Plantar- and dorsiflexor strength in prepubertal girls with juvenile idiopathic arthritis

Objective: To compare lower-leg strength of young girls with polyarticular juvenile idiopathic arthritis (JIA) with that of healthy, age-matched controls. Design: Isometric and isokinetic strength tests of the plantar- and dorsiflexors. All strength measures were made at an ankle angle of 90degrees. Isokinetic plantar- and dorsiflexor measures were made at 15degrees/s during shortening (concentric) and lengthening (eccentric) actions. Setting: Strength testing laboratory. Participants: Ten prepubertal girls diagnosed with JIA and 10 healthy girls. Interventions: Not applicable. Main Outcome Measures: Isometric and isokinetic plantar- and dorsiflexor strength. Results: Isometric plantar- and dorsiflexion torques were significantly lower (48% and 38% respectively; P < .05) for the children with JIA than for the controls. The JIA group also produced lower shortening plantarflexion torques (52%, P < .05). Lengthening plantarflexor torques did not differ significantly between the 2 groups (P < .05). Controls were stronger than the JIA group for both shortening and lengthening maximal dorsiflexor actions (P < .05). All children were 4 to 5 times stronger in plantarflexion than in dorsiflexion. Conclusions: Girls with JIA had significantly less plantar- and dorsiflexor strength than age-matched, healthy peers. The reduced strength of children with JIA is likely to affect function in daily activities and probably contributes to reduced levels of physical activity. (C) 2004 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.