ussion occurred were analysed. Tackle descriptors were analysed in similar manner to Hendricks et al.19 ,20 Video analysis research for the ruck and aerial collision is limited, and therefore descriptors for the ruck and aerial collision were based on coaching resources and consultations with rugby coaches, sports scientists and rugby administrators. Depending on the phase of play in which the injury occurred (eg, tackle, ruck or aerial collision), all the player's previous non-injury situations in the same phase of play, within the same match and previous matches were identified and analysed as controls. Match situational variables were analysed for all injury and non-injury events.
Statistical analyses was performed by STATA V.12. Given the small sample size, descriptive statistics are reported. Frequency percentage tables were generated for each descriptor under injury and non-injury events. Concussion incidence rate was based on the player match-exposure and the number of concussion events and reported per 1000 player match-hours with corresponding 95% CIs.
Three players were randomly selected using a random number generator (http://www.random.org/). Each player's injury and non-injury events were coded on two separate occasions, separated by at least 1 week. The κ statistics were used to test the intrareliability of the coder for each of the three players. For concussion variables κ=0.92, for match situation κ=0.98 and for ruck κ=0.96. For the tackle, precontact κ=0.77, contact κ=0.74, postcontact κ=0.91, and performance outcome κ=1. The κ values between 0.81 and 0.99 represent ‘excellent agreement’, and values between 0.61 and 0.80 represent ‘substantial agreement’.
The average (±SD) age, height, mass and body mass index of the concussed players was 18.1±0.4 years, 183.2±7.9 cm, 90.2±10.1 kg and 26.9±2.6 kg/m², respectively. For the 10 players analysed in this study, 5 of the concussed players were not wearing protective gear (ie, neither a mouthguard nor a scrum cap), 4 players were using a mouthguard and 1 player was using both a mouthguard and a scrum cap.
Only one of the injurious tackles was ‘completed’ (n=1 of the 5), as opposed to 53% of non-injury tackles (n=10 of the 19). From a tackler perspective, 60% of concussive tackles were ‘unsuccessful’ (n=3 of the 5), and 11 of the 19 non-injury tackles were ‘successful’ (58%).
Over the 3 years, 18 concussions were recorded, representing 11% of all injuries and translating into an incidence rate of 5.8 concussions per 1000 player hours (95% CI 3.1 to 8.5). There was no significant difference in incidence rate between 2011 and 2012 with a rate of 3.8 (95% CI 0.1 to 7.5) and 3.9 (95% CI 0.1 to 7.8) concussions per 1000 player hours, respectively. In 2013, the incidence rate increased to 9.52 concussions per 1000 player hours (95% CI 3.6 to 15.4).
A total of 10 concussions were analysed, of which 5 occurred during the tackle (4 to the tackler and 1 to the ball-carrier), 4 during the ruck and 1 during an aerial collision (table 3). All 10 concussions analysed occurred after contact with an opponent. In terms of anticipating contact, 60% (n=10) of the players were unaware of the impending contact. Fifty per cent of the injured players were forwards (2 flankers, 2 hookers and 1 lock, respectively) and 50% were backline players (2 fullbacks, 2 centres and 1 wing, respectively). In 50% (n=10) of the cases, the injured player's team was losing, 20% drawing and 30% winning. On-field medical attention was received immediately after the injury event by 9 of the 10 players. One player was attended to during half time and subsequently removed from the game.
The ‘up and forward’ head position represented 40% (n=10) of all precontact head positions while 30% of players assumed a ‘down’ head position and 20% an ‘away’ position (1 precontact head position was unidentifiable). In head position on contact, 30% of players were observed displaying a ‘down’ position, 20% the ‘up and forward’ position and 20% the ‘away’ position (3 head position on contact events were unidentifiable, n=1