When an individual suffers multiple impairments and the impairment ratings are totaled, the situation may arise in which the total becomes unreasonably large or even exceeds 100%. Simply adding impairments can result in an inflated impairment rating. Consider this example: A motorcyclist’s leg hits the front end of a late-model pickup truck at an intersection. Two years later, the motorcyclist has recuperated from his injuries, and a rating is needed. His injuries were on one side. He sustained a syme amputation (62% impairment of the lower extremity [LE]) and a total hip replacement (50% LE).

Totaling these ratings results in a 112% impairment to the LE. This is impossibly high, and one might argue that even using the examining physician’s prerogative to adjust an inappropriate rating, assigning 100% would still be excessive because the patient does have a hip (albeit artificial), a knee, and a leg down to the ankle. Alternatively, using the AMA Guides’ Combined Values Chart (Appendix B) results in an impairment rating of 81% LE, which I would contend is more appropriate to the situation.

The AMA Guides readily admits that the best scientific formula for combining multiple impairments has not been established (1); it offers the Combined Values Chart as an interim strategy. Unfortunately for the busy practitioner, the Combined Values Chart is time-consuming and cumbersome. And, when dealing with three or more impairments, don’t even think about attacking the chart without a ruler and scratch pad at hand.