Ankle Movements During Supine Kicking in Infants Born Preterm.

BACKGROUND: Knowledge of musculoskeletal factors that influence supine kicking of infants born preterm has implications for early intervention.

HYPOTHESES: Differences exist between infants born preterm and full-term in ankle kinematics during supine kicking, which are attributable to passive measures of the gastrocnemius/soleus (g/s) muscle tendon unit (MTU).

SUBJECTS: Twenty infants born full-term and 22 born preterm were measured at term, 6 weeks, and 12 weeks of age.

OUTCOME MEASURES: Ankle kinematics during supine kicking and g/s MTU length.

RESULTS: Infants born preterm demonstrated less dorsiflexion, more plantar flexion, and more total ankle range during supine kicking. Gestational age explained 69% to 85% of the variability in MTU length from term to 12 weeks of age. MTU lengths explained 0% to 42% of the variance in ankle kinematics.

CONCLUSIONS: Passive measures of the g/s MTU may inform clinicians about ankle kinematics in newborns to 12-week infants during supine kicking.