Page 24 - DMX HANDBOOK 4TH EDITION

20. DMX scans can be used to provide an AMA-based impairment rating.

The AMA Guides to the Evaluation of Permanent Impairment, 5th Ed. (2000), p. 392, states that Alteration of Motion Segment
Integrity (AOMSI) results in a 25-28% impairment rating in each of the following cases:

Alteration of Motion Segment Integrity or bilateral or multilevel radiculopathy;
alteration of motion segment integrity is defined from flexion and extension
radiographs as at least 3.5 mm of translation or one vertebrae on another, or
angular motion of more than 11 degrees greater than at each adjacent level.

This is an objective finding based on scientific, mathematical modeling!
But what about translation at lesser levels? What about angular irregularity less than 11 degrees? Assessments of impairment levels
less than that specified in the AMA Guides are appropriate. As stated in Foreman/Croft:
To adopt 3.5 mm of translation as the minimal criterion for anterior subluxation is
to leave the majority of mild to moderate instability unclassified.

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Translations greater than 2.0 mm have been determined to indicate ligamentous disruption .
In another study, measurement of 1 mm translation and/or 7 degrees of angular variation has been considered to be clinically
significant and indicative of abnormal flexibility of the cervical spine.

Therefore, it is logical that translations less than 3.5 mm should result in impairment ratings as follows:
3.5mm = 25%
3.0mm = 20%
2.5mm = 15%
2.0mm = 10%
1.5mm = 5%
And also logical that angular irregularity should result in impairment ratings as follows:
11 degrees = 25%
10 degrees = 20%
9 degrees = 15%
8 degrees = 10%
7 degrees = 5%
It is true that the AMA Guides does not recognize these numbers, affirmatively or negatively. However, the above numbers are a
logical conclusion.
The AMA Guides to the Evaluation of Permanent Impairment, 6th Ed., have recognized and addressed this oversight. The 6th Edition
recognizes 3.5 mm as loss of structural integrity (translational) and 11 degrees for loss of angular integrity. The 6th Edition recognizes
disc herniation and/or AOMSI at a single level with radiculopathy to warrant a 9-14% impairment.
It recognizes intervertebral disc herniations at multiple levels with or without radiculopathy to warrant a 15-24% impairment.

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