Video-based 2D markerless gait analysis in people with multiple sclerosis

Multiple Sclerosis is a neurodegenerative disease frequently associated with gait impairments that can emerge early and progressively worsen, substantially affecting mobility and independence. The Expanded Disability Status Scale (EDSS) is widely used to quantify overall disability in people with multiple sclerosis. However, gait alterations may present as specific spatiotemporal and kinematic changes that are not explicitly described by the EDSS scoring criteria. In this context, quantitative gait analysis can provide complementary information on motor function. This study investigates the feasibility of a markerless, single-camera two-dimensional video-based approach to extract quantitative gait parameters in people with multiple sclerosis and to examine whether these measures scale with overall disability level as indexed by scores on the Expanded Disability Status Scale. Twenty people with multiple sclerosis were recorded while walking at a comfortable pace using a standard video camera. Spatiotemporal parameters and lower-limb elevation angles (thigh, shank, and foot) were extracted using the position of the keypoints obtained with a pose estimation algorithm. Associations between these measures and disability scores were assessed. Results showed a significant reduction in normalized stride length and stride time with increasing disability level. In addition, the range of motion of shank and foot elevation angles exhibited strong associations with disability scores. These findings suggest that the range of motion of lower-limb elevation angles, particularly at distal segments, might provide sensitive indicators of disability-related gait impairment. The proposed two-dimensional video-based method offers a low-cost, non-invasive, and unconstrained tool for objective gait assessment in people with multiple sclerosis.