Spinal impairment evaluation includes determining the presence or absence of loss of motion segment (structural) integrity (LOMSI). The Guides to the Evaluation of Perm-anent Impairment, 4th Edition defines LOMSI as anterior-posterior translation of one vertebra on another (more than 3.5 millimeters in the cervical spine, or 5 millimeters in thoracic or lumbar spine), or angular motion of one vertebra on another greater than 11 millimeters (15 millimeters at L5–S1) (4th ed., 98–99). A finding of LOMSI results in at least a diagnosis-related estimate (DRE) Category IV impairment rating in any of the three spinal regions (4th ed., 108).
The definition of LOMSI comes from the work of Posner and White.1 This approach was chosen by authors of the Guides spine section because of confusion surrounding the term “instability.” Several texts define instability as disc narrowing, yet...
