Analysis of Reach-to-Grasp by School-Aged Children with Down Syndrome Elucidates Limitations in Upper Extremity Motor Control.

AIMS: To identify limitations in preparatory planning (PP) and movement execution that constrain performance of reach-to-grasp (RTG) movements in school-aged children with Down syndrome (DS) and examine the effect of chronological age (CA) on performance. METHODS: Nine children with DS ages 6 to 12 years and nine with typical development (TD) participated in this pilot descriptive study. Three-dimensional kinematic analysis was applied to RTG movements performed in the context of two functional tasks. RESULTS: PP variables focused on the coordination of reach and grasp. Compared to the group with TD, the group with DS demonstrated significant limitations in anticipatory slowing down of hand transport and orientation of the hand in preparation for object contact. There was also relatively late onset of preparatory grip formation in the group with DS. In regard to movement execution, reach trajectories of the group with DS showed significantly greater deviation from the straight path. Correlations of study variables with CA were low and insignificant in both groups. CONCLUSIONS: Motor control mechanisms that mediate both PP and execution of the fundamental RTG movement are potential factors limiting upper extremity activity in school-aged children with DS. They should be addressed in future intervention-based research.

Kinematic and kinetic analysis of dogs during trotting after amputation of a thoracic limb.

OBJECTIVE: To characterize biomechanical differences in gait between dogs with and without an amputated thoracic limb. ANIMALS: Client-owned dogs (16 thoracic-limb amputee and 24 quadruped [control] dogs). PROCEDURES: Dogs were trotted across 3 in-series force platforms. Spatial kinematic and kinetic data were recorded for each limb during the stance phase. RESULTS: Amputees had significant increases in stance duration and vertical impulse in all limbs, compared with values for control dogs. Weight distribution was significantly increased by 14% on the remaining thoracic limb and by a combined 17% on pelvic limbs in amputees. Braking ground reaction force (GRF) was significantly increased in the remaining thoracic limb and pelvic limb ipsilateral to the amputated limb. The ipsilateral pelvic limb had a significantly increased propulsive GRF. The carpus and ipsilateral hip and stifle joints had significantly greater flexion during the stance phase. The cervicothoracic vertebral region had a significantly increased overall range of motion (ROM) in both the sagittal and horizontal planes. The thoracolumbar vertebral region ROM increased significantly in the sagittal plane but decreased in the horizontal plane. The lumbosacral vertebral region had significantly greater flexion without a change in ROM. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with results for quadruped dogs, the vertebral column, carpus, and ipsilateral hip and stifle joints had significant biomechanical changes after amputation of a thoracic limb. The ipsilateral pelvic limb assumed dual thoracic and pelvic limb roles because the gait of a thoracic limb amputee during trotting appeared to be a mixture of various gait patterns.

Kinematic and kinetic analysis of dogs during trotting after amputation of a pelvic limb.

OBJECTIVE: To evaluate biomechanical gait adaptations in dogs after amputation of a pelvic limb. ANIMALS: Client-owned dogs (12 pelvic limb-amputee and 24 quadruped [control] dogs). PROCEDURES: Dogs were trotted across 3 in-series force platforms. Spatial kinematic and kinetic data were recorded for each limb during the stance phase. RESULTS: Pelvic limb amputees had increased peak braking forces in the contralateral thoracic limb and increased propulsive forces and impulses in both the ipsilateral thoracic limb and remaining pelvic limb. Time to peak braking force was significantly decreased, and time to peak propulsive force was significantly increased in all remaining limbs in amputees. Amputees had an increase in range of motion at the tarsal joint of the remaining pelvic limb, compared with results for the control dogs. Amputees had increased vertebral range of motion at T1 and T13 and increased vertebral extension at L7 within the sagittal plane. In the horizontal plane, amputees had increased lateral bending toward the remaining pelvic limb, which resulted in a laterally deviated gait pattern. CONCLUSIONS AND CLINICAL RELEVANCE: Pelvic limb amputees adjusted to loss of a limb through increased range of motion at the tarsal joint, increased range of motion in the cervicothoracic and thoracolumbar vertebral regions, and extension of the lumbosacral vertebral region, compared with results for the control dogs. Amputees alternated between a laterally deviated gait when the pelvic limb was in propulsion and a regular cranially oriented gait pattern when either forelimb was in propulsion with horizontal rotation around L7.