Between 1965 and 1991, 132 patients with vertebral dislocation following hyperextension injury of the cervical spine were treated at the Spinal Injury Department of the Metropolitan Rehabilitation Centre in Konstancin, Poland. The series accounted for over 25 per cent of patients with hyperextension injuries and for about 7 per cent of all cervical-spine-injured patients treated during these years. These changes are most commonly found in two situations: (1) Injuries of the upper cervical spine. (2) Injuries sustained by individuals with advanced pathological changes in the spine. Such conditions are found in advanced spondylosis and ankylosing spondylitis. Such changes were noted in nearly 65 per cent of the patients in the series analysed. The improved results seen in surgically treated patients encourage the wider application of surgery in such groups of patients.