## Facts

- Thaddeus Williamson worked for Slover Masonry, Inc. as a hod carrier performing physically demanding construction tasks.
- Williamson fell from a scaffold and suffered a compensable fracture to his right knee.
- Despite five surgeries, he had chronic pain, neurological problems, and limited motion in his right leg and foot.
- A treating physician rated Williamson’s permanent impairment at 50% functional loss of the right leg under the AMA Guides.
- Williamson testified he could no longer perform five of seven primary hod carrier tasks, reflecting a substantially greater functional loss in work performance.
- A labor-market consultant testified that Williamson could not perform roughly 65% of typical hod carrier job requirements.
- The physician acknowledged the AMA Guides rate impairment of a body part generally and do not directly measure the ability to perform job-specific tasks; he agreed Williamson’s described limitations were consistent with the medical condition.
- The Industrial Commission issued a notice awarding scheduled benefits based on a 50% loss of use; Williamson protested and sought a hearing.

## Issues

1. In determining the percentage of a scheduled permanent disability to a limb, may an ALJ depart from an AMA Guides impairment percentage when the Guides do not adequately reflect the worker’s actual loss of use?
2. If so, may the ALJ consider competent non-medical evidence, including job-task limitations and vocational testimony, to determine the percentage loss of use?

## Decision

- The Arizona Supreme Court vacated the Court of Appeals’ decision and reinstated the ALJ’s award.
- The Court held an ALJ is not bound by the AMA Guides percentage when the Guides do not adequately or accurately measure the worker’s true loss of use of the scheduled member.
- The Court approved consideration of all competent evidence, including the worker’s functional inability to perform job tasks and vocational evidence, in setting the scheduled percentage.
- The Court rejected a rule requiring an express physician opinion as a prerequisite to finding the AMA Guides inadequate.
- The Court deferred to the Industrial Commission’s factual findings where supported by substantial evidence and concluded the record supported the ALJ’s 70% loss-of-use determination.

## Legal Principles

- The AMA Guides are a standardized tool for rating impairment, but they are not conclusive in scheduled-injury ratings when they fail to reflect actual functional loss.
- For scheduled injuries, “loss of use” is a functional concept and may include the practical ability to use the injured member in work-related activities.
- An ALJ, as fact-finder, may weigh medical impairment ratings alongside competent lay and vocational evidence to determine the percentage loss of use.
- Appellate review should not reweigh evidence or replace reasonable factual inferences made by the Industrial Commission when supported by substantial evidence.

## Conclusion

The court held that when the AMA Guides do not accurately capture a worker’s functional loss of use of a scheduled member, the ALJ may set a higher percentage based on all competent evidence, including job-task and vocational testimony, and reinstated the 70% scheduled award for loss of use of the right leg.


Slover Masonry, Inc. v. Indus. Comm’n of Ariz., 158 Ariz. 131, 761 P.2d 1035 (Ariz. 1988)