This dissertation aims to quantitatively analyze functional lower- and upper-extremity movement in toddlers born preterm with very-low birth-weight (VLBW). Children born preterm with VLBW have increased risk of motor impairment, and early identification of impairment guides treatment to improve long-term function. Temporal-spatial parameters were quantified and analyzed in the context of neurodevelopment for two functional tasks:​ gait and reaching. 81 VLBW (≤1500 g) preterm (≤32 weeks) and 43 typically-developing (TD) toddlers successfully completed motor assessments at 18-22 months of age, adjusted for prematurity. Neurodevelopment of VLBW preterm participants was assessed with Bayley Scales of Infant Development-3rd Edition (BSID-III) motor composite, gross motor, and fine motor scores.

Temporal-spatial gait parameters are an easily-recorded assessment of lower-extremity grossmotor function. Velocity, cycle time, step width, step length and time asymmetry, %stance, %single-limb support, and %double-limb support were calculated. Mean step width was wider in preterm compared to TD toddlers (p=.009). Preterm toddlers with <85 BSID-III motor composite scores, indicating mild-to-moderate delay, had significantly increased step width, step length asymmetry, and step time compared to TD toddlers. Step time was also significantly longer for lower-scoring compared to higher-scoring (≥85 BSID-III motor composite scores) preterm toddlers, suggesting that step time may be particularly sensitive to gradations of motor performance. Velocity, cycle time, step length asymmetry, %stance, step length, and step time significantly correlated with BSID-III gross motor scores, suggesting that these parameters may be revealing of gross motor function. The differences in gait between lower-scoring preterm toddlers and TD toddlers, together with the correlations between gait and BSID-III motor scores, suggest that temporal-spatial gait parameters may be useful in building a clinically-relevant, easily-conducted assessment of toddler gross motor development.

We aimed to develop a gait index for use in the pediatric clinic as well as research that quantifies gait deviation in 18-22 month-old children:​ the Toddle Temporal-spatial Deviation Index (Toddle TDI). Principle component analysis of TD children’s temporal-spatial gait parameters quantified raw gait deviation from typical, normalized to an average(standard deviation) Toddle TDI score of 100(10), and calculated for all participants. The Toddle TDI was significantly lower for preterm versus TD children (86 vs. 100, p= 0.003), and lower in preterm children with <85 vs. ≥85 BSID-III motor composite scores (66 vs. 89, p= 0.004). The Toddle TDI correlated with BSID-III gross motor (r = 0.50, p <0.001) and not fine motor (r = 0.19, p= 0.09), suggesting sensitivity to gross motor development. The Toddle TDI, which by design plateaus at average (BSID-III gross motor 8-12), correlated more strongly with gross motor scores ≤8 (r = 0.60, p<0.001). The Toddle TDI demonstrated sensitivity and specificity to gross motor function in very-low-birth-weight preterm children aged 18-22 months, and has potential as an easilyadministered, revealing clinical and research gait metric.

Reaching is a well-practiced functional task crucial to daily living activities, and temporal-spatial measures of reaching reflect function for both adult and pediatric populations with upperextremity motor impairments. Inertial sensors offer a mobile and inexpensive tool for clinical assessment of movement. We developed a method for measuring temporal-spatial reach parameters using inertial sensors, and validated the method with traditional marker-based motion capture. 139 reaches from 10 adults and 30 reaches from 9 TD children aged 18-20 months were recorded and analyzed using both inertial sensor and motion capture methods. Inertial sensors contained 3-axis accelerometers, gyroscopes, and magnetometers. Gravitational offset of accelerometer data was measured when the sensor was at rest, and removed using sensor orientation measured at rest and throughout the reach. Velocity was calculated by numeric integration of acceleration, using a null-velocity assumption at reach start. Sensor drift was neglected given the 1-2 seconds required for a reach. Temporal-spatial reach parameters were calculated independently for each data acquisition method. There was strong agreement between sensor and motion-capture results for path length (adults:​ rho=.851, p<.001;​ toddlers:​ r=.832, p<.001), peak velocity magnitude (adults:​ r=.946, p<.001;​ toddlers:​ r=.838, p<.001) and timing (adults:​ r=.984, p<.001;​ toddlers:​ r=.815, p<.001), acceleration at contact (adults:​ rho=.866, p<.001;​ toddlers:​ r=.816, p<.001) and peak acceleration (adults:​ rho=.838, p<.001;​ toddlers:​ rho=.758, p<.001). Ultimately, several reach parameters related to function may be reliably measured with inertial sensors.

Finally, we explored the relationship between toddler temporal-spatial reach parameters measured with inertial sensors and neurodevelopment as assessed with the BSID-III. Temporal-spatial reach parameters are revealing of upper-limb function in children with motor impairments, but had not been quantified in a toddler population. This work quantitatively characterizes temporal-spatial reach in typically-developing (TD) and very-low-birth-weight (VLBW) preterm toddlers. 48 children born VLBW and 22 TD children completed the reaching assessment at 18-22 months of age, adjusted for prematurity. Inertial sensors were fixed to toddlers’ wrists while they reached for a cube. Reach time, path length, velocity at contact, peak velocity magnitude and timing, acceleration at contact, peak acceleration, and number of unnecessary movement units (a measure of reach smoothness) were derived from inertial-sensor and high-speed video data. Reach path length, velocity at contact, peak velocity magnitude and timing, acceleration at contact, peak acceleration, and number of movement units from one were significantly lower for TD compared to preterm toddlers. Among preterm toddlers, decreased reach time (rho=-.306, p=.036, and rho=- .349, p=.016), decreased time to peak velocity (r=-.494, p<.001, and -.390, p=.007), and increased peak acceleration (r=.309, p=.034, and r=.296, p=.043) correlated to increased BSID-III composite and fine motor scores, respectively. Toddlers with below-average fine motor scores had significantly higher peak and contact velocity. Preterm toddlers demonstrated substantial differences in temporal-spatial reach compared to TD toddlers, and evidence indicated several reach parameters were revealing of function and may be useful as a clinical assessment.

Ultimately, quantitative temporal-spatial measures of both gait and reaching were revealing of function in VLBW preterm toddlers at risk for motor impairment, and may be useful for identifying children at risk for motor impairment who would benefit from intervention.