Ko, MS, Brunt, D, Bishop, M, Pathare, N, Choi, BS, Lyons, JM; Departments of Physical therapy and Neurology, University of Florida, Gainesville, FL, USA. mansooko@ufl.edu.

PURPOSE: The purpose of this study is to determine the significant characteristics of persons with Parkinson’s disease that predict the toe-clearance during obstacle crossing. BACKGROUND: Patients with Idiopathic Parkinson Disease (IPD) are exposed to the risk of tripping over an obstacle by their slow movement execution. Tripping may increase their risk for falls. However, the mechanisms, which influence this risk in patients with IPD, have not been thoroughly explored. SUBJECTS: This study sample consisted of 16 participants with IPD who were tested while on medication. Based on the time of swing toe-off during gait initiation, subjects were divided into: Fast group (mean=0.556s) and Slow group (mean=0.963s). METHOD: Two force platforms, embedded in a level walkway (5m in length and 1.22m in width), measured the ground force of stance and swing limb while subjects stepped over a 10cm cubic obstacle. Kinematical toe-clearance data were collected at 100Hz. Subjects stood in a predetermined position with each foot on a force platform and were asked to begin walking in response to a light signal. ANALYSIS: Multiple Regression Analysis was adopted to predict the relationship between toe-clearance and a set of independent variables (peak vertical loading of the swing limb, peak vertical unloading of the stance limb, time to toe off of swing limb, time to peak vertical loading of swing limb, time to peak vertical unloading of stance limb, peak horizontal loading of swing limb, time to peak horizontal loading of swing limb, and acceleration ground force of swing limb, and time of swing toe-off during gait initiation). Fast (n=8) and slow groups (n=8) were separately analyzed, after initial analysis (n=16). RESULTS: Swing limb: the time to toe-off and the acceleration ground force explain 35.8% of the variability in toe-clearance in subjects with IPD (R²=0.358, F=3.628, p>0.05). However, in the fast group, 88.7% of the variance in toe-clearance is explained by the same predictor variables (R²=0.887, F=19.627, p<0.05), whereas these predictors explain only 18.9% of the variability in the slow group (R²=0.189, F=0.589, p>0.05). CONCLUSIONS: Swing limb acceleration ground force and time to toe-off during obstacle crossing are good predictors of toe-clearance in persons with IPD demonstrating a lesser time to initiate gait. However, predicting the toe-clearance in severe hypokinetic persons with IPD is likely to be multifactorial. FUNDING SOURCE: None.

Reprint Information
Requests for reprints should be directed to the corresponding author of the article. Students and other academic customers may receive permission to reprint copyrighted material from Physical Therapy by contacting the Copyright Clearance Center Inc, 222 Rosewood Dr, Danvers, MA 01923. Similar inquiries by all others should be made to the APTA Editorial Office, Attn: Physical Therapy.