Should trunk movement or footfall parameters quantify gait asymmetry in chronic stroke patients?

The purpose of this study was to investigate gait asymmetry in chronic stroke patients in comparison with subjects with no known asymmetries. Further, we wanted to decide which gait symmetry parameter has the best ability to discriminate between the two groups. Twenty subjects with hemiplegia (mean age 58 years, S.D.=8 years) and 57 subjects with no known gait asymmetry (mean age 77 years, S.D.=5 years) walked six times along a 7-m walkway at slow, preferred and fast speed. Measures of vertical, anteroposterior, and mediolateral trunk asymmetry were assessed from triaxial accelerometry data. The footfall parameters of single support (% of stride time) and step length (m) asymmetry were assessed from data obtained using an electronic walkway. Vertical (p<0.001), anteroposterior (p=0.01), mediolateral (p=0.01) trunk movement and single support (p=0.03) showed significant differences in asymmetry between the two groups. No difference in step length asymmetry was found between the two groups. Neither single support asymmetry nor step length asymmetry showed the ability to discriminate subjects with hemiplegic gait from subjects in the comparison group. Measures of trunk movement asymmetry, however, were able to discriminate between the two groups (p<or=0.001). The results indicate that trunk movement should be included in the assessment of gait asymmetry in chronic stroke patients.