Dynamic Measures of Balance during Obstacle-Crossing in Self-Selected Gait in Individuals with Mild-to-Moderate Parkinson’s Disease

Individuals with Parkinson’s disease (PD) have postural instability and gait dysfunction that lead to falls and disability with disease progression. Increased fall risk is particularly seen during challenging gait tasks such as obstacle-crossing. The purpose of this study was to determine if there were differences in dynamic postural control during self-paced walking and obstacle-crossing between persons with mild-to-moderate PD and healthy controls. Participants included nine individuals with PD and nine age- and gender-matched controls (CON). This study examined margin of stability metrics using instrumented 3D motion analysis during the two-step sequence of the obstacle-crossing task. Dynamic balance variables and spatiotemporal (ST) parameters at distinct gait events related to the leading (step one) and trailing leg (step two) were compared for the PD and CON groups using a mixed-model ANOVA. No differences were found between groups for ST gait parameters during obstacle-crossing, except for a significantly reduced step length (p = 0.005) for the trailing limb for the PD group. The PD group demonstrated significantly larger mean values for mediolateral center of pressure–center of mass (COP–COM) distance at first double support (p = 0.004) and center of pressure–extrapolated center of mass (COP–XCOM) distance at second double support (p = 0.016) for the second step. Our results suggest that the margin of stability may be useful in discerning postural control adaptations during obstacle negotiation in persons with PD.