Gait Kinematics and Interlimb Symmetry in Individuals with Rett Syndrome Across Age Groups

Individuals with Rett Syndrome (RTT), a rare neurodevelopmental disorder, face significant deficits in bipedal postural control and walking ability. The present cross-sectional study examines whether specific gait parameters exhibit stable or varying patterns with advancing age. Twenty-nine females diagnosed with RTT participated in this study. For analysis, participants were separated into three age groups 2-7-year-olds (n=9), 8-15 year olds (n=9) and 16 years and older (n=11). Participants walked on a treadmill while bilateral sagittal plane flexion angles of the hip, knee, and ankle were captured using a 16-camera motion capture system. Joint angles were processed to calculate joint range of motion (ROM), peak angular velocity, angle-angle diagrams, phase portrait areas and asymmetries. For each variable and age group, grand means and standard deviations were computed. Given the limited sample size per group, a permutation-based one-way ANOVA was used for each variable, joint and side (greater/lesser) separately with Holm-Bonferroni adjusted pairwise comparisons. No statistically significant differences for any joint and limb were found between groups in Range of Motion, Peak Angular Velocity, Phase portrait areas and angle-angle diagrams areas. Waveform-based symmetry indexes revealed that symmetry of the Hip and Knee remained constant across the three age groups. Permutation-based pairwise comparisons indicated a significant difference in Ankle Symmetry index between the 2-7 and >16 age groups (p = 0.01), with younger participants showing higher asymmetry. Although the current sample size is relatively small, this is the first study to use technology-based gait measurements of individual with RTT with such a large overall sample. Our database allowed us explore whether there were systematic changes in gait related to age. Consistent with previous reports of gait kinematics collected from individuals with RTT, inter-subject variability was quite large across the various measures. The large variability, which was generally consistent across our age groups, reinforces the idea that there is not a stereotypical kinematic gait pattern exhibited by those with RTT. It is suggested that future work explore within subject analyses that may provide more insightful information to clinicians and rehabilitation specialists regarding changes in response to interventions designed to improve gait control.