The number of body parts that can be created, synthesized or replaced has grown rapidly over the last several decades. That's led to predictions that, eventually, all of our body parts will be replaceable. After all, who needs original parts when replacement parts work better and last longer? Does this mean that body parts that are replaceable are useless or that one day electronic body parts will replace the original ones?
As a kid, I used to hear often about the rapidly approaching reality of a "bionic" human. Television series (including The Six Million Dollar Man and its spin-off, The Bionic Woman) in the mid-1970s promoted this idea of super-heroes with bionic eyes, ears, arms and legs. This notion is still very much alive alive in action movies featuring human-machine hybrids such as Dr. Octopus in Spider Man 2.
The term "bionic" is a combination of "bio-," meaning living, and "-onic," referring to something electronic. The idea is that a person’s body parts could be replaced or work better using an electronic device. A pacemaker is a good example of bionics at work.
In fact, a number of body parts can be replaced or transplanted by the miracle of modern medicine, though many are not "bionic." For example, a hip replacement isn't bionic as there are no electronic components.
Although the movies and television would have you believe otherwise, replaced parts rarely work as well as the original, healthy versions. For example, an artificial joint rarely has normal range of motion and recipients are routinely advised not to stress the joint too much with athletics or other activities. The stability and function of the replaced joint almost never matches that of a normal, healthy joint. The same can be said for artificial skin, dialysis machines and ventilators, which attempt to duplicate bodily functions but often fall short.
The notion that we will someday have totally "bionic" people or that our bodies will become readily replaceable part by part is a myth — at least for now.
Replacement parts don't mean our original organs are useless, but they do mean that some parts are less vital than others.
Advances in modern medicine have made it possible for doctors to support many organs (as with a ventilator for lung failure) or to replace them entirely. Some are only temporary, some maintain life, and others improve quality of life.
Many come with their own set of problems. For example, would you rather have a kidney transplant and take potentially toxic medications for years or possibly the rest of your life to prevent rejection? Or, would you prefer to continue with dialysis three days a week for the rest of your life? Would you rather take pain medicines and continue limping with significant pain? Or, does it make more sense to endure a major operation to replace your worn out knee, knowing the operation can be risky and might not completely eliminate the pain? These are often tough decisions.
Here are some of the most commonly replaced body parts.
Replacement body parts and organ transplants have lengthened lives, improved quality of life and created a whole new set of problems and challenges. Even so, it's no small matter to have a joint replaced or a liver transplanted. It's major surgery with major risk. And, after a transplant, potentially risky medications are needed to prevent rejection. To make matters worse, people who need these procedures are often not so healthy to begin with – it's hard to get to the point of needing a vital organ transplanted while maintaining excellent overall health.
Although it's reassuring to know these "replacements" are available when needed, it is clearly best to do everything you can to keep your body parts in good working order. Perhaps someday in the future, even more body parts will be cloned, transplanted or built from scratch to replace a faulty original. For better or worse, the day of the bionic human will not arrive anytime soon.
Robert H. Shmerling, M.D. is associate physician at Beth Israel Deaconess Medical Center and associate professor at Harvard Medical School. He has been a practicing rheumatologist for over 20 years at Beth Israel Deaconess Medical Center. He is an active teacher in the Internal Medicine Residency Program, serving as the Robinson Firm Chief. He is also a teacher in the Rheumatology Fellowship Program.