Abstract
In this paper, we aim to investigate the effect of proprioceptive neuromuscular facilitation (PNF)-based rehabilitation for ankle plantar flexors spasticity by using a Robotic Ankle–foot Rehabilitation System (RARS). A modified robot-assisted system was proposed, and seven poststroke patients with hemiplegic spastic ankles participated in a 3-month robotic PNF training. Their impaired sides were used as the experimental group, while their unimpaired sides as the control group. A robotic intervention for the experimental group started from a 2-min passive stretching to warming-up or relaxing the soleus and gastrocnemius muscles and also ended with the same one. Then a PNF training session including 30 trials was activated between them. The rehabilitation trainings were carried out three times a week as an addition to their regular rehabilitation exercise. Passive range of motion, resistance torque, and stiffness were measured in both ankles before and after the interventions. The changes in Achilles tendon length, walking speed, and lower limb function were also evaluated by the same physician or physiotherapist for each participant. Biomechanical measurements before interventions showed significant difference between the experimental group and the control group due to ankle spasticity. For the control group, there was no significant difference in the 3 months with no robotic intervention. But for the experimental group, passive dorsiflexion range of motion increased (p < 0.01), resistance torque under different dorsiflexion angle levels (0°, 10°, and 20°) decreased (p < 0.05, p < 0.001, and p < 0.001, respectively), and quasi-static stiffness under different dorsiflexion angle levels (0°, 10°, and 20°) also decreased (p < 0.01, p < 0.001, and p < 0.001, respectively). Achilles’s tendon length shortened (p < 0.01), while its thickness showed no significant change (p > 0.05). The robotic rehabilitation also improved the muscle strength (p < 0.01) and muscle control performance (p < 0.001). In addition, improvements were observed in clinical and functional measurements, such as Timed Up-and-Go (p < 0.05), normal walking speed (p > 0.05), and fast walking speed (p < 0.05). These results indicated that the PNF-based robotic intervention could significantly alleviate lower limb spasticity and improve the motor function in chronic stroke participant. The robotic system could potentially be used as an effective tool in poststroke rehabilitation training.
Highlights
IntroductionAnkle spasticity is one of the most common movement disorders after Cerebrovascular Accident (CVA) (O’dwyer et al, 1996)
In our previous study (Zhou et al, 2015), we showed the feasibility of the proposed robotic ankle–foot system in the rehabilitation of plantar flexors spasticity for the poststroke patients
This study provides some evidences that the PNF-based robotic system could potentially be used as an effective tool in clinical rehabilitation for ankle plantar flexors spasticity
Summary
Ankle spasticity is one of the most common movement disorders after CVA (O’dwyer et al, 1996). Several studies show that limb spasticity is mostly caused by hyperactive reflexes (Rack et al, 1984; Thilmann et al, 1991; Meinders et al, 1996), while others believe that spastic hypertonia is dependent of non-reflex biomechanical change of muscle and connective tissues (Lee et al, 1987; Dietz et al, 1991; Sinkjaer et al, 1996). The underlying mechanism of the spasticity is not very clear (Krebs et al, 2003), increased resistance in spastic limb movements can often be observed
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