The evolution of medical technology: lessons from the Burgess Shale.

Many forthcoming medical advances-growth factors, tissue engineering, gene therapy, attachable prosthetic limbs, and implantable computers--are so new that as yet there is no clinical experience with them. Each therapeutic technique will evolve in an environment containing few guideposts to help judge its efficacy and safety. Recent developments in evolution theory (based on an analysis of Cambrian fossils in Canada's Burgess Shale quarry) suggest that evolution passes, at times, through innovative cycles of progress--when diversification of design leads to perfection of form--with the concomitant production of many unsuccessful models. The evolution of the total knee replacement is a perfect example of the process, because many of the early devices have proven to be dismal failures. However, modern knee replacements would not have been developed without them. Because the risk of unforeseen complications associated with new medical products cannot be discerned in advance, each patient-consumer should have the opportunity to intelligently weigh an innovative product's risk potential against its possible benefit. The proposal made here, for a temporary New Product status for new drugs and devices after a product is cleared by the Food and Drug Administration for general marketing, provides a mechanism for making such decisions.