title: Biomechanical analysis of acute subdural hematoma resulting from judo.
abstract: This study investigated biomechanical mechanisms of acute subdural hematoma caused by judo and sought preventive measures to reduce injury. A Japanese judo expert repeatedly threw an anthropometric test device using two throwing techniques, Osoto-gari and Ouchi-gari. Linear and angular accelerations of the head were measured. Both throwing techniques resulted in the dummy falling backwards, with the occipital area of the head contacting the mat, and peak linear and angular accelerations being observed when the head contacted the mat. For linear acceleration, the posterior-anterior direction showed the greatest force (41.0 ± 2.6 G using Osoto-gari, and 86.5 ±4.3 G using Ouchi-gari). For angular acceleration, values for sagittal plane rotation were greatest among the three directions measured (3315 ± 168 rad/s(2) using Osoto-gari, and 1328 ± 201 rad/s(2) using Ouchi-gari). We concluded that occipital head contact produced the most forceful longitudinal linear and sagittal plane angular accelerations; subsequent stretches and ruptures of parasagittal bridging veins resulting in acute subdural hematoma. As severe head injuries can result if a person's head comes into contact with the mat, offensive throwing techniques should be restricted to participants able to sufficiently demonstrate the Ukemi technique.
authors.affiliation: Department of Legal Medicine, Shiga University of Medical Science.
authors.forename: Masahito
authors.initials: M
authors.lastname: Hitosugi
authors.forename: Haruo
authors.initials: H
authors.lastname: Murayama
authors.forename: Yasuki
authors.initials: Y
authors.lastname: Motozawa
authors.forename: Kanto
authors.initials: K
authors.lastname: Ishii
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ogino
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Koyama
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D020199:Hematoma, Subdural, Acute / Q000209:etiology*; D006801:Humans; D008297:Male; D016139:Martial Arts