The AMA Guides to the Evaluation of Permanent Impairment (AMA Guides), Sixth Edition, caused controversy with respect to changes in rating percentages. Impairment ratings in this edition are more specific than in previous editions and are intended to reflect lesser impairment in cases when symptomatology has improved with appropriate treatment. Grids in the AMA Guides, Sixth Edition, include impairment ratings for multiple-level conditions, so an alternative rating system (such as the range-of-motion method in the fifth edition) are not needed. The Diagnosis-related estimate (DRE) categories described in the fifth edition have been modified and expanded by the creation of regional grids that are used in the sixth edition to rate spinal impairments. The grids provide clearer categorization of many conditions and are consistent with clinical outcomes; ratings in the sixth edition reflect the results of treatment rather than the method of treatment. A significant difference in impairment ratings occurs between the fifth and sixth editions of the AMA Guides with respect to the classification of diagnoses of Alteration of Motion Segment Integrity, which includes fusion and, in the sixth edition, motion preserving technologies. A table compares the fifth and sixth editions for single-level spinal disease with or without radiculopathy and with or without surgery, including fusion.