Study Offers Hope for Sensory Control

The introduction of the iLimb, allowing a patient to control individual digits on a prosthetic hand through neuromuscular signals, was a breakthrough for the O&P industry. The ability for an upper extremity amputee to grab an object using myoelectric-controlled digits has paved the way for researchers to investigate the next step in O&P innovation – sensory feedback.

e“In the past 5 or 6 years, so many advancements have been made as far as being able to find out clever ways to interface with the nervous system, that I think it is starting to open the door to a lot of opportunities that were not available before,” Paul Marasco, PhD, sensory neurophysiologist for the Neural Engineering Center for Artificial Limbs at the Rehabilitation Institute of Chicago, said.

The discovery of a new polymer that conducts electricity and promotes the stimulation and growth of nerve fibers raised the possibility of amputee patients gaining sensory feelings through their prosthesis. Physicians announced the discovery of the polymer, 3, 4- ethylenedioxythiophene (PEDOT), at the Plastic Surgery 2009 conference in Seattle.

Dustin Tyler, PhD
Dustin Tyler

According to the study, the PEDOT polymer, along with biologic and synthetic materials, helped ignite nerve endings and muscles that were unable to be stimulated due to nerve injury. The reigniting of nerve endings would provide amputees with greater neurological control of their prosthesis.

“The two great challenges that lie ahead for the O&P industry are how do you control the prosthesis as the mechanical technology improves and can the patient obtain sensory feedback?” Dustin Tyler, PhD, associate professor, Case Western Reserve University and investigator at the Cleveland VA Medical Center, told O&P Business News.

Sensory feedback would allow the patient to not only grab an object using their prosthesis but also control the amount of pressure on the object. The ultimate goal of researchers is to have the patient independently move their digits, grab an object with the appropriate amount of pressure and feel the sensation of the object. While this research is still in the early stages, O&P technological innovations have made this scenario a distinct possibility in the coming years. — Anthony Calabro


Body powered upper extremity prosthetic users have enjoyed a modicum of proprioception with the use of cable attachments and intimate interface fittings. The interface and cable can transmit the vibration of contact and cable movement can indicate the position of the elbow, wrist or terminal device. External power users can now experience more positional proprioception with linear potentiometers and transducers, but sacrifice a sense of feel.

These new polymers and carbon nanotubes have the promise of increasing the exchange of information and feeling to the residual limb, so that the prosthesis becomes more integrated into the total body image. Combined with osseointegration and direct neural control, the prosthesis of the future can be directly linked to the patient for fixation, activation and feeling.

Pragmatically, these futuristic concepts will require a significant amount of development and financial backing to create production-level componentry since they must be connecting directly to nerve endings.

— Gerald Stark CPO, FAAOP
Vice president of product development and education, Fillauer Inc.

For more information:

Leave a Reply

Your email address will not be published.