Robo therapy

A robotic system that mimics the action of trained physiotherapists could help patients with lower limb difficulties take more control of their treatment, claim its developers in Dundee and Sheffield.

The system, which can guide patients’ legs through a complicated series of movements, could also reduce waiting times for physiotherapy.

Physiotherapy is hard work for patient and therapist. Helping people with spinal injuries keep their muscle tone or orthopaedic patients recover from injuries or operations involves guiding limbs through a lengthy series of repetitive movements — and limbs are heavy.

The robotic system evolved from a project to develop an exoskeleton to help people who had lost the use of their legs regain mobility, said David Bradley of the School of Computing and Creative Technologies at the University of Abertay Dundee. ‘It was intended to go in parallel with the existing limb but would provide some of the strength to allow it to move.’

In developing this concept, Bradley realised it also had potential to be used for physiotherapy. He brought Sue Mawson, a research physiotherapist from Sheffield Hallam University, into the project, and obtained a proof of concept grant from the Department of Health’s New Emerging Applications of Technology (NEAT) programme.

Mathematical models

Mawson worked with therapists at Barnsley Teaching Hospital to determine how a ‘robot physio’ might be used and the type of tasks it would undertake. Dozens of videos of physiotherapy sessions were also produced, illustrating the types of movements used in different sorts of therapies.

Bradley’s team of engineers and software specialists analysed these videos, converting the movements into a series of mathematical models and developing a system that could both mimic the movements and fulfil the needs stipulated by the therapists’ focus groups. The result was the NeXOS (NEAT exoskeleton) system. Attaching to the patient’s foot and ankle, the system consists of jointed beams linked to pneumatics that allow it to move in all the degrees of freedom of the patient’s leg.

In an initial consultation, a physiotherapist would devise a programme of therapy and move the patient’s leg through the series of movements he or she would need to complete (known as a ‘track’). The pneumatics are linked to a computer whose software would remember that sequence and replay them to repeat the track in the absence of the therapist.

The use of pneumatics in the system allows it to function in different modes — it can pull the leg along, or create resistance for the patient to push against. These modes can be used at different points along a single track, depending on the sort of therapy needed. For someone with spinal injuries, unable to move their legs, it could provide passive exercises to maintain muscle tone, said Mawson. For people recovering from knee replacement or leg fractures, it can help build up specific muscle groups that had wasted while bones had re-knitted. Moreover, sensors in the system provide feedback for the therapist via the internet, so the patients’ progress can be assessed.

The software is the key to the system, said Bradley. ‘It allows the device to be deployed in a variety of ways, some of which are radically different from our original concept.’ The system is not designed to replace physiotherapists, he explained; it should work in conjunction with them, allowing them to maintain hands-on contact with the patients when needed, but freeing them up to work with other patients when appropriate.

More control

‘It’s about people with long-term conditions taking more control of their own therapy,’ said Mawson. ‘They need a lot of repetitive, time-consuming limb movements, so they could have therapy at home without the therapist there all the time.’

Alternatively, said Mawson, as the device is quite large and bulky for the home, it could be based at a clinic, with the therapist setting a patient up on it then leaving them to their therapy while they deal with another patient, thus making more efficient use of their time. Another possibility is to use NeXOS as a training aid, illustrating physiotherapy tracks to students.

Mawson and Bradley stress that NeXOS is just a proof-of-concept model and has to undergo clinical trials and regulatory testing before it can be deployed. ‘We need more funding to take it to the next level,’ said Bradley, ‘and we’re looking for a commercial partner to help take the risk, which is actually quite considerable.’

The NeXOS is still several years from commercialisation, added Mawson, ‘but we know the concept works — and that’s what we were setting out to prove’.