A Case\u2013Control Study of Tackle-Based Head Injury Assessment (HIA) Risk Factors in the National Rugby League

Andrew J Gardner,Suzi Edwards,Grant L Iverson,Ross Tucker

doi:10.1186/s40798-021-00377-9

Abstract

BackgroundThe tackle is the in-game activity carrying the greatest risk for concussion in rugby. A recent evaluation of tackle characteristics in rugby union precipitated a rule modification to reduce head impact risk during tackles. This study aims to replicate the work conducted in rugby union by examining the association between tackle characteristics and head injury events in professional rugby league.MethodsThere were 446 tackles resulting in a head injury assessment (HIA) and 5,694 tackles that did not result in a head injury from two National Rugby League (NRL) seasons that were reviewed and coded. Tackle height, body position of players, and contact area on an opponent’s body were evaluated, with the propensity of each situation to cause an HIA calculated as HIAs per 1000 events.ResultsThe propensity for tacklers to sustain a head injury was 0.99 HIAs per 1000 tackles, 1.74-fold greater than for the ball carrier (0.57 HIAs per 1000 tackles). There was a 3.2-fold higher risk for an HIA when the tackler was upright compared to bent-at-the-waist. The greatest risk of a tackler HIA occurred when head contact was very low (knee, boot) or high (head and elbow). HIAs were most common following head-to-head impacts. The lowest propensity for tackler HIA was found when the tackler’s head was in proximity with the ball carrier’s torso.ConclusionsThe result of this study replicated the findings in professional rugby union. This has implications for the injury prevention initiatives implemented to reduce HIA risk because the majority of injuries are sustained by the tackler.

Highlights

Rugby league is an international full-contact collision sport that involves numerous tackle events
The finding that upright body position and higher contact tackles were more likely to cause Head Injury Assessments (HIAs) drove injury prevention initiatives including emphasis on current tackle height laws and potential law changes in an attempt to create more tackles where the tackler adopts a bent at the waist body position and avoids tackles where head-to-head contact is likely [27]
The primary objective of this study was to review and code video footage of tackles that resulted in HIAs, medically diagnosed concussions, and a series of tackles that did not result in any head impact, to explore how the body position of the tackler and ball carrier was associated with the propensity and incidence of HIAs to both players during tackles in the National Rugby League

Summary

Introduction

Rugby league is an international full-contact collision sport that involves numerous tackle events. Video analysis of concussion in rugby league [18,19,20,21,22] has revealed that the tackler is more frequently concussed than the ball carrier, and that headto-head and head-to-shoulder contact in upper body tackles, and head-to-hip contact in lower body tackles are the most frequent mechanism for head impact events in concussed tacklers [18,19,20,21,22,23] This body of work was primarily concerned with identifying the signs of concussion through video analysis, and did not provide a detailed mechanistic description of the contributing risk factors to the head injury, which meant that propensity and relative risk of various player behaviours was not a primary outcome. This study aims to replicate the work conducted in rugby union by examining the association between tackle characteristics and head injury events in professional rugby league

Objectives

Methods

Results

Conclusion