Colo. Doctors May Use AMA Guides, Other Methodologies for Impairment Ratings

Frank Ferreri

Denver, CO ( – Relying on the American Medical Association’s Guides to the Evaluation of Permanent Impairment is a traditional best practice for determining impairment ratings in workers’ compensation cases.

But as the court in Fisher v. Industrial Claim Appeals Office, No. 20CA0732 (Colo. Ct. App. 03/04/21), state law directing that ratings “shall be based on” the Guides doesn’t prevent doctors from using a different evaluative process to determine an impairment rating.


A correctional officer for the state experienced a knee injury while walking up stairs at work. The officer’s treating physician determined that the officer was at maximum medical improvement and that the knee injury was permanent.

Using a method known as “normalization,” the physician calculated that the net impairment was 13 percent of the lower leg.

According to the physician, “normalization” is a process by which doctors compare the range of motion of a patient’s uninjured joint with the range of motion in the injured joint. Once, the range of motion in both joints is determined, the doctor subtracts any impairment to the range of motion of the uninjured joint from the impairment of the injured joint to reach the final impairment figure.

The officer thought his impairment rating should have been higher, so he challenged the “normalizing” methodology.

An administrative law judge rejected the officer’s challenge, concluding that normalization was a legitimate process. The ALJ awarded the claimant benefits based on the 13 percent impairment rating.

A reviewing panel upheld the ALJ’s decision, prompting the officer to appeal to court.

‘Based On’

A provision of Colorado law directs that, in workers’ compensation cases, physical impairment ratings shall be based on the AMA’s Guides.

According to the court, using the normalization process did not circumvent state law requirements because the “shall be based on” language meant that the Guides were a “starting point, not the exclusive fount, of impairment rating methodology.”

In the court’s analysis, the provision at issue showed that the Colorado legislature “made clear that doctors should have some leeway and discretion when determining a patient’s final impairment rating.”

Additionally, the court reasoned that nothing in the law prevented Colorado doctors from using the normalization process in making their ratings.

“The determination of whether normalization is necessary rests squarely with the examining doctor, who ‘may’ follow normalization procedures ‘when deemed appropriate,’” the court explained, citing guidance from the state labor department.

As a result, the court affirmed the panel’s order that upheld the ALJ’s conclusion that the 13 percent impairment rating was acceptable.

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