Turning is a common trigger for freezing episodes in patients with Parkinson’s disease (PD). Freezing during turning can lead to falls and fractures and decreased quality of life.
Does foot-strike contact variability also increase during turning, as previously reported in straight gait in PD patients with Freezing of Gait (FOG)?
Subjects were instructed to walk on a gait mat, making “normal pivot” (180°) turns at each end. ProtoKinetics Movement Analysis Software (PKMAS) software was used for analysis. Video recordings and foot-pressure-prints were studied to identify and define turn segments. Spatiotemporal gait and turn measures were then determined only for the turn segments. A movement disorders neurologist determined clinical freezes.
100 subjects (28 controls, 38 noFOG and 34 FOG) were included. Compared to non-freezers (noFOG), FOG subjects had a smaller foot-strike during turning (a measure of completeness of foot contact with the mat) and increased foot-strike variability. FOG subjects also had a shorter stride-length, slower stride-velocity, and greater swing phase time and percentage during turns. After adjusting for turn direction, inner/outer leg dynamics showed heavier inner leg footsteps in FOG subjects. 38% of FOG subjects experienced freezes during turning. 69% of freezes occurred during the middle third of the turn. Turn-freezers had more severe spatiotemporal gait deficits.
Developing targeted therapies to retrain subjects to plant their whole foot on the ground with more consistency could help decrease episodes of freezing of gait.

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