Associations of Supported Treadmill Stepping With Walking Attainment in Preterm and Full-Term Infants

Abstract

Treadmill training in supported stepping has been used as part of rehabilitation programs for children with neurodevelopmental problems to facilitate earlier onset of walking. However, information concerning the developmental continuity between supported stepping and walking is limited. The aims of this study were to longitudinally examine supported stepping in preterm and full-term infants and to explore the step parameters associated with walking attainment. A cohort study with a longitudinal follow-up design was used. Twenty-nine preterm infants and 20 full-term infants were examined bimonthly with supported stepping on a treadmill from 7 months of age until walking attainment or 18 months of corrected age. The associations between step variables and walking outcome were examined using Cox proportional hazard regression and logistic regression. Walking attainment for preterm infants was later than for full-term infants (median = 12.8 versus 11 months, respectively). The percentage of alternating steps, hip-knee correlation, hip-ankle correlation, and asymmetry ratio (AR) of stance time of stepping movement from 7 to 9 months of corrected age were found to be associated with age of walking attainment in all infants. Manifestation of at least 3 of 4 step features (ie, > or = 80% alternating steps, < or = .37 hip-knee correlation, > or = .73 hip-ankle correlation, and < or = 1.40 AR of stance time) at 7 months predicted walking attainment prior to 11 months of corrected age (accuracy = 75%-77%). Failure to achieve such competencies at 7 or 9 months of corrected age was predictive of failure in walking attainment by 15 months (accuracy = 72%-98%). Limitations The limitations of this study included a small sample size and commencement of stepping assessment as early as 7 months of corrected age. The emergence of walking may involve cooperation of alternating pattern generation, interjoint coordination, and interlimb coordination in supported stepping in preterm and full-term infants. The identified step predictors may assist clinicians in designing appropriate treadmill training programs for those infants with delayed walking.