Gait parameters, functional performance and physical activity in active and inactive Juvenile Idiopathic Arthritis

Background: Children with Juvenile Idiopathic Arthritis (JIA) may adopt different movement patterns and participate in physical activity during different states of disease. Research question: Which specific features of gait and physical function performance differ among children with active or inactive JIA compared to healthy children? Methods: Forty-three children participated (14.5 +/- 4.2 yrs; 60 % female). 3D-motion analysis methods were coupled with force measures from an instrumented treadmill captured gait mechanical measures. The 30-second Chair Rise Test (repetitions) and stair ascent-descent tests were performed, and the 11-point Wong-Baker face scale assessed pain after each test. Results: Compared to healthy controls children with active and inactive JIA had worse outcomes (12-21 % slower self-selected and fast walking speeds, 28-34 % slower stair navigation times, 28 % fewer chair rise repetitions in 30 s; all p < .05). Children with active JIA had 8-13 % slower gait speeds, 4 % fewer chair rise repetitions and 14-16 % slower stair navigation times. At faster walking speed, children with active JIA had less hip joint flexion/extension excursion in the sagittal plane during the gait cycle, produced higher leg stiffness, and demonstrated greater interlimb asymmetry in GRF vertical impulse during loading than healthy children (all p < .05). The Pedi-FABS subscore of "Duration: performing athletic activity for as long as you would like without stopping" was rated lower in children with active JIA compared to controls (p < .05). Conclusion: Gait speed, specific load-bearing functional tasks and leg stiffness features of gait may be informative 'functional biomarkers' for assessing JIA burden and tracking treatment efficacy. Additional prospective studies are needed to determine how these features change over time with pain change, and understand impact on quality of life and physical activity participation.