Lower extremity coordination patterns and muscle contributions in post-stroke gait based on self-selected walking speed classification
Date
2012
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
University of Delaware
Abstract
Every forty seconds someone in the United States has a stroke, which often leads to long term disability. Eighty percent of post-stroke patients suffer from hemiparesis, which is characterized by altered lower extremity kinematics during walking. Post-stroke walking performance has been classified based on self-selected walking speed into three groups, household ambulators: <0.4 m/s; limited community ambulators: 0.4-0.8 m/s; community ambulators: >0.8 m/s. This speed-based classification system stratifies highly variable levels of impairment in post-stroke patients and can be used to discover hip, knee and ankle functional trends within these groups. The objective of this study was to compare hip, knee and ankle motion and function for stroke survivors in each ambulatory classification. Through the use of experimental biomechanics, thirty post-stroke patients underwent a gait analysis session in which kinematics and kinetics were recorded. By assessing hip, knee and ankle function and coordination at terminal stance as well as initial swing we investigated differences in function across community ambulation classifications. During terminal stance, household ambulators displayed sagittal plane knee and ankle angle asymmetries between paretic and non-paretic limbs; however, this was not evident for limited community and community ambulators. During initial swing, many asymmetries and distinctions across speed classifications were present with notable knee-dominated coordination patterns for community but not household ambulators. Using musculoskeletal simulation, we found pronounced paretic dorsiflexion and plantar flexion co-contraction for the slowest ambulators, making walking less efficient since muscle actions are working against each other. Increased hip extension moments in household ambulators revealed hip compensation mechanisms to overcome plantar flexor weakness. Favored hamstring contribution to peak hip extension moment was also noted. Identifying factors that discriminate between functional classification groups is important when targeting rehabilitation interventions to improve walking speed.