8–10 and specifically for concussion in sports such as American football11 and ice hockey.12–14 In the Canadian NHL, for example, 3½ years of video records and all cases of medically diagnosed concussions were analysed using a standardised framework for coding the mechanisms of concussions.12–14 When studying injury using video analysis, the majority of studies are limited to studying the injury event only. The more favourable approach would be to understand the athlete's injury event in comparison with a representative ‘control’ sample of non-injury events. Using this approach, one would be able to identify differences or deficiencies in the injury event compared with the non-injury event. Moreover, in a technically demanding sport such as rugby, where technical proficiency is a risk factor for injury,15 ,16 this approach will allow for the study of technical discrepancies between the injury and representative non-injury sample.
The implementation of an effective injury prevention strategy relies on a clarification of the extent of the injury problem, and the identification of the injury mechanism. Given the breadth of epidemiological studies on concussion in rugby, the studies identifying the mechanism of injury are lacking. Therefore, we conducted a video analysis of the mechanism of concussion injury in junior level rugby union and compared it with a representative and matched non-injury sample.
Injury surveillance was completed as previously described between 2011 and 2013 at the annual South African Rugby Union (SARU) Coca-Cola Youth Week tournaments.17 Focusing on the under-18 Craven Week tournaments only, data were obtained from the SARU injury database that is part of an ongoing injury surveillance project coordinated in conjunction with the BokSmart National Rugby Safety Programme.18 Video footage containing the concussion injury events at the under-18 Craven Week tournament was also accessed for analysis from the SARU video database. Over the 3 years, 18 concussions were recorded. However, only 10 were available for analysis due to the poor quality of the video footage. On the basis of the 10 injury events (5 tackle events—4 tackler injured and 1 ball-carrier injured; 4 ruck and 1 aerial collision), 83 non-injury events were identified (19 tackle, 61 ruck and 3 aerial collisions). The concussion event was first analysed in a similar fashion to that by Hutchison et al,13 using descriptors specific to concussion. Thereafter, both the injury and non-injury events were analysed using coding variables for each phase of play, and for general playing situational variables as outlined by to Hendricks et al.19 ,20 The authors were granted access to these databases by SARU and the UCT Human Research Ethics Committee (injury database HREC Ref: 438/2011; video database HREC Ref: R042/2013).
Injury data collection
The under-18 Craven Week tournament is an annual fixture aimed at showcasing the country's top schoolboy rugby players. Often a precursor to provincial and national selection, these tournaments are highly contended and thought to be associated with a high injury incidence.15 Details about each injury sustained during the tournaments were recorded on an injury collection form that was designed on the basis of the Consensus Statement for injury surveillance.21 Information collected included the player's team, body height, body weight, age, whether the player had medical insurance or not, and the presence or absence of protective gear during the inciting event. Written informed consent allowing for the analysis of recorded information was provided prior to the tournament by all players and by the player's parent or legal guardian in the event of the player being younger than 18 years of age. In addition, assent was required by the injured player or by the player's parent or legal guardian at the time of recording the injury. If a player, by virtue of the nature of their injury on the day, was unable to give written assent, verbal assent was acquired after an explanation of the nature of the study was given.
Data wer