Biomedical engineering: Exoskeleton improves walking in patients with above-knee amputation

An autonomous, powered hip exoskeleton capable of improving walking for people with above-knee amputation is presented in an early-stage clinical study published in Nature Medicine.

For the millions of people with above-knee amputation, walking with leg prostheses currently available is highly energy inefficient, which limits their mobility. Autonomously powered hip exoskeletons have been shown to reduce the metabolic cost of — or the energy demands associated with — walking in young people who have not undergone amputation. However, their use by people with above-knee amputation has not yet been tested.

Tommaso Lenzi and colleagues tested the efficacy of a powered hip exoskeleton for six people (four male, two female; average age of 33.8 years) with above-knee amputation, as they walked on a treadmill at a speed of 1 metre per second and also as they walked on a 12-meter walkway. The authors found that — compared with the metabolic cost of using a standard prosthesis — use of the hip exoskeleton, on average, reduced the metabolic cost of walking by 15.6%. This improvement is equivalent to removing a 12-kg backpack from a person who has not undergone amputation. All participants were additionally able to walk with the exoskeleton without a negative effect on their gait.

The authors indicate the need for future clinical studies to optimize the device and to assess its efficacy for people with different types of amputation and with varying potential for rehabilitation.