Discussion

Few studies have addressed the specific mechanisms of shoulder injury in rugby players. The authors undertook a larger video analysis than previous studies and also used a range of reviewers from the sports-rugby arena to independently analyse the injuries. The authors also investigated serious injuries only which required a specialist referral and led to the longest time off play. Glenohumeral joint dislocations were found to be the most common injury in 67% of players. Dislocations were accompanied by associated injuries such as anterior, posterior or SLAP-type labral tears and Hill-Sachs lesions. ACJ dislocations were seen in only 8% of players in this study. Headey et al reported ACJ injuries as the most common shoulder injury in elite rugby players, followed by rotator cuff injuries and subacromial impingement, then glenohumeral dislocation.5 This study only included injuries referred to a specialist shoulder surgeon, which would account for this difference, as it is likely that many ACJ injuries in rugby often settle and do not require specialist opinion.

SLAP lesions were less common in this study than previously described, at 21% compared to 37%,6 although rotator cuff tears were more common, seen in 25%, compared to the rate of 9.9% previously reported.10 The tackle was responsible for injury in 71% of our cohort, similar to Headey et al's 67%.5 Six rotator cuff tears occurred in our study, five of which were in the Try Scorer group. Rotator cuff tears are traditionally found in older populations, but are now more commonly being reported in younger contact athletes and are associated with high-energy anterior traumatic shoulder dislocations. Bankart tears were predictably seen in all players who sustained an anterior glenohumeral dislocation. One Bankart tear occurred in the apparent absence of dislocation. This may be due to a subclinical subluxation.

Longo et al describe the first study of shoulder dislocation mechanism in elite rugby players. Videos of four professional rugby players sustaining a primary shoulder dislocation during match play were retrospectively analysed to describe the shoulder affected; position of the shoulder and elbow; direction of force and direction in which the injured shoulder was moved during the injury event. Three of the four players sustained anterior shoulder dislocation, with two injuring it during tackling with the arm abducted and externally rotated. The other fell on the flexed, internally rotated arm with another player on top of him, levering the humerus away from the glenoid. The final player fell on the point of the flexed elbow, longitudinally loading the humerus and dislocating the humeral head posteriorly. The authors acknowledged abduction and external rotation as the accepted mechanism of anterior dislocation and suggested that rugby players are also at risk of anterior dislocation by hyperflexion with internal rotation.12 These correspond with the Tackler and Try Scorer mechanisms in this study.

Understanding the mechanisms by which injuries occur in rugby can guide the processes of rehabilitation and prevention. In a physical game such as rugby, where high force collisions are commonplace, some injuries will remain inevitable despite efforts to prevent them. It is difficult to see how to modify the game of rugby to reduce risk of shoulder injury without losing the essence of the game itself. Players should be advised to avoid tackling opposing players with the outstretched abducted arm only, instead concentrating on contacting the opposing player with their shoulder, to minimise the risk of Tackler-type injuries. Similarly, players can be advised to avoid diving for the try line with the ball in the outstretched flexed arm, as this places them at a high risk of dislocation and rotator cuff injury. In the competitive game of rugby, however, this may prove challenging to implement. The Direct Hit-type mechanism is also difficult to avoid. With foul play responsible for only a small proportion of injuries,1 high-impact forces will always be encountered and it follows that preparation of players with dedicated shoulder strength and conditioning must improve to minimise risk of shoulder injury.

A limitation of the study is the quality of video footage acquired for analysis. All videos provided at least one angle that showed the injury mechanism. Due, however, to the dynamic nature of rugby and the number of players involved in any one sequence of play, establishing the exact sequence of events with accuracy required careful, repeated analysis from reviewers and was difficult at times. Only injuries occurring during match play were reviewed, due to the availability of footage for video analysis. It is acknowledged by the authors that training includes match-play scenarios and also off-the-field preparation such as strength and conditioning that have the potential for different mechanisms of injury to those described herein. Differences exist between Rugby Union and Rugby League in terms of the type of plays and roles of the players; however, the mechanisms and injuries described by this study were common to both sports. In addition, only serious injuries requiring specialist investigation and management were included. Other mechanisms that produce more minor injuries may not have been elucidated. It may be, however, that the same mechanisms described herein are also responsible for less severe injuries, occurring at slower speeds or with less force.