Injury and biomechanical perspectives on the rugby scrum: a review of the literature

Abstract

As a collision sport, rugby union has a relatively high overall injury incidence, with most injuries being associated with contact events. Historically, the set scrum has been a focus of the sports medicine community due to the perceived risk of catastrophic spinal injury during scrummaging. The contemporary rugby union scrum is a highly dynamic activity but to this point has not been well characterised mechanically. In this review, we synthesise the available research literature relating to the medical and biomechanical aspects of the rugby union scrum, in order to (1) review the injury epidemiology of rugby scrummaging; (2) consider the evidence for specific injury mechanisms existing to cause serious scrum injuries and (3) synthesise the information available on the biomechanics of scrummaging, primarily with respect to force production. The review highlights that the incidence of acute injury associated with scrummaging is moderate but the risk per event is high. The review also suggests an emerging acknowledgement of the potential for scrummaging to lead to premature chronic degeneration injuries of the cervical spine and summarises the mechanisms by which these chronic injuries are thought to occur. More recent biomechanical studies of rugby scrummaging confirm that scrum engagement forces are high and multiplanar, but can be altered through modifications to the scrum engagement process which control the engagement velocity. As the set scrum is a relatively 'controlled' contact situation within rugby union, it remains an important area for intervention with a long-term goal of injury reduction.

Cervical range of motion, cervical and shoulder strength in senior versus age-grade Rugby Union International front-row forwards

“…Additionally, the Senior players were significantly heavier than the Age-grade players and given that scrum engagement forces are high, the relatively low body mass of the Hookers may be a contributory factor in them being at the highest risk of scrum related cervical injury (Bohu et al, 2009;Quarrie, Cantu, & Chalmers, 2002;Wetzler, Akpata, Laughlin, & Levy, 1998). Other factors that may predispose Hookers are that during scrum engagement they wrap both of their arms around the adjacent players (Loosehead and Tight-head) making them reliant on these players for support, and limiting their ability to adjust their body position to reduce cervical stress (Trewartha et al, 2014).…”

“…Effective scrummaging requires coordinated pushing by the eight players (Trewartha, Preatoni, England, & Stokes, 2014), which produces forces greater than the sum of each forward's individual scrummaging force (Quarrie & Wilson, 2000). Unsurprisingly, scrum engagement forces are positively related to the total body mass of the opposing pack (Du Toit, Olivier, & Buys, 2005;Milburn, 1990).…”

Epidemiological Review of Injuries in Rugby Union

“…However, the rate of acute spinal cord injuries with permanent neurological damage and traumatic brain injuries remains at 4.25/100,000 players, according to a study carried out between 2008 and 2011 in South Africa [26]. However, due to a low incidence of this type of injury and to a lack of epidemiological census, there exists an issue here to estimate exactly the number of injuries of cervical spinal cord in any given country [24]. However, this data is comparable to that observed in other contact sports, such as American football, but, this rate of catastrophic injuries is higher than in mountain biking [27] but lower than in horse riding [28] or paragliding [29].…”

“…Other reported causes of injury, such as rucks and mauls (15% to 36%), running and changing direction (10%) and entry into the scrum (1% to 7%), cause fewer injuries [8,10,13,15,30,32], but these can potentially be more serious, particularly in relation to entry into the scrums [22,23,26]. Approximately 40% of all rugby-related spinal cord injuries can be attributed to the scrum [24]. During the engagement phase, the forces generated at the interface between the two front rows during scrummaging are considerable and include forces in multiple directions, mainly forward but also downward [24].…”

“…Spinal injuries can lead to catastrophic neurological consequences (tetraplegia) and deaths have been reported [22,23]. The rate of this type of injury has decreased in recent years [24], as the rules of the game relating to entry into the scrum have changed, to ensure greater safety for the players [25]. However, the rate of acute spinal cord injuries with permanent neurological damage and traumatic brain injuries remains at 4.25/100,000 players, according to a study carried out between 2008 and 2011 in South Africa [26].…”