Our ability to use the thumb as an opposable digit is a critical part of what sets us apart as a species. “That’s how you’re holding a pen,” Leia Stirling, PhD, a senior staff engineer at the Wyss Institute for Biologically Inspired Engineering told me recently as we talked about the Wyss’ latest collaboration with Boston Children’s Hospital. “That’s how you hold your phone; that’s how you open a door; that’s what makes us unique.”
It’s also an ability that children who have suffered a stroke or have cerebral palsy or hemiplegia (paralysis on one side of the body) can lose or fail to develop in the first place.
Stirling, along with Hani Sallum, MS, and Annette Correia, OT, in Boston Children’s departments of Physical and Occupational Therapy, are the architects of a robotic device that may improve functional hand use. The device assists children with muscle movements, using small motors called “actuators” placed over the hand joints, while giving them sensory and visual feedback. It’s called the Isolated Orthosis for Thumb Actuation, or IOTA.
IOTA grew out of conversations that Stirling had with Correia as well as orthopedic surgeons Brian Snyder, MD, PhD, and Donald Bae, MD, about how few robotic systems designed for the hand exist, especially for children. As the team would discover, designing robotic systems for anything as complex as the human hand presents huge challenges.
While early interventions—ideally in early childhood—work best when it comes to learning new motor skills after neurological trauma, most existing robotic devices for the hand are made for adults. They tend to be too heavy for children to wear, and their size, covering large parts of the hand and palm, can actually interfere with a child’s ability to manipulate objects.
“Even when devices are made for the pediatric population, they are often made for older teenagers and are created by simply making an adult device smaller,” explains Correia. “What’s exciting is that we had the opportunity to make a device specifically for children that is consistent with their developmental needs.”
Most existing devices are meant to assist movement of all five digits, known as whole-hand shaping. But Correia wanted to focus on the thumb as a key component of grasping. Currently, occupational therapists (OTs) use several treatment approaches, including rigid or semi-rigid orthotics, Constraint Induced Movement Therapy and functional electrical simulation, but these don’t always allow for a full range of thumb motion. Aided by recent advances in materials and technology, Stirling and Sallum made the thumb the focus of IOTA’s design.
The new device fits over a child’s hand with actuators placed over thumb joints. Sensors on the device detect attempts at thumb and wrist movements, relaying the information to a computer housed inside a small, portable control box. The device then helps the child complete the motion. Because IOTA is small enough to leave the palm open, children using it can more freely grasp and interact with objects, forging and strengthening their nerve pathways.
The team hopes that IOTA, incorporated into an OT treatment program, will eventually allow a child to achieve enough dexterity and control to zip up a jacket or hold a pencil unassisted. A pilot clinical study currently underway will examine 15 Boston Children’s patients during visits to the hospital and follow five of them for six weeks as they use the device at home and in the hospital.
Since the current design only fits children 6 to 16 years of age, Correia and Stirling would like to eventually create smaller versions for younger patients. “We’re continuing to bridge the gap between the lab and the treatment area,” Correia says. “We see the IOTA as the first step towards a more complex device.”
Read about another collaboration between Boston Children’s Hospital and the Wyss Institute to build robotic clothing with built-in actuators to help children at risk for cerebral palsy.