C - DISLOCATIONS OF THE VERTEBRAL COLUMN
93
mechanism of the cord lesion as a longitudinal traction effect as a result of considerable
elongation of the vertebral column, due to its great elasticity in children, which is in
accordance with Bedbrook's previous pathological findings (1963-66) in cord lesion
following fractures and fracture-dislocations in adults.
(3) DIRECTION OF THE ACTING FORCE
The driving force generated by the impact of the violence may speed in cranio-caudal
(vertical), horizontal or lateral directions and be coupled with rotation. As a result,
displacement may occur in forward, backward or sideways direction, with compression
and with or without rotation of the affected vertebrae.
(4) RELATIONSHIP OF THE ACTING FORCE TO THE POSITION OF THE BODY
AT THE TIME OF THE IMPACT OF VIOLENCE
In coalmine or quarry accidents, for instance, the acting force will produce different
fractures or fracture-dislocations depending on the position of the body at the time of the
impact of falling rocks i.e. whether the individual had been standing or kneeling in a
stooping-forward position or lying in semi-lateral position. It is also important to know
whether parts of the spine had been fixed by external supports at the time of accident.
In this connection, special mention should be made about the mechanism of spinal cord
injuries in the upper thoracic region after 'plane crash landings, as they demonstrate
the importance of the position of the body at the moment of injury as an important
factor in determining the level of the spinal cord lesion. As Watson-Jones (1941) pointed
out, the special fixation of the pilot in the cockpit by his harness over the front of both
shoulder joints holds the pilot in his seat and thus prevents the violent forward move–
ment of the trunk, which would otherwise occur at the moment of the crash. Conse–
quently, it raises the site of angulation from the thoraco-lumbar junction to the upper
thoracic level hence the resulting fracture occurs not at the thoraco-lumbar junction
(jack-knife mechanism), as commonly found in coalmine and other industrial injuries,
but at the upper thoracic or cervical spine. Experience gained at Stoke Mandeville on
spinal cord injuries following air-crash landings is in accordance with this conception.
(5) THE RESULTING ANATOMICAL LESION OF THE SPINAL CORD OR CAUDA
EQUINA
Post-mortem examinations of patients with vertebral fractures resulting in paraplegia
or tetraplegia have greatly clarified the mechanism involved by demonstrating the
relationship of the bony, cartilagenous and ligamentous lesions with the spinal cord
or cauda equina lesion. As a rule, the cord lesion is only rarely confined to the point of
impact on the vertebral body, although there will be the maximal destruction of the
neural elements and vascular supply, but through stretching or pressing effects the cord
lesion continues beyond the bony or cartilagenous protrusion and may involve numerous
segments above and below, confirming clinical observations of ascending cord lesions
in the early stages following vertebral injuries (Guttmann, 1963; Frankel
et
#/., 1969).
