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Abstract
Objective To determine the frequency and nature of injuries sustained during the IRB 2011 Rugby World Cup.
Design A prospective, whole population survey.
Population 615 international rugby players representing 20 teams competing at the IRB 2011 Rugby World Cup in New Zealand.
Method The study was implemented according to the international consensus statement for epidemiological studies in rugby union; the main measures included the players' age (years), stature (cm) and body mass (Kg) and the incidence (number of injuries/1000 player-hours), mean and median severity (days absence), location (%), type (%) and cause (%) of match and training injuries.
Results The incidences of injuries were 89.1/1000 player-match-hours (forwards: 85.0; backs: 93.8) and 2.2/1000 player-training-hours (forwards: 2.7; backs: 1.7). The mean severity of injuries was 23.6 days (forwards: 21.2; backs: 26.2) during matches and 26.9 (forwards: 33.4; backs: 14.3) during training. During matches, lower-limb muscle/tendon (31.6%) and ligament (15.8%) and, during training, lower-limb muscle/tendon (51.4%) and trunk muscle/tendon (11.4%) injuries were the most common injuries. The most common cause of injury during matches was the tackle (forwards: 43.6%, backs: 45.2%), and during training was full and semicontact skills activities.
Conclusion The results confirm that rugby, like other full-contact sports, has a high incidence of injury: the results from IRB Rugby World Cup (RWC) 2011 were similar to those reported for RWC 2007.
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Introduction
As part of its commitment to the welfare of rugby players, the International Rugby Board (IRB) implements injury surveillance studies at all its international tournaments.1 The focal point for world rugby union is the IRB Rugby World Cup (RWC), which has been contested by teams from all six continents every 4 years since 1987; this tournament is considered to be one of the largest sports events in the world and is subjected to worldwide media interest. Sedeaud et al2 claimed that success at the IRB RWC has historically gone to those teams with the tallest backs and heaviest forwards and that the stature and body mass of backs and forwards taking part in the RWC steadily increased from 1987 to 2007. If teams select and train their players to perpetuate this trend then it may have an effect on the incidence and severity of injuries sustained during the game's flagship competition. Injury surveillance was implemented at RWC 19953 and continued at the 20034 and 20075 tournaments. The incidences of match injuries at these tournaments were reported as 32, 98 and 84 injuries/1000 player-match hours, respectively; however, only the protocol used at RWC 2007 was consistent with the international consensus statement for epidemiological studies in rugby.6 Because of the differences in definitions and procedures used in the three studies, comparisons of injury data for trends across tournaments are difficult. The aim of this study was, therefore, to collect further data using the international consensus procedure for epidemiological studies to characterise the incidence, severity, nature and causes of match and training injuries and to report on the anthropometric characteristics of players competing at the RWC. Secondary to this was the aim of comparing the results obtained at RWC 2011 with those obtained at RWC 2007 in order to identify any significant changes in the risk of injury over this period.
Method
RWC 2011 took place in New Zealand over a 7-week period from 5th September to 23rd October 2011. All definitions and procedures used in the study were compliant with the international consensus statement on injury surveillance studies for rugby,6 and were the same as those used for the RWC 2007 study.5 An injury surveillance manual, which included the aims of the study together with definitions, procedures and all necessary report forms required to implement the study, was provided to the medical team of each country taking part in the tournament approximately 2 months before the start of the tournament. The University of Nottingham and the Auckland University of Technology Ethics Committees approved the study protocol.
Baseline information (normal playing position; date of birth; free standing stature (cm); body mass (kg); dominant leg and arm) and informed consent were obtained for every player taking part: these data are reported as means (SD). Match exposures were calculated for each team based on 15 players (forwards: 8; backs: 7) being exposed for 80 min per game; no allowances were made for players temporarily (medical treatment) or permanently (yellow or red cards) missing during a match. No matches required extra time to be played. Training exposures were calculated for each team based on the number of players (forwards, backs) attending team training sessions and the number, length (minutes) and structure (skills: full-contact, semicontact, non-contact; conditioning: weights, non-weights) of the sessions.
The primary injury definition used in the study was ‘Any physical complaint sustained by a player during a RWC match or training session that prevented the player from taking a full part in all training activities or match play for more than 1 day following the day of injury, irrespective of whether match or training sessions were actually scheduled’.6 When necessary, injuries were followed-up post-tournament for at least 4 months to obtain return to play/training dates: beyond this time team physicians provided an estimated return to training/play date based on the player's condition at that time (nine injuries). Return to play dates for players were checked against RWC national team sheets during the tournament and post-tournament against the player's club team sheets when these were available on the club's web site. Injuries were reported as recurrences on the basis of the clinical judgement of the player's medical team using the definition: ‘An injury of the same type and at the same site as an index injury and which occurred after the player’s return to full participation from the index injury’.6 Player absences related to illness and non-sport related medical conditions were not included in the study. Team physicians or physiotherapists were responsible for recording and reporting injury details (date of injury, date of return to play, location, type, Orchard Code,7 recurrence and use of diagnostic tests and invasive procedures) and risk factors for match (playing position, starter/replacement, period of match (0–20; 20–40+; 40–60; 60–80+ min), activity at time of injury, removal from play (immediately, later, not-at-all)) and training (back/forward, training activity, removal from training) injuries. Incidences of injury are reported separately for matches and training as the number of injuries/1000 player-hours of exposure together with the 95% CI; severities of injury are reported as mean (days; 95% CI) and median (days; 95% CI) values and grouped within the recommended severity categories of minimal (2–3 days), mild (4–7 days), moderate (8–28 days) and severe (>28 days).6
Differences in anthropometric data were assessed using t tests, in numbers of injuries by χ2 tests, in incidence and mean severity of injuries by z-tests, and in median severity of injuries by Mann–Whitney U tests.8 These tests were used to compare values of these parameters for different groups competing at the RWC 2011 and also in a series of hypothesis tests to determine whether there were significant differences in these parameters between RWC 2011 and RWC 2007.5 Because of the large number of hypotheses tested, differences were accepted as being statistically significant if p<0.01.
Results
Six hundred and fifteen players (forwards: 334; backs: 281) consented to take part in the study and provided baseline information. Six hundred of the players were the original squad players (20 teams×30 players and 15 were IRB approved replacements for players injured during the tournament (forwards: 7; backs: 8). Table 1 shows the mean age, stature and body mass of the cohort as a function of playing position.
Anthropometric data for the sample population
All teams submitted appropriate match and training exposures and injury report forms. There were 48 (group stage: 40; knockout stage: 8) matches in the tournament, which is a total of 1920 (forwards: 1024; backs: 896) player-match hours. These matches resulted in 171 time-loss match injuries (forwards: 87; backs: 84), which equates to an incidence of 89.1 (95% CI 76.7 to 103.5) injuries/1000 player-hours and 1.8 injuries/team-game (range by country: 0.3 to 3.5). Of the 171 injuries, 14.0% (forwards: 14.9%; backs: 13.1%; p=0.726) were recurrent, 92.6% acute (forwards: 92.6%; backs: 92.6%) and 7.4% gradual onset (forwards: 7.4%; backs: 7.4%) injuries: of the 24 recurrent match injuries, 10 (forwards: 3; backs: 7) were shoulder injuries. There were an additional seven injuries (forwards: 4; backs: 3) sustained while teams were warming up (forwards: 1; backs: 1) and cooling down (forwards: 3; backs: 2) for matches. During the 7-week tournament period, 15628 (forwards: 8448; backs: 7180) player-training hours were recorded: this exposure resulted in 35 time-loss injuries (forwards: 23; backs: 12), which equates to an incidence of 2.2 (95% CI 1.6 to 3.1) injuries/1000 player-hours. Of the 35 training injuries, 17.0% (forwards: 34.8%; backs: 8.3%; p=0.037) were recurrent injuries; 82.9% (forwards: 82.6%; backs: 83.3%) were acute and 17.1% gradual onset (forwards: 17.4%; backs: 16.7%). No player sustained a catastrophic injury during the tournament but one forward retired from rugby following the recurrence of a tear to the medial meniscus of the knee. Of the 213 injuries, teams used single or multiple imaging techniques (MRI: 59; ultrasound: 26; x-ray: 23; CT: 8) to assess 105 (49.3%) of the injuries (match – forwards: 39, backs: 42; training – forwards: 12, backs: 7; warming up/cooling down – forwards: 3, backs: 2); 16 (7.3%) injuries (match – forwards: 7, backs: 6; training – forwards: 2, backs: 1) required surgery and 10 (4.7%) injuries (match – forwards: 2; backs: 4; training – forwards: 3; warming up/cooling down – forwards: 1) were treated with corticosteroid injections.
Incidence, severity and nature of injury
The incidences and mean and median severities of match and training injuries for forwards and backs are presented in table 2, while the incidences of injury as a function of severity categories are shown in table 3. In total, 5046 player-days were lost from matches and training as a consequence of injury (match injuries: 4020; training injuries: 940; warm-up/cool-down injuries: 86).
Incidence and mean and median severity of injuries sustained by forwards and backs during matches and training
Incidence of match and training injuries grouped by injury severity and playing position
The incidences and mean severities of injuries are presented as functions of injury location in tables 4 and 5 (match, training) and as a function of injury type in tables 6 and 7 (match, training).
Incidence and mean severity of match injuries as a function of playing position and location of injury
Incidence and mean severity of training injuries as a function of playing position and location of injury
Incidence and mean severity of match injuries as a function of playing position and type of injury
Incidence and mean severity of training injuries as a function of playing position and type of injury
The cervical spine injury resulting in 129 days absence (table 5) was a recurrence of a cervical disc prolapse by a front row forward during a skills-full-contact training session. Cross-tabulations of the major groupings for injury type and location of match and training injuries are presented in table 8 and the most common injuries and the injuries causing the greatest total loss of time for all players during the tournament are shown in table 9.
Cross-tabulation of location and type of all injuries as a function of activity
The most common match and training injuries and the match and training injuries causing the greatest overall loss of time
Following match injuries (n=171), 45 players (forwards: 17; backs: 28) were removed from play immediately and 60 (forwards: 32; backs: 28) were removed from play later in the game. Of the 15 concussion injuries, seven were removed from play immediately (mean severity: 15.6 days), six removed later in the game (mean severity: 5.2 days) and two were not removed at all (mean severity: 6.0 days). During matches, there were no significant differences in the numbers of injuries sustained to the dominant and non-dominant upper (forwards – dominant: 3; non-dominant: 6; p=0.317; backs – dominant: 12; non-dominant: 11; p=0.835) or lower (forwards – dominant: 18; non-dominant: 22; p=0.527; backs – dominant: 19; non-dominant: 18; p=0.869) limbs. There were too few upper- (forwards: 2; backs: 0) and lower- (forwards: 14; backs: 8) limb injuries sustained during training to assess whether there was a bias towards the dominant or non-dominant limbs.
Injury causation
The incidence of match injuries is shown as a function of the period of play in table 10; there were statistically significant differences in the numbers of injuries in each quarter (p=0.003) and there was a statistically significant higher incidence of injury in the second half of matches compared with the first half (p=0.014). The incidence of match injuries as a function of match activity at the time of injury and the incidence of training injuries as a function of the training activity at the time of injury are shown in tables 11 and 12.
Incidence of match injury as a function of injury severity and period in match
Incidence of match injury (injuries/1000 player-hours) as a function of activity at time of injury
Training activity and incidence of injury as a function of training activity at time of injury
Discussion
Forwards and backs at RWC 2011 were younger, taller and heavier than players at RWC 2007;5 however, none of the differences were statistically significant – age (forwards: p=0.453; backs: p=0.497), stature (forwards: p=0.719; backs: p=0.433), body mass (forwards: p=0.285; backs: p=0.192). The increases in stature and body mass over the values reported for RWC 2007 were less than those predicted by Sedeaud et al,2 which may indicate that the emphasis previously placed on size as a primary selection factor has started to slow.
Twenty-three experimental law variations were trialled and examined by the IRB since RWC 2007 of which 10 were implemented into the laws of the game; however, these 10 changes related mainly to technical aspects of the laws and none were found to impact on the incidence of injury.9 There were some changes in the nature of the game at RWC 2011 compared with RWC 2007; namely, more passes (262 vs 224) and rucks/mauls (162 vs 144) but fewer kicks (41 vs 56), scrums (17 vs 19) and lineouts (24 vs 31).10 The trend of increasing ball-in-play times at the RWC observed in the period from 1991 (31%) to 2007 (44%) did not continue at RWC 2011, as the time remained at 44%;10 ball-in-play time should therefore not have influenced the incidence of injury calculated for 2011 compared with 2007. There were no significant differences in the overall incidence of match injuries (p=0.582) or the incidences of injuries calculated for forwards (p=0.936) and backs (p=0.478) at RWC 2011 compared with RWC 2007.5 Nevertheless, this study confirms that the incidence of injury at the RWC remains at the top of the range of values reported for rugby and is similar to values reported for elite club competitions in the Northern11 ,12 and Southern9 hemispheres. The proportions of acute and gradual onset match injuries at RWC 2011 were similar to those reported in previous studies of elite rugby.5 ,9 ,11 ,12 The overall incidence of training injuries (p=0.029) and the incidence of training injuries for backs (p=0.043) were lower at RWC 2011 compared with the values reported for RWC 2007; for forwards the difference in training incidence was not significant (p=0.342).
The mean severities of match injuries for forwards and backs at RWC 2011 were higher than those observed at RWC 2007 (forwards: 21.2 vs 14.0; backs: 26.2 vs 15.5); however, the median severities were very similar at the two tournaments (forwards: 6 vs 6; backs: 9 vs 8).5 This apparent anomaly is explained by the higher severities of a small number of knee and shoulder injuries sustained at RWC 2011 which raised the mean severity values for all injuries but did not affect the median values. The distribution of match injuries within the severity categories minimal, mild, moderate and severe was similar at RWC 2011 to the distribution reported for RWC 2007.5 The mean severities of training injuries were higher for forwards and lower for backs at RWC 2011 compared with RWC 2007 (forwards: 33.4 vs 15.9; backs: 14.3 vs 19.8) but median severities were similar at both tournaments (forwards: 7 vs 9; backs: 8.5 vs 10).5
For injury location, the distribution of match injuries was similar at RWC 2011 to that observed at RWC 2007, although there were more head/neck injuries in 2011 (p=0.034): for training injuries, there were significantly more trunk (p=0.004) and fewer lower-limb (p=0.014) injuries at RWC 2011 compared with RWC 2007.5 In terms of the type of injury, the distribution of match injuries at RWC 2011 was similar to that reported for RWC 2007: for training injuries, the distribution in 2011 was also similar to that in 2007, although the difference in joint (non-bone)/ligament injuries approached significance (p=0.064).
Overall, head/face injuries were the most common match injury for forwards while shoulder injuries were the most common match injury for backs: knee injuries had the highest mean severity for both backs and forwards. In terms of specific pathologies, posterior thigh muscle strains were the most common match injury and knee ligament match injuries, which included five anterior cruciate and three medial collateral ligament sprains, were responsible for the greatest time loss. Although the proportion of recurrent match injuries in this competition was similar to that reported in previous studies of elite rugby,5 ,9 ,11 ,12 and there was no significant difference in the numbers sustained by forwards and backs, it should be noted that 42% of recurrent injuries were shoulder/clavicle injuries, of which four were subluxations and two were acromioclavicular joint sprains; this is a higher proportion than reported in previous studies of elite players.11 Forwards sustained significantly more recurrent injuries during training than backs. Although the number of concussions reported at RWC 2011 was higher than reported at RWC 2007 (15 vs 5)5 the difference was not statistically significant (p=0.376).
Back row and inside backs were the two positional groups with the highest risk of injury at RWC 2011 and 2007,5 although at RWC 2011 inside backs took over the role of being the highest risk group from the back row forwards. The tackle represented the highest risk activity during matches for forwards (43.6%) and backs (45.2%), although forwards were more likely to be injured when tackling and backs more likely to be injured when being tackled; running (forwards: 11.5%, backs: 20.3%) was also a relatively high-risk activity. The tackle was the highest risk activity at RWC 2007 but being tackled was the higher risk aspect of the tackle for both forwards and backs.5 Although the average number of rucks/mauls per game increased at RWC 2011 compared with RWC 2007,10 injuries resulting from rucks/mauls at RWC 2011 were less than half of those recorded at RWC 2007.5 Skills-full-contact and semicontact training caused the highest incidences of training injury for forwards but these activities represented only 25% of the forwards' training load. For backs, skills-semicontact training had the highest incidence of injury but skills-full and skills-semicontact training together represented less than 20% of the training load for backs. With teams focusing their tournament training loads on the lower risk skills-non-contact and conditioning-weights activities (∼70%), training injuries were maintained at a relatively low incidence during the tournament.
Overall, the results from RWC 2011 confirm the high incidence and severity of injury at the highest level of rugby; it is difficult to compare the risk of injury in rugby with the risks in other full-contact team sports, as the International Rugby Board is the only governing body of a full-contact team sport to regularly monitor and report injury risks. The incidence, severity, nature and cause of match injuries at RWC 2011 were similar to those reported for RWC 2007.
What is already known on this topic?
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Rugby union is a contact sport with a high incidence of injury.
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The incidence of injury increases as the standard of competition increases.
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IRB Rugby World Cup represents the highest standard of international competition.
What this study adds
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The incidence and severity of injuries sustained by forwards and backs confirms the high risk of injury at the elite level of rugby.
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There were no significant changes in the overall risk and nature of injury at IRB Rugby World Cup (RWC) 2011 compared with RWC 2007.
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There were no significant changes in the causes of injury at RWC 2011 compared with RWC 2007.
Acknowledgments
The authors would like to acknowledge the contribution made by Kit McConnell (2011 RWC Tournament Director) in facilitating and actively supporting the implementation of this study. The authors would also like to acknowledge the invaluable support provided by the national team doctors and physiotherapists who provided the injury data: M Barr, M Blair, G Botto, M Bundy, E Cotenescu, E Falvey, N Gill, P Grime, J-P Hager, M Hulme, M Keating, W Koong, R Louw, B Matalavea, P Mathema, W McDonald, P McGinley, C Morriss, H Murakami, F Pifeleti, P Pook, S Porcelli, R Pozzoni, C Roberts, D Robinson, M Taylor, P Watson.
Footnotes
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Funding International Rugby Board.
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Competing interests None.
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Ethics approval University of Nottingham Medical School Research Ethics Committee.
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Provenance and peer review Not commissioned; externally peer reviewed.
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▸ References to this paper are available online at http://bjsm.bmj.com