Page 26 - DMX HANDBOOK 4TH EDITION

21. Proof of causation of ligamentous laxity from CAD trauma.

The causal connection between the trauma and the ligamentous laxity is probable for each of the following reasons:
1. If the patient was asymptomatic prior to and immediately acutely symptomatic after the trauma, the causal connection
should be clear.
Delayed onset of symptoms of ligamentous injury is well recognized. Delayed neck pain of up to 24 hours is a classic feature of
CAD trauma. Foreman and Croft recognize that the delay can be as much as weeks or months. However, more immediate
symptoms are consistent with more severe lesions of the anterior longitudinal ligament (ALL).
2. Motion segment alteration is extremely rare in the absence of trauma. The AMA Guides states:
When routine X-rays are normal and severe trauma is absent, motion segment alteration is rare; thus, flexion and
extension X-rays are indicated only when the physician suspects motion segment alteration from history are findings on
routine X-rays.

3. If the DMX shows ligamentous laxity that is present at specific levels and not generally throughout the spine, it is highly
probable that the laxity is traumatic rather than the result of natural progressive degeneration. As stated in Lin,
“characteristics of sagittal vertebral alignment in flexion determined by dynamic radiographs of the cervical spine.”
The aging changes of the cervical spine should be similar at each level, if no trauma affects a specific level.

4. If the ligamentous laxity occurs in whole or in part in the upper cervical spine, that is an additional indicator that the
laxity is trauma-induced because laxity due to non-traumatic degeneration typically occurs at the lower cervical levels,
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rather than the upper levels .

5. If the ligamentous laxity is centered at the C4-5 joint, it is likely due to trauma. It is well recognized that the C4-5 joint is
the single most vulnerable of the cervical spine joints and the location at which ligamentous laxity is most likely to
occur. Accordingly, if the ligamentous laxity includes that joint, it is an additional indicator that the laxity was caused by
traumatic forces.

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