Gait characteristics in children with Duchenne Muscular Dystrophy during the last 2 years of free ambulation (Preprint)

BACKGROUND Duchenne Muscular Dystrophy (DMD), the most common neuromuscular disease in children, is a severe, progressive disease that affects skeletal muscle. Abnormal gait patterns in children with DMD result from compensatory adaptations of their locomotor system to maintain free ambulation in response to the slow, progressive muscle weakness, contractures and osteoarticular changes caused by the disease. Identification of gait abnormalities can be challenging because current understanding of how gait patterns changes progressively in children with DMD is limited. 3D gait analysis could thus increase understanding about the effects of the disease on gait, guide treatments and help to predict key milestones, such as ambulation loss. This latter event is important because it is an endpoint for clinical trials and studies of DMD disease progression. OBJECTIVE The primary aim of this study was to analyze the gait characteristics of children with Duchenne Muscular Dystrophy (DMD) during their last 2 years of free ambulation. The secondary aim was to explore the capacity of gait variables to predict the time of loss of ambulation. METHODS The gait of eighteen children with DMD and fourteen age-matched control children was recorded using a 3D optoelectronic system. Statistical parametric mapping was used to compare kinematic and kinetic variables between groups. Multivariate regression was used to identify predictors of the time of ambulation loss among spatiotemporal, kinematic and kinetic variables. RESULTS Compared with the controls, anterior pelvic tilt was increased during the whole gait cycle, hip flexion was increased during the second part of stance phase and of the entire swing, knee flexion was increased during swing, dorsiflexion was reduced during stance, and plantar flexion occurred in swing in the DMD group. Maximal ground reaction force, ankle dorsiflexion moment at initial contact, knee power absorption and generation during loading response, and maximal power generation of the hip at the end of stance were all reduced. A combination of gait variables, mostly kinetic, predicted the duration before ambulation loss to be less than three months. CONCLUSIONS The gait of children with DMD who are close to losing ambulation is characterized by specific deviations. The time of ambulation loss was accurately predicted by 3D gait variables, particularly kinetic. Combined with data from the clinical examination, 3D gait analysis provides valuable information to guide physical therapy, including targeted muscle strengthening and stretching, to help patients maintain free ambulation as long as possible.