An impairment rating is a percentage that represents how much permanent physical or mental function you’ve lost due to an injury or illness. A 0% rating means no measurable permanent loss, while 100% represents total impairment of that body part or system. This number is central to workers’ compensation claims, personal injury cases, and veterans’ disability benefits because it directly determines how much money you receive.
Impairment vs. Disability
These two terms sound interchangeable, but they mean different things in medical and legal settings. Impairment refers to a problem with a specific organ or body part: a torn rotator cuff that never fully heals, a spinal disc that still bulges after surgery, or permanent nerve damage in your hand. It’s measured at the body-part level.
Disability is broader. It describes how that impairment limits your ability to perform activities as a whole person, like working, driving, or caring for yourself. Two people with the same 15% shoulder impairment rating could have very different disability levels depending on whether they work at a desk or on a construction site. The impairment rating captures the medical loss; disability captures the real-world consequences.
When You Can Get Rated
You can’t receive an impairment rating while you’re still actively recovering. First, you need to reach what’s called maximum medical improvement (MMI). This is the point when your doctor determines your condition is unlikely to get significantly better with additional treatment. It doesn’t necessarily mean you’re pain-free or fully healed. It means your condition has stabilized enough that a physician can reliably assess what’s permanent.
In workers’ compensation, reaching MMI is a formal milestone. Your treating physician or an independent evaluator will declare it, and only then can you be scheduled for an impairment evaluation. In personal injury cases, MMI serves the same purpose: giving doctors a clear picture of what ongoing limitations you’ll carry forward.
What Happens During the Evaluation
An impairment evaluation is a structured medical exam, not a routine office visit. The rating physician reviews three categories of evidence: your clinical history, a physical examination, and diagnostic studies like X-rays, MRIs, CT scans, or nerve conduction tests.
Your clinical history covers more than just the injury itself. The evaluator looks at how the injury happened, what treatment you received (and whether it was appropriate), your current symptoms, how the condition affects your daily activities, and whether you had any pre-existing conditions in the same body area. You may be asked to fill out a questionnaire about your ability to perform daily tasks like dressing, bathing, lifting, or walking.
During the physical exam, the doctor assesses appearance, range of motion, sensory function, muscle strength, and blood supply to the affected area. If you injured your back, for example, they’ll measure how far you can bend, twist, and extend, then compare those numbers to normal ranges. For nerve injuries, they’ll test sensation and reflexes.
The evaluator then matches all of this information to standardized tables published in the AMA Guides to the Evaluation of Permanent Impairment, which is the reference most states and federal programs require. The most recent edition (2024, sixth edition) uses diagnosis-based tables where the physician locates your specific diagnosis, confirms it with objective findings, and reads the corresponding impairment value. Every rating must cite the specific tables and page numbers used, creating a paper trail that can be reviewed or challenged.
Who Performs the Rating
Not just any doctor can issue a legally binding impairment rating. In workers’ compensation systems, the evaluator is typically a Qualified Medical Evaluator (QME) or an Agreed Medical Evaluator (AME) certified by the state. Eligible professionals include medical doctors, osteopaths, chiropractors, dentists, optometrists, podiatrists, psychologists, and acupuncturists, depending on the nature of the injury. Each must complete specific certification requirements and demonstrate competence with the AMA Guides before they’re authorized to rate impairment.
How Ratings Translate to Compensation
The percentage you receive has a direct financial impact. The exact formula varies by state and by the type of claim, but the principle is consistent: higher percentages mean larger payouts.
In federal workers’ compensation programs administered by the Department of Labor, for example, claimants can receive $2,500 per percentage point of impairment. A 10% whole-person impairment rating would yield $25,000; a 40% rating would yield $100,000. The maximum payable compensation under certain federal programs (excluding medical benefits) is $250,000. State workers’ compensation systems use their own multipliers, which can be higher or lower. Some states also factor in your age, wage level, and the specific body part affected.
In personal injury lawsuits, the impairment rating doesn’t plug into a fixed formula the same way. Instead, it serves as powerful evidence during settlement negotiations or at trial, helping to quantify the severity of your injury for insurers, judges, and juries.
Example Ratings for Common Injuries
Impairment percentages vary widely depending on the body part, the severity of the condition, and how much function you’ve lost. The VA’s rating schedule for musculoskeletal injuries illustrates the range:
- Spinal disc herniation: Rated based on incapacitating episodes. If disc problems caused at least six weeks of incapacitating episodes in the past year, the rating is 60%. One to two weeks of episodes yields 10%.
- Frozen shoulder (ankylosis): Ranges from 20% to 50% depending on the position the joint is locked in and whether it’s your dominant arm. A shoulder frozen in a favorable position (you can still reach your mouth and head) rates 20-30%, while one locked with the arm pinned close to your side rates 40-50%.
- Frozen knee: A knee locked in a favorable position near full extension rates 30%. One locked at 45 degrees of flexion or more rates 60%.
- Frozen hip: Ranges from 60% for a favorable position up to 90% for severe ankylosis where your foot can’t reach the ground and you need crutches.
- Frozen ankle: Ranges from 20% to 40% depending on the angle the joint is locked in.
These are ratings for complete loss of joint motion. Partial losses of range of motion receive proportionally lower percentages. Your rating also depends on whether the affected limb is your dominant side, with dominant-side injuries typically receiving a higher number.
If You Disagree With Your Rating
Impairment ratings are not final the moment they’re issued. If you believe your rating is too low, you have options. The specifics depend on your state and the type of claim, but the general process follows a predictable path.
First, review the report carefully. The evaluating physician is required to cite the exact tables, page numbers, and diagnostic criteria from the AMA Guides. If the doctor didn’t account for all of your conditions, missed a body system, or applied the wrong diagnostic table, that’s grounds for a challenge. A claims examiner also reviews the report to make sure the physician addressed every relevant factor.
You can typically request a second evaluation from a different qualified medical evaluator. In some systems, this is an independent medical examination (IME) arranged by the insurer or the court. In others, you and the insurance company agree on a physician together. If the two ratings conflict, the dispute may go to a medical review board or an administrative law judge for resolution.
Having your own attorney review the rating before accepting it is common practice, especially in workers’ compensation cases where a single percentage point can mean thousands of dollars in benefits.