The employer urges that the trial judge impermissibly deviated more than 10% from IME's impairment rating because he failed to provide the explanation required by § 17(D) of the compensation law. This issue calls for an analysis of the conceptual distinction between disability and impairment embodied in the 1977 Workers' Compensation Act [1977 Act]. When examining the impact of this legislation, it is helpful first to explore Oklahoma's pre-1977 benefits regime.
The Pre-1977 Disability-Based Compensation Scheme
When first enacted in 1915, Oklahoma's regime for delivery of benefits to an injured worker was designed to restore lost earnings for compensable harm from "hazardous employment". This institutional design established four categories of disability-based [895 P.2d 722] benefits (permanent total, temporary total, permanent partial and temporary partial). The key term "disability" was not defined by statute. The court eventually came to measure it by a worker's capacity to perform "ordinary manual or mechanical labor". An injury to a specific, scheduled member of the body (a classified disability) was measured by the number of weeks in the member schedule, while one to an "unclassified part of the body" fell under the "other cases" clause of § 22 and was compensated on the basis of percentage disability to the body as a whole.
The 1977 Act's Disability-Based and Impairment-Related Benefits Regime
The 1977 Act made two significant changes in the compensation law. It extended coverage to nearly all Oklahoma employees (not just to those in "hazardous employment") and introduced a mixed impairment-related and disability-based benefits regime. The terms disability and impairment were given distinct meanings.
Disability is designed to measure an employee's capacity for work, i.e., the degree to which an injury affects a person's ability to perform any task for which the worker is reasonably suited by training, education and experience. The purpose of disability-related compensation in the 1977 Act is to replace the incapacitated worker's lost earnings for injury to the limbs based on the number of weeks assigned as a maximum for each limb. The Act left intact this (pre-1977) wage-replacement concept of disability but confined its application solely to (1) temporary (temporary total and temporary partial) and (2) permanent total benefits. Permanent total disability is defined as "[i]ncapacity because of accidental injury or occupational disease to earn any wages in any employment for which the employee is or becomes physically suited and reasonably fitted by education, training or experience." In short, a permanently and totally disabled worker within the meaning of the Act is one eligible for wage replacement because of lack of capacity to earn any wages.
Impairment, on the other hand, is a medical condition; it refers to the effect of the injury upon a person's ability to perform basic life functions. The term permanent impairment is defined as "any anatomical or functional abnormality or loss after reasonable medical treatment has been achieved, which abnormality or loss the physician considers to be capable of being evaluated at the time the rating is made." Permanent partial disability means "permanent disability" and is the "same as permanent impairment." This definition not only signifies a complete departure from the old theory of ordinary manual or mechanical labor, but also introduces a new and more specific concept for evaluating permanent partial disability by placing it on a footing absolutely equal with permanent impairment, i.e. loss of bodily function.
The American Medical Association Guides to the Evaluation of Permanent Impairment [AMA Guides] provides helpful insight into the impairment-disability dichotomy. An impairment is viewed as a "medical matter", whereas disability is deemed to "arise out of the interaction between impairment and external demands." As used in the AMA Guides, (a) impairment means "an alteration of an individual's health status that is assessed by medical means," and (b) disability, "which is assessed by nonmedical means, means an alteration of an individual's capacity to meet personal, social, or occupational demands, or to meet statutory or regulatory requirements." With the sole exception of scheduled member losses, total or partial, the AMA Guides must be used for rating permanent impairment. In short, permanent partial disability, as distinguished from other payout classes, contemplates recompense for lost physical fitness, though the amount paid the worker must be measured by a percentage age of wages he (or she) would have earned but for the covered injury.
The terms of § 17(D) require that a trial tribunal specifically identify the reason for its award's deviation of more than 10% from the impairment rating by an independent court-appointed physician. Section 17(D), construed together with §§ 3(11) and (13) - the latter two of which define the terms permanent impairment and permanent partial disability - indicates that it is intended to deal with medical permanent partial impairment ratings.
The issue of permanent total disability turns on the evaluation of the worker's present capacity "to earn any wages in any employment for which he is presently suited or fitted by education, training or experience." The determination of a claimant's disability-based benefits presents a fact question for the trial tribunal. Its finding in this case declared Bucek to be totally and permanently disabled. Because § 17(D) has no application to disability-related benefits, the trial tribunal neither grounded its award in the AMA Guides nor was it statutorily required to explain why that award deviated (by 89%) from the IME's impairment rating.
Farm Fresh, Inc. v. Bucek, 1995 OK 44, 895 P.2d 719 (footnotes omitted).