Medical technology is currently capable of treating such physical hardships as loss of limb, eyelid paralysis, and chronic osteoarthritis – but researchers are continually finding ways to improve upon the effectiveness of these and other implanted and prosthetic device technologies. What follows is a sample of new technologies and research efforts that hold promise for a future in which human beings are able not just to survive, but thrive in the face of any conceivable physical difficulty.
Sling Mechanism for Eyelid Paralysis
Now, Craig Senders and Travis Tollefson of the University of California-Davis Department of Otolaryngology, Head, and Neck Surgery, are developing a more attractive third option: an artificial muscle used in conjunction with a sling mechanism to help facial paralysis patients restore the ability to blink more naturally. Illustration of left eyelid sling that is attached to the electroactive polymer artificial muscle device (EPAM) after passing through an interpolation unit that is implanted in the lateral orbital wall (note screw fixation). (UC Davis Health System photo)
The mechanism uses an artificial muscle – invented by SRI International of Menlo Park, CA – to drive eyelid movement. The muscle includes a piece of soft acrylic or silicon layered with carbon grease. When a current is applied, electrostatic attractions cause the outer layers to pull together and squash the soft center. This motion expands the artificial muscle, which is powered by an implanted battery source similar to what is used in cochlear implants. Once the charge is removed, the muscle contracts and flattens the shape of the sling, blinking the eye. When the charge is reactivated, the muscle relaxes and the soft center reverts back to its original shape.
Operating experimentally on cadavers, the researchers inserted a sling made of muscle fascia or implantable fabric around the eye. Small titanium screws secured the eyelid sling to the small bones of the eye. The surgeons disguised the entire device in a natural hollow located at the temple. For patients with one functioning eyelid, a sensor wire threaded over the normal eyelid could detect the natural blink impulse and program the artificial muscle to blink at the same time. Patients with two paralyzed eyelids could use an electronic pacemaker to blink their eyes at a steady rate.
Researchers are still refining the mechanism on cadavers and animal modes, but it is estimated to be available for human patients within the next five years.
Smaller Heart Monitor Implants
The new MIT monitor prototype is an L-shaped device, about 4” long on each side, that sticks to the chest and can be worn without any external wires protruding. It is capable of storing up to two weeks of data in Flash memory, and runs on just two milliwatts of power. In the future, researchers hope to engineer chips that can be powered by energy from the body of the person wearing the device.
ECG data from the chip can be downloaded for analysis, allowing doctors to spot future problems. Down the line, the researchers envision working the algorithm into the chip so that data can be analyzed more immediately. They also plan to incorporate an alarm that will alert the patient and/or doctor if a heart attack appears imminent. The researchers plan to start testing the device on healthy subjects this spring, followed by trials involving patients with cardiovascular disease.
Smarter Bone Implant Material
The novel composite foam is lighter than solid aluminum, and can be made of either 100% steel or a combination of steel and aluminum. The rough surface of the foam would also help foster bone growth into the implant, improving its strength. It is lightweight and displays high-energy absorption capability, but most importantly, it exhibits a modulus of elasticity that is very similar to that of bone. Modulus of elasticity is crucial to the success of a biomedical implant, said Dr. Afsaneh Rabiei, an associate professor of mechanical and aerospace engineering who led the research. It is measured in gigapascals (GPa), and refers to a material’s ability to deform when pressure is applied, and then return to its original shape when pressure is removed. The closer the implant material’s modulus of elasticity is to that of bone, the higher the likelihood that the body will accept the implant.
Pocket-Sized Device Treats Musculoskeletal Pain
Energy-Recycling Prosthetic Foot
“All prosthetic feet store and return energy, but they don’t give you a choice about when and how. They just return it whenever they want. This is the first device to release the energy in the right way to supplement push-off, and to do so without an external power source,” said Art Kuo, professor in the UM departments of Biomedical Engineering and Mechanical Engineering.
Working together with Steve Collins, a UM graduate student at the time, Kuo created the prosthetic device, which is powered by a small, portable battery that uses less than 1 Watt of electricity. The foot naturally captures the dissipated energy, and a microcontroller prompts the foot to return the energy to the system at the right time. When the researchers tested the device on non-amputees wearing a rigid boot and prosthetic simulator, they found that test subjects spent just 14% more energy walking with the new artificial foot compared to natural walking – a noticeable improvement over the 23% difference observed with conventional prostheses.
The artificial foot is now being tested on amputees at the Seattle Veterans Affairs Medical Center. Commercial devices based on the technology are also under development by an Ann Arbor, MI company.
Hip Replacement Measurement
Working in collaboration with Damian Griffin, a professor of trauma and orthopedic surgery at Warwick Medical School, the pair developed KingMark™, a double-marker calibration device that measures radiological hip magnification. The kit consists of a pad with an incorporated measurement system that includes two separate radio-opaque markers – one behind the pelvis and one in front – as the patient lies with his or her hips on the pad. A string of five linked precision balls is placed on the patient’s abdomen; the anterior (ball) and posterior measurements from the radiograph are entered and calculated. An accurate value for magnification is then generated. This system is less intrusive than the measurement systems currently in place, and is better at generating measurements for larger patients. Voyant Health of Columbia, MD began distributing this technology in the U.S. in March of 2010.