Evaluation of elbow joint proprioception with RehabRoby: a pilot study

The aim of this study was to evaluate the proprioceptive sense of elbow flexion through a robot-assisted rehabilitation system, RehabRoby, and to understand the usability of RehabRoby as a robotic system in physiotherapy.

The study included 20 volunteer, healthy students studying either physiotherapy (PT) (5 females and 5 males) or electrical and electronics engineering (EEE) (5 females and 5 males). Using the RehabRoby, they were asked to flex their elbow joints in pronation actively and then against a comfortable resistance to the target angles (20°, 45° and 90°), with eyes open and closed. Angle of movement and applied torque for each target angle and error of movement with respect to the target angle (error of matching) were recorded as absolute values. Participants' socio-demographic and physical features were also evaluated.

Physiotherapy students had less matching error at 45° with eyes opened than EEE students. A negative correlation was found between resistive elbow flexion and applied torque while eyes closed at 20° (p<0.05). Biceps brachii strength and being female were significant predictive factors for the least matching error in active elbow flexion at 20° with eyes closed. Error of matching at 45° without vision was lower in the PT group (-0.31) than in the EEE group (0.77). In addition, it was noticed that biceps brachii muscle strength played an important role in the proprioceptive sense of the motion at 20°.

The RehabRoby can be considered a usable system for the evaluation of joint proprioception sense. With future validity studies, the RehabRoby may be used to assess, diagnose and improve the proprioceptive sense of patients.