Estimating Proprioceptive Position Sense of Upper Limbs Using Joint Distance and Joint Angle Symmetries

Abstract

Background Proprioceptive position sense (PPS) plays a critical role in movement and coordination of the upper limbs. It is commonly affected in neurological disorders such as unilateral spastic cerebral palsy (USCP) and stroke. However, UL PPS is often not considered during assessment or treatment in motor rehabilitation programs, in part due to limitations of current methods to quantify PPS. Traditional methods assess the similarity or symmetry of angles of a single joint and may not be sufficiently sensitive nor accurate. Emerging methods such as the use of robotic technology typically are limited to 2D and are also not standardizable as they are not easily available to clinics and research labs. This study aims to introduce a standardized and accessible way to quantify multi-joint PPS using 3D kinematic measures. Methods We developed novel multi-joint angle and distance-based measures of symmetry to assess upper limb PPS. Healthy adults (N = 17) and children with USCP (N=9) participated in this study. Kinematics were extracted during upper limb 3D pose matching tasks using a VICON Nexus system. Brunner-Munzel permutation tests were used for statistical comparisons between groups. Pearson’s correlation coefficient was used to investigate the relationship between the different symmetry measures and pose matching tasks. Results We introduced novel angle and distance-based measures of symmetry to estimate PPS. Healthy adults scored higher on both these symmetry measures compared to children with USCP. Angle and distance-based symmetries did correlate with each other. Exploratory factor analysis indicated that both angle symmetry and joint distance symmetry were highly loaded by the latent factor that best explained variance in the data. These results suggest that the two measures of pose symmetry are not redundant. It was also observed that distance symmetry was less sensitive to the different poses while angle symmetry varied across poses. Conclusions Symmetry measures derived from kinematics during upper limb pose matching tasks can estimate multi-joint PPS. Angle and distance-based symmetries together provide information about an individual’s ability to sense joint position. This framework will allow clinicians and researchers to measure PPS of upper limbs only using kinematic acquisition devices.