The Day I Cured Arthritis

This is an account of a true occurrence shortly after I took up the Hunter Chair of Bioengineering at Clemson University. It was written in 1989 and originally published, in slightly different forms, as: A Bioengineer's dilemma: When is a potential gain worth the certain risk? (Clemson World 43(3):32, 1990) and: New (and Improved?) vs. Tried and True - A Biomedical Dilemma. (J. Applied Biomaterials 1:329, 1990). Since it was completed, five years have passed and my doubts, as expressed here, have become even stronger. (Note that the time references have been adjusted to 1994)

Early one day, five years ago, I cured degenerative joint disease. Well, perhaps not cured but, in a still moment between night and morning, I had a clear waking vision of a new implant which surgeons could use to replace human hip joints destroyed by one of the diseases we know collectively as "arthritis." The pain and physical disability which are central parts of arthritis are not fatal; they merely steal the enjoyment of life away. Surgical intervention to replace the affected joint with an artificial substitute is a frequent response, rapidly restoring most patients to a full, active life.

By profession I am a bioengineer and have for a good part of the past quarter century worked and reasoned with my Orthopaedic surgical confreres concerning the origins and treatment of this affliction which impairs the quality of life for millions. The surgical replacement of degenerated joints with engineered devices is one of the great success stories of modern medicine.

The modern era began in earnest nearly 35 years ago by the English surgeon Sir John Charnley (now deceased) demonstrating his concepts for low friction replacement of the hip joint. Since then replacement of major joints in the body has become almost commonplace with probably more than 250,000 operations being done in the United States alone. Yet despite the great achievements - a better than 95% probability of good or excellent results for at least ten years for typical hip replacement patients - nagging problems of progressive clinical failure remain, particularly for younger, more active individuals.

The day before I had spent several hours with a graduate research student planning an experiment to examine a small point concerning the reaction of live bone to contact with implanted materials. As I fell asleep that night, I had been mulling over our discussion and the following morning, in a moment between sleeping and waking, its' implications for human clinical application were clear and exciting. The concept would deal definitively with a difficult problem, that of "fixation": of forming the integral connection between the device and the patient's skeleton required for effective, pain free function. It is the failure of fixation which is the most common origin of clinical failures of such devices. My approach would also permit near infinite adjustments to be made to the device by surgeons to accommodate individual anatomical differences between patients. Before dozing off again, I could visualize the device and its use in all its beauty, its rapid introduction and adoption, the conversion of skeptics, etc.

Later, after rising, dressing, and walking with the family dog¹ to fetch the newspaper, I had second thoughts. The idea which I had now seemed less good. Extensive in vitro and animal tests would be required even before clinical trials could begin. And when the design was sufficiently perfected for clinical testing, how could I advise my clinical colleagues concerning these studies? How could I suggest that patients be asked to forgo the more certain results of known technology for the chancier outcome of the experimental procedure?

Suppose we persevered and the usual two year clinical trial with several hundred patients produced promising results. Could we then justify petitioning the Food and Drug Administration for approval for commercial production and sale of the device, knowing that problems with similar devices had sometimes emerged only after seven or ten years or even longer of widespread clinical use? The last point was particularly arresting due to my strong concern that changes in the mid to late 1980s in the designs and clinical use pattern of hip replacement implants manufactured from cobalt-base alloys may already be exposing patients to long-term elevated biological risks not encountered with older technology.

Thinking further, I wondered if it is possible that improving a medical device with a highly satisfactory long-term performance record is simply not feasible on a rational prospective basis. Perhaps attainment of some level of success simply precludes further improvement because the risk of a worse outcome for the many is too great a price to pay for a hope of better outcome for a few. Is it possible that by continuing to strive for improvement in surgical technology we run the risk of snatching defeat from the jaws of victory? Do we know enough about why present designs fail or, more to the point, what aspects of them are critical for their success? Should we (and can we?) restrict design changes to conserve the gains of experience? Or is there a Gresham's Law operating here, such that new (and improved?) designs will continue to drive out tried and true ones, depriving present patients of the benefits gained by risk takers who went on before? Perhaps some problems reach a level of solution where we should say, "Enough!", and move on to other issues.

I think that I and my colleagues are called "professors" rather than "knowers" because we have such morning thoughts and harbor such uncertainties. I went up to the university and did not mention my "cure" for arthritis to my graduate student.

BLACK'S LAWS OF IMPLANTOLOGY:

1st Law: The inventor has the best (clinical) series.

2nd Law: The surgeon does best what he learns as a resident.

(Nixon's Corollary: "...in his first year as a resident."

3rd Law: It's always the patient's fault.

1 Miss W. H. Wickersham, better known to us and her many friends as Wickie. Unfortunately, in the winter of '93-'94, at the age of 15+, she reached the end of a long and valued life