Clarifying the structure of serious head and spine injury in youth Rugby Union players

Abstract

This study aimed to clarify the cause of rugby head and spinal cord injuries through a network centrality analysis of 14-year (2004-2018) longitudinal data in Japan. The study hypothesis is that understanding the causal relationship among the occurrence of serious injuries, the quality of player experience and play situation as a network structure could be possible to obtain practical knowledge on injury prevention. In this study, bipartite graphs are used to make it easier to understand the situation of players and injuries. This would also help to elucidate more characteristic subgroup. A network bipartite graph and subgroup (cluster) analyses were performed to clarify the injured players' experience and the cause of injury. We used the algorithm of R program, IGRAPH, clustering edge betweenness. For subgroup extraction, the modularity Q value was used to determine which step to cut. The Japanese rugby population was 93,873 (2014-2018 average), and 27% were high school students. The data showed that careful attention would be particularly needed for groups of inexperienced Japanese high school players. Our study suggests that we should consider introducing rules that prohibit "head-on collisions" in youth rugby.

Fig 1. Age, grade, years of rugby playing experience, presence of head injury [inexperienced players (16 years old and with only 1 year of experience, 16 years old and with many years of experience, 17 years old and with 2 years of experience, 17 years old and with many years of experience), and presence of serious injuries like such as ASH: acute subdural hematoma, FR: skull fracture, CI/CA: cerebral infarction/cerebrovascular accident others (the circle was the extracted subgroup by clustering edge betweenness, Modularity Q value = 0.5)].

Fig 2. Causes of serious injuries (T: own tackle, OT: oppose tackle, S: saving, R: rack, C: other collisions, H-H: head to head, H-B: head to opponent’s body, RH: head under opponent’s body, O: other; the circle was the extracted subgroup by clustering edge betweenness, Modularity Q value = 0.23).

Fig 3. Injury and cause of injury for acute subdural hematoma only (THG: tackle and head to ground, THB: tackle and head to the opponent’s body, OTHG: oppose tackle and head to ground, C: other collision, S: saving, R: rack, O: other; circle was the extracted subgroup by clustering edge betweenness, Modularity Q value = 0.37).

Fig 4. Spinal injuries and years of playing experience (VF: vertebral fracture, DS: dislocation of spine, FD: fracture dislocation, S: spinal cord, CC: central cord, CSC: cervical spinal cord, O: others; Circle was the extracted subgroup by clustering edge betweenness, Modularity Q value = 0.14).

Fig 5. Years of playing experience and cause of spinal injuries (T: tackle, OT: oppose tackle, SC: scrum, R: rack, M: maul, SV: saving, C: other collision; circle was the extracted subgroup by clustering edge betweenness, Modularity Q value = 0.1).