Wearable knee robot could help children with muscle weakness

A lightweight robotic device that facilitates neuromuscular recovery in children with spinal muscular atrophy (SMA), helping them to stand unassisted, is published in Nature this week. Improved function persists after discontinuing training, demonstrating the potential for enduring recovery.

SMA is a neuromuscular disorder that affects the nerves and causes muscle weakness, which can limit movement in affected individuals. Symptoms can be managed with physical therapy, such as isokinetic resistance training, which uses speed-controlled exercises to improve strength. However, such training requires equipment that is only available at specialist institutions, and the devices used for this training are often too bulky and difficult for children to use.

Yanggang Feng and colleagues designed a lightweight (0.96 kg) wearable knee robot to assist isokinetic training for children with SMA type II, an intermediate form of the condition. In a clinical trial, they tested outcomes in six children (aged 6–10 years old) who could not stand from a seated position without assistance.

After six weeks of training with the device, using it five times a week, the children in the study showed improvements in movement (all six were able to stand from a seated position without the help of the robot), knee function, and muscle volume (the quadriceps increased by 19%). The children continued with a further six weeks of low-intensity isokinetic training (using the device three times per week) and then returned to conventional physical therapy and were followed up for 30 days.

The participants maintained the gains in function after discontinuing isokinetic training, indicating that temporary exposure to the wearable isokinetic training robot device can facilitate prolonged neuromuscular recovery.

Future trials with larger cohorts are needed to accurately determine the efficiency of this treatment, although recruitment was limited because SMA is a rare disease with poor outcomes, the authors note. They add that further modifications that target different muscles may improve the potential of the device.

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Lisa Lock

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Robert Egan

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