Douglas Weber, PhD, program manager for the Defense Advanced Research Projects Agency, delivered the keynote address at the 2017 Advanced Arm Dynamics’ Symposium this week, where he described an ongoing project to restore naturalistic hand function to upper limb amputees.
“We want to re-establish communication between the motor parts of the nervous system and the prosthetic hand through the use of implantable electronics,” Weber said in a press release.
The research project, called Hand Proprioception and Touch Interfaces (HAPTIX), arose out of the agency’s Revolutionizing Prosthetics program, according to the press release. The Defense Advanced Research Projects Agency (DARPA) is the “innovation engine” for the U.S. Department of Defense, Weber said.
The HAPTIX program is in its second phase, which is scheduled to continue through 2018. The third phase is scheduled for 2019, when transradial amputees will be allowed to take home a HAPTIX-controlled system for extended trials outside the laboratory, the press release noted.
In their research, the HAPTIX team is implanting electrodes in a patient’s muscles between the elbow and shoulder, as well as in individual nerve fascicles that correspond to wrist and finger control. According to the release, the researchers are also looking to develop minimally invasive procedures to implant electrodes in the spinal cord. The HAPTIX researchers seek to acquire and decode neural signals that could provide intuitive prosthetic control and restore sensory feedback using these neural interface systems.
DARPA is working with several research teams across the country on HAPTIX, including Nerves Incorporated, in Dallas, which has partnered with Advanced Arm Dynamics to test motor control and sensory feedback procedures with upper limb prosthesis users, the press release noted.
“Our multidisciplinary team is committed to being informed and involved with new and emerging technologies that will ultimately benefit our patients,” John Miguelez, CP, FAAOP (D), president and senior clinical director of Advanced Arm Dynamics, said in the release. “The researchers presenting at our 2017 symposium broaden and stimulate our clinicians and together, we are developing the best methodologies to introduce new technologies into our care model.”
The AAD symposium also allowed researchers to update attendees on recent advances in transcutaneous osseointegration and neuroprosthetics, which have led the way to increased prosthetic hand function.
According to a press release, Richard McGough III, MD, chief of the Division of Musculoskeletal Oncology at the University of Pittsburgh Medical Center, described the case of Johnny Matheny, a transhumeral amputee whose left arm was amputated in 2008 due to cancer. Matheny is the first arm amputee in the United States to have both targeted muscle reinnervation surgery and osseointegration surgery, which allows him to attach a prosthesis directly to his body, McGough said.
Developed at the Johns Hopkins University Applied Physics Lab, features of the modular prosthetic limb include dexterous in-hand manipulation of objects; more than 100 on-board sensors that measure force, vibration, and temperature; 26° of freedom; 17 individual motors; a neural interface for intuitive closed-loop control; and 40 pounds of torque for human-like strength.
“It feels natural and does not take a lot of thought,” Matheny said in the release. “With this technology, all of us arm amputees may get back to where we want to be.”