Using The AMA Guides

1. General Principles

An analysis of the AMA Guides and the conceptual distinction between disability and impairment embodied in the 1977 Workers' Compensation Act is explained in an excerpt from the opinion of Justice Marian Opala in Farm Fresh, Inc. v. Bucek, 1995 OK 44, 895 P.2d 719.

The AMA Guides to the Evaluation of Permanent Impairment (the "Guides") are used to determine impairment to all injured or diseased body parts, except scheduled members. 85 O.S. §3(19). An examining physician must rely on the edition of the Guides in effect on the date of a claimant's injury. However, diagnosis-related estimates (DREs) may not be used for evaluation of spinal injuries, but diagnosis-based estimates may be used where available for other anatomical regions, for example total hip or total knee replacement (Guides, §17.2j, p. 545). Rule 21 of the Rules of the Workers' Compensation Court.

Effective Dates of Each Edition of AMA Guides
Edition From Through
5th June 28, 2001 Present
4th November 1, 1993 June 27, 2001
3rd Rev. May 1, 1991 October 31, 1993
3rd January 1, 1989 April 30, 1991
2nd November 1, 1984 December 31, 1988
1st July 1, 1978 October 31,1984
OML1 Inception June 30,1978
1Ordinary manual labor

1.1. Maximum Medical Improvement

The injured worker must be at maximal medical improvement (MMI), to produce an impairment rating. It is necessary to determine that the patient is stable, and that no further treatment will reasonably improve his condition. Assuming the worker has reached MMI and is not having a flare-up or other problem, the physician can go forward with the impairment rating.

1.2. Activities of Daily Living (ADL)

Impairment percentages or ratings are estimates that reflect the severity of the medical condition and the degree to which the impairment decreases an individual’s ability to perform common activities of daily living (ADL), excluding work. Throughout the Guides, the examining physician is given the opportunity to adjust the impairment rating based on the extent of any ADL deficits. Guides, Table 1-2, 4.

1.3. Total Compliance Requirement

The examining physician shall not deviate from said guides or any alternative thereto except as may be specifically provided for in the guides or modifications to the guides or except as may be specifically provided for in any alternative or modifications thereto, adopted by the Administrator of the Workers' Compensation Court as provided for in Section 201.1 of this title. These officially adopted guides or modifications thereto or alternative system or method of evaluating permanent impairment or modifications thereto shall be the exclusive basis for testimony and conclusions with regard to permanent impairment with the exception of paragraph 3 of Section 22 of this title, relating to scheduled member injury or loss. . .
85 O.S. §3(19).

The language "shall not deviate" was first incorporated into the Act in 1985. The legislative intent of "requiring total compliance" with the Guides is expressed in the title to Senate Bill 158, 1985 First Regular Session of the Oklahoma Legislature. This amendment to the Act legislatively changed the holding of Special Indemnity Fund v. Stockton (and the version of Court Rule 20 then in effect) which only required "substantial compliance" with the Guides.

"This statute [now §3(19)] states plainly that a physician must evaluate impairment according to the Guides. An impairment rating may deviate from the Guides if the exception is 'specifically provided for in the guides'. In other words, to deviate from the Guides such deviation must be allowed by the Guides itself." York v. Burgess-Norton Mfg. Co., 1990 OK 131, ¶5, 803 P.2d 697; Branstetter v. TRW/Reda Pump, 1991 OK 38, 809 P.2d 1305.

1.4. Standard for Reviewing Medical Reports

A medical expert's permanent impairment evaluation must substantially [totally for injuries occurring on or after November 1, 1985] comply with the methods and standards prescribed by the Guides. Noncompliance may be apparent from mere reference to the Guides. That was the case in LaBarge v. Zebco. There, a specific impairment percentage for each of two ruptured discs that required surgery was plainly mandated by the AMA manual and ignored by the rating physician. The LaBarge test for determining whether the standards are followed when clearly applicable is whether, from a medical report's four corners, an unexplained, facially apparent and substantial deviation from the Guides can be detected by mere reference to their text.
Whitener v. South Central Solid Waste Authority, 1989 OK 62, 773 P.2d 1248.

1.5. Making Probative Value Objections

Making proper objections to medical reports is discussed in the section on Medical Evidence. Failure to make a specific objection that clearly identifies the deficiencies in the physician's report will be treated as a waiver of the objection.

1.6. Constitutional Issues

The constitutionality of the mandatory use of the Guides to evaluate permanent partial disability has never been raised as an appellate issue. The question was stated as dicta in a concurring opinion by Justice Opala (joined by Justice Kauger):

I would give here a far more qualified affirmative answer by holding that in this case the court rule will have to yield to the contrary text of the statute whose constitutional validity has not been challenged. A statute that is free from fundamental law infirmity prevails over the contrary content of a rule which is not rested upon the promulgating court's constitutional authority. There is no suggestion in this case that under the doctrine of delegata potestas non potest delegari §3(11) [now §3(19)] may in its present or former version constitute an unlawful delegation of the state's legislative power to a private entity (the AMA), or that the AMA texts binding force may be vulnerable to challenge as an impermissible legislative predetermination of an adjudicatory scientific fact. I would hence narrowly conclude that §3(11) must control here over the contrary content of Rule 20(i) because the statutes validity has not been drawn in question.
Branstetter v. TRW/Reda Pump, 1991 OK 38, 809 P.2d 1305 (Opala, concurring in result).

Justice Kauger seems to assert that mandated use of the Guides violates the separation of powers clause of the Oklahoma Constitution, Okla. Const. art. 4, §1:

Section 3(11) [now §3(19)]vests in a purely private organization, the American Medical Association, the unbridled authority to set standards for permanent impairment which govern an employee's right to collect compensation for on-the-job injuries. This delegation is made without guides, restrictions or standards. It has resulted in the requiring of often unnecessary but expensive tests which increase the cost of the system, the cost of workers' compensation insurance, the cost of doing business, and the cost of products to the ultimate consumers. The Legislature may not delegate the legislative power to a privately controlled national organization. Section 3(11) is unconstitutional because it vests the American Medical Association with the authority to determine the standards for the evaluation of permanent impairment - a power reserved to the Legislature acting in its law making capacity.
Davis v. B.F. Goodrich, 1992 OK 14, 826 P.2d 587 (Kauger, dissenting)

2. Cardiovascular System

3. Respiratory System

Davis v. B.F. Goodrich, 1992 OK 14, 826 P.2d 587

4. Mental and Behavioral Disorders

"A clear diagnosis is required to assess permanent mental or behavioral impairment. This diagnosis needs to be established according to DSM-IV criteria." Guides, §14.1, p. 358.

Mental and behavioral disorders are impairments of function of the brain. Guides, Introduction, p. 357.

There are four main categories to assess functional limitations due to mental disorders: activities of daily living; social functioning; concentration, persistence and pace; and, deterioration and decompensation in work or worklike settings. Guides, §14.3, p. 361.

The Guides no longer provide a rating system for impairment due to mental and behavioral disorders. "No available empirical evidence supports any method for assigning a percentage of impairment of the whole person." Guides, §14.3, p. 361.1 "Translating these guidelines [from Table 14-1] for rating individual impairment on ordinal scales into a method for assigning percentage of impairments, as if valid estimates could be made on precisely measured interval scales, cannot be done reliably." Guides, §14.3, p. 364.

How then are impairments due to mental disorders rated? The Guides state the following: "Most adult conditions with measurable impairment can be evaluated under the Guides. In situations where impairment ratings are not provided, the Guides suggests that physicians use clinical judgment, comparing measurable impairment resulting from the unlisted condition to measurable impairment resulting from similar conditions with similar impairment of function in performing activities of daily living."2 Guides, §1.5, p. 11.

Use of the Zung Self-Rating Depression Scale. The Zung Depression Rating Scale (ZDRS) was designed in 1965 by Dr. William Zung to assess the level of depression for patients diagnosed with depressive disorder. The patient answers 20 questions on a scale of 1 to 4. The total score provides indicative ranges for depression severity that can be useful for clinical and research purposes, but the Zung scale cannot take the place of a comprehensive clinical interview for confirming a diagnosis of depression. World Health Organization. While studies find the ZDRS is generally valid and reliable, "[I]ts development was not based on the contemporary definition of depression but rather on that of the sixties, thus. . . .the interpretation of its results should be made with caution." Reliability of the Zung Depression Rating Scale.
Online versions of the test automatically score the answers.

5. Spine

There are four regions of the spine: cervical, thoracic, lumbar and sacral.

There are two methods to evaluate impairment of the spinal regions: diagnosis related estimates (DREs) and range of motion (ROM). DREs found in the 5th edition of the Guides are not used to evaluate impairment of the spine. Only the ROM method is allowed. Rule 21 of the Rules of the Workers' Compensation Court.

5.1. Range of Motion Method

This method is used for evaluation of the cervical, thoracic and lumbar regions. Guides, §15.8d(2).

"An impairment rating based on loss of motion is valid only if there is medical evidence of a documented injury or illness with a permanent anatomic and/or physiologic dysfunction." Guides, §15.8 at 398.

Method for Evaluation of a Spinal Region, Guides, §15.8d, p. 402
1. Proceed if the patient is at MMI and the impairment is stable.
2. Use Table 15.7 (p. 404) to determine the percentage of impairment based on the diagnosis. "If there are two or more diagnoses within a spinal region, use that which is most significant." Guides, §15.8d(3).
3. Measure the ROM in all relevant planes. Guides, §15.8d(4).
4. "Use the maximum motion from a reproducible set of measurements to determine any impairment rating from the appropriate table." Guides, §15.8d(7).
5. "Determine any impairments due to neurologic deficits, such as radiculopathy or spinal nerve injury." See Guides, §15.12, p. 423.

  • Identify each involved nerve by its dermatomal distribution.
  • Use Table 15-15 to evaluate sensory deficit.
  • Use Table 15-16 to estimate loss of strength.
  • Apply the findings from these tables to Table 15-17 (cervical and thoracic nerve roots) or Table 15-18 (lumbar and sacral nerve roots).

6. Combine the Step 2 percentage and the sensory deficit and loss of strength percentages from Step 5 using the Combined Values Chart (p. 604). Guides, §15.8d(9).
7. Repeat the steps for either of the other two regions if injured.

Note: the Guides include a step for combining findings for more than one spinal region using the Combined Values Chart, but this step would blend all body parts into one whole person rating and make Crumby findings problematic. In general, this final step is not allowed under Oklahoma law. The Supreme Court has held "separately derived ratings to the same part of the body should be added, not combined using the tables." Norwood v. Lee Way Motor Freight, Inc., 1982 OK CIV APP 4, 646 P.2d 2 (combining neck and shoulder injuries). See also, Special Indemnity Fund v. Choate, 1993 OK 15, 847 P.2d 796 (Combined Values Chart may not be used in cases against the MITF).

5.2. Pelvic Fractures

Such fractures are rated according to Table 15-19, Guides, §15.14, p. 428.

6. Upper Extremity

Fingers, hands, arms and shoulders are included in the term upper extremity. At this time only ratings for the shoulder are rated by the Guides since scheduled members are excepted from the statutory requirements for their use.

6.1. Shoulder

An injury to the shoulder falls within the "other cases" provision of section 22(3) for the purpose of determining the number of weeks of compensation to which a claimant may be entitled. However, the Guides required the examining physician to evaluate upper extremity impairment and then convert to whole man impairment. When it is not clear whether Claimant's expert converted Claimant's shoulder injury to whole man impairment under the Guides, it is error for the trial court to rely on such report. Shebester-Bechtel, Inc. v. Higginbottom, 1995 OK CIV APP 120, 905 P.2d 1137.

6.1.1. Range of Motion Method

Method for Rating Shoulder Impairment, Guides, §16.9, II(3), p. 512

  • Determine loss of motion using §16.4i.
  • Determine impairment from other disorders using §16.7.
    • If shoulder surgery includes a distal clavicle excision, impairment to the upper extremity equals 10 percent. §16.7b, Table 16-27, p. 506.
    • Joint swelling cannot be combined with impairment due to decreased joint motion or other findings. §16.7a, p. 500.
  • Combine the values of the upper extremity impairments.
  • Convert the upper extremity combined value to the whole body using Table 16.3, p. 439.

Loss of strength "cannot be rated in the presence of decreased motion, painful conditions, deformities, or absence of parts (e.g. thumb amputation) that prevent effective application of maximal force in the region being evaluated." This method is only used if the injured worker has full range of motion and demonstrable shoulder weakness. Guides, §16.8a, p. 508. See also, Guides, Example 16-72, p. 511.

"Joint crepitation is not rated separately because other findings, such as [joint swelling, persistent joint subluxation or dislocation, and musculoligamentous disorders], are more reliable indicators of the severity of the same arthritic process." Guides, §16.7a, p. 499.3

7. Lower Extremity

"Typically, one method will adequately characterize the impairment and its impact on the ability to perform ADL. In some cases, however, more than one method needs to be used to accurately assess all features of the impairment. When more than one rating method is used, the individual impairments are combined using the Combined Values Chart (p. 604)." Guides, §17.2, p. 527.

Since the hip is not a scheduled member, its rating must be converted to the body as a whole using Table 17.3 (p. 527).

7.1. Gait Derangement

Gait derangement may not be combined with any other method of determining impairment to the lower extremity. Guides, Table 17.2, p. 526.

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