Arizona Workers Comp Impairment Rating

Arizona Workers Comp Impairment Rating
Arizona Workers Comp Impairment Rating


Prepared and Presented by:

Weston S. Montrose, Esq. – Montrose and Chua PLLC – Phoenix Workers’ Compensation Attorneys

An injured worker who has an accepted workers’ compensation claim may be entitled to “temporary” compensation (either partial or total) while he/she is under active medical care. This section is a discussion of those financial benefits that an injured worker may be entitled to receive once their injury has become “permanent and stationary” and the case is closed for further active care. The injured may still be entitled to receive “supportive care” or not. Once a determination has been made that the claim is closed, the next important step before making a determination about whether/what permanent benefits the worker is entitled to receive is to evaluate and quantify the “impairment rating”.


Arizona Administrative Code R20-5-113(B) states:

When a physician discharges a claimant from treatment, the physician:

  1. Shall determine whether the claimant has sustained any impairment of function resulting from the industrial injury. The physician should rate the percentage of impairment as published by the most recent edition of the American Medical Association in Guides to the Evaluation of Permanent Impairment, if applicable; and
  2. Shall provide a final signed report to the insurance carrier, self-insured employer, or special fund division that details the rating of impairment and the clinical findings that support the rating.


Currently, the “most recent” edition of the AMA Guides is the 6th Ed. The 6th Ed. was adopted in December 2007. However, when Rule 113(B) was adopted, the “most recent” edition of the AMA Guides was the 5th Ed. Differences in ratings between the two editions resulted in litigation over the meaning of the phrase “most recent”. Gutierrez v. ICA, 226 Ariz. 395, 249 P.3d 1095 (2011)

In the Gutierrez case, the Arizona Supreme Court determined that Rule 113(B) refers to the edition of the AMA Guides in effect at the time an injured worker is rated for the existence of permanent impairment.

Thus, until we have a newer edition, Arizona relies on the 6th Ed. of the AMA Guides


In Gutierrez the Court also said this:

“…although use of the AMA Guides is generally required, the physician rating the impairment retains some discretion whether to use the Guides. In other words, Arizona courts recognize that a physician may rely on the AMA Guides if the physician finds them to be an appropriate measure of impairment, but if not, the physician may use other appropriate rating criteria.”

This holding was consistent with prior case law considering the subject of using medical evidence to establish a permanent impairment.

-W.A. Krueger Co. v. ICA, 150 Ariz. 66, 722 P.2d 234 (1986) Use of the AMA Guides is not required if the doctor determines that the Guides either don’t address the injured workers’ impairment.

-Cassey v. ICA, 152 Ariz. 280, 731 P.2d 645 (App. 1987) AMA Guides were inadequate to address the injured workers’ impairment.

-Cavco Indus. V. ICA, 129 Ariz. 429, 631 P.2d 1087 (1981) (Other appropriate rating criteria can include the doctor’s own clinical judgment and experience.


General Rating Concept

The Guides are meant to incorporate the latest evidence in diagnostic and clinical tests and the latest scientific research and evolving medical opinion provided by nationally and internationally recognized experts. In theory, the Guides provide a framework of objective criterion that should result in consistent numerical impairment ratings regardless of the impairment examiner.

The Guides are divided into chapters based on parts of the human anatomy (i.e. the visual system, upper extremities, lower extremities, spine). Each chapter is then divided into subsections. For example the upper extremity section is subdivided to include component body parts such as: digits, wrist, elbow, and shoulder. Once the impairment evaluator has turned to the appropriate body part section, he/she would then reference a table that specifies major diagnostic categories (for example: ligament injury, dislocation, or fracture). Next the evaluator would place the injury into an appropriate “class” ranging from 0 – 4 depending on the specific severity of the injury. Within each class there are then “default” numerical ratings that can be adjusted up or down based on specific “modifiers” (functional history, physical examination, and clinical studies).

Converting Ratings

The Guides provide a methodology for converting a small body part rating into a larger body part rating and then into a “whole body” rating. Example:

8% impairment of the thumb converts to a 3% impairment of the hand

3% impairment of the hand converts to a 3% impairment of upper extremity

3% impairment of upper extremity converts to a 2% whole person impairment

Impairment conversion is important because the injured worker may be entitled to a greater benefit depending on how the rating applies to the schedule. Camis v. ICA, 4 Ariz.App. 312, 420 P.2d 35 (1966) (see discussion of schedule below). The worker is entitled to the most favorable of the possible scheduled awards.

Combining Ratings

The Guides also provide a consistent methodology for combining impairments for injuries that have impacted multiple body parts. For example, if a worker injured a finger and the wrist and the elbow, the examiner can determine the numerical rating for each individual body part and then use a chart from the Guides to come to an applicable numerical rating of the upper extremity and/or whole body. However, if the examiner assigns an impairment rating to two or more body parts from different extremities then the impairment becomes “unscheduled” and the numerical value looses importance (see discussion below).


There are situations that require deviation from the AMA Guides in determining the appropriate impairment rating. These categories often cause confusion for the examiner, claims adjuster, and legal professionals alike. The following are the most commonly encountered categories.

Fingers and Toes

Amputation ratings deviate from the AMA Guides depending on the level of the amputation. A.R.S. §23-1044(B) creates the following rating scheme:

  1. The loss of a distal or second phalange of the thumb or the distal or third phalange of the first, second, third or fourth finger, shall be considered equal to the loss of one-half of the thumb or finger, and compensation shall be one-half of the amount specified for the loss of the entire thumb or finger.
  2. The loss of more than one phalange of the thumb or finger shall be considered as the loss of the entire finger or thumb, but in no event shall the amount received for more than one finger exceed the amount provided for the loss of a hand.
  3. The loss of the first phalange of any toe shall be considered equal to the loss of one-half of the toe and compensation shall be one-half of the amount for one toe.
  4. The loss of more than one phalange shall be considered as the loss of the entire toe.


The AMA Guides direct the examiner to rate the impairment based on corrected vision (i.e. with glasses or contacts) and to provide a binocular rating (based on the vision system that considers both eyes). However, A.R.S. §23-1044(B)(17) provides compensation based on the rating to “one eye”. Case law establishes that the award must be based on uncorrected vision. Ross v. ICA, 22 Ariz.App. 209, 526 P.2d 416 (1974).

Scars and Teeth

A.R.S. §23-1044(B)(22) states,

For permanent disfigurement about the head or face, which shall include injury to or loss of teeth, the commission may, in accordance with the provisions of section 23-1047, allow such sum for compensation thereof as it deems just, in accordance with the proof submitted, for a period of not to exceed eighteen months.

The injured worker is entitled to compensation under this section even if a lost tooth is replaced and there is no resulting “disfigurement”. Bridgestone Retail Tire Operations v. ICA, 227 Ariz. 453, 258 P.3d 271 (App. 2011). The calculation for teeth loss is straight forward and based on a schedule adopted by the ICA. See Exhibit section (reproduced with approval from the ICA Claim Seminar Manual, 2013).

Facial disfigurements are a little more complicated. First of all, only scars about the head or face that are observable are compensated under this section. Scars that are visible on the neck satisfy the “about the head” requirement. Bulk Transportation v. ICA, 1CA-1C 12-0035(2013). The scar is then rated by the ICA based upon a variety of factors such as the color, size, and distance from which the scar can be detected. The ICA has a “Facial Chart” for use in rating a facial scar. See Exhibit section (reproduced with approval from the ICA Claim Seminar Manual, 2013). The carrier can submit a completed Facial Chart or the injured worker can present himself/herself to the ICA and personnel from the Claims Division will inspect the scar and take pictures, measurements, etc.


A scheduled impairment award involves a rating to one of the body parts specifically listed in A.R.S. §23-1044(B). An impairment to one of the specified body parts is presumed to affect the worker’s earning capacity but the benefits are limited by the statute (“schedule”).

If the scheduled body part has been totally impaired (100%) because of amputation or total functional loss then the injury is compensated at the rate of fifty five percent of the average monthly wage. The 55% rate applies to loss of teeth because by definition the tooth must have been “lost” in order to support an impairment award.

If the body part has been partially impaired and the worker is able to return to his/her date of injury employment then the injury is compensated at the rate of fifty per cent of their average monthly wage. If the employee is unable to return to the work the employee was performing at the time the employee was injured due to the total or partial loss of use of a scheduled body part then compensation is calculated based on seventy-five per cent of the average monthly wage.


Scheduled awards are paid on a monthly basis. The maximum monthly value of body parts are specified by A.R.S. §23-1044:

Thumb                                               fifteen months.

First finger (index finger)                nine months.

Second finger                                   seven months.

Third finger                                       five months.

Fourth finger (little finger)               four months.

Great toe                                           seven months.

Toe other than the great toe          two and one-half months.

Major hand                                        fifty months, or of a

Minor hand                                        forty months.

Major arm                                          sixty months

Minor arm                                          fifty months.

Foot                                                    forty months.

Leg                                                     fifty months.

Eye by enucleation                          thirty months.

Loss of sight w/o enucleation       twenty-five months.

Loss of hearing in one ear            twenty months.

Loss of hearing in both ears         sixty months.

Example of a Scheduled Partial Permanent Impairment

If the worker’s average monthly wage was $4,250 and the doctor has declared a permanent impairment rate of 8% of the foot and medical restrictions didn’t prevent the worker from returning to their date of injury job then the award would be calculated as follows:

$4,250 x .5 = $2,125.00 monthly benefit

40 month maximum for a foot x 8% = 3.2 months

3.2 months x $2,125 = $6,800 total permanent impairment award

If the worker couldn’t return to the date of injury employment because of the injury then the award would be calculated as follows:

$4,250 x .75 = $3,187.50 monthly benefit

40 month maximum for a foot x 8% = 3.2 months

3.2 months x $2,125 = $10,200 total permanent impairment award


If the injury causes a permanent impairment to a body part that is not listed on the schedule then it is “unscheduled”. Unscheduled impairments are NOT compensated based on the numerical value assigned by the AMA Guides. The only necessary determination is whether the impairment is anything more than 0%. If there is an impairment of more than 0% that is not covered by the schedule then the important question is whether or not the injury has resulted in work restrictions that impact the worker’s “earning capacity”. Determination of unscheduled permanent impairment benefits and earning capacity is discussed in a separate section.

Shoulders are deemed unscheduled even though it may logically belong to the “upper extremity”. Reno v. ICA, 156 Ariz. 94, 750 P.2d 852 (1988). Similarly, a hip impairment is unscheduled even though it could be associated with the “lower extremity”. Miller v. ICA, 110 Ariz. 229, 517 P.2d 91 (1973).

If an impairment rating is assigned to two or more body parts not on the same extremity, the claim converts to an unscheduled injury. Ossic v. Verde Central Mines, 46 Ariz. 176, 49 P.2d 396 (1935).

If the worker has a prior industrial scheduled impairment rating and then sustains a subsequent impairment to a scheduled body part, the second impairment will automatically be “unscheduled”. A.R.S. 23-1065(B).

If the worker has prior non-industrial impairment that “is of such seriousness as to constitute a hindrance or obstacle to employment or to obtaining reemployment” a subsequent industrial impairment may be unscheduled even if it is of the type that appears on the schedule. A.R.S. 23-1044(E). The prior impairment need not be a result of injury, congenital defects are included.


There are a few injuries that are presumed to be totally and permanently disabling “in the absence of proof to the contrary” by A.R.S. §23-1045(C):

  1. The total and permanent loss of sight of both eyes.
  2. The loss by separation of both feet.
  3. The loss by separation of both hands.
  4. An injury to the spine resulting in permanent and complete paralysis of both legs or both arms, or one leg and one arm.
  5. An injury to the skull resulting in incurable imbecility or insanity.
  6. The loss by separation of one hand and one foot.


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