Researchers from Hong Kong have come up with a new robotic device for improving the gait and lower limb function of stroke patients.

WHAT IT'S ABOUT

The mobile ankle-foot exoneuromusculoskeleton developed by a research team from Hong Kong Polytechnic University (PolyU) is a rehabilitation robot specifically designed for stroke patients with hemiplegia, or paralysis that affects one side of the body. These patients generally have weakened muscle strength and discoordination at their affected lower limb.

The device automatically detects various walking forms, such as standing, heel strike, heel off and toe off. It features several modes: the exoskeleton and soft pneumatic muscles provide mechanical support to let patients stand stably on their affected foot, while the vibration tactile feedback and neuromuscular electrical stimulation help them learn to balance the plantar pressure and exert propelling force when walking.

Also through neuromuscular electrical stimulation, it can help effectively correct foot drop and foot inversion.

The mobile exoneuromusculoskeleton runs on a nine-volt rechargeable battery and can be used continuously for four hours.

Powered by Internet of Things (IoT) technology, the device enables patients’ rehabilitation progress to be recorded on a companion mobile app. It has near-real-time monitoring and progress evaluation features, as well as provides personalised guidance and reminders that allow patients to undertake rehabilitation exercises on their own, whether at home or outdoors. 

The IoT-enabled device also makes telerehabilitation possible so therapists can remotely monitor the progress of not just one, but multiple patients in one platform. Moreover, the companion mobile app can match different patients with one another to foster mutual support and companionship. 

So far based on clinical studies with several unidentified partner hospitals around China, the PolyU team's ankle-foot device is 40% more effective for stroke rehabilitation than applying external mechanical forces alone. Following a 1.5-month training programme, it was found that the device helped improve the dorsiflexion of the ankle (or the ability to pull the foot towards the knee) of 12 participating patients from five degrees to 10 degrees without equipment assistance.

The studies also noted that over 90% of participants corrected their foot inversion successfully. 

WHY IT MATTERS

Hong Kong records around 50,000 new stroke cases each year with 85% of patients experiencing some form of impaired physical mobility, such as foot drop and inversion, which disrupt their daily lives.

According to PolyU, to alleviate the risk of getting disabled, "[r]egular, repeated and intensive rehabilitation training is critical for restoring the physical mobility of stroke patients." 

However, patients are finding it difficult to access daytime outpatient rehabilitation services as local hospitals and clinics are getting overwhelmed with demand. This predicament leaves them unable to do timely and routine rehabilitation exercises. 

The solution by PolyU's team can help improve patients' gait and balance while walking, correct foot drop and inversion, and even contribute to rehabilitative neuroplasticity in the long run.

MARKET SNAPSHOT 

PolyU mentioned how existing exoskeleton lower-limb robots in the market only rely on external force to assist stroke patients in walking. "They are of very limited value in improving ankle joint and muscle coordination for stroke patients with hemiplegia," it claimed. Moreover, those devices are commonly heavy and power-intensive so their use is limited only in hospitals and rehabilitation clinics. Meanwhile, conventional ankle-foot orthoses can cause muscle atrophy and interfere with patients' progress in regaining voluntary motor control in their affected ankles. 

The research team at PolyU is now planning to commercialise their invention next year. Local startup Thecon Technology, which was co-founded by the team's lead Dr Hu Xiaoling, also marketed last year a similar mobile exoneuromusculoskeleton for upper limb rehabilitation called Mobilexo Arm. Its development at the university was first announced in 2018.

ON THE RECORD

"This research achievement provides stroke patients a better option for lower limb rehabilitation training, incorporating the training into their daily activities. It also enables therapists to provide tele-supervision of the rehabilitation progress of multiple patients. We hope such flexible self-help training can effectively supplement traditional outpatient rehabilitation services, helping stroke patients achieve more efficient rehabilitation progress," said Dr Hu Xiaoling, associate professor of the Department of Biomedical Engineering at PolyU.