Objective Describe the visible characteristics of concussive (HS-C) and non-concussive (HS-NC) cricket helmet strikes in first class cricketers.

Design Retrospective cohort analysis.

Setting England and Wales Cricket Board international sides and County Championship professional domestic cricket teams.

Participants 69 senior male cricketers in whom footage of a helmet strike (16 concussive, 153 non-concussive) was available between 2016 and 2018.

Outcome Measures Video criteria describing the location of ball impact and subsequent rebound direction as well as 19 observable behavioural features which may be relevant to concussion diagnosis.

Main Results Relative risk of concussion was highest when the ball impacted in the frontal, peak or grill regions (RR2.26) vs other helmet areas. The subsequent rebound direction of ball travel in the lateral direction was associated with the highest concussion risk (RR1.26). 4/19 behavioural features differed significantly between HS-C and HS-NC groups: player removing helmet (Chi 13.01, p<0.00), other players responding urgently (Chi 10.28, p 0.01), player appearing dazed (Chi 5.05, p 0.04) and player taking >4 seconds until ready to resume (Chi 8.13, p 0.01). The latter was the most sensitive feature of concussion (91.67%) while the player stumbling on returning to their feet was most specific (98.62%).

Conclusions Features described in consensus statements on video signs of sport related concussion were seen rarely in this cohort. Cricket medical guidelines should be updated to reflect the behaviours and impact characteristics observed here. The interaction between location of ball impact and rebound direction of ball travel vs concussion risk warrants further investigation.