Alterations in weight-transfer capabilities in adults with hemiparesis

The purposes of this study were (1) to examine the position and displacement in the frontal plane of the body's center of mass (CM) with respect to the base of support during single-leg flexion movements in adults with hemiplegia and (2) to examine their relationship with other clinical scores.

Fourteen ambulatory adult volunteers with hemiparesis of the right side of the body due to cerebrovascular accident participated in the study.

Subjects performed single-leg flexion movements with the paretic and nonparetic limbs while standing on two separate force platforms. Motion analysis and force platform data were used to determine the displacement of the CM.

Successful performance of the transfer and holding single-limb stance occurred for 48% (to the nonparetic side) and 20% (to the paretic side) of the trials. Lack of success was due to insufficient displacement of the CM (26% of the trials to the nonparetic side and 17% of the trials to the paretic side) or a failure to maintain single-limb stance (26% of all trials to the nonparetic side and 63% of the trials to the paretic side). Overall, the final position of the CM with respect to the single-limb support region did not differ between sides. Successful performance was highly to moderately associated with clinical assessment scores for motor function and balance. Its association with gait velocity, however, was poor.

A classification scheme that can distinguish between four categories of bipedal to single-limb stance transitions has been established. Issues concerning clinical assumptions pertaining to the relationship between static and dynamic motor dysfunction in adults with hemiparesis are discussed.