Hip Hip Hooray for Biomedical Engineering!
“Gentlemen, we can rebuild him. We have the technology.” In 1974, Biomedical Engineering and a bit of Science Fiction entertained viewers of TV’s Bionic Man series. So, those of you who did not have the good fortune to be around when this program was on TV (your loss – but check out YouTube to see what you missed), astronaut Steve Austin was critically injured in a crash landing and was rebuilt with robotics. His new legs let him run at 60 mph, his arm had super-human strength, and the bionic eye gave him a 20:1 zoom lens and night vision.
The opening continued, “Better than he was before – Better… Stronger… Faster.” While “stronger” and “faster” are great outcomes after an accident, for most being “better” is just fine. Medical technology and biomedical engineering helps to make that possible. Medical doctors and researchers familiar with the human body work with scientists and engineers to figure out a solution to a problem. Biomedical Engineers use their practical knowledge of physics, mechanics, electrical engineering, and computer science to take the ideas on paper and make them real. Last year, CNN Money listed Biomedical Engineer as the #1 Best Job in America (http://money.cnn.com/pf/best-jobs/2012/snapshots/index.html).
Engineering and science have partnered with medicine from the beginning. Long before the Bionic Man, people engineered new limbs to replace those lost. The earliest example is a Mummy’s prosthetic toe discovered in Egypt. Craftsmen were the earliest engineers and their designs created some amazingly complex ancient medical equipment discovered in the ruins of Pompeii (see link below). Yet, the hollow s-shaped catheter, a tube typically used to drain the bladder, was very simple. The common catheter has an interesting story, though. This s-shaped metal tube design remained unchanged for hundreds of years. However, Benjamin Franklin recognized his brother’s discomfort from using rigid device to drain his bladder and remove kidney stones. In 1752, Franklin worked with a silversmith to make a new catheter design of shorter tubes that were hinged to be flexible.
Sometimes, it was the advancement in science that created a new medical technique. The German physicist Wilhelm Röntgen is credited with a notable advancement in medicine – his discovery in 1895, that a new type of ray could pass through human skin and tissue but not bone. He produced the first X-ray radiographic image of his wife’s hand and received the Nobel Prize in Physics for his contribution to science.
Medical technology and medical devices are big businesses and part of a growing modern medical industry. The medical equipment you find in home, at the doctor’s office, and in the hospital owe their existence to science and engineering. Amazing new surgical techniques are possible because of new tools. Surgeons can use smaller incisions with a digital video to help guide their work. Advances in medicine though science and engineering are helping get people back on their feet.
To illustrate where medical technology and biomedical engineering places us today, let’s look at total hip replacement surgery (total hip arthroplasty) – one of the more common joint replacement surgeries performed. The US Department of Health and Human Services reported in 2011-2012 an estimated 285,000 hip replacements as a result of osteoarthritis and almost 102,000 more as the outcome of a fracture. For the purpose of this story, let’s just say you fell off a horse and broke your femur at the neck – the location that connects your lower leg to the acetabulum, which is the ball that rotates inside your hip joint. Ouch! Upon admission to the emergency room, the staff uses automated medical equipment to monitor vital signs and download the data to a computer. The patient relies on the nurses and doctors and they in turn, rely on the engineering that the equipment manufacturers provide. That flexible catheter described earlier is now made of a pliable plastic to be used once – and only once. A trip to radiology produces instant X-ray evidence which is downloaded to the hospital computer. Surgery is scheduled. (If you want to try your hand at performing this surgery, check out this cool learning game, http://www.edheads.org/activities/hip/.)
Because of the effects of the anesthetic, you might not note the technology that surrounds you in the operating room. Some of the surgical tools, like the scalpel look unchanged, but others are notably different. One simple device first designed in 1972, measures blood oxygen levels – a pulse oximeter. Years ago, blood samples were needed to measure oxygen levels. Today, a little clip with LED lights, one red and one infra-red, attaches to a finger. The lights take turns flashing and the difference in how much light is adsorbed in the finger is calculated. A read out instantly tells how much oxygen is bound by hemoglobin in the blood.As for surgery and the new hip, the invention of the modern hip replacement and prosthesis is attributed to Sir John Charnley for his work in the 1960’s. Charnley’s showed that fluid was not necessary to a joints smooth motion. Instead, a low coefficient of friction was the key to making a successful prosthetic joint. In other words, the ball attached to the femur must glide easily in the cup attached to the hip – squeaking parts are not an option. He accomplished this with a stainless steel femoral head and a high molecular weight polyethylene socket.
In the US, the Food and Drug Administration or FDA is responsible for approving all new medical devices used in the body. Check out their website for Medical Devices (http://www.fda.gov/MedicalDevices/default.htm) and Device Approvals (approvals link below) and you will find a number of applications for new hip replacement components. Companies that produce joint prosthetics now use metal alloys (mixtures of metals) to construct the leg attachment or femoral component that inserts into the femur and the new acetabulum cup; the construction of these metal parts allows the bone to grow into the prosthesis improving the joint stability. The ball or femoral head is made of a metal alloy or a ceramic material while the liner of the acetabulum cup can be a crosslinked or ultrahigh molecular weight polyethylene or a ceramic material. The amount of science and engineering that go into these parts and their design is truly amazing.But it is not just the prosthetic parts that science and engineering makes better. New advances in hip replacement are made possible by re-engineering the surgical table. Mizuho OSI, a company in California, has a great trademark – “Bringing Innovation to the Table®” – and they have done this with the hana® table (http://www.mizuhosi.com/products/orthopedic-fracture-trauma/hana/). The new surgical table gives the surgeon better control of the patient’s position and this helps the surgeon use a smaller incision and eliminate cutting muscle attached to the leg when performing an anterior approach hip replacement. You can watch one surgeon demonstrate this table in the video below.
Bionics – “a science concerned with the application of data about the functioning of biological systems to the solution of engineering problems”
As for TV’s Bionic man Steve Austin, he is looking less like science fiction these days. The Rehabilitation Institute of Chicago (RIC) is working to create better limb prosthesis’ with a technique called “targeted reinnervation”. The goal is to send signals from the brain through nerves to the prosthesis. Think “open hand” and the prosthetic hand will open. You can watch people use this fascinating technology on videos, but this is just the beginning. There is another goal – to send signals from the prosthesis back to the brain returning the lost sense of touch. Check out the TED Talk by Dr. Todd Kuiken (MD, PhD) to see where the researchers at RIC are going with bionic limbs (video link below). Hearing* is another senses that bionics can improve. Cochlear implants, first approved for use by the FDA in 1984, are used to help for those with severe hearing loss or complete deafness hear. Outside the ear is a microphone that takes in sound. A processor converts the sound’s digital information into electrical signals. These signals are sent by a transmitter outside the head to a receiver inside the head and then continue to electrodes on a wire that winds through the ear’s cochlea. Once there, the electrical information transfers to the auditory nerves and the nerves send the signal to the brain where it registers as sound. The implant cannot duplicate what is heard with a normal working ear, but noises and speech can be recognized. Earlier this year, the first Retinal implant was approved by the FDA. Use is limited to people with Retinitis Pigmentosa – a rare genetic disease which leads to partial or complete blindness when the photoreceptor cells in the retina which detect light die. A receiver and electrode array are implanted into the eye and a video camera worn as sunglasses send the images to the implant. The nerves send signals to the brain which don’t duplicate the vision but do help the person detect motion and shape.
Thanks to the work of doctors, medical researchers, scientists, and engineers new medical devices are changing lives. Biomedical engineering and technology are helping us to walk after falling off that horse. So while we might not end up Better and Stronger and Faster, we are getting Better, Faster and that is pretty good.
*Note: In 1976, TV introduced The Bionic Woman, Jamie Sommers – she had a bionic ear.
For more information on Biomedical Engineering and the sites mentioned in this story, check out the following:
- Want to engineer a human prosthesis? – http://www.todaysengineer.org/2012/jul/career-focus.asp
- Ancient Medical tools discovered in Pompeii – http://exhibits.hsl.virginia.edu/romansurgical/
- FDA Medical Device Approvals – http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/DeviceApprovalsandClearances/Recently-ApprovedDevices/ucm335803.htm
- FDA Retinal Prosthesis Approval – http://www.fda.gov/MedicalDevices/ProductsandMedicalProcedures/DeviceApprovalsandClearances/Recently-ApprovedDevices/ucm343162.htm