment, and attitudes towards headgear. Results—Some form of protective equipment was always worn by 76.1% of players: 93.6% reported using a mouthguard and 79.3% a helmet/headgear during the 1999 season. The two most important reasons for wearing headgear were related to safety concerns. Players with no recent head/neck injury were more likely to report that they felt safer when wearing headgear (p<0.001) and less likely to cite a previous injury as a motivating factor for wearing headgear (p<0.001) than those who had sustained a recent head/neck injury. Of the players who wore headgear during the 1999 season, 67% said that they played more confidently when they wore headgear, but 63% said that their head was hotter. Few players reported that their head was uncomfortable (15%) or that it was hard to communicate (3%) when they wore headgear. The main reasons for not wearing headgear were related to its design features: uncomfortable (61%) and it was hot (57%). Conclusions—The primary reason cited by players for wearing headgear is safety. Receiving an injury would also motivate non-wearers to wear headgear. Players report that they are more confident and able to tackle harder if they wear headgear, suggesting that a belief in its protective capabilities may influence behaviour. These attitudes need to be addressed in the design of effective headgear as well as in strategies to promote its use.

Impact energy attenuation performance of football headgear

Objectives—Commercially available football head protectors were tested to determine their impact energy attenuation performance and ability to reduce the likelihood of concussion. Methods—Prospective study using standardised impact test methods with both rigid (magnesium) and Hybrid III headforms. Results—Eight commercially available head protectors from six manufacturers were tested. The magnitude of the headform accelerations increased as the drop height was increased, ranging from a minimum of 64 g from a height of 0.2 m to a maximum of 1132 g from a height of 0.6 m. The head injury criterion and maximum headform acceleration values followed a similar trend. A steep increase was noted in the magnitude of maximum headform acceleration and head injury criterion when the drop height was increased from 0.4 to 0.5 m. This indicates that the foam material was completely compressed at an impact energy above about 20 J and therefore offers little protection against impacts of greater severity. Repeated tests using a drop height of 0.3 m showed that some helmets exhibit a “memory” effect, whereby impact performance is reduced by up to 50% with repeated impacts. Conclusions—Laboratory tests indicate that current commercially available football headgear performance will not reduce the likelihood of concussion. The absence of internationally recognised standards for soft headgear designed to ameliorate concussion is a major deficiency in sports injury prevention.

Should football players wear custom fitted mouthguards? Results from a group randomised controlled trial

Objective: Head/orofacial (H/O) injuries are common in Australian rules football. Mouthguards are widely promoted to prevent these injuries, in spite of the lack of formal evidence for their effectiveness. Design: The Australian football injury prevention project was a cluster randomized controlled trial to evaluate the effectiveness of mouthguards for preventing H/O injuries in these players. Setting and subjects: Twenty three teams (301 players) were recruited from the largest community football league in Australia. Intervention: Teams were randomly allocated to either the MG: custom made mouthguard or C: control (usual mouthguard behaviours) study arm. Main outcome measures: All injuries, participation in training and games, and mouthguard use were monitored over the 2001 playing season. Injury rates were calculated as the number of injuries per 1000 person hours of playing time. Adjusted incidence rate ratios were obtained from Poisson regression models. Results: Players in both study arms wore mouthguards, though it is unlikely that many controls wore custom made ones. Wearing rates were higher during games than training. The overall rate of H/O injury was 2.7 injuries per 1000 exposure hours. The rate of H/O injury was higher during games than training. The adjusted H/O injury incidence rate ratio was 0.56 (95% CI 0.32 to 0.97) for MG versus C during games and training, combined. Conclusions: There was a significant protective effect of custom made mouthguards, relative to usual mouthguard use, during games. However, the control players still wore mouthguards throughout the majority of games and this could have diluted the effect.

Tackle Characteristics and Injury in a Cross-Section of Rugby Union Football

BACKGROUND The tackle is the game event in rugby union most associated with injury. This studys main aims were to measure tackle characteristics from video using a qualitative protocol, to assess whether the characteristics differed by level of play, and to measure the associations between tackle characteristics and injury. METHODS A cohort study was undertaken. The cohort comprised male rugby players in the following levels: younger than 15 yr, 18 yr, and 20 yr, grade, and elite (Super 12 and Wallabies). All tackle events and technique characteristics were coded in 77 game halves using a standardized qualitative protocol. Game injuries and missed-game injuries were identified and correlated with tackle events. RESULTS A total of 6618 tackle events, including 81 resulting in a game injury, were observed and coded in the 77 game halves fully analyzed (145 tackle events per hour). An increase in the proportion of active shoulder tackles was observed from younger than 15 yr (13%) to elite (31%). Younger players engaged in more passive tackles and tended to stay on their feet more than experienced players. Younger than 15 yr rugby players had a significantly lower risk of tackle game injury compared with elite players. No specific tackle technique was observed to be associated with a significantly increased risk of game injury. There was a greater risk of game injury associated with two or more tacklers involved in the tackle event, and the greatest risk was associated with simultaneous contact by tacklers, after adjusting for level of play. CONCLUSIONS Tackle characteristics differed between levels of play. The number of tacklers and the sequence of tackler contact with the ball carrier require consideration from an injury prevention perspective.

Compliance with return-to-play regulations following concussion in Australian schoolboy and community rugby union players

Background There is a risk of concussion when playing rugby union. Appropriate management of concussion includes compliance with the return-to-play regulations of the sports body for reducing the likelihood of premature return-to-play by injured players. Purpose To describe the proportion of rugby union players who comply with the sports bodys regulations on returning to play postconcussion. Study design Prospective cohort study. Methods 1958 community rugby union players (aged 15–48 years) in Sydney (Australia) were recruited from schoolboy, grade and suburban competitions and followed over ≥1 playing seasons. Club doctors/physiotherapists/coaches or trained injury recorders who attended the game reported players who sustained a concussion. Concussed players were followed up over a 3-month period and the dates when they returned to play (including either a game or training session) were recorded, as well as any return-to-play advice they received. Results 187 players sustained ≥1 concussion throughout the follow-up. The median number of days before players returned to play (competition game play or training) following concussion was 3 (range 1–84). Most players (78%) did not receive return-to-play advice postconcussion, and of those who received correct advice, all failed to comply with the 3-week stand-down regulation. Conclusions The paucity of return-to-play advice received by community rugby union players postconcussion and the high level of non-compliance with return-to-play regulations highlight the need for better dissemination and implementation of the return-to-play regulations and improved understanding of the underlying causes of why players do not adhere to return-to-play practices.

Numerical reconstruction of real-life concussive football impacts.

PURPOSE To present a protocol of numerical reconstructions of concussive events in football using MADYMO. To refine the knowledge of the dynamics associated with these events. METHODS Twenty-seven cases of concussive head impacts involving unhelmeted Australian football and rugby players were simulated using MADYMO. The cases had been previously analyzed using a video analysis protocol and were fully reconstructed for the purpose of this study. The reliability of these reconstructions had been previously assessed using a sensitivity analysis of the influence of several independent variables on the dynamical outputs. The use of a complete human model enabled consideration for morphometry, initial movements of the players, and an accurate estimate of the effective masses involved in the impacts. RESULTS Mean peak values for concussion were found to be 103 g for the head center of gravity linear acceleration, 8022 rad s(-2) for the head angular acceleration, and 359 for the head impact criterion. An estimate of the average effective energy transferred to the head was 47 J. With the severity grading used in this study, the head impact power was found to be the best predictor of concussion severity. CONCLUSIONS These biomechanical results compare well with other studies. They should contribute to the identification of the energy levels at which concussive impacts occur in football for the purpose of a better evaluation of protective devices in these sports.

Sports helmets now and in the future

The paper reports on a symposium on sports helmets and presents a synthesis of information and opinion from a range of presenters and disciplines. A review of the literature shows that helmets play an important role in head injury prevention and control. Helmets have been shown to be very efficacious and effective in a range of sports and in preventing specific head injury risks, especially moderate to severe head injury. The symposium emphasised the importance of helmet standards and the need for further development. There are calls for helmets that address the needs of competitive (elite) athletes separate to helmets for recreational athletes. Deficiencies in the evidence base for head injury risks and helmet efficacy and effectiveness were identified in some sports. Issues in designing helmets that are suitable to prevent severe head injuries and concussion were discussed and explained from biomechanical and engineering perspectives. The need to evaluate helmet performance in oblique impacts and incorporate this into standards was covered in a number of presentations. There are emerging opportunities with in-helmet technology to improve impact performance or to measure impact exposure. In-helmet technology as it matures may provide critical information on the severity of the impact, the location of the injured athlete, for example, snowboarder, and assist in the retrieval and immediate, as well as the long-term medical management of the athlete. It was identified that athletes, families and sports organisations can benefit from access to information on helmet performance. The importance of selecting the appropriate-sized helmet and ensuring that the helmet and visor were adjusted and restrained optimally was emphasised. The translation pathway from the science to new and better helmets is the development of appropriate helmet standards and the requirement for only helmets to be used that are certified to those standards.