The Effect of Direct Head Impact in Judo on Internal of Cervical Spine

Abstract

PURPOSE: Judo is one of the popular combat sports, which is played worldwide and organized even in the Olympic Games. Serious neck injuries, however, have been occasionally noted in judo trainings and/or competitions. Since the pattern and severity of neck injuries largely depend on the kinematic motion of the thrown player, it is essential to investigate the mechanisms of neck injury from biomechanical view point in various different throwing techniques. Thus, the aim of this study was to evaluate a predictive indicator of cervical spine injury, neck injury criterion (Nij) with direct head impact by Judo throwing techniques using an anthropomorphic test device (ATD). METHODS: Two male judo experts (thrower) repeatedly threw the ATD for 5 times by Seoi-nage (Seoi), Osoto-gari (Osoto) and Ouchi-gari (Ouchi) techniques to make ATD's head hit directly to the mat. A 6-axis load cell (force transducer), mounted in the ATD’s cervical spine, assessed neck axial force and bending moment in each trial. To evaluate the the ATD’s neck load quantitatively, we calculated the Nij value from the neck axial force and bending moment. Kinematic data of the ATD’s whole body were also recorded during trials, using high-speed digital video cameras. RESULTS: In all trials, the largest neck loads were observed at the phase of the head contact to the mat. The peak Nij values of ATD ranged from 0.63 to 1.60 (Seoi), 0.54 to 0.58 (Osoto) and 0.19 to 0.29 (Ouchi). The average Nij value in Seoi (1.03±0.19, mean±S.E.) trials was significantly higher than those in Osoto (0.56±0.01) and Ouchi (0.24±0.02) trials (p<0.05, respectively). In three out of five tests, Nij value in Seoi trial exceeded 1.0 implying the real human tolerance limit for neck loading. However, in other two trials (Osoto and Ouchi), Nij values were less than 1.0. CONCLUSIONS: When thrown forward, the judo player might be accompanied with a direct contact of parietal and/or frontal regions of the head to the mat and suffered from neck injuries. Judo throwing technique, Seoi, has higher risk of serious neck injuries than the other techniques thrown backward including Osoto and Ouchi.