THE RELATIONSHIP BETWEEN SHOULDER LAXITY AND TRAUMATIC SHOULDER INSTABILITY IN PROFESSIONAL RUGBY PLAYERS

Abstract

Shoulder instability is a common cause of morbidity amongst Professional Rugby Union players. This study explores whether the risk of shoulder dislocation is associated with innate shoulder laxity. A prospective, randomised controlled study was completed in which all the Premiership Rugby Clubs in England were visited. 169 professional rugby players with no history of instability in either shoulder and 46 players with one shoulder with clinical instability symptoms were assessed. Shoulder laxity was measured by clinical evaluation, questionnaires and ultrasound. Anterior, posterior and inferior translation was measured in both shoulders for healthy players and the uninjured shoulder only for injured players. The results showed there was no significant difference between the left (anterior: mean 2.92 +/− 1.15 mm; posterior: mean 5.10 +/− 1.75 mm; inferior: mean 3.08 +/− 1.00 mm) and right (anterior: mean 3.07 +/− 1.14 mm; posterior: mean 4.87 +/− 1.61 mm; inferior: mean 2.91 +/− 0.99 mm) shoulders in healthy players (P > 0.05). The comparison between healthy shoulders (anterior: mean 3.00 +/− 1.15 mm; posterior: mean 4.99 +/− 1.68 mm; inferior: mean 3.00 +/− 1.00 mm) from healthy players and the uninjured shoulder (anterior: mean 4.16 +/− 1.70 mm; posterior: mean 6.16 +/− 3.04 mm; inferior: mean 3.42 +/− 1.18 mm) from injured players identified that players with unstable shoulders have a significantly higher shoulder translation in their normal shoulder than healthy players (P < 0.05). This is the first study looking at laxity and the risk of shoulder dislocations in sportsmen involved in a high contact sport. These results support the hypothesis that rugby players with “lax” shoulders are more likely to sustain a dislocation or subluxation injury to one of these lax shoulders in their sport.