Intrinsic risk factors for groin and hip injuries among academy level rugby union players: systematic review and prospective cohort study

This thesis consists of three papers taking a sequential approach to the problem of groin/ hip injury in rugby union (RU). Firstly the literature surrounding the identification of groin/ hip injury risk factors in field based sports (FBS) was systematically examined. Secondly, the reliability of the single-leg squat (SLS) test as a functional measure was examined in a RU population. Finally a prospective study was undertaken to identify groin/ hip injury risk factors in an academy level RU population. Sports injury risk factors are defined as entities that contribute to the occurrence of athletic injury (Meeuwisse 1991). They can be considered intrinsic or extrinsic to the individual as well as modifiable or non-modifiable (Maffey and Emery 2007). Groin/ hip injuries are common in the athletic population, particularly in sports requiring repetitive kicking, twisting, turning and rapid acceleration and deceleration (Quinn 2010). Such biomechanics are central in FBS, including RU. Groin injuries account for 2-5% of all sports injuries (Morelli and Smith 2001) and are among the top 6 most commonly cited injuries in RU (Brooks and Kemp 2010). In a systematic review eleven significant risk factors for groin/ hip injury for FBS players were identified from seven high quality papers. The most prominent risk factor identified was previous groin/hip injury. This review revealed a clear need for a prospective cohort study to examine groin/ hip injury risk factors in a RU based population. A reliability study was carried out to examine the intra and inter rater reliability of the SLS as a functional assessment tool. It was found to have excellent intra rater and moderate inter rater reliability. A prospective cohort study was then undertaken to examine both modifiable and non-modifiable intrinsic risk factors in relation to the occurrence of groin/ hip injuries in a group of academy level RU players. 43 players were tested throughout the playing season. The most significant risk factor identified was player’s history of previous groin/ hip injury. Another non-modifiable risk factor identified was smaller player height. Modifiable risk factors identified included; lower isometric squeeze strength, reduced dominant leg and bilateral mean adductor flexibility, greater dominant and non-dominant hip internal rotation and tenderness of adductor origin musculature. This thesis culminates with summarisation of the key findings of the three papers and a clinically reasoned discussion of these findings with their implications for current and future practice and research in groin/ hip injury risk factor identification.