A new spine brace has allowed researchers to measure for the first time the 3D stiffness of the human torso, opening the door for new treatments for spine deformities.
A team from Columbia University has developed a new brace called the Robotic Spine Exoskeleton (RoSE) and conducted the first study that looks at in vivo measurements of torso stiffness, characterizing the 3D stiffness of the human torso.
“To our knowledge, there are no other studies on dynamic braces like ours. Earlier studies used cadavers, which by definition don’t provide a dynamic picture,” the study’s principal investigator Sunil Agrawal, a professor of mechanical engineering at Columbia Engineering and professor of rehabilitation and regenerative medicine at Columbia University Vagelos College of Physicians and Surgeons, said in a statement.
“The RoSE is the first device to measure and modulate the position or forces in all six degrees-of-freedom in specific regions of the torso. This study is foundational and we believe will lead to exciting advances both in characterizing and treating spine deformities.”
RoSE consists of three rings placed on the pelvis, mid-thoracic and upper-thoracic regions of the spine, with the motion of two adjacent rings controlled by a six-degrees-of-freedom parallel-actuated robot.
Overall—the system, which can apply corrective forces in specific directions while allowing free motion in other directions— has 12 degrees-of-freedom controlled by 12 motors.
The brace is able to control the motion of the upper rings with respect to the pelvis ring or apply controlled forces on the rings during the motion.
The researchers examined eight healthy male subjects and two male participants with spine deformities in the pilot study and controlled the position and orientation of specific cross sections of the subjects’ torsos while simultaneously measuring the exerted forces and moments.
The results revealed that the 3D stiffness of the human torso can be characterized using the special brace. The team also found that spine deformities induce torso stiffness characteristics differently from the healthy subjects. Because spinal abnormal curves are three-dimensional, the stiffness characteristics are curve-specific and depend on the locations of the curve apex on the human torso.
Spine deformities like idiopathic scoliosis and kyphosis are characterized by an abnormal curvature in the spine, forcing children with the spinal deformities to wear a brace that fits around the torso and hips to correct the abnormal curve.
“Our results open up the possibility for designing spine braces that incorporate patient-specific torso stiffness characteristics,” the study’s co-principal investigator David Roye, a spine surgeon and a professor of pediatric orthopedics at the Columbia University Irving Medical Center, said in a statement. “Our findings could also lead to new interventions using dynamic modulation of three-dimensional forces for spine deformity treatment.”
While braces can prevent progression of the abnormal curve, the underlying technology has not changed much in the last 50 years. Current braces give the wearer a number of limitations due to the rigid, static and sensor-less designs of the brace. Users often complain that the brace is uncomfortable to wear and causes skin breakdown from prolonged, excessive force.
The inability to control the correction provided by the brace makes it difficult for users to adapt to changes in the torso over the course of treatment, resulting in diminished effectiveness.
The team has also designed a female version of RoSE, as idiopathic scoliosis is 10 times more common in teenage females than males.
The study was published in IEEE Transactions of Neural Systems and Rehabilitation Engineering.