In 2005, the Food and Drug Administration (FDA) approved an artificial disc replacement (ADR), and physicians likely will be called on to evaluate permanent impairment in some patients who have been treated using an ADR. The AMA Guides to the Evaluation of Permanent Impairment, (AMA Guides), Fifth Edition, was published in 2000, before the approval of ADRs, and thus is silent about evaluating ADR-associated impairment. FDA based its approval on the results of a study in which the indications were tightly limited and for which the list of relative contraindications was quite long. One review of 100 consecutive lumbar spine surgery patients found that 95% had at least 1 contraindication to ADR. The AMA Guides recommends using the Diagnosis-related estimates (DRE) method, but some situations (eg, multilevel involvement in the same spinal region) warrant use of the range-of-motion (ROM) method. Assuming a single injury and one level of loss of the activities of daily living, the DRE is the correct method to rate the permanent impairment, and the authors recommend that ADR be accepted as the equivalent to loss of motion segment integrity, warranting a rating from CRE Category IV. ADR is in its infancy, and until the AMA Guides, Sixth Edition, is available, evaluators can rate one level ADR from DRE Category IV.

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