Permanent Impairment Rating in Kentucky Injury Cases

A permanent impairment rating is a percentage a physician assigns to measure the loss of function an injury leaves behind once it stops improving. Kentucky gives that number two different jobs. In a workers’ compensation case, KRS 342.730 multiplies it into a benefit formula. In a personal injury case against the driver who caused an accident, the rating is medical evidence, and under Reece v. Nationwide Mutual Insurance Co. the jury decides what a permanent injury is worth.

Whole Person Impairment Percentages

Kentucky’s workers’ compensation statute defines the term. Under KRS 342.0011(35), a permanent impairment rating is the “percentage of whole body impairment caused by the injury or occupational disease as determined by the ‘Guides to the Evaluation of Permanent Impairment.’” The American Medical Association publishes those Guides, and the AMA says more than 40 states rely on them to assess and rate permanent loss of function.

Impairment has a narrow medical meaning. Quoting the fifth edition of the Guides in Colwell v. Dresser Instrument Division, the Supreme Court of Kentucky described impairment as “a loss, loss of use, or derangement of any body part, organ system, or organ function.” The same opinion quotes the Guides on what a whole person rating covers: it estimates “the impact of the impairment on the individual’s overall ability to perform activities of daily living, excluding work.”

Because the rating leaves work out, it measures the body. The court in Colwell made a related point about workers’ compensation, where the rating “is but one consideration in determining the amount of the worker’s benefit.”

Maximum Medical Improvement Timing

A rating comes after treatment has done what it can. According to the American Medical Association, physicians use the Guides to assess and document impairment once a patient has reached maximum medical improvement. The Guides, as quoted in Colwell, treat an impairment as permanent “when it has reached maximum medical improvement (MMI), meaning it is well stabilized and unlikely to change substantially in the next year with or without medical treatment.”

Kentucky’s workers’ compensation law uses the same milestone. KRS 342.0011(11)(a) defines temporary total disability as the condition of an employee “who has not reached maximum medical improvement from an injury and has not reached a level of improvement that would permit a return to employment.” Temporary disability belongs to the period before MMI. The permanent rating describes what remains after it.

AMA Guides Editions in Kentucky

Kentucky workers’ compensation does not use the newest edition. Under KRS 342.0011(37), the Guides means the fifth edition published by the American Medical Association, plus Chapter 12 of the second edition for psychological impairments. The AMA now publishes AMA Guides Sixth 2025.

A newer edition does not take over in Kentucky on its own. KRS 342.262 directs the workers’ compensation commissioner to recommend, within 180 days after the AMA publishes a new edition, whether all or part of it should be enacted. That recommendation “shall not become effective unless the General Assembly approves and adopts the recommendation.”

A rating made under the wrong edition cannot carry a Kentucky award. In George Humfleet Mobile Homes v. Christman, the Supreme Court of Kentucky sent a case back and told the administrative law judge to “choose among the Fifth-Edition impairments in evidence, and base the award upon that impairment.”

Physicians Who Assign the Rating

Assigning the rating is a physician’s job. In Plumley v. Kroger, Inc., the Supreme Court of Kentucky repeated that “the proper interpretation of the Guides and the proper assessment of an impairment rating are medical questions.” Humfleet put the limit on the fact finder in one sentence: “An ALJ is not authorized to interpret the Guides.”

The Guides still leave room for medical judgment. Plumley held that a rating must be grounded in the Guides, and that “to be grounded in the Guides is not to require a strict adherence to the Guides, but rather a general conformity with them.” Two physicians can examine the same person and reach different numbers. When that happens in a workers’ compensation case, the administrative law judge chooses among the ratings in evidence, as Humfleet directed.

Workers’ Compensation Benefit Formula

In a Kentucky workers’ compensation case, the rating becomes arithmetic. For permanent partial disability, KRS 342.730(1)(b) starts with 66-2/3 percent of the employee’s average weekly wage, capped at 82.5 percent of the state average weekly wage, and multiplies it by the permanent impairment rating and a factor from this table.

KRS 342.0011(36) calls the product the permanent disability rating: the impairment rating “selected by an administrative law judge times the factor.” Because the factor climbs from 0.65 to 1.70, each percentage point counts for more as the rating rises.

Two more parts of the statute use the rating. If an injury leaves the employee without the physical capacity to return to the type of work performed at the time of injury, KRS 342.730(1)(c)1 multiplies the benefit by three. Under KRS 342.730(1)(d), benefits run for 425 weeks when the permanent disability rating is 50 percent or less and 520 weeks when it is greater than 50 percent.

University Medical School Evaluations

When ratings conflict, one evaluation starts with extra weight. KRS 342.315 directs the commissioner to contract with the University of Kentucky, University of Louisville, and University of Pikeville medical schools to evaluate injured workers. The designated evaluator’s clinical findings and opinions receive “presumptive weight,” and “the burden to overcome such findings and opinions shall fall on the opponent of that evidence.” An administrative law judge who rejects them must “specifically state in the order the reasons for rejecting that evidence.”

Car Accidents on the Job

A car accident during work can create two cases at once. Under KRS 342.700(1), when someone other than the employer is legally liable for a work injury, the employee may pursue workers’ compensation, file a civil action against that other person, or “proceed both against the employer for compensation and the other person to recover damages, but he shall not collect from both.”

The same physician’s rating can appear in both cases, but each case uses it under its own rules.

Personal Injury Cases Against the At-Fault Driver

Outside workers’ compensation, no table converts a rating into money. In a Kentucky car accident case, the jury decides. In Reece v. Nationwide Mutual Insurance Co., the Supreme Court of Kentucky held that “evidence of permanent injury alone is sufficient for an instruction on permanent impairment of earning power.” Jurors may then decide from the evidence and their own common knowledge and experience whether a permanent impairment exists, how far it reaches, and what it is worth.

The court added that specific witness testimony about permanent impairment of earning power is not necessary to send the issue to the jury. In Reece, two physicians established that the injury was permanent, and the injured woman testified about how it affected her job and her schooling. A physician’s permanent impairment rating, explained by the doctor who gave it, is one way to put that kind of permanence in front of a jury.

Reece also set a limit: “a permanent injury may not always result in permanent impairment of earning power.” A rating establishes something about the body. What the injury costs the person still has to be shown with evidence.

Future Damages Evidence

A permanent injury points to costs that have not happened yet, such as more treatment, more pain, and a changed ability to work. Kentucky requires evidence for each one. In American States Insurance Co. v. Audubon Country Club, the Supreme Court of Kentucky reviewed awards for future medical expenses and future pain and suffering and said, “There must be evidence to support either award.” There, the treating physician testified that the injured man’s condition would get worse, that he would need a hip replacement, and that he would have continual pain.

The same opinion held that an award of future medical expenses is “a strong indication that a corresponding award for future pain and suffering must be considered.” For a serious permanent injury, a life care plan can lay out the future treatment a physician expects, item by item. Those future costs sit alongside the other types of damages in a Kentucky injury case.

Insurer Challenges to a Rating

A rating that raises what an employer or insurer owes will be tested. Kentucky case law shows the usual lines of attack:

• Wrong edition. A workers’ compensation award must rest on a rating made under the required edition, which is why Humfleet sent the case back for a new choice among fifth edition ratings.
• Method. An opposing physician may say the rating departs from the Guides. Under Plumley, the rating needs general conformity with the Guides, not strict adherence, and a party who thinks a rating breaks the Guides has to raise that objection before the administrative law judge.
• Pre-existing condition. An employer may argue part of the impairment existed before the injury. Under Finley v. DBM Technologies, a prior condition counts as active only if it was “symptomatic and impairment ratable” under the Guides immediately before the work injury, and “the burden of proving the existence of a preexisting condition falls upon the employer.”
• Competing evaluations. Under KRS 342.315, the party opposing a university evaluator’s findings carries the burden of overcoming them.

In an injury case against an at-fault driver, a defense physician’s opinion is evidence like any other, and the jury weighs it against the treating physician’s testimony. Car accident cases also have their own rules for a pre-existing condition.