Biomechanical Analysis of Gait Adaptability in Parkinson's Disease

Parkinson's Disease (PD) subjects are less able to adapt gait to fluctuating motor demands in daily life situations than the healthy elderly, e.g. in crowded places, crossing the road, and starting or stopping at traffic lights. Several studies proved gait abnormalities in PD. However, to our knowledge there is currently no biomechanical test that deals with the ability in gait adaptation. The aim of this study was to develop and evaluate a new biomechanical test which proves the adaptability of gait to fluctuating external conditions. In order to have a reproducible, quantitative gait-test, a treadmill was used, accessed by a special software. The so called adaptability-of-gait test (AOG) changed the treadmill's velocity ballistically and unpredictably for the test subjects. 49 PD-subjects and 10 age-matched controls (HC) participated in the study. In order to subdivide PD subjects in homogeneous groups, we used a cluster analysis. In a first-step of evaluation we focused on differences between PD with moderate (PDM) and severe disease stages (PDS) and HC and examined correlations according to existing, valid tests, e.g. Unified Parkinson Disease Rating Scale (UPDRS) subscales, clinical and biomechanical gait-assessments. Results showed significant differences in gait-adaptation between the groups. Severe PD had a worse gait adaptation compared to PD moderate and HC. Correlation analysis of the PD sample showed significance differences between the AOG-test and bradykinesia and facial expression, but no significances differences according to conventional clinical gait assessments, e.g. Webster gait-test. We conclude that the AOG-test has potentials to identify a new gait performance: the adaptation of gait.