GAIPOS-2481; No of Pages 7 Should trunk movement or footfall parameters quantify gait asymmetry in chronic stroke patients? Caroline Hodt-Billington a, * , Jorunn L. Helbostad b,1 , Rolf Moe-Nilssen a a Section of Physiotherapy Science, Department of Public Health and Primary Health Care, University of Bergen, Kalfarvn 31, 5018 Bergen, Norway b Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway Received 28 August 2006; received in revised form 12 June 2007; accepted 9 July 2007 Abstract 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  0.001). The results indicate that trunk movement should be included in the assessment of gait asymmetry in chronic stroke patients. # 2007 Elsevier B.V. All rights reserved. Keywords: Gait asymmetry; Accelerometer; Trunk movement; Single support; Step length 1. Introduction Previous investigators have suggested gait symmetry as a determinant of recovery in patients with stroke [1,2], lower limb amputation [3], osteoartritis [4], and hip replacement [5], since optimal gait enhances ambulation and encourages participation in activities of daily living. Observational analysis is frequently used in the evalua- tion of gait, but may show significant differences between and within specialties [6]. An objective, validated and sensitive to change gait assessment methodology that identifies disease specific features of gait, is required for the evaluation of gait asymmetries. Hemiplegic gait is characterized by asymmetry [7] and is frequently seen in stroke patients. The movement pattern is diverse [7,8] and the direction of asymmetry may vary [8,9]. Some patients have longer steps or single support phase on the unaffected limb, while others show the opposite pattern. The asymmetries often seen in footfall patterns may also influence upper body movements during gait and are associated with asymmetrical positioning of the trunk and asymmetrical arm swing [10]. Simultaneous assessment of trunk movement and footfall patterns may therefore be required when analyzing asymmetrical gait. Trunk move- ment can be measured by body fixed sensors that are easy to use in clinical settings as well as in the patient’s home environment [11–13]. Footfall parameters can be measured simultaneously using a portable electronic walkway. www.elsevier.com/locate/gaitpost Gait & Posture xxx (2007) xxx–xxx * Corresponding author. Tel.: +47 92 24 30 01. E-mail addresses: caroline.hodt@isf.uib.no (C. Hodt-Billington), jorunn.helbostad@ntnu.no (J.L. Helbostad), rolf.moe-nilssen@isf.uib.no (R. Moe-Nilssen). 1 Department of Geriatric Medicine, St. Olav University Hospital, Olav Kyrresgt, 7006 Trondheim, Norway. 0966-6362/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.gaitpost.2007.07.015 Please cite this article in press as: Hodt-Billington C, et al., Should trunk movement or footfall parameters quantify gait asymmetry in chronic stroke patients?, Gait Posture (2007), doi:10.1016/j.gaitpost.2007.07.015