Objective To determine the features of catastrophic judo head injuries and the effects of prevention activities.

Study Design Retrospective descriptive epidemiological study

Methods We reviewed catastrophic head injuries in 44 judo players reported in the System for Compensation of Loss or Damage in the All Japan Judo Federation from 2003 to 2015. Prevention activities such as safety manual creation and enlightenment courses for judo instructors, including understanding of the consensus statement on concussion, were introduced in 2011. The incidences of death and poor outcomes before (Group A) and after (Group B) these prevention activities were compared.

Results The majority of catastrophic head injuries were acute subdural hematoma. The average patient age was 16.5 years. Most of the injured patients were novices without fully developed physical stamina and skills. Furthermore, Ukemi, a protection technique applied while being thrown, had not been fully mastered. Among 36 Group A players, 8 (23%) had a prior history of judo-related head injury with posttraumatic headache. In 4 of these 8 patients, CT and/or MRI detected a thin subdural hematoma during evaluation for persistent headache. Annual rates of catastrophic head injury were 4.0 in Group A for 9 years and 2.0 in Group B for 4 years, and the annual respective mortality rates were 2.0 and 0.25. Both rates were reduced after the prevention action introduced in 2011, although the decreases were not statistically significant.

Conclusions Continuous prevention activities can reduce catastrophic judo head injuries.

Competing interests Authors have no conflicts of interest regarding this study.