Understanding the Difference Between Impairment and Disability Ratings

Introduction

What is an Impairment?

In the most basic sense, an impairment is a loss, loss of use, or derangement of a body part.

• Loss: For example, if an auto accident results in an arm amputation, that constitutes a loss of the limb.
• Loss of Use: If a nerve injury makes the arm non-functional, even though the limb is physically present, that also qualifies as an impairment.
• Derangement: All traumatic injuries (e.g., a torn ligament, herniated disc, or severe sprain) are considered “derangements” of a body part, meaning the structure is altered or damaged.

According to the AMA Guides to the Evaluation of Permanent Impairment, an impairment specifically measures the extent of injury and how it affects the patient’s activities of daily living (ADLs) outside of work. For instance, can the person dress themselves, drive, cook, or partake in recreational activities without limitation?

Key Takeaway: An impairment rating is about the physical or anatomical injury and the resulting functional limitations in everyday life.

What is a Disability?

A disability goes one step further. While impairment looks at overall functional loss in daily activities, disability focuses on how that impairment affects a person’s ability to perform their job or earn a living.

• High Impairment, Low Disability: Imagine someone who has a severe spinal injury and cannot walk but works in a desk job they can do from home. Their impairment is significant, yet their ability to earn a living (and thus disability rating) might be relatively low.
• Low Impairment, High Disability: Conversely, losing a little finger may not greatly affect daily life for most people, but if the individual is a concert pianist who relies on that finger to perform at a world-class level, the disability could be profound.
  
  Key Takeaway: Disability is job-specific. You need to analyze the tasks, functions, and demands of a person’s occupation to determine how the impairment impacts their earning capacity or work performance.

Why the Distinction Matters

• Medical vs. Vocational
  
  • Impairment is essentially a medical concept: the diagnosis, the degree of anatomical or physiological loss, and how it affects personal independence.
  • Disability is both a medical and vocational concept: how the impairment hinders job duties or reduces earning potential.
• Assessment Tools
  
  • For impairment ratings, standardized guidelines (like the AMA Guides) outline how to measure functional loss.
  • For disability evaluations, additional tests—such as functional capacity evaluations—help determine how the impairment aligns or conflicts with workplace demands.
• Legal and Compensation Implications
  
  • Workers’ compensation and insurance claims often require separate calculations for impairment vs. disability.
  • A person can have a recognized impairment yet still work with little to no disability claim—or vice versa.
    
    
    

Practical Examples

• Spinal Cord Injury:
  
  • Impairment: The inability to walk or perform essential ADLs (e.g., bathing, dressing) indicates a high impairment rating.
  • Disability: If the individual’s job doesn’t require ambulation (e.g., desk-based computer work), the disability rating may be lower than expected.
• Amputation of a Finger:
  
  • Impairment: Losing the little finger might have a moderate impairment rating for daily functions.
  • Disability: If that person is a professional musician relying on full use of both hands, the disability could be substantial.

Key Takeaways

• Impairment is about the anatomical or functional loss and its impact on daily life.
• Disability is about how that loss affects one’s ability to perform job-related tasks or earn a livelihood.