Inter-tester Reliability and Precision of Manual Muscle Testing and Hand-held Dynamometry in Lower Limb Muscles of Children with Spina Bifida

Reliability and measurement precision of manual muscle testing (MMT) and hand-held dynamometry (HHD) were compared for children with spina bifida. Strength measures were obtained of the hip flexors, hip abductors, and knee extensors of 20 children (10 males, 10 females; mean age 9 years 10 months; range: 5 to 15 years) by two experienced physical therapists and a student physical therapist. Inter-tester reliability [ICC(2,1)] for HHD varied from 0.76 to 0.83, indicating excellent reliability for the three muscle groups. Inter-tester reliability for MMT was 0.75 for the hip abductor muscle group, indicating good reliability, and 0.37 to 0.40 for the remaining muscle groups. The minimum detectable change was 15N for HHD and 1 scale unit of a 0 to 5 MMT scale. The results suggest a situation-specific solution to the question of which method to use. To detect small strength changes over time in children with spina bifida, MMT should be used when the child has insufficient strength to move the limb against gravity; otherwise, HHD should be used.