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Every five minutes around one person has a stroke in the UK. While this is a leading cause of death, there are 1.2 million stroke survivors in the country resulting in widespread need for rehabilitative care.
In this work, we propose a multi-function rehabilitation device for stroke patients. This constitutes a novel system which is capable of detecting gait abnormalities, whilst providing real-time biofeedback to the user, and of communication with an external computer for targeted training.
Stroke survivors typically suffer from a variety of neurological disorders. These include cognitive deficits and, in approximately 50-60% of the cases, motor impairments, which render patients in need of personal assistance in their activities of daily living (ADL)[1].
Hemiplegia, i.e. weakness of one side of the body, is among the most common impairments which stroke patients suffer from, and significantly affects their gait performance[1]. Although a variety of kinematics deviations are observed in the hemiplegic patient through the entirety of the gait cycle, in this work, only abnormalities in the ground reaction force (GRF) and in the angles of the knee and ankle joints will be discussed.
The GRF is the force exerted by the ground on the body during the gait cycle. On the vertical plane, it is characterised by the typical butterfly shape with two peaks and a local minimum in the mid-stance. As illustrated in the figure below, are almost absent in the hemiplegic gait, with only minor differences arising between the affected and unaffected sides. Furthermore, hemiplegia results in a notable reduction of the walking speed and in uneven stride lengths, which can be observed from the limited overlapping of the curves of the hemiplegic gait[2].
Analysis of the ankle joint reveals that the foot undergoes dorsiflexion from the moment of initial contact with the ground (i.e. heel strike) to the terminal stance, prior to lifting of the foot at the beginning of the swing phase, whereby, as a result of plantarflexion, the joint angle becomes negative. Towards the end of the gait cycle, the ankle finally dorsiflexes before returning to its initial position. The figure below shows a decrease in both the maximum dorsiflexion and plantarflexion in patients affected by stroke[3].
In order to optimise the gait performance of hemiplegic subjects, training is an essential part of the rehabilitation strategy typically employed. Among the most common exercises are weight shifting from one foot to the other, single leg standing, and calf rise. These exercises have been demonstrated to improve the walking ability, independence, and overall quality of life of stroke patients, and are part of the predominant physical therapy approach in the UK and in several other countries.
- J.D Schaechter. “Motor rehabilitation and brain plasticity after hemiparetic stroke,” Progress in neurobiology, vol. 73, pp. 61-72, 2004.
- S. Lauzière et al. “Understanding spatial and temporal gait asymmetries in individuals post stroke,” International Journal of Physical Medicine and Rehabilitation, vol. 2, no. 201, pp. 1-11, 2014.
- H.-S. Kim et al. “Primary and secondary gait deviations of stroke survivors and their association with gait performance,” The Journal of Physical Therapy Science, vol. 28, pp. 2634-2640, 2016.