Cyclograms Reveal Alteration of Inter-Joint Coordination during Gait in People with Multiple Sclerosis Minimally Disabled

Subtle alterations of gait patterns in people with Multiple Sclerosis (pwMS) with minimal or no disability often coexist with normal spatio-temporal parameters. Here, we retrospectively in- vestigate the existence of possible anomalies in lower limb inter-joint coordination (i.e., the functional relationship between joint pairs) in pwMS with apparently physiologic gait features. Twenty-seven pwMS with Expanded Disability Status Scale scores  2, and 27 unaffected age-and-sex-matched individuals, were tested using 3D computerized gait analysis. Raw data were processed to extract the main spatio-temporal parameters and the kinematics in the sagittal plane at the hip, knee, and ankle joints. Angle-angle diagrams (cyclograms) were obtained by coupling the flexion-extension values for the hip-knee and knee-ankle joint pairs at each point of the gait cycle. Cyclogram area, perimeter, and dimensionless ratio were employed to quantify inter-joint coordination. The results demonstrate that cyclograms of pwMS are characterized by significantly reduced perimeters for both investigated joint pairs and reduced area at the hip–knee joint pair. In the latter pair, the differences between groups involved the entire swing phase. For the knee-ankle pair, the average cyclogram of pwMS departed from normality from the late stance until the mid-swing phase. Such findings suggest that inter-joint coordination is impaired even in minimally disabled pwMS who exhibit a normal gait pattern in terms of spatio-temporal parameters. The quantitative and qualitative study of cyclogram features may provide information that is useful for better understanding the underlying mechanisms of walking dysfunctions in MS.