Objective: Juvenile idiopathic arthritis (JIA) affects body structure and function and physical activity outcomes. The present study was undertaken to examine differences in gait kinematics during fixed-speed treadmill walking for youth with JIA and typically developing (TD) youth.
Methods: Sagittal plane gait kinematics were obtained using a 12-camera system (Motion Analysis) for youth with JIA (n = 30) and their age and sex-matched TD peers (n = 30). Outcomes included disease activity, pain, well-being, and peak sagittal hip, knee, and ankle joint angles. Kinematics were analyzed for the indexed leg (IL) (i.e., the affected leg of participants with JIA) compared to the dominant leg of TD participants and for the contralateral leg (CL) (i.e., the less/not affected leg of participants with JIA) compared to the nondominant leg of TD participants. Kinematics differences were investigated using multivariate Hotelling's T2 statistic (paired samples; α = 0.05) and simultaneous 95% confidence intervals (95% CIs). Potential confounders (age, sex, body mass index) were assessed using linear mixed-effects models with random effect for pairs.
Results: Youth with JIA had low disease activity, pain, and disability scores. Deviations in bilateral joint angles were observed (IL P = 0.015, CL P = 0.009). Youth with JIA walked with greater initial hip flexion (mean difference IL 2.8° [95% CI -0.6, 6.2]; CL 3.0° [-0.9, 6.9]) and lower knee extension (mean difference IL -2.2° [95% CI -4.4, 0.1]; CL -3.3° [-7.4, 0.8]), and lower hip extension during terminal stance (mean difference IL 3.4° [95% CI -0.3, 7.0]; CL 4.0° [1.0, 7.0]).
Conclusion: Despite low disease activity, youth with JIA avoided the close-packed knee position, commonly associated with joint inflammation and pain. These findings highlight secondary consequences of JIA and inform targets for physical therapy management for youth with JIA.
© 2019, American College of Rheumatology.