Kinematic gait asymmetry assessment using joint angle data in patients with chronic stroke-A normalized cross-correlation approach

Background: Gait asymmetry is an important characteristic often studied in stroke patients. Several methods have been used to define gait asymmetry using joint angles. However, these methods may require normative data from healthy individuals as reference points. This study used normalized cross-correlation (CCnorm) to define kinematic gait asymmetry in individuals after stroke and investigated the usefulness of this assessment. Research question: Is the analysis of kinematic gait asymmetry based on joint angle data using CCnorm useful for gait assessment in patients with chronic stroke? Methods: The study involved 12 patients with chronic stroke. A motion analysis system was used to record gait speed, hip joint angles, knee joint angles, ankle joint angles, stance time, and swing time. The CC(nor)m was calculated using the flexion-extension joint angles of hip, knee, and ankle in the sagittal plane to assess the degree of kinematic gait asymmetry. The symmetry ratio (SR) was calculated using stance and swing times to assess the degree of temporal gait asymmetry. Clinical outcomes were measured using the Fugl-Meyer Assessment for the lower extremity (FMA-LE), Berg Balance Scale (BBS), and Functional Independence Measure (FIM). Results: Hip CCnorm was correlated with SRswing (r=-0.612, p < 0.05). Knee CCnorm was correlated with SRstance (r=0.807, p < 0.01), SRswing (r=-0.752, p < 0.05), gait speed (r=0.654, p < 0.05), BBS (r=0.717, p < 0.01), and FIM (r=0.735, p < 0.01). Significance: Hip and knee joint CCnorm appear to be useful tools for the assessment of gait asymmetry in stroke patients. In addition, kinematic gait asymmetry of the knee joint could reflect physical function, balance, and activities of daily living. These findings underline the importance of using kinematic gait asymmetry assessment in chronic stroke patients.