Background: Mechanisms previously described for traumatic shoulder injuries in rugby may not adequately describe all the mechanisms that result in shoulder dislocations.
Purpose: To investigate the mechanism of shoulder dislocation events in professional rugby players through use of systematic video analysis.
Study design: Case series; Level of evidence, 4.
Methods: In our series, 39 cases of shoulder dislocations from games played in top professional leagues and international matches across a 2-year period were available for video analysis. All cases were independently assessed by 2 analysts to identify the sequence of events occurring during shoulder dislocation. This included injury circumstance such as contact with another player or the ground, game scenario, injury timing, and the movements and force vectors involved in the dislocation mechanism.
Results: We identified 4 distinct injury mechanisms. The previously described mechanisms "try scorer,""tackler," and "direct impact" were identified in 67% of cases. We describe a new injury mechanism occurring in the "poach position," accounting for 18% of all shoulder dislocations studied. The remaining 15% could not be categorized. Shoulder dislocations occurred to a ball carrier in 15% of cases (n = 6) and a non-ball carrier in 85% of cases (n = 33). The injury most commonly occurred during a tackle (49%; n = 19) followed by ruck/maul (26%; n = 10). Time of injury showed that 36% (n = 14) of cases occurred in the last quarter of the game.
Conclusion: Shoulder dislocations have now been shown to occur predominantly as a result of 1 of 4 distinct mechanisms, most frequently in the second half of the game. A new mechanism for shoulder dislocation has been described in this series, termed the poach position.
Keywords: injury mechanism; rugby; shoulder instability; video analysis.