Accidental Personal Injury

The term "accidental injury", as used in the Workmen's Compensation Act of this state, . . . , must not be given a narrow meaning, but the term is to receive a broad and liberal construction, with a view of compensating injured employees, where the injury results through some accidental means, was unexpected and undesigned, or may be the result of mere mischance or miscalculation as to the effect of voluntary action.
Choctaw County v. Bateman, 1952 OK 387, 252 P.2d 465

1. Date of Injury

1.1. Single Event

Benefits for a single event injury shall be determined by the law in effect at the time of injury. 85 O.S. §315.

1.2. Cumulative Trauma or Occupational Disease

Benefits for a cumulative trauma injury or occupational disease or illness shall be determined by the law in effect at the time the employee knew or reasonably should have known that the injury, occupational disease or illness was related to work activity. 85 O.S. §315.

Liability for cumulative trauma injuries is governed by 85 O.S. §317, formerly 85 O.S. §11(B)(5) which became effective on October 23, 2001:

Where benefits are payable for an injury resulting from cumulative trauma, the last employer in whose employment the employee was last injuriously exposed to the trauma for a period of at least ninety (90) days of such injurious exposure, and the insurance carrier, if any, on the risk when the employee was last so exposed under such employer, shall alone be liable therefor, without right to contribution from any prior employer or insurance carrier. If there is no employer in whose employment the employee was injuriously exposed to the trauma for a period of at least ninety (90) days, then the last employer in whose employment the employee was last injuriously exposed to the trauma and the insurance carrier, if any, on the risk when such employee was last so exposed under such employer, shall be liable therefor, with right to contribution from any prior employer or insurance carrier.

"In conclusion, we reiterate that the date of injury for cumulative trauma claims is the date of awareness." American Airlines, Inc. v. Crabb, 2009 OK 68, 221 P.3d 1289.

1.3. Death Benefits

Benefits for death shall be determined by the law in effect at the time of death. 85 O.S. §315.

1.4. Dormant Injuries

Hepatitis C due to exposure to blood pathogens by medical workers, emergency responders and police. Dyke v. Saint Francis Hosp., Inc., 1993 OK 114, 861 P.2d 295; Wheaton v. City of Tulsa Fire Department, 1998 OK CIV APP 155, 970 P.2d 194

Hepatitis C is a single event injury from a virus that goes through an incubation period before it manifests itself symptomatically. Mere exposure is not enough to qualify as an injury and commence the statute of limitations, which does not begin to run until the manifestation of the disease. It is not cumulative trauma or occupational disease. Deaconess Hospital v. Ledbetter, 2002 OK CIV APP 29, 41 P.3d 1050

City of Nichols Hills v. Hill, 1975 OK 39, 534 P.2d 931 (histoplasmosis)

2. Causation and Major Cause

2.1. Causation in General

It is claimant's burden to show the injuries were caused by accidents arising out of and in the course of and in the course of his employment. Jarvis v. Hopkins, 1967 OK 209, ¶8, 434 P.2d 208. This includes the burden of both producing evidence and persuading the trier on these critical matters. Corbett v. Express Personnel, 1997 OK 40, 936 P.2d 932, n. 5; American Management, Inc. v. Burns, 1995 OK 58, 903 P.2d 288, 291. It is only after claimant has established his injury was caused by his employment that employer must refute the causation. Pauls Valley Travel Center v. Boucher, 2005 OK 30, 112 P.3d 1175.

Medical evidence is not required to refute causation. Brown v. Mom's Kitchen, LLC, 2004 OK CIV APP 66, 96 P.3d 808; Adair Public Schools v. Haley, 2005 OK CIV APP 83, 122 P.3d 490. The Supreme Court held:

. . . both statutory provisions and case law require only the claimant to present medical evidence showing that an injury or disease was job-related. . . . Where respondent produces any admissible evidence which refutes the claimant's medical testimony concerning causation, the trial court must consider all the evidence is determining causation of the injury or disease. Both parties are permitted to present lay evidence, whether direct or circumstantial, on the issue of causation.
Collins v. Halliburton Services, 1990 OK 118, ¶8, 804 P.2d 440.

2.2. Major Cause

For an article published in the Oklahoma Bar Association Journal, see Leonard, Tom. Major Cause, What Does It Mean?, analysis of the meaning of the major cause element for determining compensability of work injuries.


"Major cause" means the predominate [sic] cause of the resulting injury or illness. 85 O.S. §3(16).

"Compensable injury" means any injury or occupational illness, causing internal or external harm to the body, which arises out of and in the course of employment if such employment was the major cause of the specific injury or illness. An injury, other than cumulative trauma, is compensable only if it is caused by a specific incident and is identifiable by time, place and occurrence unless it is otherwise defined as compensable in this title. A compensable injury must be established by objective medical evidence, as defined in this section. 85 O.S. §3(13)a.

"Objective medical evidence" means evidence which meets the criteria of Federal Rule of Evidence 702 and all U.S. Supreme Court case law applicable thereto. 85 O.S. §3(17).

[Emphasis added.]

To understand major cause, we may need to compare the new definition of "compensable injury" to the law that it superseded:

12. a. "Injury" or "personal injury" means only accidental injuries arising out of and in the course of employment and such disease or infection as may naturally result therefrom and occupational disease arising out of and in the course of employment as herein defined. Only injuries having as their source a risk not purely personal but one that is causally connected with the conditions of employment shall be deemed to arise out of the employment.

The "major cause" of a compensable injury must result from employment. 85 O.S., §3(7), (13), (16), (18). Medical opinions supporting employment as the major cause of occupational disease or age-related deterioration or degeneration, must be supported by objective medical evidence (i.e. in these cases, permanent anatomical abnormality and causation must be established by objective medical evidence). This term does not eliminate injury due to an aggravation of a pre-existing condition in cumulative trauma or single event injury cases.


Dempsey v. Ballard Nursing Center, 2004 OK CIV APP 18, 84 P.3d 1071, is an instructive COCA case written by Judge (now Justice) John F. Reif that predates the 2005 changes. This case is discussed in the next section on aggravation. Claimant's pre-existing spondylolisthesis became symptomatic after lifting patients at a nursing home. Employer's medical expert said that she was "in need of surgery to her back, but it is due to spondylolisthesis which is a pre-existing condition and not as a result of the injury she sustained on July 12, 2002, while working for [nursing home]." If these facts had arisen after July 1, 2005, employer would have used them to prove a "major cause defense." Justice Reif rejected the argument and stated:

The problem with this opinion [of the medical expert] is that it essentially says claimant needs surgery for the effects of the spondylolisthesis, and the injury of July 12, 2002, did not cause the spondylolisthesis. The question which the doctor did not address is whether the injury of July 12, 2002, aggravated the spondylolisthesis so that it requires surgery now, as opposed to surgery being the general medical treatment that would have eventually been needed to correct this condition.
Dempsey v. Ballard Nursing Center, id at ¶10.


Major cause is not a defense to the need for a particular course of medical treatment recommended for an injury determined to be compensable. Irisndt, Inc. v. Brock, 2008 OK CIV APP 5, 176 P.3d 370. Although claimant had two prior injuries to his knee, including surgery and advanced chondromalacia, employer admitted a work-related aggravation to the knee. When the treating physician recommended a total knee replacement, the employer asserted that the prior chondromalacia was the major cause of his need for a TKR. COCA held that major cause only applies to the determination of whether the injury arises out of and in the course of the employment. Once a claim is determined to be compensable, "major cause" analysis cannot be used to determine the need for medical treatment.

3. Aggravation Injury

Aggravation of a pre-existing injury, disease or condition is compensable even when "evidence may indicate a claimant may be disabled by [pre-existing] disease in the future even though accidental injury had not occurred." Halliburton Services v. Alexander, 1976 OK 16, 547 P.2d 958.

Compensation benefits are not limited to perfectly healthy workmen. Firemen's Fund Insurance Co. v. Standridge, Okl., 467 P.2d 461 (1970). This is true although evidence may indicate a claimant may be disabled by disease in the future even though accidental injury had not occurred. This rule has been applied since Christian v. Hanna, 144 Okl. 89, 289 P. 708 (1930). Claimant's arthritic condition created a weakness of the back. Due to prior injury and disease his back gave way causing the fall which resulted in injury. The fall did not have to result from a traumatic incident, since it was sufficient if this occurrence was brought about by a hazard of the employment and would not have ensued except for the employment.
Halliburton Services v. Alexander, supra.


In the case of Dempsey v. Ballard Nursing Home, 2004 OK CIV APP 18, 84 P.3d 1071, it was uncontroverted that claimant lifted patients in the course of her work, such lifting involved strain that can hurt a person's back, and claimant experienced a hurt back injury that required medical attention after lifting patients at work. "It appears that the trial court and three-judge panel treated these facts as uncontroverted in view of the fact that neither made a finding that claimant lacked credibility, that her testimony had been impeached, or that she failed to carry her burden of proof and persuasion." Id. at ¶6.

When there is no conflict in the evidence, the question of whether an employee has sustained an accidental injury arising out of employment is a question of law. Lanman v. Oklahoma County Sheriff's Office, 1998 OK 37, ¶6, 958 P.2d 795, 798. In this regard, it has long been recognized "[w]here accidental injury results from a risk factor peculiar to the task performed it arises out of the employment." Halliburton Services v. Alexander, 1976 OK 16, ¶11, 547 P.2d 958, 961. Also, "[s]train or over-exertion relates entirely to the person injured, as to whom the principal ingredient is found in unusual effect, rather than from unusual cause." Meadow Gold v. Oliver, 1975 OK 67, ¶19, 535 P.2d 290, 294. The workers' compensation court determination that claimant did not sustain an "injury" is unsupported by competent evidence and is contrary to the uncontroverted evidence in the record.
Id at ¶7.


Evidence established that work related stresses aggravated the claimant's arthritic condition resulting in his physician's ordering him to quit work to avoid the stress. Stiles v. Oklahoma Tax Commission, 1987 OK 85, 752 P.2d 800.

It is a general rule in Workers' Compensation Law that an employer takes an employee as he finds him. That is, if an employee has a predisposition to be sensitive to stressful situations, the employer cannot avoid liability when the stresses imposed by the employment situation result in disability on the part of the employee.

In Oklahoma disability resulting from the aggravation of a pre-existing disease or condition is compensable.
Stiles v. Oklahoma Tax Commission, supra.

For a discussion of proneness or predisposition to injury and idiopathic injury, see Pauls Valley Travel Center v. Boucher, 2005 OK 30, 112 P.3d 1175.

4. Occupational Diseases

Heat Transfer & Equipment v. Cauthon, 2004 OK 80, 100 P.3d 722

Zinc Corporation of America v. Reeder, 2007 OK CIV APP 66, 164 P.3d 1132.

4.1. Inhalation Injury

Prior to the 2005 amendments, a physician's opinion on injury from inhalation of a harmful substance was based upon (1) information that the claimant actually inhaled a particular substance, (2) information that this substance was harmful, and (3) information showing that claimant's medical condition is consistent with inhalation of a harmful substance so that the physician could draw a "causal nexus" between the claimant's post-exposure medical condition and the inhaled substance. Zebco v. Houston, 1990 OK 113, 800 P.2d 245.

In City of Nichols Hills v. Hill, 1975 OK 39, 534 P.2d 931, the inhalation injury was shown by a physician's report that claimant's medical condition showed "classic symptoms" of inhaling a particular harmful agent and by biopsies that showed dissemination of the disease resulting from exposure. Id. 534 P.2d at 934. The parties did not dispute that claimant suffered from the medical condition, but rather the cause of that condition. We observed that the evidence included claimant's working conditions, absence of prior physical difficulties, facts of exposure, immediate onset of the physiological symptoms, and the ensuing progression of the diagnostically established disease. Id. 534 P.2d at 935. The same method is thus used in both Zebco and City of Nichols Hills to show causation.
Scruggs v. Edwards, 2007 OK 6, 154 P.3d 1257

5. Intervening Cause

After undergoing lumbar spine surgery, David Lee Cox returned to work in July 2002, but with a medically prescribed forty (40) pound weight restriction. In August 2002, at home, claimant lifted his twenty (20) pound daughter (who was afflicted with Down's Syndrome) out of her playpen preparatory to suctioning her trachea. Upon lifting his daughter, Cox again experienced back pain and right leg pain; an MRI scan revealed a recurrence of his disc herniation. Trial judge denied employer's intervening cause defense and authorized a second spinal surgery. On appeal the Supreme Court in the case of Mrs. Baird's Bakery v. Cox, 2005 OK 28, 112 P.3d 1168 held:

The question of whether disability should be attributed to an initial accident or a second depends on whether the second injury is merely a recurrence of an initial injury or, instead, the result of an independent and intervening cause. See Chromalloy-Am., Okla. Div. v. Wright, 1977 OK 93, 567 P.2d 71, 72-73. A "[s]ubsequent incident or accident aggravating [an] original injury may be of such nature and occur under such circumstances as to make [the] original injury [the] responsible cause." Patterson Steel Co. v. Stevens, 1965 OK 184, 408 P.2d 782, 782 (First Syllabus by the Court). "Where there have been two accidents to an employee, the question of whether the disability sustained by him should be attributed to the first accident or to the second accident depends on whether or not the disability sustained was caused by a recurrence of the original injury or by an independent intervening cause." New York Indemnity Co. Miller, 1933 OK 303 22 P.2d 107, 108 (Seventh Syllabus by the Court). Of course, the question as to the responsibility for medical care, i.e., whether the necessity therefore may be attributed to an initial work-related accident or a second non-work-related accident or event, is controlled by the same test(s) or standard(s) related in the above three cases.

Further, "[t]he cause and extent of the disability resulting from an accidental injury is a question of fact, and where the evidence is in conflict and there is any competent evidence reasonably tending to support the finding of the State Industrial Commission [predecessor to the WCC - hereafter referred to as WCC], an order or award based thereon will not be disturbed on review." Griffith v. Viersen Oil and Gas Co., 1956 OK 278, 302 P.2d 969, 969 (Syllabus by the Court). Thus, when there is conflicting competent evidence as to the factual causation issue supportive of a decision in favor of either the employer or the claimant, and no issue is raised upon review other than that the record does not contain competent evidence supporting the decision of the WCC tribunal, an appellate court must sustain the WCC decision when there is, indeed, competent evidence supporting its decision, regardless of whether that decision is in favor of the employer or the claimant.
Mrs. Baird's Bakery v. Cox, 2005 OK 28, 112 P.3d 1168

In support of the Court's decision Justice Lavender quoted at length from early decisions that addressed the same issues:

In Patterson Steel Co. v. Stevens, 1965 OK 184, 408 P.2d 782, 784-785, citing and quoting from Deep Rock Oil Corp. v. Betchan, 1934 OK 406, 35 P.2d 905, 907-908, is contained the following:

The instant case is analogous to the circumstances disclosed in Deep Rock Oil Corp. v. Betchan . . . wherein we considered the question of whether the cause of an employee's second injury was from slipping while engaged in the course of his employment, or from cranking his Model A Ford automobile. Therein we said:

. . . Not every incident (referring to the cranking of his automobile) following an injury which physically aggravates it can be treated as a responsible intervening agency. . . .
"It seems that a law designed to compensate workmen for loss of earning capacity from industrial accidents must have been intended to extend its shield at least to aggravations affecting the course of the injury during convalescence when such are produced by not unnatural events and involve no omission or breach of duty. We therefore think the [WCC] (is) sustained by the record in disregarding the automobile incident (cranking) as a responsible cause."

In the instant matter, competent evidence was presented at the trial before the WCC trial judge to show that claimant was adhering to his doctor-ordered forty (40) pound weight restriction when he reasonably picked up his twenty (20) pound daughter to suction her trachea. There was also plainly competent evidence presented at the trial supportive of a finding that the incident involving his daughter caused only a recurrence of the original work-related injury at the L4-5 level and that the recurrence was the result of mere inadvertence and accident on his part.

Thus, although the reasonableness of a home or non-work event is not always determinative of the causation issue, depending on the facts existent it may be a pertinent factor impacting the issue in certain circumstances. If the event is found by the WCC to be merely inadvertent and accidental and the injury suffered to be only a recurrence of an original work-related injury, the chain of causation or causal nexus will properly still be linked to that original work-related injury. However, if a recurrence of the former work-related injury is brought about by the deliberate, conscious act of the injured person, as in the Sinclair Prairie Oil Co. situation, it would be improper to attribute the recurrence back to the original work-related event.
Mrs. Baird's Bakery v. Cox, 2005 OK 28, 112 P.3d 1168

6. Injuries by Body Part

6.1. Heart

"Compensable injury" includes heart-related or vascular injury, illness or death only if an accident or the claimant's employment is the major cause of the heart-related or vascular injury. Such injury shall be compensable only if it is demonstrated that the exertion necessary to produce the harm was extraordinary and unusual in comparison to other occupations and that the occupation was the major cause of the harm.
85 §3(13)(b)

Early cases required proof of heart muscle damage to prove an accidental injury. Haynes v. Pryor High School, 1977 OK 1, 566 P.2d 852 (awards for injury by heart attack are limited to injuries attributable to coronary occlusion, thrombosis, or myocardial infarction); Refrigerated Transport Inc. v. Creek, 1979 OK 11, 590 P.2d 197 (an injury may be compensable if the evidence determines that an episode of unusual exertion has compromised claimant's cardiovascular system by aggravating a medically established heart condition with pre-existing heart muscle damage).

In 1977 the legislature amended the definition of compensable heart injury to include "illness," a term that has persisted through the current definition set out above. The distinction between heart injury and illness is discussed in Johnson v. City of Woodward, 2001 OK 85, 38 P.3d 218:

This limitation [the Haynes requirement of heart muscle damage] on compensable injuries was lifted by the legislative amendments of November 1, 1977, that resulted in the current § 3(10)(a) and (b). Today, under Oklahoma's Workers' Compensation Act, coronary artery disease such as that suffered by Johnson is, indeed, a heart-related illness.

Based upon the medical record in this case, coronary artery disease undermines and weakens a person's constitution and is not a temporary condition. The record allows that this illness affects the general soundness of the heart and its health. As such, coronary artery disease constitutes a heart-related illness within the confines of (10)(b).
Johnson, id at ¶9, 10.

Cockrell v. City of Broken Arrow, 2006 OK CIV APP 6, 128 P.3d 1098
Decker v. Oklahoma State University, 1988 OK 152, 766 P.2d 1371

6.2. Hand

Carpal tunnel syndrome is caused by compression of the median nerve which passes through the wrist to the hand. THE MERCK MANUAL OF DIAGNOSIS AND THERAPY 1444 (15th ed. 1987). Symptoms include numbness, tingling and pain in the hand and fingers, loss of sensory feedback from the hand and, consequently, decreased motor functioning of the hand, i.e. weakness and loss of grip. Armstrong, An ergonomics guide to carpal tunnel syndrome, found in U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES, CARPAL TUNNEL SYNDROME SELECTED REFERENCES (March 1989). Although the syndrome is widely associated with occupations involving repetitive hand movements, its causes are varied, including one-time acute trauma to the wrist. Id.
Thomas v. Elephant Run, 1991 OK 72, 814 P.2d 496, fn5.

6.3. Psychological Overlay

"Injury" or "personal injury" shall not include mental injury that is unaccompanied by physical injury, except in the case of rape which arises out of and in the course of employment.
85 O.S. Supp. 1997 §3(13)(c)

Wal-Mart Stores, Inc. v. Reinholtz, 1998 OK 11, 955 P.2d 223 (mental injury accompanied by the physical injury of rape by supervisor)

Shivel v. Wexford Health Sources, 2003 OK 25, 66 P.3d 414 (assault by prisoner).

This topic is also discussed under the term consequential injury.

6.4. Mental Stress Induced Injuries

If the claimant's injury resulted from stress and anxiety caused by the employment's work conditions, not by a self-generated innate propensity to worry, then the injury results from a risk reasonably incident to his employment. Decker v. Oklahoma State University, 1988 OK 152, 766 P.2d 1371. However, heart-injury cases must also meet the threshold requirements of 85 O.S. §3(13)(b) for compensable injury.

Injuries precipitated by stress were compensable in Oklahoma City v. Schoonover, 1975 OK 52, 535 P.2d 688 (aggravation of ulcer leading to death during surgery); City of Norman v. Garza, 2003 OK 111, 83 P.3d 851 (stress induced stomach ulcer coupled with PTSD and depression); and Stiles v. Oklahoma Tax Commission, 1987 OK 85, 752 P.2d 800 (flare up of preexisting arthritic condition).

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