Lower extremity isometric strength in children with juvenile idiopathic arthritis

Area of Science:

• Pediatric Rheumatology
• Musculoskeletal Health
• Clinical Biomechanics

Background:

• Juvenile idiopathic arthritis (JIA) can impact muscle strength in children.
• Assessing lower extremity isometric strength is crucial for monitoring JIA progression and treatment effectiveness.
• The utility of specialized equipment like adjustable dynamometer chairs in pediatric populations needs evaluation.

Purpose of the Study:

• To measure lower extremity isometric strength in children diagnosed with JIA.
• To assess the clinical applicability of an adjustable dynamometer chair for strength measurements in JIA.
• To compare muscle strength and perceived exertion between children with JIA and healthy controls.

Main Methods:

• Isometric maximal strength of knee and ankle muscles was measured in 25 children with JIA and 25 age-matched healthy controls (aged 7-12).
• Measurements were performed bilaterally using an adjustable dynamometer chair.
• The Children's Effort Rating Table (CERT) assessed physical exertion before and after testing.

Main Results:

• A trend towards lower muscle strength was observed in JIA patients across tested groups.
• Significant strength deficits were found in knee extension (at 80° knee angle) and bilateral ankle plantarflexion in JIA patients.
• No significant differences in perceived exertion were noted between JIA patients and controls, with both groups reporting increased exertion post-measurement.

Conclusions:

• Children with inactive JIA can exhibit near-normal isometric muscle strength.
• Muscle weakness, especially in knee extensors and ankle plantarflexors, may still be present in JIA.
• The adjustable dynamometer chair is a viable tool for assessing isometric maximal strength in pediatric JIA patients.