Multi-axis robotic rehabilitation system

The limb is strapped to the robot's arm while the patient lies or sits on the treatment bed. The therapist guides the leg or arm through the exercise they want — a knee bend, a hip lift, a reach — and the robot records the path. It then repeats that movement, in as many planes as the joint needs, for as many repetitions as the plan says.

The movement can be fully passive, assisted only where the patient's own effort fades, or resisted, and the setting is changed within a session as the patient tires or improves. The robot measures the force the patient contributes on every repetition.

The early phase after stroke, spinal cord injury and brain injury, when the patient is still largely in bed and the aim is to keep joints moving and to start rebuilding movement before standing is possible. Also after orthopaedic surgery, where the permitted range is fixed and repetitions within it matter.

It is used for the leg more often than the arm, because for the arm the group's dedicated upper limb robots are usually the better tool, and the assessment decides which.

Recovery of movement after neurological injury depends on the number of correctly performed repetitions, and in the first weeks that number is limited by what a therapist can physically do by hand. A robot that repeats the movement precisely increases the number of repetitions possible in the same session time, without the therapist's shoulders paying for it.

Consistency is the second gain. The same path and the same force on a late repetition as on an early one, which manual assistance cannot promise.

After surgery the permitted range is set in the device itself, so the joint physically cannot be taken beyond it. The patient is not relied upon to stop at the right point while tired or distracted.

That is why it is used early after ligament reconstruction and joint replacement, where an unintended movement in the first weeks can undo the operation.

Direct evidence comes from small studies. In a feasibility study in four people with recent spinal cord injury, hip flexion exercise lying down with this robot was safe and acceptable, though one physiotherapist was needed to set up and supervise each session 2. The participants saw it as a supplement to their usual physiotherapy, not a replacement 2.

In a pilot randomised trial in 12 people with incomplete spinal cord injury and marked weakness, 8 weeks of extra robot-assisted or resisted hip flexion training on one leg did not make that leg stronger than the other 1. The trial was small, but it gives no support to the idea that the robot builds strength on its own.