Spare Parts

 

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What a gorgeous piece of machinery the human body is! Without even a conscious thought we do things like wake up each day, breathe and swallow—and that’s just the basic stuff. We also do an infinite variety of more complicated tasks, like changing light bulbs and baby diapers, climbing stairs and getting in and out of the car, gardening, playing the violin or competing in triathlons. It’s all made possible by a collection of complex bodily systems—containing a multitude of smaller parts perfectly designed to perform highly specific functions—that work in synchrony.

Surgery has been called a blend of art and science but it may be time to add an entirely new discipline to that description—engineering. Surgeons today are performing not only organ transplants and hip and knee replacements, but wondrous feats like face and hand transplants, and cochlear transplants that enable the deaf to hear again. Biomedical engineers have even developed a prosthetic arm that can be controlled by thought!

Here we travel to some of the state’s hospitals to look at the science and technology involved in developing “replacement parts” for the human body right here in Connecticut.
 

Engineering tissue to make a new blood vessel

In a 14-hour surgical procedure involving 50 doctors, nurses and other medical professionals who’d practiced their tasks with stopwatches for months beforehand, a Connecticut toddler born with a life-threatening heart defect received this country’s first-ever “tissue-engineered vascular graft” at Yale-New Haven Hospital. Cells taken from her bone marrow were attached to a biodegradable scaffold that will grow into a new blood vessel that will function in place of the one she was born without.  

This operation, which took place last August and was led by Drs. Toshi Shinoka and Gary Kopf, was the first in an FDA-approved clinical trial that is evaluating the technique as a treatment for children born with single ventricular congenital heart disease. The mortality rate for infants born with this birth defect, commonly called “blue baby syndrome” because the lack of oxygen in the blood gives the child a bluish tint, is 70 percent in the first year of life if left untreated.  

According to Christopher Breuer, M.D., a pediatric surgeon at Yale-New Haven Hospital who conducted the research leading to the surgery, this is groundbreaking because what gets produced is a blood vessel that will grow with the child since it was made with cells from her own body. It’s a major improvement over the procedure that employs a blood vessel made of a synthetic material, a procedure that has to be repeated periodically as the child outgrows the vascular graft.  

Breuer, who initially wanted to be a pediatrician, was drawn to the nascent field of tissue engineering because, he says, it brought together medicine and science in a way that he found rewarding and exciting. Trained at Harvard, he joined the tissue-engineering program at Yale because of its singular focus on blood vessels. “It was incredibly enabling to be in a program where all the resources were concentrated in one area,” he says.  

With the first young patient doing very well six months after her operation, Breuer anticipates performing this surgery on several more pediatric patients in the months to come, and envisions a time in the not-too-distant future when adults, too, will receive these vascular grafts in cardiovascular surgeries.    

Yale “provides an incredible environment to allow us to do this stuff,” says Breuer. He also credits the Food & Drug Administration and the National Institutes of Health (“some people find their approval process long and arduous but I think it is time well spent improving the safety of the operation”) and the Doris Duke Charitable Foundation, which continues to fund this important research.
 

Wrist and knuckle replacements

The human hand is an amazingly complicated arrangement of 27 bones and numerous muscles, tendons and ligaments that enable us to move our fingers, thumbs and wrists up, down and around to write, pick up small objects, button clothing and perform a host of other complex tasks. Most of us never think about any of this—until, that is, those parts don’t work so well. Where hand surgeons used to be limited in what they could offer such patients, there are now about 30 surgeons around the country who can replace faulty wrist and/or knuckle joints with devices that allow them to resume full function.  

“In the past, the options for arthritic wrists and knuckles have been to perform a fusion, which is when we keep the wrist in one position, or to do nothing at all,” explains hand surgeon Sep Sajjad, M.D., of the New England Hand Center, who operates at Lawrence & Memorial Hospital in New London. “Now we have a technology that allows us to take out the bad bones and replace them with a prosthetic wrist or knuckle that moves in various directions.” Sajjad says that he has performed five wrist replacements in the past year, along with 35 knuckle replacements in 15 patients, replacing several joints at a time in some.

He learned to do these complex surgeries under the tutelage of J. Grant Thomson, M.D., director of the hand surgery program at the Yale School of Medicine. Most wrist and knuckle replacement patients are in their 50s or older, suffering either rheumatoid arthritis or osteoarthritis that makes it difficult to use their hands. Wrist replacements have been available for only about 10 years, Sajjad says, pointing out that they offer great mobility—a tremendous advantage over fusion, which “can solve the pain of hand arthritis but results in a joint that doesn’t move normally.”

The new replacement parts allow patients to move their fingers and wrists quite normally, according to Sajjad (though weight-lifting and impact sports, like tennis, aren’t an option after the procedure). The joint replacements look natural too, which is a major improvement since arthritic knuckles tend to become swollen and misshapen. Sajjad says that his patients—who have included a police officer (who can now hold his gun securely), a pianist (who now hits every note) and even a surgeon (now operating with confidence)—have been thrilled with their new joints.
 

Spare Parts

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