The biomechanics of helmets and helmet removal.

To better understand motion in the cervical spine related to helmet wearing and removal, normal volunteers underwent videotaped fluoroscopy during helmet removal and lateral spine X-rays in various positions. There was a tendency towards increased flexion in the supine position in the helmeted volunteers which disappeared with minimal traction. In forced hyperextension, the posterior lip of the helmet did not guillotine the cervical spine. There was no significant difference in cervical spine motion between a one-person and two-person technique of helmet removal, and in both techniques, a minimum amount of flexion occurred in clearing the occiput.