The study, the first of its kind, assessed professional players from both codes of rugby and found abnormal levels of fractures, potentially reflecting the impact of repeated collisions over time, suggesting that the risk may previously have been underestimated.
The research, published today in PLOS ONE journal and led by Dr Karen Hind from the University's Carnegie Faculty, is particularly timely, given the news earlier this year that Australian NRL player Alex McKinnon severely fractured the C4 and C5 vertebrae in his neck following a three man tackle.
Ninety-five professional rugby league and rugby union players took part in the research and were assessed using state-of-the-art vertebral fracture assessment (VFA) dual energy X-ray absorptiometry (DXA) imaging.
The research identified 120 vertebral fractures in 51 of the 95 players that took part in the study, with 74 graded as mild (grade 1) (62%), 40 as moderate (grade 2) (33%) and six as severe (grade 3) (5%). Multiple fractures were identified in 37 players (39%) with three players each found to have five fractures to the thoracic spine and each of these players had a fracture identified as 'severe'. An additional five players had four vertebral fractures each (all with 'moderate', and two with 'severe'). There were no differences in average number of spine fractures per player between rugby union and rugby league players or between forwards and backs.
Speaking about the findings of the study, lead researcher Dr Karen Hind said: "Our study has found a high prevalence of vertebral fractures in professional rugby league and rugby union players, which is much greater than reported for the general population. Rugby union and rugby league are intensely physical contact sports that place players at risk for frequent traumatic injury. This risk has increased in parallel with the introduction of professionalism to the sport, given that a greater advantage can be gained from larger, stronger players.
"The multiple physical collisions, tackles and high impact hit-ups repeatedly expose players to very high magnitudes of direct force, with reports of 'g' forces as high as 7-10g during professional games of rugby. We were not able to assess whether rugby players' vertebral bone structures differ from the non-rugby playing population however our results may indicate that peak strain magnitudes in the spine generated during tackling and in collisions, or significant hyperextension, can exceed the vertebral bone strain threshold."
Dr Hind added: "Medical management of pain in professional rugby players, including the use of steroid injections, local anaesthetic and chiropractor therapy may exacerbate vertebral bone injury and may return players to the game before micro-damage can be repaired, thereby exposing them to increased risk of fatigue fracture at the spine."
Co-author, Dr Belinda Beck, from the School of Allied Health Sciences, Griffith University, Gold Coast, Australia, added: "The demands on professional players to maintain training and game time may increase vertebral micro-damage and muscle fatigue thereby exposing the spine to even greater mechanical stress during impacts.
Dr Fraser Birrell, MD Institute of Cellular Medicine, Newcastle University, said: "We recommend that pre and post season vertebral fracture screening protocols for all professional players are considered by rugby league and rugby union governing bodies and clubs. We also recommend the development of sport-specific vertebral fracture safe-management guidelines to help reduce the short and long term consequences of spinal fractures in professional rugby players."
The majority of the identified spinal fractures were located in T8, T9 and T10. Fractures classified as severe (grade 3) were prevalent in T7, T8, T12, L3 and L4. The most common type identified was wedge, followed by biconcave then compression. All six severe fractures were wedge type. There were also no differences in the type or grade of fracture between rugby union and rugby league players.
Click to view the full research paper.