A proprioceptive neuromuscular facilitation integrated robotic ankle–foot system for post stroke rehabilitation

•We developed a proprioceptive neuromuscular facilitation (PNF) integrated robotic ankle–foot system for post stroke rehabilitation.•It is the first time that PNF method has been used in ankle spasticity/contracture rehabilitation.•Five able-bodied subjects participated in the experiments and five stroke patients were recruited with a six-week PNF treatment.•The proposed system can offer more effective treatment than passive stretching in improvement of both passive and active joint properties.

Ankle joint with spasticity and/or contracture can severely disable the mobility and the independence of stroke survivors. In this paper, we developed a proprioceptive neuromuscular facilitation (PNF) integrated robotic ankle–foot system for post stroke rehabilitation. The system consists of a robotic platform and a control system with graphic user interface. We employ five normal subjects to test the reliability and feasibility of the proposed system. To validate the effectiveness of the PNF integrated robotic system, we recruit five stroke patients and carry out a six-week PNF treatment. Treatment outcome was evaluated quantitatively in passive and active joint properties. The passive hysteresis loop shows that the maximum dorsiflexion angle increases from 32.9°±1.5°32.9°±1.5° to 42.0°±3.2°42.0°±3.2° (p=0.014p=0.014) while the resistance torque decreases from 45.6 Nm±5.8 N m to 29.8 N m±4.4 N m (p=0.019p=0.019). The active joint properties are improved significantly with the training score increasing from 5.7±0.95.7±0.9 to 8.1±0.68.1±0.6, and getting close to that of normal subjects (9.5±0.39.5±0.3). In addition, muscle strength has a rising trend as time goes on. The results demonstrate that the proposed PNF integrated robotic ankle–foot rehabilitation system is effective in improving ankle spasticity and/or contracture and is a promising solution in clinical rehabilitation.