Land-Jump Performance in Patients with Juvenile Idiopathic Arthritis (JIA): A Comparison to Matched Controls

Objective . The purpose of this study was to determine if high functioning children with Juvenile Idiopathic Arthritis (JIA) with minimal disease activity have different biomechanics during high loading tasks compared to controls. Patients were included if they had minimal inflammation documented in one or both knees. Methods. The subject groups consisted of eleven patients with JIA and eleven sex, age, height, and weight matched controls. Sagittal plane kinematic and kinetics were calculated during a drop vertical jump maneuver. The Child Health Assessment Questionnaire (CHAQ) was collected on each patient with JIA. Results. The subjects with JIA had increased knee ( P = .011) and hip flexion ( P < .001) compared to control subjects. Subjects with JIA also demonstrated decreased knee extensor moments during take-off ( P = .028) and ankle plantar flexor moments during landing ( P = .024) and take-off ( P = .004). In the JIA group, increased hip extensor moments were predictive of increased disability ( R 2 = .477, S E E = .131). Conclusions . Patients with JIA may demonstrate underlying biomechanical deviations compared to controls. In addition, biomechanical assessment of hip extensor mechanics during dynamic tasks may provide an objective assessment tool to determine overall function in patients with JIA.