Gait analysis of myopathic children in relation to impairment level and energy cost

The electromyographic and kinematic patterns of gait and its energy cost were studied in 12 myopathic patients who were still walking and 12 normal subjects. On the basis of significant gait variables, three distinct levels of impairment were defined in the group of myopathic subjects: early, intermediate and final. These clusterings were predicted with 95.7% accuracy by two gait variables: the stance phase duration and the heel vertical excursion. The gait patterns of each group were compared to the control group. Reduced speed and range of motion, short stride length, small foot-floor clearance, increased energy cost and lateral displacements of centre of gravity were typical and increased with the muscular weakness. The activation of soleus muscle occurred progressively earlier as did the cessation of tibialis anterior activity. In severe disorders, there was increased activity in the muscles acting on the hip and knee. When muscular dystrophy leads to more disability the myopathic patients tended to change from the normal plantigrade gait pattern to an infantile digitigrade-like pattern with a decrease of the tibialis anterior muscle work.