Children with neuromuscular diseases, like muscular dystrophy, have a hard time moving their arms and doing basic things like eating, playing, or hugging their loved ones. Now, a new 3D printed exoskeleton is helping these kids move in ways they never thought possible.

During her fifth month of pregnancy, Jennifer Mohn was told to prepare for the worst for her unborn daughter.

“They told us to make arrangements for her,” Jennifer Mohn, Hannah’s mom, told Ivanhoe.

Baby Hannah Faith survived, but was born with a list of health conditions, including arthrogryposis, a disease that affects muscle strength.

“She was just really unable to move,” Jennifer said.

Four years later she’s making great strides, thanks in part to 3D printed arms known as the Wilmington Robotic Exoskeleton, or WREX.

Each WREX is constructed of lightweight plastic and rubber bands and can be custom made overnight with the use of a 3D printer.

“If you do the geometry right and you put the bands in the correct place, you can get this floating sensation for a kid,” Tariq Rahman, PhD, Senior Research Engineer, Nemours/Alfred I. duPont Hospital for Children, told Ivanhoe.

It’s allowing kids like Hannah the ability to move their arms and even flick a rubber band.

“To see her have the ability to reach her arms out, to reach out and grab something is just a really amazing feeling for a mom,” Jennifer explained.

Since a 3D printer is used, the customized exoskeletons can easily be made to grow with the child.

The WREX can also be used by children with other neuromuscular diseases or by adults with stroke and spinal cord injury.


BACKGROUND: Arthrogryposis is a term for the development of non-progressive contractures affecting one or more areas of the body. A contracture is a condition in which a joint becomes permanently fixed in a bent (flexed) or straightened (extended) position, completely or partially restricting the movement of the affected joint.  When congenital contractures occur only in one body area, it is not referred to as arthrogryposis, but rather an isolated congenital contracture. The most common form of an isolated congenital contracture is clubfoot. When arthrogryposis affects two or more different areas of the body, it is called arthrogryposis multiplex congenita (AMC). (Source:

CAUSES: Arthrogryposis is usually developed before a baby is born. Six common causes of this condition are: abnormalities of connective tissue, restricted movement of the uterus, maternal illness, abnormalities of the nerves that connect to muscles, abnormalities of muscle function, and the loss of neurons.  Each of these factors occur while the mother is still pregnant, then symptoms of the condition will appear after birth. (Source:


SYMPTOMS: The symptoms of AMC vary depending on the patient, severity, and location of the condition. The joints of the legs and arms are usually affected, but the legs are affected more often.  It can also occur in the joints of the elbows, shoulders, knees, wrist, ankles, toes, fingers, and hips. In addition, the jaws and back are also often affected in patients with AMC.  More than 300 different conditions can cause isolated or multiple contractures and the causes, genetics, specific symptoms, and severity of these disorders vary dramatically.


NEW TREATMENT: The Wilmington Robotic Exoskeleton, also known as WREX, is a device made of resistance bands and hinged bars. It is also described as an anti-gravity upper limb orthotics.  It was constructed to help children with little residual strength from muscular and joint disorders to move their arms in space.  The problem was that it was only available for patients under six years old.  Now, researchers are using 3D printing to allow even younger patients to use it.  The use of a 3D printer allows doctors to customize the WREX to each patient.  (Source: Dr. Tariq Rahman)


Tariq Rahman, PhD, Senior Research Engineer, Nemours/Alfred I. duPont Hospital for Children, talks about a new treatment for children with neuromuscular conditions. 

Can you tell us about the WREX?

Dr. Rahman: It is relatively simple. It is constructed of mechanical pieces, links, and rubber bands. If you do the geometry right and if you put the bands in the correct place, then the kids with weak arms can get a floating sensation as if they were in in zero gravity.

And that’s important because this is made for children with what kinds of conditions?

Dr. Rahman: Children with neuromuscular conditions such as muscular dystrophy and arthrogryposis, which Hannah has. So these kids have weak limbs, particularly in their arms and their biceps and they have a difficulty moving their hands. The WREX helps them to defy gravity; allowing them to move their arms in space in front of them.