June 1999 Bulletin

Cumulative trauma: Fact . . .

The proposed OSHA Ergonomic Program Standard has added another ember to the cumulative trauma controversy, addressed in these Point of View articles. The authors also will debate the issues at a meeting of the American Society for Surgery of the Hand and American Association for Hand Surgery in October.

By Peter C. Amadio, MD

A famous baseball pitcher tears the medial collateral ligament of his elbow, and his career is over. The last pitch was not unusual; he had thrown harder many times before. Everyone assumes that his arm just gave out after many years of hard throwing. They are amazed it lasted this long. Everyone knows that if you throw hard like that for 20 years, you will have to pay a price. The human body was just not made to endure such prolonged punishment. Everyone is happy to see from newsreels that the pitcher is still able to enjoy his hobbies and a new job, and they look forward to his election to the Hall of Fame. Truly, the pitcher deserves all the rewards that society will shower on him.

One day, lifting a 50 pound weight as he has hundreds of times per day in the past, a laborer's back gives out, and he is no longer able to do his job. Unfortunately, the laborer does not get to go to a Hall of Fame. No one outside his family sympathizes with him. Instead, his employer questions why he should hurt now. Didn't he work for 20 years without complaint? Is he sure it wasn't from that deck he built last summer? Maybe it is a consequence of smoking, poor diet or other poor "lifestyle habits"? Everyone knows that repetitive use makes the body stronger, not weaker. The employer may even hire a private investigator to show with secret videotapes, that the laborer enjoys hobbies, or holds another job. Medical experts will testify that cumulative trauma is a fiction. Everyone wishes the laborer would stop goldbricking and get back to work. After all, he is costing society money.

What is different between these two scenarios-aside from the fact that the first we read about in the newspapers, while the second we see regularly in our offices? In both cases, a career-ending episode occurred at work, following a stress no different from those the worker had tolerated for years. Yet, the response was rather different. In the first example, few people, if any, doubted that the pitcher's problems were really the result of a lifetime of hard throwing, rather than that last, not particularly fast pitch. In the latter example, there will be many people who will be willing, indeed anxious, to challenge the laborer's claim that his injury was the result of repetitive loading at work. Why? Is cumulative trauma fact or fiction? Cumulative trauma is a fact. It is as real as the blisters we all get, the stress fractures and decubitus ulcers we have all diagnosed, or the many backaches, rotator cuff injuries and other ailments that are brought on, not by a single extraordinary tissue load, but by too many repetitions of ordinary ones. Living tissues have amazing recuperative powers, but it stands to reason that there is some threshold, below that which would cause acute tissue failure, beyond which repetitive or prolonged loading will cause, eventually, tissue damage.

Most people who can control the frequency and duration of their activities will modify that activity as they enter this zone of risk, in response to the normal protective mechanisms of fatigue and pain. Those who have no control over their activities may be less fortunate. No bodybuilder would lift all day, five days a week, but many workers are obliged to. Few pianists will sit at the keyboard without a break for more than an hour or two; few data clerks have that luxury.

This is not to say that all complaints of workers are the result of cumulative trauma, or that the trauma in question occurred on the job. There must be, after all, some evidence that the load and repetition of a particular activity exceed the normal capacity for healthful work hypertrophy.

Unfortunately, such data is available only for the heaviest and most repetitive industrial jobs. At the opposite extreme, it is unlikely that an office worker who types, for example, a few hours per day would exceed such thresholds. In between is a broad gray area that encompasses the vast majority of U.S. workers. More and better research is needed to identify the danger zones. Activities, posture, and loading that exceed sustainable physiological capacity ought to be eliminated where possible, and at the very least recognized as hazardous where they cannot.

The real difference between the story of the pitcher and the story of the worker is not medical; it is economic and political. Cumulative trauma is a fact. As medical professionals, we have a duty to focus the light of science more sharply on this area. As citizens, we also must address the political and economic barriers that prevent us from managing these problems as advocates for good health rather than as adversaries over who pays.

Peter C. Amadio, MD, is Professor of Orthopedic Surgery, Mayo Clinic, Rochester, Minn.

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