Category: Implants and Prostheses

Categories : Implants and ProsthesesTags :

Neural Control of Prosthetic Ankle Can Restore Agility

On By ModernMedia
Female athlete with prosthetic leg relaxes on a sporting field. Photo by Anna Shvets from Pexels

A recent case study demonstrates that, with training, neural control of a prosthetic ankle with a powered joint can restore agility. 

Traditional prosthetic ankle joints result in slower walking and abnormal gaits due to the way they differ from normal human ankles in distributing walking loads. Autonomously controlled powered prosthetic ankles can restore additional function to users by providing the extra work involved in a natural walking gait. However, they are currently only designed to assist walking or standing, and not to tackle specialised tasks such as squatting.

“This case study shows that it is possible to use these neural control technologies, in which devices respond to electrical signals from a patient’s muscles, to help patients using robotic prosthetic ankles move more naturally and intuitively,” said corresponding author Helen Huang, Jackson Family Distinguished Professor in the Joint Department of Biomedical Engineering at NC State and UNC

“This work demonstrates that these technologies can give patients the ability to do more than we previously thought possible,” says Aaron Fleming, first author of the study and a Ph.D. candidate in the joint biomedical engineering department.

Most research on robotic prosthetic ankles has focused on autonomous control, meaning that the prosthesis handles the fine motions when the wearer decides to walk or stan.

Huang, Fleming and their collaborators sought to find out if amputees could be trained to use a neurally controlled prosthetic ankle to regain more control in the many common motions that people make with their ankles beyond simply walking.

Their powered prosthesis reads electrical signals from two residual calf muscles, which are responsible for controlling ankle motion, and converts the signals into commands for moving the prosthesis.

The researchers recruited a study participant with an amputation between the knee and the ankle, and fitted the powered prosthetic ankle on the participant and did an initial evaluation. Over two and a half weeks, the participant then had five, two-hour training sessions with a physical therapist. A second evaluation was conducted on training completion.

Having had the training, the participant was able to perform a variety of previously challenging tasks, such as going from sitting to standing without any external assistance or squatting to pick something up without compensating for the movement with other body parts. However the participant’s own stability, both self-reported and empirically measured in such tests as standing on foam, was dramatically improved.

“The concept of mimicking natural control of the ankle is very straightforward,” Huang said. “But implementation of this concept is more complicated. It requires training people to use residual muscles to drive new prosthetic technologies. The results in this case study were dramatic. This is just one study, but it shows us what is feasible.”

“There is also a profound emotional impact when people use powered prosthetic devices that are controlled by reading the electrical signals that their bodies are making,” Fleming said. “It is much more similar to the way people move intuitively, and that can make a big difference in how people respond to using a prosthesis at all.”

More participants are already undergoing the training, with the researchers expanding their testing to match. But before this technology is made more widely available, the researchers would like real-world testing, with the prosthesis being used in people’s daily routines.

“As with any prosthetic device for lower limbs, you have to make sure the device is consistent and reliable, so that it doesn’t fail when people are using it,” Huang said.

“Powered prostheses that exist now are very expensive and are not covered by insurance,” Fleming explained. “So there are issues related to access to these technologies. By attempting to restore normal control of these type of activities, this technology stands to really improve quality of life and community participation for individuals with amputation. This would make these expensive devices more likely to be covered by insurance in the future if it means improving the overall health of the individual.”

The researchers are currently working with a larger group of study participants to see how broadly applicable the findings may be.

Source: News-Medical.Net

Journal information: Fleming, A., et al. (2021) Direct continuous electromyographic control of a powered prosthetic ankle for improved postural control after guided physical training: A case study. Wearable Technologies. doi.org/10.1017/wtc.2021.2.

Categories : Implants and Prostheses PaediatricsTags :

Lab-made Heart Valves That Can Grow With The Recipient

On By ModernMedia

In a new study, lab-made heart valves were shown to grow along with their recipient when implanted into lambs for a year, making a new alternative possible for thousands of paediatric patients who need replacement heart valves. 

Researchers from the University of Minnesota Twin Cities’ College of Science and Engineering and the Medical School published the results in Science Translational Medicine. The production procedure for the valves has also been patented and licensed to the University of Minnesota startup company Vascudyne, Inc.

Compared to currently used animal-derived valves, these new valves also showed reduced calcification and improved blood flow when tested in the same growing lamb model. Current solutions for children involve prosthetic valves, but these calcify over time and cannot grow with the patient. This requires up to five open-heart surgeries to replace them as the children grow towards adulthood, involving considerable risk and expense, as well as demanding lifelong anticoagulation therapy.

“This is a huge step forward in paediatric heart research,” commented senior researcher Robert Tranquillo, a University of Minnesota professor in the Departments of Biomedical Engineering and the Department of Chemical Engineering and Materials Science. “This is the first demonstration that a valve implanted into a large animal model, in our case a lamb, can grow with the animal into adulthood. We have a way to go yet, but this puts us much farther down the path to future clinical trials in children. We are excited and optimistic about the possibility of this actually becoming a reality in years to come.”

Using a combination of tissue engineering and regenerative medicine, they were able to grow the heart valves. Implementing a tissue engineering technique they had previously developed, they grew tube-like structures out of skin cells. This involved combining the skin cells in fibrin, and providing nutrients in a bioreactor. After washing the skin cells out with detergent, the researchers were left with a collageneous matrix which would not provoke an immune response when implanted. They then sewed and trimmed three of these tubes together to make a 19mm diameter heart valve-like structure.

“After these initial steps, it looked like a heart valve, but the question then became if it could work like a heart valve and if it could grow,” Tranquillo said. “Our findings confirmed both.”

The valves grew from 19mm to 25mm over a year, and showed little of the calcification or clotting associated with prosthetic valves, while performing better than animal-derived valves.”We knew from previous studies that the engineered tubes have the capacity to regenerate and grow in a growing lamb model, but the biggest challenge was how to maintain leaflet function in a growing valved conduit that goes through 40 million cycles in a year,” said lead researcher Zeeshan Syedain, a University of Minnesota senior research associate in Tranquillo’s lab. “When we saw how well the valves functioned for an entire year from young lamb to adult sheep, it was very exciting.”

The next steps are to implant the valve into the right ventricle of the heart to see how it performs, and apply for FDA approval to proceed to human trials. 

Source: Medical Xpress

Journal information: Zeeshan H. Syedain et al, Pediatric tri-tube valved conduits made from fibroblast-produced extracellular matrix evaluated over 52 weeks in growing lambs, Science Translational Medicine (2021). DOI: 10.1126/scitranslmed.abb7225

Categories : Implants and ProsthesesTags :

New Type of Corneal Implant Fuses into the Eye

On By ModernMedia

A new type of artificial cornea has been successfully implanted into an elderly patient, who demonstrated recovered sight the day after his surgery.

When the cornea is damaged by disease or injury, blindness can result, necessitating a cornea transplant. Artificial corneas are a much sought-after technology, as the normal treatment for a damaged cornea is to seek a transplanted replacement. However, for every 70 corneas sought, there is only a single donor cornea. CorNeat Vision is set to offer the first commercially available synthetic cornea implant, the KPro.

The new cornea has a clear centre section, surrounded by a white skirt consisting of electrospun nanofibres. Electrospun nanofibres have already found application in many medical applications, such as a new kind of translucent burn dressing. This skirt’s nanofibre material allows fibroblasts and collagen to infiltrate its structure, allowing full integration within a few weeks of surgery. This biomimetic technology results in faster healing times, the ability to use fully synthetic implants and is fully scalable as it does not rely on any harvested tissue.

The implantation procedure involves removing the epithelium covering the cornea, marking the location of where the artificial cornea implant should go, removing the cornea and then suturing its replacement into position.

Only a day after his surgery, the first recipient of this new artificial cornea was able to make out the faces of his relatives and read numbers off of a chart.

Source: Medical Xpress