| A number of neuropathologies such as Duchenne's muscular dystrophy (DMD), cause disability in the upper extremity due to the loss of muscle strength. This will eventually prevent the individual from being able to move their arm in three-dimensional space so it has been proposed that a robotic orthosis could support and augment movement. This orthosis would need to accommodate the movement capabilities of the user. To accomplish this knowledge of how movements are formed and controlled in the presence of neuromuscular disease need to be determined. For this reason, the formation and control of pointing movements in the horizontal plane made by subjects with DMD are examined.; While the arm was supported in a floatation device, DMD subjects were asked to make pointing movements to various targets from two start positions with trunk movement constrained and unconstrained. The trajectories formed in DMD had essentially straight hand paths that did not necessarily improve with the additional degrees of freedom trunk movement allowed. There is evidence that a hierarchy exists in the kinematic parameters based on the extent of degradation in each feature. The hand paths remain essentially straight at a cost to the other variables, hand velocity profiles improve in modality from constrained to unconstrained configuration, and there is little to no improvement in measures of hand path straightness or the linearity of the joint angular velocity ratio between configurations. The linearity of the joint angular velocity ratio was found to decay at a linear rate related to manual muscle tests. |
